LT5 ECM Tuning thread

[ShawnZR-1]

Most of you saw my thread on the "other forum" about IAC counts. It started to turn into more of a general tuning thread. The best (or worst) thing I got out of it was that nobody really has a consolidated summary of the code for the LT5's ECM's.

In my free time :rolleyes: I'm going to start to delve deeper into the inner workings of the code for my '91. I don't expect this to take a weekend... it could quite possibly take a couple! :D

What I'd ask is if you have information, tips, tricks, trials, tribulations, or any advice, post up! I would love to gather as much information as the LT1 guys have wrung out of their ECMs :pray
:handshak:

[tpepmeie]

The best (or worst) thing I got out of it was that nobody really has a consolidated summary of the code for the LT5's ECM's.

Really? I think at least a couple people have done this. As I have said before, I have the whole code commented in a working assembly file. I have this for each production year. The effort was in the hundreds of hours.

Having said that, I am more than happy to contribute to this thread and answer anybody's questions that I can. If I don't know the answer, I'll look it up in the code.

What I have seen a lot are questions like "...such and such isn't in TunerCat...where is it located so I can add it to my definition?..." I don't think it is productive to just give that stuff away. First of all, it's different in different model years, and second it can be dangerous if the person doesn't understand what "such and such" does.

Now if a person says, "I'd like to change this parameter to solve this problem, and I think it is located at 0x??. Is that right?" I'll definitely help confirm what you have found.

I'd love to get a four or five page thread going on this, so post away and I'll contribute what I can.

PS. Have you reviewed this? http://www.zr1netregistry.com/PromTuning.ppt

Todd
93 #411

[XfireZ51]

Most of you saw my thread on the "other forum" about IAC counts. It started to turn into more of a general tuning thread. The best (or worst) thing I got out of it was that nobody really has a consolidated summary of the code for the LT5's ECM's.

In my free time :rolleyes: I'm going to start to delve deeper into the inner workings of the code for my '91. I don't expect this to take a weekend... it could quite possibly take a couple! :D

What I'd ask is if you have information, tips, tricks, trials, tribulations, or any advice, post up! I would love to gather as much information as the LT1 guys have wrung out of their ECMs :pray
:handshak:

Shawn,

There's already definitions($8E, $AF, and $D0, along with the "A" versions for each) for the 90-92 ECMs that I have from Tunerpro. Some of the work has already been done. Unfortunately, they're pretty bare bones, nothing like what Todd has available. We might be able to pick up some additional items by going through the corresponding Tunercat .tdfs and merging the two into a single def file.

[tpepmeie]

I think the available Tunerpro definitions were made from .tdfs, so they will be very very similar, if not identical.

[We Gone]

Shawn good to see you post this over here :thumbsup: we need to hook up...

Steve

[bradslt5]

shawn , dont mean to hijack the thread , did you like the results of taking the secondaries out . and did you have to redo your prom

[ShawnZR-1]

Really? I think at least a couple people have done this. As I have said before, I have the whole code commented in a working assembly file. I have this for each production year. The effort was in the hundreds of hours.


Todd
93 #411
Yeah, I misspoke, I know that it had been done but I should have said it wasn't widely available as some of the other ECM code is.

In that you have the in depth knowledge, here is one of my dilemmas that has pushed me into the wonderful world of ECM programing:
I have a PIA surge when I'm coasting down in neutral or clutch in. As I come to a stop, the idle drops very low and sometimes actually stalls the engine. From what I have gathered, it may be related to the IAC follower portion of the code, however, there are no parameters for that in either TunerCat or TunerPro.

I played with the DFCO parameters but ultimately simply disabled it entirely to get rid of the popping in the exhaust (and a nasty surge on decel).

IIRC, it started happening sometime after installing my headers. I can't be absolutely sure though. I also have a Fidenza flywheel so the rotating inertia is obviously less than it was stock.

This is just the beginning of my unraveling of the inner workings of the code. I'm sure I will have even more questions....

[ShawnZR-1]

shawn , dont mean to hijack the thread , did you like the results of taking the secondaries out . and did you have to redo your prom

Yes, I'd remove them again in a heartbeat! A couple of things had to be ironed out in the prom but I think I'm about 90% of the way to optimization now. It's smooth as silk from idle all the way to 7200RPM!

My plan is to hit the dyno with a wideband in the next month and play. I am pretty sure I'm running rich but I don't want to pull fuel without making sure I'm staying safe.

[tpepmeie]

I have a PIA surge when I'm coasting down in neutral or clutch in. As I come to a stop, the idle drops very low and sometimes actually stalls the engine. From what I have gathered, it may be related to the IAC follower portion of the code, however, there are no parameters for that in either TunerCat or TunerPro.

In my experience, this is not throttle follower related. What are the IAC counts doing during this surge? The throttle follower routine opens quickly as the throttle is opened, and decays slowly once the delta TPS stops increasing. It would almost certainly be decayed out in the coast down scenario you described.

I have found the consequence of getting too aggressive with the decay rates. What typically will happen is that on a very quick stop, when the clutch is dipped, the revs will drop too fast and the car can stall. IF the throttle blades are adjusted to high single digits at idle, that is usually enough airflow to avoid the stall.

curious, does this situation occur with the stock calibration, or just with a modified one?

Do you have a data recording of this event occurring?

Todd

[-=Jeff=-]

Does the LT5 ECM ( 1990 specifically for me) have any exrta inputs?

on my 89 with 1991 ECM and dash I use an extra input to feed my WBO2 voltage into the ECM and then using info from Craig Moates on Thirdgen I was able to send the data from that extra input to the ALDL stream in place of Battery voltage or such so I could correlate the WB with the ALDL Data

Can this be done with the LT5?

