What the heck is my ECM doing???? - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums

indigorhages · 11-13-2012, 01:01 PM

This one has me mega-stumped.

So I have this 1995 Supercharged, boosted, z28 camaro. 6 speed of course. A few weeks ago, the car had the service engine soon light on, then it turned off, but I discovered then that it's OBD1 with 16-pin connector. So I bought the ALDL 16-pin connector that plugs into your computer via usb and I was using Datamaster TTS.

To the best of my knowledge, all I did was record two test sessions with the program. I did not erase or change any of the ECM setup. BUT, when I analyzed the data from those sessions, things got WEIRD.

Let me first say that the car hasn't been okay. First it rubbed into 4th gear, then we found out the slave cylinder was bad, then the master cylinder, then while on the test drive for the master cylinder, the tranny locked in 4th gear and wouldn't budge. It was towed home (so sad) and is still sitting in my driveway, stuck in 4th gear.

Well, the data I got from my tests included trouble codes for everything from the car is misfiring (knew that), to it lacks EGR equipment (knew that) to shift solonoids a & B failure, transmission component slipping, etc. to some really odd ones: codes that the Haynes manual for my car says should only exist for the v6 model. If my car is a v8, why is my ecm giving me DTCodes for a v6 model?

I contacted the former owner of the car, who was mildly helpful. -_- Apparently, he insists that the ECM in the car IS for a 95 z28, but that it includes some custom tuning software and setup (part of the boosted/supercharged deal). In his words, the DTCodes for shift solonoids should not exist because in a manual car, the driver IS the shift solonoid (I'm a newbie, I have no idea if I'm being told BS or truth, but I'd like to think he wouldn't lie to me :-S). He also said the ecm should not have any v6 codes (duh) but suggested that if it did (do what I say it did), it's possible that someone erased or modified the ecm tuning setup, causing the weird codes to show up. I'd love to get more information out of the former owner, such as the type of software, a copy of the custom tuned setup, etc etc etc, but since getting responses out of him is like pulling teeth, I don't know where to turn anymore. (Being fair, I'm sure I annoy the hell out of him with questions and he's really busy so I'm sure that answering my millions of questions isn't a priority)

I can probably post the details of the data later if someone would like, but what the heck is up with my v8 ecm throwing v6 codes?

cocobolo95 · 11-13-2012, 03:57 PM

Since you already have a cable, I would download the free trial version of tunercat obd1 tuner. You will have to pony up 20 bucks for the $EE definition file that is needed to read your lt1 95 pcm. The program comes with a definition file for a Cutlass. 30 day free trial on tuner. Get at TunerCat

Use it to read the data in your pcm, it will log it to a file you can study and compare to a stock 95 manual trans tune. Your now asking, where can I get a file of a stock 95 tune at. The answer is Monodax Homepage - TunerCat OBDII Scanner and Data Logger - MXScan Info- they have a forum dedicated to tunercat where people post up tunes for others to download. You may even find a tune for the mods your car has. SO compare the tune of what your car has in the pcm to what you've downloaded from the forum and see what's not right.

bobdec · 11-15-2012, 12:39 PM

Are you running Datamaster "EE" not another version other than EE. If so does the car information on the Datamaster display screen say "F-Car MT" (F-Body manual transmission).

indigorhages · 11-15-2012, 01:52 PM

Yes, it is Datamaster "EE" and yes, it says F-Body Manual Transmission. Again, I could upload the data if that would be helpful.

cocobolo95, I will do that as soon as I can. Thank you for that advice.

bobdec · 11-15-2012, 04:05 PM

Can you post up the .uni file on a sharing site ? When you do get Tunercat remember w/boost your tune has to be customized, so whatever you do make sure you save the original tune before you try loading any changes. Up front without seeing anything my guess is the tune is not completely correct for you setup. If tune is for a M6 then all the tranny diagnostics s/b disabled. Is you tranny a stock 6 speed, with skipshift working ?.

indigorhages · 11-15-2012, 04:49 PM

test.uni - 4shared.com - online file sharing and storage - download - Kelsey Minton
TESTING MASTER.uni - 4shared.com - online file sharing and storage - download - Kelsey Minton
Those are the links. The one titled Test is the first one I ran, the one thats Testing Master was run immediately after the transmission locked itself into 4th.

Here is what I know about the tranny: it is technically a stock 6 speed, I know the 1-2 ans 2-3 synchro were replaced with carbon kevlar. The skip shift light comes on at appropriate times, but I have no way of knowing if it's actually working. I know the former owner did a ton of work to this car, but unfortunately getting the information out of him is next to impossible.

2cat95TA · 11-15-2012, 06:57 PM

Not sure if this helps, but where was the car originally from? In 1995, Cali cars had an OBDII 16 pin connector, but were still OBDI cars

indigorhages · 11-15-2012, 08:17 PM

As far as I could tell from the carfax, the vehicle was purchased in Texas originally and the first owner moved to Georgia with it. It is an OBDI car, but has the 16 pin OBDII style connector. That's why I bought the ALDL cable, because no autoparts store around here has the 16 pin adapter for an OBDI reader (unless you buy it from them).

aappss01 · 11-15-2012, 08:32 PM

Quote:

Originally Posted by 2cat95TA

Not sure if this helps, but where was the car originally from? In 1995, Cali cars had an OBDII 16 pin connector, but were still OBDI cars

No all cars in 1995 had an OBDI computer and an OBDII connector. Regardless of the state they originated in.

cocobolo95 · 11-15-2012, 09:04 PM

All 95 f-bodies, no matter what state, were obd1 cars with the 16 pin obd2 style dlc. That is why people have trouble reading codes and scanning for data. They try using an obd2 scanner, which fits the dlc but won't read the pcm because of the different protocols used for obd1 and obd2.

obd1 only scanners are no longer made, execpt for the cheap ones that simulate a paper clip across the terminals. They only read 93 f-bodies.

If you want to scan your 95, you will need an obd1 & obd2 combo scanner in the hand held type. Or you can turn your laptop into a scanner by buying a special cable and using the free program freescan or the trial version of DataMaster. If anyone wants, I'll post up where to get the cable and programs.

indigorhages · 11-15-2012, 09:18 PM

updated program links would be wonderful. I have datamaster, but the freescan link I had didn't work :-(

cocobolo95 · 11-16-2012, 09:31 AM

Freescan link has been going down a lot lately, but it worked yesterday.
www.andywhittaker.com

The link is still up at 10:30 AM eastern time.

indigorhages · 11-16-2012, 11:07 AM

The link to download FreeScan on the webpage you sent was down as of 11:51 AM EST.

A few questions:

Is it possible that the computer was switched over to OBDII when the tuning occurred, or is it not possible to switch a 95 over to OBDII programming?

Also, along those lines, if an OBDII connector and reader were to be hooked up to this PCM (just a regular handheld) is it possible that they might have messed with or even erased the tuning setup?

bobdec · 11-16-2012, 04:12 PM

Never tried this site.. let us know if is valid .. FreeScan | Free Communications software downloads at SourceForge.net

cocobolo95 · 11-16-2012, 05:41 PM

Obd1 pcm can not be programed into an obd2 pcm. If obd2 scanner is hooked up, it will simply say that it can't communicate with the pcm. Tried the freescan site at 6:40 PM and it was up again, but took about 20 seconds to load up.