LT5 ECM Tuning thread - ZR-1 Net Registry Forums

ShawnZR-1 · 01-08-2008

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

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!

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

tpepmeie · 01-08-2008

Quote:

Originally Posted by ShawnZR-1

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 · 01-08-2008

Quote:

Originally Posted by 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

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!

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

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 · 01-08-2008

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

We Gone · 01-08-2008

Shawn good to see you post this over here

we need to hook up...

Steve

bradslt5 · 01-09-2008

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 · 01-09-2008

Quote:

Originally Posted by tpepmeie

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 · 01-09-2008

Quote:

Originally Posted by 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

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 · 01-09-2008

Quote:

Originally Posted by ShawnZR-1

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=- · 01-09-2008

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?

01-08-2008	#1
ShawnZR-1 Join Date: Jul 2005 Location: Atlanta, GA Posts: 81	LT5 ECM Tuning thread 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 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! 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 __________________ 1991 Chevrolet Corvette ZR-1

01-08-2008	#5
We Gone Join Date: Apr 2004 Location: ATL. GA. Posts: 2,170	Re: LT5 ECM Tuning thread Shawn good to see you post this over here we need to hook up... Steve __________________ Steve 1990 Steel Blue/Black #2355 1990 Red/Red #1473 1991 Quasar /Black #118 Sold 1991 Turquoise/Black #766 Parted Out 1993 Yellow/White #179 Sold 1990 Black/Gray #1361 Headers/4:10s Sold

01-09-2008	#6
bradslt5 Join Date: Oct 2007 Location: lone pine and mammoth lakes ca. Posts: 544	Re: LT5 ECM Tuning thread 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

01-09-2008	#10
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,169	Re: LT5 ECM Tuning thread 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? __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

01-08-2008	#4
tpepmeie Join Date: Aug 2005 Location: Fishers, IN Posts: 815	Re: LT5 ECM Tuning thread I think the available Tunerpro definitions were made from .tdfs, so they will be very very similar, if not identical.