[XfireZ51]

Yeah, I misspoke, I know that it had been done but I should have said it wasn't widely available as some of the other ECM code is.

In that you have the in depth knowledge, here is one of my dilemmas that has pushed me into the wonderful world of ECM programing:
I have a PIA surge when I'm coasting down in neutral or clutch in. As I come to a stop, the idle drops very low and sometimes actually stalls the engine. From what I have gathered, it may be related to the IAC follower portion of the code, however, there are no parameters for that in either TunerCat or TunerPro.

I played with the DFCO parameters but ultimately simply disabled it entirely to get rid of the popping in the exhaust (and a nasty surge on decel).

IIRC, it started happening sometime after installing my headers. I can't be absolutely sure though. I also have a Fidenza flywheel so the rotating inertia is obviously less than it was stock.

This is just the beginning of my unraveling of the inner workings of the code. I'm sure I will have even more questions....

Shawn,

Maybe Todd can tell us where the Prop Gain tables are for the $AFA, $AF Mask ID. If you're getting a surge, it may be due to too high a Prop Gain. That could also explain the popping exhaust on decel. You'll want to start by lowering the Prop Gain in the <16gm/sec cell.
I'd agree with Todd that you'll want to check the #of steps at DFCO and not drop the IAC steps too quickly. Had same issue with my old 84. At some rpm points in DFCO, I'd push in clutch and motor would go dead.

Whadya think Todd, would that help?

[ShawnZR-1]

In my experience, this is not throttle follower related. What are the IAC counts doing during this surge? The throttle follower routine opens quickly as the throttle is opened, and decays slowly once the delta TPS stops increasing. It would almost certainly be decayed out in the coast down scenario you described.

I have found the consequence of getting too aggressive with the decay rates. What typically will happen is that on a very quick stop, when the clutch is dipped, the revs will drop too fast and the car can stall. IF the throttle blades are adjusted to high single digits at idle, that is usually enough airflow to avoid the stall.

curious, does this situation occur with the stock calibration, or just with a modified one?

Do you have a data recording of this event occurring?

Todd

This seems to occur with both the stock and modified. With the stock one however, it seems worse. I can't say for sure since I am unable to test back to back easily.

My IAC counts are well into the double digits at idle (15 or so). I honestly can't remember what they are during the surge. I'm assuming they run pretty low when it surges.

Question: Why does it only do it until the speed goes below a certain MPH? It seems to settle down around 5 MPH and if I blip the throttle when I'm not moving, the idle drops like a rock right to the set idle RPM and doesn't dip at all.

[ShawnZR-1]

Shawn,

Maybe Todd can tell us where the Prop Gain tables are for the $AFA, $AF Mask ID. If you're getting a surge, it may be due to too high a Prop Gain. That could also explain the popping exhaust on decel. You'll want to start by lowering the Prop Gain in the <16gm/sec cell.
I'd agree with Todd that you'll want to check the #of steps at DFCO and not drop the IAC steps too quickly. Had same issue with my old 84. At some rpm points in DFCO, I'd push in clutch and motor would go dead.

Whadya think Todd, would that help?


I have the DFCO completely disabled.

I don't see any Prop Gain table, is it one of the ones that never made it into the masks?

[XfireZ51]

I have the DFCO completely disabled.

I don't see any Prop Gain table, is it one of the ones that never made it into the masks?

Right. That's why I asked. Is the exhaust popping with DFCO disabled? Is the motor dying with DFCO disabled?

[tpepmeie]

Question: Why does it only do it until the speed goes below a certain MPH? It seems to settle down around 5 MPH and if I blip the throttle when I'm not moving, the idle drops like a rock right to the set idle RPM and doesn't dip at all.

The idle air PID control takes over at 5 mph to control the idle speed.

While it is tempting to go in and start changing the calibration, such as has been suggested here, I honestly don't think that is the solution. GM didn't miss the tune on 6000 cars, and they all don't surge. Some things to check...

1) if the condition exists only with the modified cal, is the spark advance smooth in the region of low load, low rpm? Has the closed throttle advance been increased?

2) check the MAP hose for contamination. When I had this condition, the MAP reading at coast down was fluctuating wildly, and causing the surge.

3) if you still suspect the IAC movement is responsible, try to reset the IAC motor as outlined in the service manual.

Todd

[rkreigh]

Hi todd,

I have a question, I had the secondaries removed and unfortunately VA has cut the HC standard down to 48. it's made it impossible to pass.

car does have cats (random ss, probably not nearly as good as stock) and I haven't yet had a wideband to see how rich the car is running but it seems WAY rich at light throttle.

I need some help to tune the car to pass emissions. marc is a bit too far away in chicago. I do have EASE, and I could install a wideband or take the car to a shop with a dyno.

the car is an LPE 390 and has the big 234 cams. do you think there is ANY way I can get this car to pass??? I tried doctoring the gas with alchy a few years back when I had the LPE chip in the car (open loop). it was even more rich and I could get the HC down to about 97 running 2/3 alchy, but I don't think that will work anymore, when I last tried the "cocktail" it still was up to 150 HC and I couldn't get the car to run with as much alchy in the gas. I love the ZR-1, but this is a problem

any ideas (besides moving) :mrgreen:

[XfireZ51]

Shawn,

I did a search on ThirdGen regarding surging decel. This was in a thread that deals with another ECM, the EBL. I won't go into what ot is but I used it for almost 2 years. Outstanding piece of work by RBob. That ECM in combination with Moates OStrich and Tunerpro RT really changed tuning.

