RNAVDAVE

Tried that but got nothing, no codes, so decided to invest in special software an have a shot. I have determined that if I disconnect the battery for 60 seconds all is well for an undetermined amount of time. Last week this fix lasted from GA to TX and back then went dead after startup the next morning in GA when I got back. Really want to get the car fixed since it was ordered with the hardtop option and I still have it.

John A. Marker

RNAVDAVE, I checked on the INNOVA scan tool web site. Nothing there is jumping out at me. I am assuming that your getting one of the OBD1/II tools. Can't find a definitive answer on their site if it will work on the Corvette. The combo scanner indicates the ABS portion will work only on the 96 and newer Vette.

I tried Tuner Pro RT to data log the 94, but the data is garbage. It is all over the board. IE sitting at idle it tells me that some times the car is traveling over 100 MPH.... or the the RPM is now 3000 when your at 800-900 RPM.

I do find it interesting that your disconnecting the battery will give you almost a "refreshed clean slate" with out problems for an extended time period. The last time we had the car without any problem was for 30 days and the battery had not been disconnected at all. This kind of makes you wonder if the disconnection of the battery is somehow resetting the computer or something.

I will be interested to know what if anything you get from your scanner.

-John

RNAVDAVE

John an old friend of mine who is a retired Chevy mechanic who for over 25 years worked on nothing but corvettes told me that a battery disconnect on the 94 and 95 was an instant computer clear. He told me about one car he worked on for over a year and finally just installed a marine battery disconnect so the owner could do instant resets and the guy is still driving it that way after 200000 miles and says t may run for months sometimes. He had a look at mine a few days ago and told me he had never seen but three do it and they were all 94's. I really want to keep this car because I ordered it in 93 with the hardtop option and have had it all these years, along with 7 more I might add. Yes I have a large garage.

Let me know if you find anything else and by the way the INNOVA came in and will not work on 94/95 corvettes.

John A. Marker

When a company advertises a product....they should be up front with you if it will work with our cars! There was nothing on their web site that said it would or not work on the 94-95 Corvette. How difficult is it to have a listing? I think I would give them a piece of my mind on returning it.

Years past I bought a Auto-Xray for my 85. When I finally had a problem and used it...it told me it was a Vats issue. The 85 does not have a Vats system. I called them and they told me....Sure it will work on your 85. I had to make several calls and finally ended up with a technical specialist (after bouncing from phone to phone at least 10 times). He knew the product and the 85 Corvette and said No it will not work on the 85 because it has the 870 chip.

RNAVDAVE

WOW, as you noticed on the web site this one is supposed to work on the car. Problem is the 94/95 corvette has the 6 pin connector and this is for the 12 pin connector. I am sending it back.

John A. Marker

Assume it is a typo.....16 pin not 6.

Lynda has had her 94 for 4-1/2 years and this is the first time this issue has come up. Sounds like your the original owner of yours. If resetting the computer clears up the problem then this would lead me to believe the it is a computer problem and could be eliminated with a replacement.

RNAVDAVE

I am the original owner and this is working for me right now. Was out in her today for an hour and no problem. Wife got afraid of her and bought her a 2015 but I love the old red car.

cardo0

John i dont know how u can pull any codes on a '94 using the jumper (4-12). U need a scanner to look at codes and as kg4 mentioned look at the code history. I think OBD II has trouble faults that dont throw the CEL unless they repeat a certain number of times - maybe OBD 1.5 does to but id have to hook up my AutoXray to look again.
Ok now i read in later postes u are scanning for codes.

Something that i learned recently is u dont need to lose full pwr to trip the PCM/ECM. Just low voltage will do this. I know this is opposite your 41 code diagnose but if it trips the PCM then i think the PCM can get a little stupid (maybe a lot stupid). Not a full pwr loss but a voltage drop from an accessory or too many accessories. Maybe a "hot" connector from a bad crimp or just enough oxidation on wire terminals over time. All it takes is a voltage dip somewhere below 10 volts and the PCM/ECM/ECU trips. Then like u say it restarts as voltage returns. Ive read u have done a lot of connector cleaning but something u could try is disconnecting accessories one at a time. Or maybe turn them all on and add a load to the cig lighter circuit.

BTW John im ready to spend for the tunercats software and please let me know if it does the job. As far as i can read i need the TunerPro with the DataMaster and get the Y cable (Y not?). But i think the tunercats is the best choice - can u verify its good stuff? Its what my tuner used last time i had a tune.

OMT i dont like smacking anything electronic, it can create problems u didnt have before. Wiggling wire can do the same thing, more so with screwed terminal lugs. Myself i would do as in the pwr plant industry and take a photo copy of the wiring diagram and yellow line (highlighter) all ckts that have been tested (and in your case terminals cleaned/replaced/crimped).

