'91 #473 Tuning

[jss06c6]

Gents,

Spend most of my time on CorvetteForum (don't hit me!).. Just getting old and habits are hard to break.:???:

Finally put #473 on the rollers a couple of weeks ago. With SW Headers, full SW exhaust, Hi-Flo cats, Fidanza FW, Delphi Injectors and Marc's tune, the car put down 345 rwhp and 349 rwtq. Hot engine (drove to dyno shop) and an 80 degree day. Talked to Marc and we figure we're missing about 16 hp. Past runs (before exhaust upgrades) put the AFR at 11.9. Didn't have a tailpipe sniffer this time, so not sure what it showed, but worthless anyway since I'm running metal matrix cats. Decided to do my own tuning.. Very comfortable with LS platform and HpTuners, but not OBDI. Thanks to Dominic's counsel, I now have TunerPro RT V5, Moate's APU 1 and a new AEM wideband O2 sensor to install. I suspect the Low

I located a stock BIN on GearHead-EFI along with a BIN definition file to read it. With help from Dave Blundell at Moate's tech support, I finally got the current tune downloaded. I want to duplicate it on another SST 27SF512 chip so that I don't run the risk of messing up the tune that I got from Marc (will leave this chip "unmolested").

Now that I can interpret BIN files, I'll get the wideband O2 sensor installed and begin to log data so I can see how the tune sits here in Texas. Car runs great (of course! Marc's tunes are legendary), but I can't resist the temptation to tune:-D I really enjoyed dialing in the VE tables and spark along with other tweaks on my LS2, so looking forward to learning OBDI secrets. I'll share what I learn so that others can take advantage of my wins and headaches!

My ECM is a 1228331 with a broadcast code of AXFK. I'm using the stock BIN from GearHead-EFI along with the BIN definition file from GearHead-EFI.

AXFK_91_Vette_5_7DOHC.bin

$AF 91 Vette ZR1 LT5.xdf

Both of these are on the GH site (most complete set of BIN files and BIN Definintion files I have seen on the web!) Incredible resource!

My custom tune uses a $AFA Bin definition file.

There are some location differences for equivalent parameters between the two BIN files, so at this point, I can't see how to use a common *.xdf to easily do comparisons, but not worried, since I'm going to create a copy of the current tune on a new SST27SF512 chip using the $AFA definition file and then create a copy of the stock BIN file using the $AFA definition file. Then can do comparisons using TunerPro RT.

So, stay tuned and I'll keep everyone posted as I translate my LS tuning knowledge to the OBDI environment and TunerPro RT.

[XfireZ51]

Steve,

Shouldn't be any real difference between the AXFK ($AF)calibration and
the BRXB ($AFA). The main parts should be identical. GM added a couple of lines of code, but didn't change much else between the two versions of the cal.
IOW, you should be able to start w the BRXB cal without worrying about "converting" the AXFK to the $AFA Mask.

[jss06c6]

Good idea, I'll give that a try!

Thanks..

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[-=Jeff=-]

Don't forget the ADX file for data logging


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[jss06c6]

Yep, I've got it already.

Mainly interested in how the AFR looks and the VE tables..

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[MickeyD]

Yep, I've got it already.

Mainly interested in how the AFR looks and the VE tables..

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Hey, do I know you! Glad you came over to the dark side. David and I are trying to plan a drive over in Southwest Section. Just started convo.

[jss06c6]

Mike,

Let me know when you get it planned. Just got the wideband installed. Now ready to start getting the VE tables dialed in.

Steve

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[jss06c6]

AEM Install.. all working well.. Logging data next step.

[MickeyD]

AEM Install.. all working well.. Logging data next step.

I have no idea what you are doing will do! I need help just to change my oil and that's coming up. Kudos to ya Steve. I am just not mechanically inclined. Do you charge by the hour?

[XfireZ51]

AEM Install.. all working well.. Logging data next step.

Steve,

What r u using as a datalogger? How r u connecting to the ALDL?

[jss06c6]

Moate's APU 1.. wideband hooked up to same analog channel 1.

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[XfireZ51]

Moate's APU 1.. wideband hooked up to same analog channel 1.

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Yes but the wideband isn't an ALDL logger. It will just log WB O2 activity. Are u tuning Open or Closed Loop?

[XfireZ51]

Ok, never used APU. Will u be using TPRT as the datalogger then?

[jss06c6]

Yes.. should have it hooked up tonight to see how it goes. Need to check the *adx data stream definition and modify to monitor what I want to see.. more info as I make the transition to OBDI..

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[jss06c6]

OK, hit a snag. The ADX I have is for LT1/L98.

Jeff, do you have an ADX that will communicate with my '91 LT-5? ECM has BCC of AXFK. Using $AFA mask for my BIN definition.

Thanks gents!