So here's RBob's advice:

"'Option word 3 - bit 5 - OpDcl' is probably set. This will put the ECM in open loop fueling during decel. Once un-set, you may experience surging during decel. If so it may be either the proportional gain at the gms/sec airflow is too high. Or the ECM is switching in and out of async fuel mode.

DFCO, to enter this the vehicle speed needs to be above the MPH parameters, and the RPM above the RPM parameters. This is usually for highway speeds on a thottle lift. Keeps the CAT(s) from melting.

RBob."

Here's the link to that thread.
http://www.thirdgen.org/techboard/diy-prom/441703-ebl-decelaration.html?highlight=surging+decel

Granted EBL code is not the same as our LT-5 stuff but I think you'll find that the controls do pretty much the same thing. Its just that RBob has provided an .xdf which makes all those paramters available to the tuner along with a bunch of tuning aids.
I agree with Todd that first and foremost you make sure everything is "mechanically" correct before turning to the tune.
As a side note, if any of you don't know RBob, he is one of the more highly knowledgeable sources over at 3rd Gen. Heck of a nice guy too. I keep begging him to build a version of EBL for our LT5s. :sign10:

[bradslt5]

Hi todd,

I have a question, I had the secondaries removed and unfortunately VA has cut the HC standard down to 48. it's made it impossible to pass.

car does have cats (random ss, probably not nearly as good as stock) and I haven't yet had a wideband to see how rich the car is running but it seems WAY rich at light throttle.

I need some help to tune the car to pass emissions. marc is a bit too far away in chicago. I do have EASE, and I could install a wideband or take the car to a shop with a dyno.

the car is an LPE 390 and has the big 234 cams. do you think there is ANY way I can get this car to pass??? I tried doctoring the gas with alchy a few years back when I had the LPE chip in the car (open loop). it was even more rich and I could get the HC down to about 97 running 2/3 alchy, but I don't think that will work anymore, when I last tried the "cocktail" it still was up to 150 HC and I couldn't get the car to run with as much alchy in the gas. I love the ZR-1, but this is a problem

any ideas (besides moving) :mrgreen:I wonder if corey could burn a couple of different tunes for you to try. he has alot of different tunes in his files. just a thought

[XfireZ51]

Hi todd,

I have a question, I had the secondaries removed and unfortunately VA has cut the HC standard down to 48. it's made it impossible to pass.

car does have cats (random ss, probably not nearly as good as stock) and I haven't yet had a wideband to see how rich the car is running but it seems WAY rich at light throttle.

I need some help to tune the car to pass emissions. marc is a bit too far away in chicago. I do have EASE, and I could install a wideband or take the car to a shop with a dyno.

the car is an LPE 390 and has the big 234 cams. do you think there is ANY way I can get this car to pass??? I tried doctoring the gas with alchy a few years back when I had the LPE chip in the car (open loop). it was even more rich and I could get the HC down to about 97 running 2/3 alchy, but I don't think that will work anymore, when I last tried the "cocktail" it still was up to 150 HC and I couldn't get the car to run with as much alchy in the gas. I love the ZR-1, but this is a problem

any ideas (besides moving) :mrgreen:


RK,

I would definitely put a WB on it. Is the issue you're having at idle or all through the rpm band?

[ShawnZR-1]

Right. That's why I asked. Is the exhaust popping with DFCO disabled? Is the motor dying with DFCO disabled?
No, there's no popping with DFCO disabled. Well, there's kind of a burble on decel but with DFCO set to stock, there was a nasty surge and POP as it decelerated down the RPM band. VERY annoying to say the least! The car is almost undrivable with the stock chip.

[ShawnZR-1]

Hi todd,

I have a question, I had the secondaries removed and unfortunately VA has cut the HC standard down to 48. it's made it impossible to pass.

car does have cats (random ss, probably not nearly as good as stock) and I haven't yet had a wideband to see how rich the car is running but it seems WAY rich at light throttle.

I need some help to tune the car to pass emissions. marc is a bit too far away in chicago. I do have EASE, and I could install a wideband or take the car to a shop with a dyno.

the car is an LPE 390 and has the big 234 cams. do you think there is ANY way I can get this car to pass??? I tried doctoring the gas with alchy a few years back when I had the LPE chip in the car (open loop). it was even more rich and I could get the HC down to about 97 running 2/3 alchy, but I don't think that will work anymore, when I last tried the "cocktail" it still was up to 150 HC and I couldn't get the car to run with as much alchy in the gas. I love the ZR-1, but this is a problem

any ideas (besides moving) :mrgreen:
Well, to go along with the "Check Mechanical" before tune, I would pull the plugs and get a read on them. You'll be able to see if they are running rich.

High HC is usually a symptom of incomplete combustion. It's possible the spark is advanced too far or your plugs are fouled.

What kind of test does VA perform? Is it a two-speed, dual load or just an idle test?

[tpepmeie]

any ideas (besides moving) :mrgreen:

Ron, it'll never, ever pass. You'll have to get rid of it... just sell it to me, and that will solve your problem. :mrgreen:

Seriously, though, I'm not sure I have many good ideas in this case Especially from afar. you might have to bring somebody in to tune it in person. Is the VA test dynamic ie., on the rollers or just idle?

