Ok heres the deal.I have posted several posts the last month and heres what is going on... January I found out that my opti went,because my waterpump leaked all over it causing it to fry out,well since then I have replaced the ECM,waterpump,Crank sensor,coil,Ignition Control Module,plug and wires,and another opti.When I start up the car it runs ok,(this is when the car is cold and has sat for a while).Ill take it for a drive and when I hit the upper RPMs it misses,kind of like the car jerks at WOT.After about 15-20 minutes of driving it the car will start missing bad and then it will die.I am very fustrated,the people at my local performance shop are baffled,they think it is a ignition problem but everything has been replaced.One of the board members here and my friend suggested that it could be another bad opti since the one they put in was not a GM opti.And he thought that it could be the Harness that goes from the top of the opti to the left hand side of the intake manifold.He thought that when the water pump went,all the moisture could have gotten on the harness and caused it to get all coroded.Please any guesses,my local GM dealer wants to charge me $300 just to do a digonostic check.I have already dumped $3000 into a car that still does not run,I could have already bought a blower for my 383. Thanks and please help me!!

 

A bad MAF sensor will cause the SAME type of problems.


have you had the PCM programed for the new engine ?

 

I checked your other thread in LT1 Tech and those are difrent... no start problems. This does not belong in Adv Tech and should be discussed in a engine specific forum. Transfering to LT1 Tech, thank you.

 

It's simple to check the signals to and from the PCM & Opti. Any shop with a Modis or an Advantage can check the signals. You could also do a cruder check with a DVM. But your symptom sounds similar to a fuel pump problem we had with an Amigo 8 years ago. That is when I learned not to buy electrical parts from the cheap auto parts places like Autozone or Advanced. The replacement pump would stop working after it warmed up.

If you haven't already done so, you should eliminate the fuel pump as being the cause. Watch the fuel pressure with a gage taped to the windshield if you have to, when the problem starts to occur.

In any case, invest in the correct tools to diagnose the problem and stop throwing parts at it. One thing you'll find when you buy tools is that eventually you'll need them again.

Start pulling plugs and see if they are burning rich or lean also. While you're there, check each one for good spark.

 

Thanks for the replies.The guys who are ripping me off,said that even with the car not running and just by cranking it over they tested the fuel pressureand it read 60psi.The carhas a mail order tunefrom ed wright.Could it be possible that a injector is bad.I dont think the guy that worked on my car doesnt know what is he is doing,he thinks that my ecm is fried again and that I have to pay $700 for new one plus another tune.I dont agree with this since I just replaced it and only put on 20 miles if that.Anymore guesses?your input is needed now more then ever.And Im on my 3rd opti but to tell you the truth I think now that the second one was fine and didnt need to be replaced.And the GM dealership is very sketchy to work on my car because it is moddified. Thanks for any more replies....

 

I would definitely go get yourself a fuel pressure guage and test the fuel pressure yourself b/c that shop sounds like they are trying to rip you off. unless you have an aftermarket fuel pressure regular.. the fuel pressure with the key turned to the ON position should be around 30-35psi and with the motor running at idle should be at 43.5psi. If they claimed it read 60 then either they are lying or you have an aftermarket FPR.

what kidna diagnostic codes do you get when this spell happens? Since you have OBD2 my guess is that you should have quite a few codes thrown that may lead you into the rigth direction. Whatever you do.. dont buy another computer!

 

Thanks for all the replies.I am taking mycar in Monday to a GM dealer hopefully it wont cost alot of money.Ill let you guys know the outcome,in the meantime anymore guesses?