John A. Marker

cardo0 - You can pull computer codes on the 94 and 95 by using a jumper between 4 and 12. This is not a scanner but a valid way of obtaining the DTC codes that have been recognized by the computer. Although the 94 and 95 have a 16 pin ALDL it is NOT OBDII but OBDI. The 94-95 is another red headed stepchild in the Corvette lineup. You do not need a scanner. I will refer you to....

https://www.corvetteforum.com/forums...-pin-aldl.html

As for the code 41, the FSM defines the setting of the code if the voltage spikes above 4.6 volts.....it doesn't not have to lose all power. The power could be less than 4.6 volts and there would be no code registered. The FSM also indicates that this code is ONLY set when cranking. This could have been set when the car died and she tried to re-start the car. But it doesn't make sense that code just dropped from the computer.

I am sorry, but I can't help you on your decision to purchase Tunercats. If your tuner used that program, there is probably validity to using it to program your car. I downloaded TunerPro RT in an attempt to get real time data logs for her car. The idea was to capture data that would lead us to narrow the search for the problem. But it turned out that the TunerPro RT datalogs were garbage. We could not get decent data with the car running at idle. If you can't get good data, you sure can't trust the data that would be logged with the car running down the road and then stalling.

Right now RNAVDAVE seems to have our best lead. Symptoms are the same and are leaning toward computer replacement. I have been PM'ing with him to see if the scanner will actually work on his car and data log. If it can, I will spend the money to get decent data logging numbers to help narrow down the area of this issue.

Dr_Shakalu

Is there any way of checking the battery voltage when the car stalls. I had his type of problem on the very first car I owned. I would drive and the car would just turn off. Idling, street driving, freeway driving or turning would sometimes cause my car to turn off. Checked vacuum lines, fuel system etc... and couldn't figure it out. Remembered that the previous owner put in a new battery so I took a look at it. Found that the positive cable wasn't completely tight so any type of bump or movement disconnected the battery and stalled the car even though the alternator was still working. Just a thought for a cheap, overlooked solution. Good luck.

John A. Marker

Dr_Shakalu checked both positive and negative terminals and they are both tight and clean.

John A. Marker

We had reached the point where anything else as far as testing was beyond our capabilities or equipment. So we had turned the car over to a good Corvette shop near by. They tested things for two days and did not nail anything down. We decided to say screw it and told them to install the PETRIS Optispark we had provided. This is vented so we felt it would be better than what was in it currently...the AC Delco. Car ran fine for 7 days and stalled again yesterday. We have not tired to pull any codes yet. This time the stall was hard, Lynda said it bucked or coughed a couple of times and died. It took 4-5 tries to start.

So now we are looking at those things that are out there.....ABS and ASR. We have pulled the fuse that houses the ABS and ASR. We are told that if the car does not stall in the future it will be the ABS. Crossing our fingers that we can finally solve this problem.

Update, we have learned that pulling the fuse will not isolate the issue. We have to actually unplug the 52 pin connector to the ABS located behind the driver's seat. We unplugged that today 10/20/2015.

LBA50

John, any new updates? I've been following this because my '96 has had the same problem since last summer. New optispark, new fuel pump, new plugs, new wires, all connections checked and cleaned... runs for days then stalls for no reason. No codes. Mechanic is stumped.

What's next?

John A. Marker

The issue has not been resolved yet. We unplugged the ABS unit on some advice that this could be the issue. In the mean time she bought a new car since she could not depend on the Vette as a daily driver. We are tracking the number of days she has run the Vette to get up to about the 30 day mark. If we get there without it dying, we will replace the ABS controller.

We are also looking toward the PCM as a potential. Just can't get a good handle on anything to make it fail consistently.

LBA50

The ABS can cause the engine to shut off? Wow. New to me. I might see how the ASR could kill the throttle (and engine), but not the ABS. Then again, if all else has been tried... why not.

PCM seems more likely, though it's not an easy thing to test (other than the "slap" trick) unless you can find a good one to swap for a few weeks.

Good luck and let us know how it's going.

John A. Marker

The ABS is fed a signal from the tach and in turn sends input to the engine. The wrong input or false reading out of the ABS and it would cause it to stall. This is not something that is predominant with the ABS system or the Vette. Just a very odd occurrence that can happen rarely. We are at that the "rarely" stage in testing now.

1993C4LT1

When the car dies, see if you get 5 volts from the coolant temp sensor, intake air temperature sensor, throttle position sensor. If you get a really high reading, that means ECM grounds are dirty. Really low number, PCM is bad. Point the black probe to a good ground, and the red probe to one of the sensors. Of course, ignition must be on when doing this.

John A. Marker

If you read the whole thread. The problem is that it stalls and then starts right back up. We can't get it to stall with any consistency to be able to test. And no codes stored.

Masterho

John,

It's been almost a year since your last update. Any good news?

RNAVDAVE

Not from me, I even replaced the Opti Spark, injectors and computer and still have the same problem.