There are various tricks always mentioned, but I've never tried any of them (fortunately my state doesn't require testing). Dom is right, if it's been done, you'll find it on ThirdGen.Org DIY-PROM board. I just don't have any answers off the top of my head.

Good luck.

Todd

[XfireZ51]

No, there's no popping with DFCO disabled. Well, there's kind of a burble on decel but with DFCO set to stock, there was a nasty surge and POP as it decelerated down the RPM band. VERY annoying to say the least! The car is almost undrivable with the stock chip.

Sort of sounds like what RBob was describing. Can you do a bin compare between stock and modified and see what if any difference there is?
Do you have a scan of the motor when its doing this?



RK,

As for your issue, my "suspicion" is the cam overlap. Particularly at low rpm. I am going to stress the word SUSPICION. I don't want to do a Bill Frist on your Z from hundreds of miles away.:sign10:
Again, is your problem primarily at lower rpm and idle? I'm guessing it probably is if its on one of those IM240 EPA Test dyno cycles.

[rkreigh]

yes it's the IM240, they test at 15 and 25 mph

with the cam overlap it's going to be pretty tough at these standards

I need someone who can tune on the emissions machine which has proved hard to do.

I know the car is currently running rich, and hopefully leaning it out will help but I doubt I can get it down that low.

thanks for the advice

[XfireZ51]

rk,

Any idea what the O2 is reading at idle? Does it show lean? What about the BLMs?

[ShawnZR-1]

yes it's the IM240, they test at 15 and 25 mph

with the cam overlap it's going to be pretty tough at these standards

I need someone who can tune on the emissions machine which has proved hard to do.

I know the car is currently running rich, and hopefully leaning it out will help but I doubt I can get it down that low.

thanks for the advice
What are the numbers? Reading/limit ?

[tpepmeie]

Shawn,

Maybe Todd can tell us where the Prop Gain tables are for the $AFA, $AF Mask ID. Whadya think Todd, would that help?

Dom, Proportional Gains tables are below...Some of the formatting got messed when I pasted, but it should get you going.


ORG $86D8
************************************************** **********
** F6EEC TABLE
** BASE PROPORTIONAL STEP SIZE VS. CLFLOW
**
** TABLE VALUE = COUNTS
************************************************** **********
F6EECC FCB 9 9 'CTS' 0 AIRFLOW
FCB 24 24 16
FCB 24 24 32
FCB 24 24 48
FCB 24 24 64
;
************************************************** **********
** F9EEC TABLE
** PROPORTIONAL STEP GAIN VS. O2 ERROR COUNTS
**
** TABLE VALUE = MULTIPLIER * 256
************************************************** **********
F9EECC FCB 64 0.251 'MULT' 0 O2 ERROR
FCB 64 0.251 8
FCB 64 0.251 16
FCB 64 0.251 24
FCB 70 0.2745 32
FCB 72 0.2824 40
FCB 88 0.3451 48
FCB 96 0.3765 56
FCB 104 0.4078 64
FCB 112 0.4392 72
FCB 120 0.4706 80
FCB 120 0.4706 88



Todd

[XfireZ51]

Dom, Proportional Gains tables are below...Some of the formatting got messed when I pasted, but it should get you going.


ORG $86D8
************************************************** **********
** F6EEC TABLE
** BASE PROPORTIONAL STEP SIZE VS. CLFLOW
**
** TABLE VALUE = COUNTS
************************************************** **********
F6EECC FCB 9 9 'CTS' 0 AIRFLOW
FCB 24 24 16
FCB 24 24 32
FCB 24 24 48
FCB 24 24 64
;
************************************************** **********
** F9EEC TABLE
** PROPORTIONAL STEP GAIN VS. O2 ERROR COUNTS
**
** TABLE VALUE = MULTIPLIER * 256
************************************************** **********
F9EECC FCB 64 0.251 'MULT' 0 O2 ERROR
FCB 64 0.251 8
FCB 64 0.251 16
FCB 64 0.251 24
FCB 70 0.2745 32
FCB 72 0.2824 40
FCB 88 0.3451 48
FCB 96 0.3765 56
FCB 104 0.4078 64
FCB 112 0.4392 72
FCB 120 0.4706 80
FCB 120 0.4706 88



Todd

Thanks Todd. I was able to create items in the AFA and AF .xdf
For RK's issue, I'm wondering if we couldn't modify the O2 swing points because of his bigger cams, particularly at low airflow. Would you confirm for me that the addresses for these items in $D0A mask are the same or not?

[Pete]

yes it's the IM240, they test at 15 and 25 mph

with the cam overlap it's going to be pretty tough at these standards

I need someone who can tune on the emissions machine which has proved hard to do.

I know the car is currently running rich, and hopefully leaning it out will help but I doubt I can get it down that low.

thanks for the advice


Ron, we had the same test here in Illinois what we would do on big cams install an air pump and pump fresh air in the exhaust lots of it and alchy.
Heck connect 2 leaf blowers if you have to :)

What i use to do with my Z i had Show Car insurance 2500 miles a year or less which was legal in IL got waiver from Emmisions.

Now Illinois is done testing OBD1 cars.

Pete

[Tyler Townsley]

Dom, Proportional Gains tables are below...Some of the formatting got messed when I pasted, but it should get you going.
Todd

Damn that looks familiar. He he.

Before tearing the calibration apart get a WB, log the O2s vs other perameters and post the log. That is the way we do it on the Megasquirt forum and it has proven to be the best way to get informative help. If I read the earlier part of this post its present in both stock and moded cal. That tells me its something else. From what i read I can't tell if its a too rich or lean.

