axle2152

I just drove my Uncle's 1994 Corsica from Tucson, AZ ot Western North Carolina this past weekend and being a 23 year old car it does have it's issues and now 182k miles on it. Doesn't appear to leak any fluids, burn oil so it's not completely worn out and the intent is to give this car to my cousin once he get his license and likewise we want it to be safe and as reliable as possible without breaking the bank.

So the issue is when the engine is cold you have to give it a little gas to get it to start. For a about a minute or two the engine runs rough and as it begins to warm up it smooths out. The idle speed seems to be about normal but does slow down a good bit when put in drive but has not stalled once in the 1,800 miles I drove it. I do smell gas fumes when it is left idling for a while so it would seem that it is running rich at idle. When driving at interstate speeds the car seems to perform adequately but does seem that you have to really put your foot in it before it shifts down to 3rd and to the floor for 2nd, not sure if this is just the way it is or if there might be something to due with a throttle cable or a throttle position sensor. The "Service Engine Soon" light will come on immediately when I let off the gas to coast and will remain on until the car is stopped and shut off, when restarted the light is off until I coast again.

So my idea was to get it to flash the codes back since it is a pre OBD II system but...not so fast turns out this is OBD 1.5 but still has the 12 pin connector but with the diagnostic terminal missing, only the ground and serial data terminals are in the 12 pin socket, so it looks like the only way to get codes, assuming the computer is storing the codes, is with a specific scanner and GM cable which I have no idea what I would need to do that and likely be costly.

I have not cleaned anything up as of yet. I do plan on cleaning the throttle body and idle air control valve, see if it corrects the problem as that could be the source of the problem. I don't have much on the history of the car, but was told that the previous owner always took it to the dealer for service which I can clearly say that's horse pucky.

I'm mostly curious if anyone has had the same symptoms and could give me a few places to start looking, the idle air control valve being one of them, but these sort of problems can be caused by many things but I am probably going to have a hard time finding a scanner and the needed cables to get more information (that info would be awesome to have as I am not getting much as to what is needed for this car's configuration apparently there were some '94 models with the OBD II style port that could be read by some OBD II scanners).

Thanks

kevinkpk

What "I" would do, complete fuel system tune up, clean throttle body, fuel filter. OBD 1.5 is a "Blinking Jewel". Here is a little insite to it. Also note, you can get scanner, and adaptor for it.
https://en.wikipedia.org/wiki/On-board_diagnostics

axle2152

That's most likely what's needed. Got home from work last night, thought I would see what would happen if I left the ignition on for a few moments and started right up cold w/o any throttle. Unfortunately, after the car has ran it will still right up every time, so I will have to try again this evening and see if it will start up normally without leaving the ignition on for a longer period of time (e.g. just get in and start it right up). My thinking would be if that the ignition has to be on for a while before starting that might indicate a fuel delivery problem, or if it starts right up probably dirty throttle body/dirty sensors. As for the check engine light coming on, probably going to need a scan tool or some means of getting live data (I have a feeling that codes aren't being stored? CEL doesn't stay on).

What's interesting is that this '94 Corsica has the old 12 pin ALDL connector and not the J1968 16-pin and on the 12-pin connector there are only two terminals populated... Only "A" and "M" have a terminal in it and the rest are just blanks. Either this is just OBD I without the diagnostic terminal or some other...platypus setup for 1994 year. Back in the day I did have a '95 Camaro that did have the J1968 connector and would fit a OBD 2 scanner, so I have a feeling something is weird here.

kevinkpk

You can jump a-b, and count the number of CEL blinks, that will give you the number, then you can look up the code

axle2152

That's what I thought I was going to be able to do but the connector only has pins for A and M, nothing else, in other words it's just a plastic molding so the connector fits but only has contacts for A and M pins which is serial data and ground. Unless, the pins are recessed very deep in the connector and I can't see them... I'll upload a photo of the connector when I get home and you'll see what I mean.

kevinkpk

I'd try A, and M