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I am working on a 97 Cavalier 2.2L that will not start. I have great spark. Compression is at 170 -175lbs. There is no back pressure in the exhaust. Fuel pressure was at 38lbs, found a leaking injector, replaced the injector o-rings on all injectors, and fuel pressure now at 41lbs. each injector resistance at 12.8 ohms.

I believe that it is overfueling, when I roll the vehicle over it locks up similar to an overadvanced engine or an engine dumping fuel. the fuel injector Pulse width is at 34.5 ms at closed throttle and drops to 0 at WOT. The TPS is at .47v closed throttle and climbs to 4.6v at WOT with no dropouts or glitches. The ECT is at 13 Celcius. The Map stays close to 103 KPA even with roll over, I have smoked the intake and have found no Vacuum leaks. I have inspected the valve train and all valves are opening and closing proper. The O2 sensor is at 447mv and the vehicle is in Open Loop. Any ideas, I'm up for any sugestions , Oh yeah, there was two DTC's one was P0300 misfire, and the second was P0335 CKP sensor "A" circuit problem, I have replaced the Crank Sensor and now there are no reoccuring DTC's.

I have tried to start the vehicle with the o2 sensor removed and the results are the same. the vehicle will pop a couple of times buy it doesn't want to start, I feel that it may have disturbed vacuum, I dont feel that the engine is drawing good breath of air. I will do a leakdown test next maybe I'll find somthing there.

Leakdown tested good , cylders hold good.If I try to start at WOT the vehicle tries to start. I know that it is probably somthing simple , if anyone has any suggestions, even if you think they are not relevent, I am running out of ideas
Installed and flashed new PCM

I have gotten the vehicle to run on propane, I disconnected all injectors and supplied propane to the throttle body. So now I am positive that it is an overfueling condition. again the injector pulse width is at 34.5ms at closed throttle. What can cause the computer to demand such a high pulse width, could it be a bad PCM?

You can get a PO335 on 'cranks but does not start' if you try to start the engine more than 15 times unsuccessfully and do not shut the key off between attempts. I would ignore codes at this time.

if there was a bad injector yank an o2 sensor before the cat and see if it fires up. cat could nhave mented because excess fuel over heated it. it seems you repair the initial fault now you have to deal with collateral damage. good luck.

Three thing have major control of the fuel time
1. Coolant temp
2. Mass air flow or Map senssor
3. O/2 sensor after warm up.
4. Reported engine RPM. To ecm.

does 170 - 175 compression seems hi, for a 97 cav. maybe t-chain off a tooth

So what fixed it??

Arlin

I read "replaced and flashed pcm". It was in the original post near the bottom.

I would recommend that the authors of these posts would update a fix in a separate post instead of editing the original. It would be a much easier read.

Yes please, let's summarize the FIX in a fresh post later in the same thread. I missed it as well.

Sorry about the confusion, a new pcm fixed this one