Thank you tequilaboy! That file is for a stock 88 4+3 right? I wonder why the bad idle issue returns once I plug the old PROM in? With it out, the car idles great in OPEN or CLOSED loop. It just missfires pretty bad on acceleration. I'm kind of glad I goofed that step up during my initial install to be honest. It is very frustrating because the new PROM gave me a glimpse of how well the car could be running if tuned properly. Going to try and call TPIS today, so far they have been unresponsive to my emails.

 

Prog ID BCC Size Year Release Date Eprom ECM Prom ID Scan ID Platform Engine Disp. Trans Trans Type Gear Ratio

32 ABTP 16.00 KB 1988 31852 16074756 1227165 4757 7841 YB L98 5.7 MK2 MAN G44
32 ABTR 16.00 KB 1988 31852 16074762 1227165 4763 7851 YB L98 5.7 MH5 MAN G44
32 ABTU 16.00 KB 1988 31852 16074800 1227165 4802 7881 YB L98 5.7 MH5 MAN G44
32 ABTW16.00 KB 1988 31852 16074805 1227165 4806 7891 YB L98 5.7 ??? MAN G44
32 ABTZ 16.00 KB 1988 31852 16074820 1227165 4822 7921 YB L98 5.7 MK2 MAN G44

 

Updated: Disregard since these comments are based on review of same old data so they are out of context. Content still included for reference.

Some comments regarding the latest log:

https://datazap.me/u/ta76/closedloop...193-37-102-127

What is shown here is early into the 2nd new log with warm coolant temperature and car already in closed loop. It includes some idling followed by drive off then moderately hard acceleration in first, second, and third gear in power enrichment mode.

Idling and drive off is running very lean. It richens up once in PE mode as expected. You can see when PE mode is active by observing the target AFR drop below 14.73:1 (while in closed loop). Open loop target AFR may also be influenced by load, rpm and coolant temp changes, but this is another subject altogether. For now, were talking about closed loop and power enrichment within closed loop mode.

From my perspective, nothing has really changed from the old prom to the new prom. It was lean before, it is still lean now. It needs more fuel everywhere. Can you raise the fuel pressure? I think I already brought this up earlier in the thread, but don't recall if it was ever addressed.

Miniram intakes are notorious for intake backfires and lean-pops as the front cylinders ingest all the air under light loads due to their inherently poor air distribution, but first things first. Get the closed loop fueling in order first.

 

I didn't catch this before. Same log initial idle region running very lean with both BLM and Integrator maxed out at 160 and 180 respectively, but still lean.

https://datazap.me/u/ta76/closedloop...&mark=10-26-45

Interesting to note is that the mass airflow is very low for the conditions (4 gm/sec @ 800 rpm), this is about 1/2 of the airflow that would be expected. Maf calibration at low voltage is suspect, along with a strong possibility of a significant vacuum leak with airflow bypassing the maf sensor. Of course, the Maf calibration may have been botched in the tune (rather unlikely, but a possibility). Hard to say without seeing the bin file details.

Looking at the fuel trims only, you can see that it is lean nearly everywhere (elevated BLM) with the exception of cells 2 and 3. Just not enough integrator activity (due to low injector pulse width limitations) in cells 2 and 3 to allow the BLM to ever climb in those cells. On the next ignition cycle they should be populated with SAM data from cell 10 which was running in the 150s.

https://datazap.me/u/ta76/closedloop...65-79-81-82-84

Old prom log shows exactly the same fuel trim trends:
https://datazap.me/u/ta76/88corvette...&solo=11-70-82

 

tequilaboy, I owe you a beer! Thanks so much for looking at the logs in detail! I will bring all this up with TPIS if they ever return my calls or emails. Otherwise, I'm going to request a refund (yeah good luck right?) and try to find someone who can help me tune this sucker.

Is the Lean condition causing the missfires? I will look at the fuel pressure and request the BIN file from TPIS too.

 

Hello TA76 and tequilaboy.

I would seriously think about replacing the oxygen sensor if it is over 24 months old. Your O2 readings showed it taking it's sweet time coming into play. Older O2's tend to take time to get going and lag behind on their data being sent to the ECM which then become drive-ability issues. They are cheap and very, very important to your Corvette's engine control systems.