Steve

[XfireZ51]

U can find the .ads for the $F0 mask and convert it to an adx. Tunerpro has a utility for that.
I was able to use the .adx for $8EA on my 92, so perhaps the $F0 could work for the 92
http://www.tunerpro.net/download/datastreams/GM/F0.ads

[-=Jeff=-]

mine I know will work

it is attached

[jss06c6]

Jeff,

Thanks so much.. I uploaded the ADX and tried to establish communication through the APU 1 via the ALDL cable. No go.. I'll get back in touch with Dave at Moate's to see where I'm going wrong. Continues to show DA Not Connected. TunerPro RT5 obviously looking for something I'm not providing.

Once I can find out what I'm doing wrong, I'll post so others can see my error(s).

Best Regards,

Steve

[XfireZ51]

Steve,

Are u checking to see which port is opened when u connect. Sometimes TPRT needs the device connected thru port 2,3, or 4. Check Device Manager.

[jss06c6]

Checking.. I think it's com2.. will verify. I know it must be something simple!

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[-=Jeff=-]

Check in tunerpro and be certain what the port is. With the cable connected it should pass the self test. Also if you plug into a different USB port the com port number will change as well


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[Billy Mild]

Has anyone gotten a Windows 10 device to work with TunerPro and a bluetooth ALDL adapter?

[jss06c6]

Gents, all good! Com3 set up and connected without issue. Already see BLM low and high readings are lean. Will now modify the ADX that Jeff gave me to capture my wideband data.

Thanks to each of you for the help!

Steve

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[-=Jeff=-]

Has anyone gotten a Windows 10 device to work with TunerPro and a bluetooth ALDL adapter?

which bluetooth ALDL?

[jss06c6]

Jeff,

I've got the system communicating and logging data well when using the APU1 in bypass mode. I have set up the wideband in the ADX. I have voltage arriving at the A/D buss on the back of the APU1. Voltmeter shows about 2.5 volts DC when the WB gauge is indicating an AFR value of 14.8, which is consistent with the analog output from the AEM WB.

I have modified the dashboard to look at WB Voltage (digital) and WB AFR (analog). No WB data logging in the datastream through the APU1 in bypass mode. Per Dave at Moates support, I need to be in APU1 mode, not bypass. Switching to APU1 mode, I'm back to "DA not connected" again. Have you connected through the APU1 with the ADX you sent or only in bypass mode?

Thanks for all your help! Here's the modified ADX...

[-=Jeff=-]

I will look at the ADX tonight, but I have never used a APU1 just the basic USB cable

[jss06c6]

Ok, it will work with USB with APU in bypass mode..

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[Fully Vetted]

Like reading Chinese...

Either way, welcome to THE premier forum for The Beast, Steve. Hopefully, I'll see you in a few weeks.

[-=Jeff=-]

Did you look at this:

http://static.moates.net/zips/wideband_datalog_tunerpro_lm1.pdf

might help, although it looks like everything is correct

[jss06c6]

Did you look at this:

http://static.moates.net/zips/wideband_datalog_tunerpro_lm1.pdf

might help, although it looks like everything is correct

Jeff,

Yes, I did read this several times as well as the write-up that EagleMark did on gearhead-efi. FYI, my version of TunerPro RT 5 does not have an ALDL setup window that I can find. I simply went to the ADX values section and added the two new values (wideband voltage and wideband afr). You should be able to see these in the file I attached.

My main issue is that I cannot connect to the ECM via the ALDL cable with TunerPro RT when the APU1 is in APU mode versus pass through mode. No problems connecting when APU is in Pass through mode .

[jss06c6]

Like reading Chinese...

Either way, welcome to THE premier forum for The Beast, Steve. Hopefully, I'll see you in a few weeks.

Looking forward to the meet Dave!:cheers:

[Billy Mild]

Check in tunerpro and be certain what the port is. With the cable connected it should pass the self test. Also if you plug into a different USB port the com port number will change as well


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which bluetooth ALDL?

http://www.reddevilriver.com/ALDL_Bluetooth.html

This one.

[Billy Mild]

Jeff,

Yes, I did read this several times as well as the write-up that EagleMark did on gearhead-efi. FYI, my version of TunerPro RT 5 does not have an ALDL setup window that I can find. I simply went to the ADX values section and added the two new values (wideband voltage and wideband afr). You should be able to see these in the file I attached.

My main issue is that I cannot connect to the ECM via the ALDL cable with TunerPro RT when the APU1 is in APU mode versus pass through mode. No problems connecting when APU is in Pass through mode .

What version of Windows are you running? Also are you doing realtime tuning via emulation or burning new PROM's everytime?

[jss06c6]

Windows 10. At this point I simply want to stream my wideband O2 data along with the ALDL data. I'm not emulating with the APU1 at this time. I have not changed the tune and am running with Marc Haibeck's tune and chip.

