Data - 99 Corvette vert 6 speed, 80K miles, no mods, all stock engine, Z06 exhuast. been babied its entire life.

I did just put new plugs and wires on it about 2 months ago.

I am driving down the highway and start losing power, almost think the clutch is slipping, then it starts getting worse, hestating etc, no check engine light at this time, I am about 10 miles from home, so I pull over, shut the car off, pop the hood and start checking spark plug wires for damage etc. Nothing, so I jump in, car starts up and runs normal for about 1 mile then repeats, I pull over shut the car off, start it back up runs fine for about a mile, then starts bucking and losing power I cannot even go but maybe 10 mph. Now I am about a mile from home after repeating this process, and car is bucking when gas is pressed so I just kinda coast. then it sets the check engine light.

I pull the codes and get a P0336.. Look it up and just really dont see how crank sensor can be bad, but possibly?? So I am going to drive the car and see if it resets the code, I drive it for two weeks straight, no problems at all. runs great, no codes until this Saturday. Now it is throwing P0420 and P0430. Which is Cats or O2 Sensors both being bad?? I cleared the codes and they came back in about 2 days of driving. So I would think if a wire was damaged they would reset instantly.

You think when the car was bucking and running rough I fouled the O2 Sensors?

Plus anyone had a car buck like that and then run perfectly normal and still does? maybe something got wet? a ground? although the car hardly ever gets driven in rain. Maybe just bad gas? Water in fuel?

And I have never had any problems with the car other than replacing the balancer, AC and normal C5 stuff like oil pressure switch etc..

Just looking for some thoughts.

 

Had the exact same symptoms in my pickup. Changed the O2 sensors and no help. Found out it was the fuel pump losing pressure. Mine was only a year old but had trash in the tank and it fouled up the new pump. Everything ran fine after that.

 

I have to admit when it was acting up I was leaning towards a fuel pump issue, by just the way it was acting, plus when you shut it off, let it sit and then started it, this would allow it time to pressure the lines and give it enough fuel to run good until it burnt the fuel out of the lines. But now its running fine, probably just a matter of time.

Anyone else?

Thanks

How bout fuel filter?

 

Bumping this back to the top, as I drove the car today for about an hour with no problems, then it started missing out and throwing p0336 code, I could shut it off for 2 minutes and car will run fine for about 30 seconds then start missing out again.

Anyone know where to start? There is really hardly any information on a 336 code, other than people building new engines and this is all stock with 80K miles. I did change the plugs recently?

Thanks
Jason

 

I wouldn't be at all surprised if the crank sensor was going bad. I'm learning more and more that GM used a lot of cheap inferior electronic parts on these cars. So I would check the wiring to the sensor (if possible). You could also take it to someone with a Tech 2 scanner, I think they can communicate with the sensor and see if it is good or not.

 

I had the same intermittant problem. Had my tuner check it out but could not find problem. In the end, I kept getting oxygen sensor code set. Replaced the one sensor and the car has been fine since.

Hope its that simple for you.

'99 6 speed ...no electronic problems and 118k miles later still running good.

P.S. When it happened on the road, I would set cruise control on figuring the computer would compensate for whatever was going on. It work almost all the time while I tried to figure out the problem.

 

Thanks, I am thinking about putting a new crankshaft sensor in it, but have no idea where I would take it to do the relearn.

Just weird, I am going to get it up in the air and do some visual checks on the harness.

Its not my daily sriver so I am spending more time researching before I dive into tearing stuff apart.

 

Last night I replaced the Crankshaft Position Sensor, fairly easy job, I did'nt even have to pull the exhaust, just slid the starter back with wires attached and replaced the sensor, about an hour all in.

Also I did not have to do a relearn with a programmer, car started up and may be in my head but seems to run better. No codes...

I will keep this thread updated so someone later may find it in the search.