Yes the calibration can be changed to allow O2 info to be reported in the ALDL stream and its simular to what was reported on the other forum.

Ron I am pretty sure you could get an emissions only calibration tha would pass. PM me later in the week for some thoughts, I am at the NCRS meet this weekend and am rather busy trying to make it happen

Tyler

[tpepmeie]

Look who's come out of lurker mode. How the heck are you Tyler? Figured you would join this thread eventually.

Dominic, what I posted was for the BFXB calibration. Ron has a '93 (?), so obviously the tables are not at the same address. Not hard to find, though.

Let's get some talk going about how or why things work in the LT5 calibration, rather than just table addresses.

Todd

[Tyler Townsley]

Look who's come out of lurker mode. How the heck are you Tyler? Figured you would join this thread eventually.

Dominic, what I posted was for the BFXB calibration. Ron has a '93 (?), so obviously the tables are not at the same address. Not hard to find, though.

Let's get some talk going about how or why things work in the LT5 calibration, rather than just table addresses.

Todd

Been a little busy.

http://www.ncrsfl.org/Events/30thRegional/30thRegional.htm

OK. Something to think about. Just what do the spark tables do and how can manuliptating them solve Rons problem?

Off to the Lions Den for awhile.

Tyler

[XfireZ51]

Todd,

I thought the $D0A Mask was for the 92 which is what I was asking about. Are you saying that the code varies by broadcast code?
I was curious about the Prop Gains for Shawn's issue since he was complaining about a decl surge.
If Ron's problem isn't mechanical, I would look at lowering the O2 sensor R/L voltages. I'll be glad to discuss why I think this may help as an exercise for the members of this forum.
I would also suggest that if the members here are interested in reading material there are several good writeups available on 3rd Gen dealing with tuning in general, PID Controls, and the function of various IAC parameters.

Jeff,

I had previously asked Todd about inserting the WB data into the ALDL datastream. He brought up 2 very good points however for keeping it separate:

1. The ECM only sends data up to 6300rpm

2. My ZT-2 WB captures 35frames/sec, a data rate about 2x as much as the ECM. At WOT having that additional data makes tuning more accurate. The ECM data will "lose" significant portions of the scan even below 6300rpm.

So tapping into MAP and RPM outputs for the WB scantool would be the better way to go IMO.

[-=Jeff=-]

While I agree the ZT-2 datalogging would be better since thereis no RPM limit and the speed is faster, having it being able to connect to the ECm and show up in the ALDL datastream would be nice if you are using it to troubleshoot problems, it helps to keep the W data correlated witht he BLM / INT especially when doing part throttle tuning (where you typically are MOST of the time). Even though I have my Z now it does not mean I am going to do WOT blasts form everystop light.. just 1/2 of them :sign10:

[tpepmeie]

Yes, table addresses can vary by broadcast code (but are generally the same for a given Mask ID.).

I wasn't sure which problem we were trying to solve: 1) surging on decel w/ stock and modified chip, 2) passing emissions with highly modified LT5 w/ big cams.

$D0 is different than $AF in some areas, though I don't recall if these tables are in same place. Will have to check.

Todd

[Pete]

OK. Something to think about. Just what do the spark tables do and how can manuliptating them solve Rons problem?

Off to the Lions Den for awhile.

Tyler


Freaking computer geeks but still haven't answered this question.

Pete

[-=Jeff=-]

Freaking computer geeks but still haven't answered this question.

Pete

That is because we were waiting for you :-D

[XfireZ51]

Been a little busy.

http://www.ncrsfl.org/Events/30thRegional/30thRegional.htm

OK. Something to think about. Just what do the spark tables do and how can manuliptating them solve Rons problem?

Off to the Lions Den for awhile.

Tyler

Tyler,

The spark or SA tables are just that. Its 3D tables of the commanded
spark advance (SA). Based on the rpm and kPa at any given time, the ECM will command the stated timing. That's the simple explanation. However, there are several ancillary tables that are also used to modify the final SA depending on the parameters that are met (i.e. Idle, warmup, Decel, TPS, CTS etc.)With just what Ron has described I'm not convinced that the SA tables are the solution for Ron. Not sure that there is a solution for Ron. Getting some scantool and WB data would help in trying to narrow it down. But with big cams and more overlap, there's a tendency to overscavenge the chamber exposing the NB O2 to more air.
That causes the ECM to think the motor is running lean which in turn causes the ECM to try to "richen" the mixture which then increases the unburned HC. Lowering the O2 voltage swing points at lower airflow tells the ECM that the motor is not running lean. That's why the WB could be reading stoich but the BLMs show lean.
That's why I'm interested in the R/L O2 voltage tables. They're in the calibration just haven't been created in the .xdf or .tdf.
Make sense?

[XfireZ51]

So have we discussed everything that needs to be discussed for tuning our ZR-1s?

[-=Jeff=-]

So have we discussed everything that needs to be discussed for tuning our ZR-1s?

Apparently, since nobody has a Decent definition file for them. I wish I knew how to decode them , if I had the know how and the means to do itmost any ZR-1 owner would be able to benefit fom them.

Unfortunately I don't know where to start on decoding a MEMCAL (Bin) file for our cars or any for that matter

[XfireZ51]

Jeff,

Maybe we should start a fund and see if we could pay someone who has the knowledge to create a def file for use by members of this registry.

[-=Jeff=-]

Jeff,

Maybe we should start a fund and see if we could pay someone who has the knowledge to create a def file for use by members of this registry.

Maybe...