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[jss06c6]

Dave Blundell does not think it's the operating system...

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[XfireZ51]

What version of Windows are you running? Also are you doing realtime tuning via emulation or burning new PROM's everytime?

Unless ur riding "shotgun", I wouldn't recommend realtime tuning. Secondly, I think u r much better off collecting data from ALL driving conditions before making changes to fueling. The more data u can collect from various driving situations the better off u r.

[jss06c6]

Yes, I won't be doing any WOT Tim ng until I get the VE tables spot on. Just disappointed I can't get my AFR data stream logged along with my ALDL data stream. Should be able to do this with the APU1, but the communication protocol is apparently very specific when going through the APU1 firmware.

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[jss06c6]

Tuning, not timing..

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[jss06c6]

Anyone ever attempted to swap over to Halltech or AEM Infinity ECM on the LT-5?

I believe the ECM pinout is in our service manuals..

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[Billy Mild]

Anyone ever attempted to swap over to Halltech or AEM Infinity ECM on the LT-5?

I believe the ECM pinout is in our service manuals..

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I haven't seen it here yet, but Megasquirt did make a new ECM that was plug and play.

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[XfireZ51]

I believe Sam in Switzerland is using a Halltech to run a race LT-5. MS currently has an ECM to run an LT-5 but I do not believe it currently plays w the CCM.
However, we have a number of members w 600-700hp ZRs using the stock ECM.
More in the 500+ range.

[jss06c6]

Interesting! I'll drop him a PM to discuss.

Thanks!

Steve

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[jss06c6]

Agree that the stock ECM will do its job. Would be nice to have newest engine management system and tuning software however.. I'll tune with my stock ECM, just familiar with my son's conversion from stock LS1 OBDII to Halltech and the increased control he had in one package.. in the end he went back to stock ECM due to some triggering issues, but the Halltech had a ton of features! AEM Infinity looks nice as well.

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[jss06c6]

Left and Right Fuel Trim tables (rpm/map/BLM). Stayed out of PE mode so this should be accurate.

Noticed some rpm hunt when trying to hold a steady rpm while stopped, might just be my ability to hold a steady idle. Alternatively, may be a slight vacuum leak somewhere, but not hunting for problems that may not exist.

Still waiting on some help from TunerPro and Moates to see how to capture my wideband data through the APU 1.

[XfireZ51]

Looks like your idle hunt is related to lean fueling. Question is what is causing the lean condition.

[jss06c6]

Agree with the diagnosis... It is lean..

Here are the Integrator values in same table format.. Left and Right.

[jss06c6]

Also looks like the right side is worse than the left side.. the right O2 sensor takes it's time coming on.. Perhaps it might be weak as well..

[XfireZ51]

If u haven't already, I would suggest swapping the O2s to AC units. Much better than the Bosch.
The INT is trying to drag the BLM back but there is only so much it can do without modifying the VE table.

[jss06c6]

I'll put the car back up on the lift and change the O2 sensors.. Will be making VE tune changes over the next few days to get it back to 128..

Thanks!

[jss06c6]

If u haven't already, I would suggest swapping the O2s to AC units. Much better than the Bosch.
The INT is trying to drag the BLM back but there is only so much it can do without modifying the VE table.

Can you tell me the specific AC Delco O2 Sensor I should look for?

[XfireZ51]

Can you tell me the specific AC Delco O2 Sensor I should look for?

They're the AFS 74 AC sensor. Don't do any VE changes until u install them. I found that the ACs provided significantly different results than the Bosch units. They required a change from the tune I had using the Bosch units.
The reason I changed to the ACs was that the Bosch would "drop out" sporadically especially the passenger side. The ACs are very consistent.

[jss06c6]

Excellent counsel! Thanks much..

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[jss06c6]

Success! Many thanks to Dave Blundell at Moates and Mark Manzur at TunerPro! The *.ADX has to have the "connect" command set to <none> to connnect while in APU mode. Now have my wideband data streaming with the ALDL data!!! Note that you need to go to Tools/Moates A/D to verify which channel the data is actually coming in on. I have mine wired to what I believed was Channel 1, when in reality, it is Channel 2 (next to the ground wire connection on the DA buss on the back of the APU. trying to upload a Screen shot of my tuning dash but not working at the moment. This ADX is set up for an AEM UEGO WBO2 sensor. I'm capturing voltage as well as AFR. Now to replace the NB O2 sensors and log some more data to begin the actual tuning work..

[XfireZ51]

So Steve, are you going to tune based off WB or BLMs?

[jss06c6]

Both.. will start with BLM's to get VE tables correct, then work with PE curve and fine tune WOT with the Wideband data.. The WB is located in the driver side collector of the SW Header. It's clocked at about 2:45 looking downstream with the NB sensor at 12:00. The WB is showing an AFR of 14.8 at idle in closed loop. Definitely lean and agreeing with the BLM data..