Something wacky is clearly going on with the MAF settings. I have never seen the airflow decline like that over time.

I thank both you TA76 and tequilaboy for the educational help here, this is most interesting data and I have a LOT to learn...

 

Upon closer inspection, looks to me like the old and (both) new prom logs are exactly the same data. Somehow the same log file was uploaded multiple times to datazap with new names. Disregard my previous comments. Check the time signal. All 3 logs 299.27s duration. Thought they looked a bit too similar.

Got any new data with the new prom?

Duplicate logs for reference:
https://datazap.me/u/ta76/88corvette...20-21-50-53-70

https://datazap.me/u/ta76/closedloop...65-79-81-82-84

https://datazap.me/u/ta76/88corvette...&solo=11-70-82

 

Well bummer I must have done something wrong doing the data log. Do you have to start a new file maybe? I just plugged in the cable and started the scan. I did manage to get on the horn with TPIS today. He thinks the issue might be with original TPIS PROM too and suggested I replace it with a stock unit. I'm going to go that route first since I'm already down this rabbit hole. I'll swing by and pick up a new O2 unit today as well.

 

[QUOTE=TA76;1604130951 I will bring all this up with TPIS if they ever return my calls or emails. Otherwise, I'm going to request a refund (yeah good luck right?) and try to find someone who can help me tune this sucker.

[/QUOTE]
Back in 2005 when I had a 408 Superram engine built I had TPIS burn the proms. The first one the electric fan would not turn on and the car would die after a half hour and I would get a CEL for prom failure. The second one the car wouldn't even start. The third one the car ran like ***. They tried to blame me.

I had a company called Street and Performance (out of business) burn a prom and it ran like a bat out of hell , perfect first try. I think they just don't care about this antiquated technology anymore....

 

I would still call them and see what they can do but that being said I looked at some of there tunes and it appears to me that they do not know what they are doing when it comes to tuning. Sure if they have your car in person they may be able to make it work but sight unseen seems very questionable.

 

Generally you need to record and save the log file with a new file name. Some tools (like ALDLdroid) will provide a date based filename for you, with others (like TunerPro) you need to manually create a new file name after stopping the recording session each time. Sounds to me like you were just monitoring data without actually recording and or saving it to a new file. Once you have a valid file, you need to open or view the new file and then export the data to a new csv file and finally upload to datazap (after some clean-up editing) if you wish to share it with others.

Sounds to me like TPIS is blowing smoke with respect to a stock prom/memcal.

I would again suggest clearing codes again (by disconnecting the battery or ecm power supply) and record a fresh log with the new prom (and old memcal) installed properly to determine the current status.

 

Yep, I'm getting the impression they (TPIS) are more than happy to take your money but that is about it. I've ordered a Memcal from another source, hoping it will do the trick. At least the guy seemed interested in helping me solve my problem. I'm going to wait for that chip to arrive before I mess with it anymore.

Stay tuned... more to come!

 

We are learning lots from your experience here TA76!

I am using a Holley Stealth Sniper and it has the ability to data log as long as you have a computer or tablet inside the car with you. I have very little experience with setting up a timing table or anything so I am very happy that I have a system that self-learns! Looking at 2d charts of timing or fuel data is enough to make me cross eyed after a while. Setting up a new Fuel Injection system is not for the weak of heart so I made sure I had a good technician behind my system helping me get the most out of it. I get 2 years of awesome support from the EFISYSTEMPRO after buying my system from them.

Watching and learning along with you TA76 has been VERY HELPFUL. Unfortunately I keep coming up with questions.

We are lucky to have Tequilaboy on this forum at the right time!

I will be watching closely as you get your Corvette working 100% with a little help!

 

Reading this from the beginning, have we established adequate fuel pressure? I.d. fuel injector pph? Without PROM burning capability, if there's no vacuum leaks, I'd throw some fuel at it.