[kenthompson]

Let me know when you want the money!

[XfireZ51]

Jeff and I will keep you posted.

[Tyler Townsley]

Tyler,

The spark or SA tables are just that. Its 3D tables of the commanded
spark advance (SA). Based on the rpm and kPa at any given time, the ECM will command the stated timing. That's the simple explanation. However, there are several ancillary tables that are also used to modify the final SA depending on the parameters that are met (i.e. Idle, warmup, Decel, TPS, CTS etc.)With just what Ron has described I'm not convinced that the SA tables are the solution for Ron. Not sure that there is a solution for Ron. Getting some scantool and WB data would help in trying to narrow it down. But with big cams and more overlap, there's a tendency to overscavenge the chamber exposing the NB O2 to more air.
That causes the ECM to think the motor is running lean which in turn causes the ECM to try to "richen" the mixture which then increases the unburned HC. Lowering the O2 voltage swing points at lower airflow tells the ECM that the motor is not running lean. That's why the WB could be reading stoich but the BLMs show lean.
That's why I'm interested in the R/L O2 voltage tables. They're in the calibration just haven't been created in the .xdf or .tdf.
Make sense?

On another list there are people using advanced timing in the lower ranges to solve idle problems associated with cam overlap, that is what I was talking about. With a good datalog to see specific cells and a good wideband checked against the timing retard you might get the mixture to pass. You would have to go open loop all the time in the chip and customize it just to pass. If you went closed loop there is no way the calibration is going to let you get it right as it will try adjusting to 14.7 at all points. It may be that the motor needs cells at a different mixture range and spark point so it can interpolate between cells to get what he needs. IE you are starting the iginition early to get better combustion, since it is at lower speed should be able to monitor/adjust for any spark knock.

Todd comments?

Tyler

[Tyler Townsley]

Jeff,

Maybe we should start a fund and see if we could pay someone who has the knowledge to create a def file for use by members of this registry.

You can take the Tunercat .tdf file and create a .xdf file. The early tunercat files had a problem in the VE tables that Todd found and we contacted them and they corrected it. So you need to make sure you have the later def files. I am not sure what you need beyond what is in the .tdf files for tuning as they are pretty thorough. I have the complete 90 commented GM calibration printout and it is over 1 in thick and 250 pages. Since it is a 90 the calibration has only sketches of where they were going in the egr area so it is only good to 92.

Todd has spent literaly 100s of hours learning what he knows, he and I am somewhat leary of handing out information before we know that the reciepent has a good understanding of just what is involved. I can tell you from bitter experience you can mess up big time if you do not have a good grasp on what is happening in a calibration.

The biggest problem is as you have described, a good way to log what is going on and be able to review the logs watching what happens as you make a change. My car has been off the road for 5 years so I have not had a platform to take advantage of the new software which is why I have not had much to contribute.

I believe Todd uses a FJO wideband and datalog setup, but I also know whatever he used it was the hours on the road that was most important. There are very few who really want to play with stuff and yes it is confusing to a newcomer but thats why you can count on one hand those who have the skill and knowledge to get results.

Tyler

[XfireZ51]

If you went closed loop there is no way the calibration is going to let you get it right as it will try adjusting to 14.7 at all points. It may be that the motor needs cells at a different mixture range and spark point so it can interpolate between cells to get what he needs. IE you are starting the iginition early to get better combustion, since it is at lower speed should be able to monitor/adjust for any spark knock.

SA is likely not the issue. The condition you describe is precisely why you'd like to modify the O2 Window Terms. These will define the O2 sensor swing points that the ECM will try keeping the mixture at. And it can be varied on the basis of airflow. For those using cams with larger overlap, this helps tame idle surging and rich idle conditions. PID controls are helpful here too. These don't appear in the .tdfs and .xdfs generally available. There's nothing "hard-wired" in the cal for 14.7 being stoich. For those of us using gas with 10% ethanol, we benefit from changing stoich to 14.3:1 for greater tuning accuracy.



You can take the Tunercat .tdf file and create a .xdf file. The early tunercat files had a problem in the VE tables that Todd found and we contacted them and they corrected it. So you need to make sure you have the later def files. I am not sure what you need beyond what is in the .tdf files for tuning as they are pretty thorough.

The .tdf is pretty basic. It lacks PID controls, IAC controls, O2 sensor etc. Quite a few missing parameters allow someone to really fine tune the motor particularly if significant mods have been made. For example, I found that swapping in an AL FW benefitted from changes to the VE tables but also to IAC and Proportional Gains.

I have the complete 90 commented GM calibration printout and it is over 1 in thick and 250 pages. Since it is a 90 the calibration has only sketches of where they were going in the egr area so it is only good to 92.

Todd has spent literaly 100s of hours learning what he knows, he and I am somewhat leary of handing out information before we know that the reciepent has a good understanding of just what is involved. I can tell you from bitter experience you can mess up big time if you do not have a good grasp on what is happening in a calibration.

That's true to an extent. But you can't learn about what various controls do unless you can play with them and see what the effect is. Some of us can't disassemble code, but we certainly can utilize the parameters, once revealed, to tune the calibration to our liking. What would you like to know about someone like myself that would make you feel comfortable that we know what we are doing and therefore share the commented hack? With the majority of ZR-1s being 90s, this would be very useful for the community.

The biggest problem is as you have described, a good way to log what is going on and be able to review the logs watching what happens as you make a change. My car has been off the road for 5 years so I have not had a platform to take advantage of the new software which is why I have not had much to contribute.