[-=Jeff=-]

please post or email me the ADX.. if you could

[jss06c6]

I'll post it..

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[jss06c6]

ADX and a sample log run just sitting in the garage.. still working on my monitor frames, so don't pay attention to them yet.. I've added additional history tables as well..

[-=Jeff=-]

thanks I would like to see what was changed and I will add it to the others

[jss06c6]

thanks I would like to see what was changed and I will add it to the others

As far as connecting in APU mode, simply change the "connect" command to <none>.. I've added other tables for the AEM UEGO WB and some additional gauges for WB monitoring as well as more detailed RPM/MAP/BLM tables for left and right bank.

[jss06c6]

Correction, other Values, not Tables for the wideband..

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[Billy Mild]

Sounds like you have a complete tuning setup for datalogging now. When does the actual tuning start?

[jss06c6]

I've already collected a lot of BLM data to correct my VE tables, but am replacing both O2 sensors first, since the tuning data will change. O2 sensors should be here by the weekend, so tuning will commence next week.

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[-=Jeff=-]

How are you changing your BLM Data? I might have a program you might want to try ( requires a windows machine though)

[XfireZ51]

:notworthy:mrgreen:How are you changing your BLM Data? I might have a program you might want to try ( requires a windows machine though)

;):notworthy ;)

Yes you may want to try it.

[jss06c6]

How are you changing your BLM Data? I might have a program you might want to try ( requires a windows machine though)

Jeff,

That would be super! I'll send you a PM with my email address.

Thanks very much!

Steve

[jss06c6]

Dominic,

I've changed the O2 sensors to AC's. Slight difference from the Bosch units. I've still got a pretty decent difference between the right and left sides. Driver side (left) is about 7 BLM units LOWER than the Passenger side. Should I use the midpoint between the two to make the necessary changes to the VE tables? I'm only working on Port Closed at this time, not Port Open. I'm simply not sure which side the ECM is using to determine the volumetric efficiency of the engine.

Thanks,

Steve

[XfireZ51]

Steve,

You won't likely eliminate the +/- aspect of the left to right BLMs. So I work on averaging the 2 sides. The side to side differential should draw tighter at cruise than at idle. I tend towards the leaner side of the average than richer. IOW, I would rather have a 128/135 than a 123/127. In my experience, a leaner mixture makes for a mellower exhaust note and less drone on inclines and when MAP increases.

As for the O2s, I found that the Bosch voltage will "drop out" sporadically, the AC signal is always consistent. That's why I use them.

[jss06c6]

Perfect, that's what I thought.. I'll take the midpoint between the two. Really seeing the ECM trying to add fuel when the car gets lean! The Wideband is ranging from 14 to 16 AFR and the rpm is moving along with it! Really need to get a new chip burned to get the VE closer... Headed to Buffalo for ZR-1 meet this weekend. Need to get it done before I go. Thanks again for all the help Dominic!

[XfireZ51]

Steve,

You know that the AFR is going to swing lean/rich in Closed Loop. That's what it's supposed to do although you want the swing to be in a tighter window. This is done to keep the converter happy.
My AFR will range between 14.5-15.3 at idle. Yours sounds like it has a lean surge to it.
What kPa/RPM is the motor idling at?

[jss06c6]

Dominic,

Made changes to VE Low/High tables (Port Closed only). BLM data shows a very consistent lean profile across the Histograms. Overall average is about 4.5% lean, both tables.

With the change and new tune uploaded, the idle is rock stable in open loop. Starts at idle of 800 rpm and kPa of 30.25. AFR in open loop is stable around 13.1-13.3, again with cold engine (95 F). Spark advance is running about 18 degrees. Open loop BLM at 132 left/140 right. Integrators both stable at 128.

Open loop, engine temp 130F; Idle rpm 725, MAP at 32.5 kPa. BLM's and Integrators same. AFR same.

Closed loop, engine temp 161F, BLM's at 132/140 and integrators at 116/119 (note this is a brand new tune, so fuel trimming is actively updating. Engine idle rpm at 700, MAP at 33.6 kPa. AFR swinging from 13.6 to 15.1, normal..

Closed loop, engine temp 197F, BLM's at 125/132 and integrators at 127/125. AFR still same range.

Engine is running much smoother and easy to hold steady rpm now. Will head out on the road to collect new BLM data to check VE mapping.

Question, how do you gather data with the secondaries open without engaging PE? Changing PE threshold on TPS % will pose serious risk of knock..

Steve

[-=Jeff=-]

Steve,

Dominic no longer has functioning secondaries.

