The car is a 1990. I bought a usb cable to try and figure out what's wrong. I'm not getting any data from the car. I used HyperTerminal just to see if there is anything at all and there is nothing. I connected it to another car and the cable and computer seem to be working fine. Any ideas on what could be wrong that nothings coming out? I have 5v between A and M. I don't have an oscilloscope to test for more than that.

For the curious I've been having a stalling problem. See thread here: http://forums.corvetteforum.com/c4-t...-stalling.html

 

Possibly a bad ECM but I think you said you have a working Check Engine Light? Does Mileage and Range work? You might also disconnect the TPS with it running and see if it generates a Check Engine Light and stores a 22. If all these things work ok, then it's more probable that the Cable Connector or software isn't right for your car. If one or more don't work, then I'd suspect the ECM.

I looked at your post and though Data would be helpful, you might also do a couple of simple things:

Clamp off the purge hose from the Canister to the Throttle Body. If it's continuing to purge at idle, that could fatten it up and stall it.

Clamp off the Air Pump Hoses at the Headers. If a checkvalve or faulty switching solenoid is allowing air to flow pass the O2, it will peg lean and dump fuel.

If the above checks out, examine the MAP vacuum connection and wiring harness. A vacuum leak or an intermittent loss of the MAP signal can be the same as turning off the key - particularly at idle. Some brilliant guy I know once crimped in a new MAP harness connector and did a fairly lousy job of it. It took two Dealers with some rather sophisticated graphing software to figure it out so when I see a MAP car with a stall, I usually bring this up. I recommend you go over the harness with a fine tooth comb particularly if you've done any work in that area.

If it's an Auto, see what it does in Park/Neutral and then in Drive. If it idles fine in the former and dies in the latter, you might suspect that it's lost the Park/Neutral Signal. Have you had the console apart for any reason? Most of these switches last forever but it's a bit tight under the console and when you start moving things around, wiring can get pinched.

Have the ignition module checked at a Discounter, but if this is a hot issue, it might check fine so you'll have to decide if you want to fork over the $'s to try a new one. Do examine Distributor wiring carefully, particularly the ECM connector which carries the Module ground.

Finally, quit monkeying with the Minimum Idle and TPS - there's no reason for either to be out of adjustment and it's a good way to cause additional problems.

 

Thanks anyway but I give up. Car is going to a mechanic.

 

Hyper terminal only works with a serial cable. You said you have a USB cable. You just need the proper PC application.

Try Datamaster - first 20 scans are free.

http://www.ttspowersystems.com/DataM...downloads.html

 

Mechanic still has the car. I'll let you know what the problem was once he figures it out.

The usb ones are actually the same as the serial ones it's just they have a usb to serial converter built in. It still shows up as a com port and comes up in hyper terminal.

 

Apparently the no data issue is intermittent. After playing with the connector and turning the car and the scanner on and off a bunch of times the mechanic was able to get data from it. Everything checked out fine. He said he doesn't know for sure what it could be and he would just be throwing parts at it. I don't know if I'm going to monkey with it anymore or bring it to another mechanic.
http://www.youtube.com/watch?v=wH26K9X71UM

 

A flakey ECM can drive the best mechanics nuts. Had one on my wife's 91 L98 car and finally got a used ECM at a local junk yard. Problem solved for $55 - the L98 ECM crosses to about 8 other GM applications and is a common part. Worth a try instead of continuing to throw parts at it. I read both threads and didn't see if you have a check engine light?

 

Yeah, it may be worth the $50 gamble. Check engine light is functional but no codes. If I do the paperclip thing I just get the normal code 12 or whatever. I'm hoping it gets bad enough that it finally throws a code. What ever the issue is I think it's very slowly worsening. It went from every once in a while stalling only in reverse, to always stalling in reverse, then every once and a while in drive, and now I can't drive it without popping it in neutral or it will stall at every stop.

 

Where did you buy the cable?

 

Just for the hell of it lower the baud rate, and see if it starts to talk.