I believe Todd uses a FJO wideband and datalog setup, but I also know whatever he used it was the hours on the road that was most important. There are very few who really want to play with stuff and yes it is confusing to a newcomer but thats why you can count on one hand those who have the skill and knowledge to get results.

Tyler

As =Jeff= can attest, I've burned over 1000 bins using either proms or Ostrich/TunerPro RT combo. I use a ZT-2 WB for WOT tuning. Datalogging with EASE and http://www.dynamicefi.com/. I think you'll find that there is quite a large community of "tuners" out there pretty adept at making all kinds of engine combos run well. I need to give a great deal of credit for to people like Bruce Plecan ( generally acknowledged as the father of GM ECM tuning) and Rob Rauscher (RBob moderator on 3rd Gen) for freely sharing what they learned.
I don't think tuning an LT-5 would be any more difficult than some of the stuff you see on 3rd Gen. The fundamentals are the same, and as Todd has stated, much of the calibration is based off of the $8D code.

[tpepmeie]

Some of us can't disassemble code, .

Dominic,
Tell you what, you guys give it a shot and post up here, or in a new thread, when you get stuck. I assure you if you get stuck along the way I will offer help. I couldn't disassemble code either when I started...heck, I have no training at all in this field.

Which calibration are you working with? AYBK? How far have you gotten into it?

Todd

[XfireZ51]

Todd,

I appreciate the offer of help. I have not started disassembling code. I have both the .tdf and .xdf editors. I have ported a .tdf over to an .ecu and .xdf file. (Pretty simple since both John and Mark built a function to do just that). I have previously created and modified .xdf items. I prefer working with TP but have used both as well as modifying calibrations directly in hex. I have modified .ads so as to output aldl items that were not supported in the scantool I was using. I've been able to introduce new output to the ALDL datastream (i.e. WB O2). Basically, if I have a hack, I can create the .xdf. What other tools do I need?
If you want to take people like myself, Shawn ZR-1 and =Jeff= through the steps, I'd do it as a learning experience. Not sure how that changes anything regarding my understanding and use of the parameters I'd like access to. But I'm willing to keep an open mind.

[Tyler Townsley]

Todd,

I appreciate the offer of help. I have not started disassembling code. I have both the .tdf and .xdf editors. I have ported a .tdf over to an .ecu and .xdf file. (Pretty simple since both John and Mark built a function to do just that). I have previously created and modified .xdf items. I prefer working with TP but have used both as well as modifying calibrations directly in hex. I have modified .ads so as to output aldl items that were not supported in the scantool I was using. I've been able to introduce new output to the ALDL datastream (i.e. WB O2). Basically, if I have a hack, I can create the .xdf. What other tools do I need?
If you want to take people like myself, Shawn ZR-1 and =Jeff= through the steps, I'd do it as a learning experience. Not sure how that changes anything regarding my understanding and use of the parameters I'd like access to. But I'm willing to keep an open mind.

I will offer some tips and questions to make sure you understand just what is being changes. The one that bit me first was something called.
'Secondary inj on fuel PW scaler.' Its in TC under a different heading, I used it on Rons car when Jim ran out of ideas, and TP, anyone know what it does and just how you can use it. I know Todd does but it is not to obvious and can have a dramatic difference.

Tyler

[tpepmeie]

Tyler,
It is a multiplier used to cut the fuel pulsewidth in half when the second set of injectors is active. For example, say you have an base pulsewidth of 10 milliseconds when the engine is running on only the 8 primary injectors. When the ECM commands the secondary throttles open, there is a very slight delay (0.3 sec) then the secondary injectors are energized, and the NEW pulsewidth is now 10ms x 0.51 = 5.1ms. Of course, since it is being delivered with twice the number of injectors, the overall fuel injected is the same as before the port throttles opened.

Increasing this multiplier would have the effect of adding fuel when the secondary injectors are energized. If it were, say, .75, then you would end up with 2 injectors x 10ms x .75 multiplier = 15ms total fuel delivered. This could be used as a band-aid to increase fueling if the injectors are too small or the VE table is not correct. However, I would think the transition would be terrible, and you'd end up with a surge due to the sudden enrichment.

just my $0.02.

Todd

[Tyler Townsley]

Tyler,
just my $0.02.

Todd

In my book your $0.02 is worth at least $1.00.

You are of course correct. When Jim Smith was trying to tune Ron Ks motor several years ago the car had a lean at this transission and he had the VE tables up to 100 and the car was still lean in transition. We took this to .56 or .57 and solved the problem and were able to back the VE table down some.

The above only applies if you are using secondary throttle plates.

Todd what did you with this when you change the calibration to have both injectors on all the time.

Tyler

[tpepmeie]

Todd what did you with this when you change the calibration to have both injectors on all the time.
Tyler

I left it alone. So basically had half pulsewidth provided by each injector all the time.

The base fuel calculation has no idea there are two injectors. In fact, the base calculation only knows the constant for 1 injector (.35 sec/gram). The pulsewidth is calculated using this. So, therefore, when you bring the second injectors online with the same calculated base pulsewidth, the scaler has to be used so that you don't deliver twice the required fuel.

Now, about that delay factor....who wants to discuss what effect that has?

Todd

[XfireZ51]

Todd,

Why don't we discuss Proportional Gain?

[bradslt5]

wow todd really know his stuff. this is a good read . when i got a prom from mark haibeck he says he takes some of that out to give a better responce . is that what you mean. i just want to learn all i can . what are your thoughts on tunning is one takes the secondary throttle blades out . do they then run all the time ?

