Please don't say that. I'm scared that's what my problem may be.

 

OK, new clue today:

I left work early today to run by the post office by home. On the way home the car dies. I pull over quickly and throw on the flashers.

I put the car in neutral and crank it. Nothing.... After two more tries, it fires up very hesitantly. I rev it to make sure its good to go and I resume my trip home.

SES light is set, I'm about to go down and pull the code. Also, the tach is going NUTS. It was bouncing all over the place like it wasn't getting anything but an intermittent signal, and didn't once go over the 1K mark.

Codes are:

P0102 MAF circuit low input

P0372 Timing reference High-Res signal too few pulses

Both could have been the result of a separate cause like a short in the ignition, it is unlikely that either would be the cause because A) the MAF and opti are known good and B) the PCM uses the Lo-res pulse to guestimate timing if the high-res fails.

 

This is probably the only time I'll say this, but congrats on getting a possible tell-tale SES light.

Sounds like you're narrowing in on it.

 

Hey I know it man, I am actually pleased to have this happen because it may mean I'm closer to a solution.

I think the "mechanic" did not scope it after all. I think he didn't want to work on it so he just claimed it was all cam-lope.

 

Definitely go get your money back if he didn't do the assigned task and charged you for it.

 

I've worked on a few Corvettes... We've had MAF anomalies on the C4s. The customer insisted it was a bad MAF, but I wasn't convinced. Nonetheless, it wasn't a MAF after she insisted on replacing it.

There were two issues... one of the grounds was rusty which caused resistance and unusual readings. The other was another symptom for something else but we found a fuse in the main harness on the bulkhead... it was an oldschool short glass fuse which was blown. We replaced that and I scrubbed the ground. I fastened everything together with dielectric grease... still runs good.

 

Hi, I'm a newbie. I have a '96 that is totally stock. I have this same problem and am also going nuts. Unfortunatly I don't have the answer, but i have noticed that the scanner says, "desired idle; 650" while the Rpms are fluctuating around 750.
I can't find any vacuum leaks so I don't know what is causing this. My miss gets worse as the engine warms up, are you guys seeing these symptoms also?

 

I have seen mine doing a similar thing. In my case it says "desired idle" 650 and it idles 625 then 650 and back to 625.

Sometimes if fluctuates 675 to 650. its slow and almost un-noticeable. Maybe your IAC needs a quick cleaning.

Marvin

 

I'm pretty sure that any car isn't going to sit exactly on it's desired idle.

Mine bounces anywhere from -50 to +100 or so RPM from the desired. Factor in the cam lope too.

 

Well kiddies, time for a little update.

The last two nights I've checked voltages and ground in the ignition system to and from the PCM, ICM and coil, key on, key off, and running.

Even put the DVM away and got out my old analog volt meter, voltages were rock solid.

There does not appear to be anything wrong with the ignition system.

Next step I'm going to put the car on the dyno at a steady speed and see if its still cutting out like it was in September. After that......I have no idea.

 

Have you run datamaster on it? You think that would show it as u can look at the rpm it hesitated and look at all the other sensor readings while it's paused at that point. You can even graph up to 5 sensor readings so u can look at them over time in relation to one another.

Joe

 

I have autotapped the car over and over and over again. I have not seen anything unusual in the logs except the MAP reading fluctuating about 1" and the RPM dipping a little.

 

Died again today on my way home. Its started bucking and sputtering really bad like the opti was out, then died.

Managed to get it off into an office complex. Refired after a few minutes but it rans really rough and then died again.

My wife picked me up on her way home, we went by the BMW dealer and walked around some 3 series coupes (used), and ate dinner and then went to the car.

It fired right up and made it home, though it was cutting out a bit more pronounced than usual.

I think that somehow, through a bad connection or something, the ignition got really weak, and caused a bunch of missfires and the car loaded up with gas. Letting it sit for a while helped it clear up and dry out the plugs, etc.

So, I will not be driving it PERIOD until it is fixed once and for all. I'll carpool with my wife as long as necessary, and we may move up our plan to buy a 3rd car due to necessity.

Does anybody know the part number for the opti wiring harness that goes from the opti and plugs into the PCM harness over the pass. side valve cover? I am thinking of just outright replacing that one just for good measure.

It has to be something ignition related that I am missing with the volt meter and scans, must be something that is too quick for those things to pick it up.

It behaved like a dying opti, but we know the opti is good and it drove fine on the way home other than the "miss".

 

Sounds like you've definitely got a loose connection somewhere, or a blockage in said connection that is loose enough to work it's way around causing the intermintent problem.

Do a search for the vented opti conversion on here, someone just recently posted all the part numbers. But be ready, that wiring harness is like $65 bucks or so.

 

Well what did you end up finding out?

-CAL