engine problem-any idea?

[v96gts]

last autumn i revved my engine into the limiter.after that it bocked,cherked(missed?) at rpm´s over 4000 and full throttle.after a few miles normal driving everything was fine again.during winter i checked the engine-valve train-all was fine.now somethimes at hard driving the same thing happens again:cherking ,no power at accelerating....,suddenly everthing is good again -car runs strong like before.i already changed the plugs and computer(no engine code appears),but still the same.the car is a 96 GTS (98 engine with 16000 miles in it) with roe 10 psi ,w/m,heads,cam,headers,exhaust,fuel pump voltage booster,tb´s,etc....any idea? may be the coils or fuel pump?has it anything to do with the rev limiting?

thanks

Peter

 

[Fred(DrivingSchool)Kinder]

Try the plug wires.

 

[Schulmann]

I would say it is either a fuel or an electrical issue.
Rare that it is related to mecanical parts.

It looks like your Viper is "KIT" car rebuilt from other Vipers. What year is your PCM ? Some newer PCMs have a bad habit to break up ignition (around 4000rpm and above 5000rpm).

4000rpm is a special area for the ignition where you transition from retard to advance.

Above 5000rpm the newer PCMs have a grounding and a chip issues.

With a WBO you could easily diagnose if you have a fuel or an ignition trouble. Once you isolation this, you can easily fix the trouble. The WBO often helped me isolate my troubles. With a 10lb pulley I would even say, a WBO is a must to have. You miss fuel, and your engin instead of burning fuel it will burn your pistons.

Check also your VEC2 program, maybe your are not running on the right one.

Otherwise check ALL your wiring for loose connections ...

 

[Jack B]

You might want to take a close look at the plugs right after this event happens. If you drive it after the event the plugs won't give you any good data. A problem that comes and goes is probably electrical, as was mentioned earlier.

 

[v96gts]

I also don´t think that it is a mechanical problem,the next thing i will do is change the plug wires (as soon as i get the new set(next week)),the coils and fuel pump.
The vec 2 programming is okay,i tested 3 different programs.
The pcm i use now is the stock 96 pcm-i tried a 98 with 2000 update but the car likes the 96 more(problem occurs with both of them).

Peter

 

[davem]

I've diagnosed several VEC installed cars with this problem. Check your wiring harness very carefully - its there somewhere. Check 3 areas

1. Where the VEC plugs into the stock harness. If any wires in this harness are near or resting on plug wires or coils, fix it so they don't. Reseat these connectors while your at it. Make sure the resistor box is not near the plug wires or the exhaust header. The original harness clips into a bracket above the coil packs, some installers don't clip them back in and the harness lays on the coil/plug wires and creates lots of problems.

2. Check the VEC2. The connector going to that is not automotive grade. The little female pins in the black plastic harness that plug into the VEC can slide out and just make contact - but not enough under load. Push them all in with a tiny screwdriver.

3. Did you replace the injector clips when you installed the VEC? Another source of intermittent problems. Check the ground on the PCM.

good luck,
Dave.

 

[Jack B]

No intent to hijack this thread, but, I do have a similar question. Does anyone have a Gen1 with a VEC2 and the following problem - the car dies on de-accleration and takes several seconds till it starts. It seems to be more pronouced when accelerating on to a highway, then, backing off the throttle.

 

[Schulmann]

Read this thread :

Engin stalling

 

[v96gts]

It took a little time to check the car,but today i tried it again. New plugs-new plug wiring,car runs a little bit smoother but after a fast ride it happened again. It does not feel like it is ignition related-it is a jerking under load (80-100% throttle),starting at 3500 rpm.It seems that it is gone when i let the car idle for a few seconds-then it runs good again.In 2 weeks there is a corvette/viper race,i hope i have found it ´til then.I still think it has something to do with hitting the rev limiter last autumn,because it appeared right after that.

Peter

 

[v96gts]

I think i found the problem(s).1:Slipping belt-changed to a new one.2:weak belt tensioner-changed to a new one.3CM had faulty tables-repragrammed it to 96´version.4irty fuel pump-changed to a new one.
It was not one of these things , but a combination of all of them.That might be the reason why it happened only sometimes and was so hard to find(and so time consuming).Tried it a few times now and it id not happen again.
But now we have winter and i can´t try it anymore.Hopefully next season there won´t be any problem again.
I forgot: bank 2 is running leaner than bank 1-i will change that soon.

Peter