[tpepmeie]

Todd,

Why don't we discuss Proportional Gain?

OK. What do you want to know about it? It is pretty simple, and the first of three potential PID parameters to control pulsewidth based on feedback from the O2 sensor. There are primarily two tables at work...one is the base response to O2 error vs. airflow. There is a smaller proportional step at zero airflow (idle).

These steps are then multiplied by a factor, depending on how large the O2 error is. The bigger the error, the larger the multiplier. You end up with an adjustment "count" to modify the base pulsewidth. If the error is positive, fuel is removed and vice versa.

Todd

[XfireZ51]

OK. What do you want to know about it? It is pretty simple, and the first of three potential PID parameters to control pulsewidth based on feedback from the O2 sensor. There are primarily two tables at work...one is the base response to O2 error vs. airflow. There is a smaller proportional step at zero airflow (idle).

Isn't there a constant that defines the max airflow to be considered as IDLE? The 7747 code used a separate Prop Gain Bias constant for idle and the 2D table was pretty coarse.
EBL has 2 constants for Prop Gain at idle based on offset and duration and 4 tables.
So 1 Prop Gain table defining a gain based on Gms/sec which then gets further modified by a second table with factors based on O2 Error, right?
Which one do you usually modify and why?
If I change the gain up or down, what would I feel in the way the motor runs?
Why wouldn't I want to be able to modify this in the bin?

Thanks for this. Any more on the disassembly lesson?
Dominic

[tpepmeie]

Isn't there a constant that defines the max airflow to be considered as IDLE?

No. Idle fueling is determined by TPS < 2% and vehicle speed <= 0. That combination sets the airflow term to zero.

There is a scaler term available to modify the Prop Steps, but it is not used (ie, = 1.00)

Todd

[XfireZ51]

No. Idle fueling is determined by TPS < 2% and vehicle speed <= 0. That combination sets the airflow term to zero.

There is a scaler term available to modify the Prop Steps, but it is not used (ie, = 1.00)

Todd

Thanks Todd. Think I understand what's going on here now. :hello:

[Tyler Townsley]

Now, about that delay factor....who wants to discuss what effect that has?

Todd

The delay factor is there to let the air velocity catch up to the needed fuel. When you go from 1 to 2 runners in a cyl the increased airflow and pressure change has to be factored into the fueling equation and that is what the factor does.

I hadn't thought about that one in a while. On a removed secondary situation would you lower the delay or remove it alltogeather?

Tyler

[bradslt5]

tyler thankyou so much for the insightfull info . guess i will send my prom to corey after i remove the secondaries

[Tyler Townsley]

tyler thankyou so much for the insightfull info . guess i will send my prom to corey after i remove the secondaries

If you do not include porting etc with pulling the secondaries it is a waste. If you do not go that far why not just have Corey change the calibration to allow dual injectors on all the time and force the secondaries open, Todd was the developer of this little trick and seems to work ok. Will B has this on his 90 and it works well.

Tyler

[Tyler Townsley]

Todd,

Why don't we discuss Proportional Gain?

From a calibration engineer:

Quote

Proportional gain is a method of controlling a signal of some sort generally idle speed control or EGR controller, etc; where a certain type of damping or control of a signal is required. It in it's self is not a
calibration parameter but exerts control over a device.
Generally the P part of a PID controller where I = integral and D = derivative. Any of these terms can be used in isolation but are generally used to fine control a feedback system of some kind. Look up PID controllers on the Internet for the full skinny! Should keep you amused for hours!!

Unquote

Tyler

[XfireZ51]

If you are interested in learning about the PID controls, have a read of the attached paper. Don't be surprised if it takes a few run thrus' to grasp what they do. Actually making the changes to the cal will solidify for you how these controls help in fine tuning the behavior of the motor. This paper was written for a TBI system but the operating principles and results are very applicable even to an LT5.

[tpepmeie]

Picking this thread back up, using a question asked on the list...

Are the cam timing and VE/SA table specs for the BW "public domain" and if so where are they available?


No idea about the cam timing. I have a Daytona 24hr calibration from Jan-93. I am sure it is not the same as the BW cars, because it was intended for racing, not passing 50-state smog.

The bin I have is based on a '90 (AUAH) calibration. Surprisingly, the changes are fairly minimal, compared to what one would suspect for a race engine. The SA table has few changes, mainly at WOT. About 28d total advance.

The VE tables are largely unchanged, except the high RPM table w/ SPT's open, no doubt where the car spent most of its lap. It is also clear that the race car had no Port throttles, O2 feedback, or knock feedback... not unlike the Snakeskinner calibration, in that regard.

Just trying to keep this thread alive ... ;)

Todd

[scorp508]

Just wanted to drop in and say this thread was still very informative some 16 years later. :D

[tpepmeie]

Yeah it was. I miss Tyler around here. RIP


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[scorp508]

Yeah it was. I miss Tyler around here. RIP


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)


Tyler too? Man... I stepped away from this hobby for ~15 years and so much has changed. :( I also learned Grumpy from the DIY-Prom scene passed.

[XfireZ51]

Tyler too? Man... I stepped away from this hobby for ~15 years and so much has changed. :( I also learned Grumpy from the DIY-Prom scene passed.

Grumpy(aka Bruce Plecan) passed away quite a long time ago. We held a tuning symposium in his honor near his home in Ohio. He and RBob were the brains behind a great deal of the tuning knowledge we have today. Craig Moates still around we hope but out of the business. Mark Mansur for TPRT