Did you try my program out? did it work for you? It has been a while since I used it

[XfireZ51]

Steve,

Overall it sounds good. Until C/L BLMs are not doing anything so they somewhat meaningless as they indicate where they were prior to shutdown. With a new tune, I would pull the BATT and reset the BLMs so u start from scratch.
It may take 10 or so cycles to hone in on a final tune. For many people that do their own tunes it never ends actually 😂.
As for tuning the Port Throttle Open tables, u can change the point that secondaries open. Should be TPS% v Port Throttle Open. Since I don't have secondary throttles, mine are all set to 0. The only time they shutoff is at Closed Throttle which is under 1.9% TPS.
This assumes Valet Mode is disabled.

[jss06c6]

Steve,

Dominic no longer has functioning secondaries.

Did you try my program out? did it work for you? It has been a while since I used it

Jeff,

I downloaded it but have not used it yet. Had a simple Excel workbook built to generate the revised VE data tables using BLM data compared to ideal (128) to generate a %change and apply it to the existing VE table..

Just saw Dominic's post that he's taken the secondaries out, so will need to think this through since I'm leaving mine in at this time. I'll probably look at the difference between VE Low/High with secondaries closed and secondaries open and extrapolate a set of tables for secondaries open.

Any other thoughts are certainly appreciated!

Steve

[jss06c6]

Steve,

Overall it sounds good. Until C/L BLMs are not doing anything so they somewhat meaningless as they indicate where they were prior to shutdown. With a new tune, I would pull the BATT and reset the BLMs so u start from scratch.
It may take 10 or so cycles to hone in on a final tune. For many people that do their own tunes it never ends actually 😂.
As for tuning the Port Throttle Open tables, u can change the point that secondaries open. Should be TPS% v Port Throttle Open. Since I don't have secondary throttles, mine are all set to 0. The only time they shutoff is at Closed Throttle which is under 1.9% TPS.
This assumes Valet Mode is disabled.

So... bring the port throttle opening point way down and then log more data (VE will obviously change due to additional fueling and intake air volume). What about using the stock tune tables to compare port open to port closed and use same scalar to generate a new one using the new VE Low/High tables?

[XfireZ51]

The ALDL differentiates between open and closed port throttles. If u set the TPS% to 0, that will log BLMs for Port Throttle Open VE tables. No need to interpret anything. If u use Jeff's VE Tuner, it separates the log between Closed/Open port throttles and modifies the correct VE table. I've used it hundreds of times and helped him develop it.
Whether u have 2 injectors going or 1, they all only need to supply the same amount of fuel. Doesn't matter.
If u are leaving in the secondary throttles, frankly I'd leave the Port Open VE tables alone unless u have modified the motor somehow. Even then u probably won't be getting into the secondaries until 3k or so, well above a cruising rpm.

[jss06c6]

The ALDL differentiates between open and closed port throttles. If u set the TPS% to 0, that will log BLMs for Port Throttle Open VE tables. No need to interpret anything. If u use Jeff's VE Tuner, it separates the log between Closed/Open port throttles and modifies the correct VE table. I've used it hundreds of times and helped him develop it.
Whether u have 2 injectors going or 1, they all only need to supply the same amount of fuel. Doesn't matter.
If u are leaving in the secondary throttles, frankly I'd leave the Port Open VE tables alone unless u have modified the motor somehow. Even then u probably won't be getting into the secondaries until 3k or so, well above a cruising rpm.

Understand.. Interesting however, is that the Port Throttle Open vs. RPM table in the 91brxb bin is "0" across the board, while my current tune is shown below..

[XfireZ51]

[QUOTE=-=Jeff=-;253092]Steve,

Dominic no longer has functioning secondaries...

[QUOTE]

I beg your pardon. I may be older than you but my secondaries inject just fine.

:-D:-D:dancing

[jss06c6]

[QUOTE=-=Jeff=-;253092]Steve,

Dominic no longer has functioning secondaries...

[QUOTE]

I beg your pardon. I may be older than you but my secondaries inject just fine.

:-D:-D:dancing

Now That's good!!! Glad to hear that you're still firing on all cylinders!!!:fahne:

[-=Jeff=-]

I beg your pardon. I may be older than you but my secondaries inject just fine.

:-D:-D:dancing

LOL.. that goes along with the custom 3 bolt bottom end.. :dancing

[mike100]

sounds like it is time for an ostrich2 emulator so you don't wear out your chip socket.

maybe the lean condition is due to modern fuels?.. or maybe that' how they always were since new.

[jss06c6]

Probably a correct assumption! I've got the APU1 so can emulate and tune real time with it, but it's too bulky to leave it installed on a semi permanent basis. Would work well for tuning work however and could then burn a chip "every so often"..

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[BigIke]

Need another Montgomery County LT5 to tweak on? I'm getting a little detonation right now...

[XfireZ51]

Not a fan of "real time tuning" L'd rather collect as much data in as many driving situations as possible and THEN make changes based on overall results. Besides it can dangerous.