 

Agree with you there about Tequilaboy and learning about this system! I picked up one of the books I think he recommended in another thread. Got it yesterday and have already read all of the TPI related info. One thing I learned that surprised me is that the car goes back and forth from OPEN to CLOSED modes. WOT is OPEN, cruising around is CLOSED. I assumed that OPEN was for warmup only, then the car stayed in CLOSED mode after that.

Stew86 - my plan is to put in a new O2 (book explained why they decay), put in the new MemCal and see what happens. If that doesn't get it, I'm going to check FP and move forward. I think I mentioned earlier that the idle was spot on with the new TPIS PROM when I omitted the MemCal. The car even seemed to run better (until I got on the throttle). So, I have hope that this is a software issue that can be resolved by finding the right setup.

 

Hello again TA76!

I was surprised when I first learned of the "Open Loop" happening at long stop lights and such. One way to keep it in Closed Loop more of the time is to use a Heated Oxygen Sensor. Our non-heated variety on the earlier C4's have a habit of cooling off and going off-line when they sit idling. Having the heated O2 would make the emissions cleaner by keeping the car in closed loop longer.

This is another reason to replace the O2 as the older they are the more they cool down faster and the signal starts to lag behind the actual driving conditions. Older O2's just don't work as well as a new one will in most cases.

There is a Book I use often and it is called:
(How to Understand, Service and Modify) Corvette Fuel Injection & Electronic Engine Management, Author: Charles O. Probst Published by Bentley Publishers

This book is very in depth with the way things work on the C4 Corvettes. It covers the L83, L98, LT1, LT4, LS1, LS6 and ZR-1 engines and is a very handy book to read. This is One book I strongly recommend for C4 Corvette Owners. It explains the EFI systems in a very easy to understand format. It explains HOW things work and what they do and even how to get more performance out of the parts. It is well worth the money...

 

Next time you take the ecm out, take a peek under the blue cover on the old TPiS memcal to see if it has a socket installed (or if the eprom is soldered in place like a factory memcal). You might get lucky and find a socket installed that will allow for easier eprom swaps. A socket and eprom might not fit under the blue cover, so that by itself may be a clue, but worth it to take a look once you have access.

I prefer to use a socketed memcal rather than a plug in adapter to eliminate potential connection issues, but haven't used the blue cover for about 20 years or so.

Note: if you really want to test the limp-home functionality of the old memcal itself, you could try it with the adapter installed but no eprom or a blank eprom to simulate a prom error. It won't run very well, but should be able to run with rudimentary spark and fuel control with stock-ish injectors. I don't think a factory memcal is going to do anything for you. It is possible that it will be better than what you have now, and a stock bin such as ABTR may make a better base for future tuning endeavors, but tuning will be required in either case.

Would still love to see new data with the current configuration (adapter with new eprom and old memcal installed properly in ecm). Try and record a log before pulling things apart.

 

New MemCal came in this afternoon and new O2 sensor should be in tomorrow. Looking forward to seeing how this goes this weekend maybe. tequilaboy, I do intend on experimenting with the chips I have. I'll take a photo of the old MemCal with the blue cover off (had to remove it anyway to hook up to the adapter TPIS sent). One thing I have noticed on my setup is that it still retains the factory fuel injectors albeit blueprinted/rebuilt. I would have expected larger injectors. Am I wrong?

 

Yep, that is the book... it might have been you that recommended it. Lots of good info there on how the system works. Any suggestions on a book to learn tuning on one of these?

 

Hello again TA76!

I apologize for repeating the suggestion about the book by Probst. I think that book should be a "must read" or a "must have" for most of us C4 owners as the way he explains the systems makes sense. If I find a good tuning book I will share it with you as that would be very useful to have as well.

"Tuning I am learning with my Holley Stealth Sniper and the Holley Software. The computer learns and slowly is filling in the blanks on some of the charts. This system will tune itself and get the best overall performance but the opportunity is there to go in and "tell it what to do" versus "Self-learning". The software is really meant for more specific applications but it can and will be able to control my Methanol/Water injections system for me along with the timing and fueling. Holley spent some money developing the software, it is pretty good from my perspective. I am also working on a way to get the system to have a Knock Alert using one of the extra 0-5 vdc inputs.