[jss06c6]

Not a fan of "real time tuning" L'd rather collect as much data in as many driving situations as possible and THEN make changes based on overall results. Besides it can dangerous.

Not doing any real time tuning. Would be good to use the emulator to upload new tunes rather than swapping chips, but I'm not changing that often anyway..

Here's a BLM data log from this morning. This is against stock Port Open VE tables, no modifications. Low kPa low/midrange RPM shows rich. Commanded Secondaries open via BIN table. Gathered data after 25 minutes of driving to achieve stable temp and integrators relatively stable.

[jss06c6]

Need another Montgomery County LT5 to tweak on? I'm getting a little detonation right now...
sent you a PM. I'm still learning.. let me get comfortable and happy to help!

[jss06c6]

Gents,

Have the VE tables dialed in pretty well now. Passenger side is lean side, driver side averaging about 3 BLM units lower than passenger side. Above 2000 rpm and MAP of 40 kPa, they are only 1 BLM unit apart. 126-127 on driver side and 128-130 on passenger side.

WOT work now. AFR pretty steady at 12.5-12.6 from 2200 to 6000 in fourth gear. Seeing some knock retard in this zone. Spark tables at 27 degrees advance. Will pull a degree and re-log to see if I can tweak the knock retard out. Doesn't need fuel since I'm at 12.5+, so will pull some timing and repeat data log. More to come..

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[XfireZ51]

I'm guessing KR is kicking in somewhere around 4500-5500 rpm. U could think about backing off timing in that area depending on how bad the knock is. Altho the motor isn't there for long during a WOT run. BTW, the KR is very conzervative in the cal, so u could reduce the sensitivity and amount as well.
I tried 34d at top end w No Knock detected. I just lost power.

[Hog]

I'm guessing KR is kicking in somewhere around 4500-5500 rpm. U could think about backing off timing in that area depending on how bad the knock is. Altho the motor isn't there for long during a WOT run. BTW, the KR is very conzervative in the cal, so u could reduce the sensitivity and amount as well.
I tried 34d at top end w No Knock detected. I just lost power.
The KR is aggressive that results in timing advance that is conservative, or the actual KR is conservative resulting in aggressive timing advance?

[XfireZ51]

The KR is aggressive that results in timing advance that is conservative, or the actual KR is conservative resulting in aggressive timing advance?

The Knock Retard in the stock calibration is pretty aggressive, meaning that it reduces timing rapidly and extensively. In all my datalogging, I have found little need for that level of timing retard. So I have reduced it significantly from stockwith no detrimental effect. I try to time things just so it "tickles" the KR.. ��
Also want timing at where MAP is at its lowest, indicating highest vacuum.

[Hog]

The Knock Retard in the stock calibration is pretty aggressive, meaning that it reduces timing rapidly and extensively. In all my datalogging, I have found little need for that level of timing retard. So I have reduced it significantly from stockwith no detrimental effect. I try to time things just so it "tickles" the KR.. ��
Also want timing at where MAP is at its lowest, indicating highest vacuum.
Thanks for the clarification. I would assume that having some timing advance at lowest MAP(highest vacuum) would also help fuel economy and some throttle response?

[XfireZ51]

When tuning, you'll work w the VE (fuel) tables and the SA (spark advance) tables. Typically, u will start w VE getting the BLMs close. Then tweak the SA tables to achieve the lowest MAP in various modes of operation, ie idle, Part throttle etc. Not much different than tuning a carb and adjusting a distributor using a vacuum gauge. Only now, it can be done across many more levels of throttle position and rpm.

[jss06c6]

I'm guessing KR is kicking in somewhere around 4500-5500 rpm. U could think about backing off timing in that area depending on how bad the knock is. Altho the motor isn't there for long during a WOT run. BTW, the KR is very conzervative in the cal, so u could reduce the sensitivity and amount as well.
I tried 34d at top end w No Knock detected. I just lost power.
Dominic,

It's coming in lower, about 3000 rpm. I'll try to set up a monitor log to see exactly where its coming in and how much it's taking out.

Are you changing the attack rate?

Steve

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[XfireZ51]

Dominic,

It's coming in lower, about 3000 rpm. I'll try to set up a monitor log to see exactly where its coming in and how much it's taking out.

Are you changing the attack rate?

Steve

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Depends on how severe the detonation is. And if the BLMs are ok, why is it knocking? Back it off 2d and see what happens.

[jss06c6]

That's exactly my plan..

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[jss06c6]

Knock Retard history table from WOT pass. Pulling 2 degrees and making another pass. With AFR running solid at 12.5-12.6, can't believe fueling is issue.. I've attached spark curve for Secondaries Open as well.

[mike100]

took out spark near torque peak because you can hear it pinging on CA 91 octane if it is warm outside. Funny though as soon as you get over about 1000ft above sea level, this diminishes greatly.

You can still run 27 deg on the top end, but need to compromise a little on the curve and be closer to the stock curve in certain regions. I think the LT5 will always rattle a little, but I guess it comes down to how much you want to pull out on the attack rate reduction. I usually see one degree from time to time.

ON Edit: these cars were meant for pure gasoline 92 octane on the stock timing. I have seen chips that just had more ign timing in the 90-100 kPa regions only for safety(?). Even so, if it pings during summer, I back off the acceleration.

[XfireZ51]

Steve,

BTW, what is the Stoich AFR for the fuel u are using?

[jss06c6]

Steve,

BTW, what is the Stoich AFR for the fuel u are using?
Should be about 14.11.. 10% ethanol and 93 octane..
took out spark near torque peak because you can hear it pinging on CA 91 octane if it is warm outside. Funny though as soon as you get over about 1000ft above sea level, this diminishes greatly.

You can still run 27 deg on the top end, but need to compromise a little on the curve and be closer to the stock curve in certain regions. I think the LT5 will always rattle a little, but I guess it comes down to how much you want to pull out on the attack rate reduction. I usually see one degree from time to time.

ON Edit: these cars were meant for pure gasoline 92 octane on the stock timing. I have seen chips that just had more ign timing in the 90-100 kPa regions only for safety(?). Even so, if it pings during summer, I back off the acceleration.


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[jss06c6]

I'll switch Wideband to Lambda mode to verify..

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[jss06c6]

took out spark near torque peak because you can hear it pinging on CA 91 octane if it is warm outside. Funny though as soon as you get over about 1000ft above sea level, this diminishes greatly.

You can still run 27 deg on the top end, but need to compromise a little on the curve and be closer to the stock curve in certain regions. I think the LT5 will always rattle a little, but I guess it comes down to how much you want to pull out on the attack rate reduction. I usually see one degree from time to time.

ON Edit: these cars were meant for pure gasoline 92 octane on the stock timing. I have seen chips that just had more ign timing in the 90-100 kPa regions only for safety(?). Even so, if it pings during summer, I back off the acceleration.
Mike,

I can't actually hear any knock, but knock retard is definitely kicking in.. I rolled the timing down 2 degrees and will make another pull to see if I've tamed it a bit.

Steve

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[mike100]

Mike,

I can't actually hear any knock, but knock retard is definitely kicking in.. I rolled the timing down 2 degrees and will make another pull to see if I've tamed it a bit.

Steve

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You reduced the timing from stock, or from an aftermarket curve? I wouldn't go less than stock except for an emissions calibration to game a test.

[jss06c6]

After market tune.. still substantially more timing than stock.

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[jss06c6]

Crap.. just lost my post.. will do this again!

Have finished the VE tunes, both port closed and port open. BLM now hovers around 125-127 on driver side and 128-130 on passenger side. Had to command the secondaries open to get Port Open VE tables tuned without PE kicking in. Started WOT tuning using Wideband O2 data and Knock Retard table. Timing on first WOT pass was unchanged from my Haibeck tune. Had significant knock at WOT as you will see on the attached KR table. I rolled back timing from 29 degrees to 25 degrees (stock) at WOT and made another pass. Much better, very little knock now at WOT (see second KR table attached for comparison). I will probably roll a little timing back into it. My AFR is running 12.2 to 12.6 from 3500 to 6500 rpm at WOT. I'll probably take some fuel out before rolling timing back in to see were I begin to see some knock starting and hopefully get AFR in the 12.8-13.1 range. Then will roll back some timing.

I've attached the spark table for comparison. Black is my current tune, Green is the initial tune and Red is stock tune for '91.

I had also replace my MAP sensor hose that connects the hard tubing to the plenum. I guess the one I put on was too old and a bit small because it split when I was driving home after the WOT 4th gear pass! Glad it didn't fail during that pull!! Crazy trying to drive with MAP saying engine was at 85 kPa and the TB said it was at 3-4%! Impressed the LT-5 got home! Got it replaced with better hose (1/4" fuel/emissions hose, which is fiber reinforced) and all good again. I also pulled and cleaned the IAC as well as the port on the side of the Throttle Body housing. Both were very dirty (carbon deposits). IAC was going to zero before I cleaned it, so on Dominic's sage advice, i was able to take a couple of turns out of the TB stop screw to allow the blades to close up a bit. Now IAC is running at 10 steps at hot idle of 625 rpm. Exactly as commanded in the calibration.

More updates later as I dial in timing and fuel at WOT.

Can't seem to upload images to website... will try again in another post..

[jss06c6]

attachments

[XfireZ51]

I'd be interested in seeing table of the actual knock counts. The knock sensitivity in my calibration is significantly diminished from stock and I run more SA. Don't get any knock past torque peak, and that's very little anyway w 12.8-13.0 AFR.

[jss06c6]

I'll post it.. knock retard as you know is hysterisis, so it will pick it up at a certain rpm and load and take a bit to return to normal.. I wanted to get a feel for what I could do with timing to see if I could kill it, with stock sensitivity in place, then go up from there. I deliberately moved it down aggressively on this first pass..

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[jss06c6]

running sample count over same interval.. first is with reduced timing, second is original timing.. trying to post, but errors again. Will put in post on it's own to follow.

[jss06c6]

attachments

[jss06c6]

I've got a knock count table created, same x & y axes. Are you looking looking for running range? Sample count is not what we're looking for, yes?

[Billy Mild]

Are you burning new chips or using an APU1 unit?

[jss06c6]

Burning chips. Still fine tuning spark and fuel (VE). I've dropped the point where the secondaries open to bring the power in sooner. Nice rush without lots of throttle required. Been a while since I've updated everyone. I'll try to get a good summary posted later today!

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[Billy Mild]

Were there any issues you had with Haibecks tune, or are you just wanting to squeeze every last HP out of the tune?

[jss06c6]

Most of my time is spent in getting the Volumetric Efficiency dialed in. The engine was running very lean, but at WOT, it was a bit rich. Marc can't tune the VE remote since each engine has its own signature. He can do it if he has the car, but his mail order tunes are based upon his intimate knowledge of the LT-5 and he gets most of the way there while keeping the engineering safe. I've made substantial changes to the VE tables which dials in the fuel when not in Power Enrichment mode (WOT). The engine will have some additional HP as a result, but not a huge gain. It simply will run at peak efficiency. I have made some changes to the PE curve to bring down the fuel (think of it as a sustained pump shot in a carbureted set up). Using wideband O2 sensor, my AFR is now about 12.5. I will bring it down to 12.8-13.1, which matches Marc's ideal.

In summary, Marc's tune is exceptional for not having access to my car. I love to tune, so my time is spent refining his work to match my car.

I'll head back to the dyno later this spring to see where it sits, but I'm not trying to get HP as much as I am focused on optimizing the tune to get the engine operating at its best.

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[XfireZ51]

The curse and blessing of doing your own tuning is that you customize the performance and responsiveness of the car to your tastes.
On the other hand, you never stop which is why I usually have the Ostrich running the car.
Sometimes I take a break. Recently put in 4.10s so I want to check what if anything needs to be modified because of that.

[jss06c6]

Ostrich is a good next step. I'll be pulling the plenum and doing some mild porting, so will start all over again with fuel and spark! Insanity, but fun!!!

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[XfireZ51]

Ostrich is a good next step. I'll be pulling the plenum and doing some mild porting, so will start all over again with fuel and spark! Insanity, but fun!!!

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Yeah, I just pretty much leave it in there. I carry a spare prom just in case, but I've had Ostrich running the motor for months at a time. Need to be careful it doesn't get wet so I put it in a ziplock sometimes.

[jss06c6]

Yeah, I just pretty much leave it in there. I carry a spare prom just in case, but I've had Ostrich running the motor for months at a time. Need to be careful it doesn't get wet so I put it in a ziplock sometimes.
Dominic,

Also thinking about locating the APU in the center console and building a custom cable to the ECM so I can leave it in place out of the weather for extended periods of time...

Steve

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[jss06c6]

Gents,

Been a while and a lot of chips burned in the last 60 days. I got the VE tables looking good below 3500 RPM, but couldn't get the guts to try higher revs without the insurance of PE in place. I left my PE% change to Fuel/Air Ratio vs. RPM where Marc H. put it. Logged enough VE data with secondaries commanded open to get a decent look at the upper VE table (port open).

Had a number of 100 kPa zones at or exceeding VE of 100%! With the help of my Wideband and the ability to log this data, I could see three RPM zones where I was running rich at WOT. 2,000-3,000 was at AFR of 12.8 (target), 3,000-4,000 was at AFR of 12.3, 4,000-5,225 was at AFR of 12.1, 5,250-5,825 was at AFR of 12.5.

All power bands were rich, as suspected. I rolled timing down a bit as I was seeing too much knock (23-24 degrees at WOT and 3,000 to 6,500 rpm).

Tried to fine tune the PE curve... No luck. The algorithm overrode my entries and forced some wierd numbers. I left them alone and made the changes to the VE table to lean it out. Results put me spot on the target AFR of 12.8 at WOT across the board. #473 pulls well into the 7,000 band! I'll head back to the dyno to check the results of my tuning efforts. Suspect I found some of the 16 HP Marc suspected was there for the taking.. Will see! Meantime here's the dyno pass before the tuning work.. 345 rwhp, 349 rwtq..

https://youtu.be/lWVm_iVYpII


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