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Tech Xpert
Tech Xpert, ASE Certified Technician
Category: Car
Satisfied Customers: 292
Experience:  33 Years of experience including ASE Master Tech 27 certifications, L1 Advanced Diagnosis
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95 pontiac grand am SE: doesnt start..shakes..nasty misfire and dies

Customer Question

The Car is a '95 pontiac grand am SE quad 4 dual overhead cam w/ an automatic trans. The car is hard to start or doesn't start at all. When it does start it shakes the entire car with a nasty misfire and dies shortly after starting; sometimes within seconds sooner if you apply gas. When you press the gas while in drive little to no power is produced from the engine. Both coils are good along with the IDI computer; replaced the car's powertrain computer, map sensor, crankshaft position sensor, spark plugs and wires and checked fuel pressure at the fuel rail. Also when the inital problem happened the cat had turned cherry red and the honey cone inside the cat either melted or became blocked so for testing purposes the cat has been removed. When the car dies i get a late detonation while the exhaust valves are open, resulting in the occasional "fireball" from the exhaust manifold. I am all out of ideas unless i threw a rod but i am still getting compression on all cylinders.
Submitted: 5 years ago.
Category: Car
Expert:  Tech Xpert replied 5 years ago.
Hi eisele, Is the check engine light on?
Customer: replied 5 years ago.

it was on and off since i had bought the car read the computer and no codes are present got a malfunction from the crankshaft position sensor and low voltage on the maf sensor replaced both no codes returned i had also looked at the timeing and it was correct according to the hanes manuel with the proper timing marks alingned but still same problem

 

Expert:  Tech Xpert replied 5 years ago.
Was the replacement MAF new or remanufactured? Was the powertrain control module new or remanufactured? Do you know if the powertrian control module had a replaceable PROM? If so, did you switch the PROM when you replaced the powertrain control module? If not, was the powertrain control module flash reprogrammed?
Customer: replied 5 years ago.
maf sensor was new and the pcm was used in a junk car with rear end damage did not replace the prom or flash reprogram called GM dealer for replacment part numbers. Repalcement p/n matched and the junked car matched year engine and transmission. but i still had the same problem
Expert:  Tech Xpert replied 5 years ago.
So the car still runs exactly the same even after you replaced all of these parts?
Customer: replied 5 years ago.
yes i still have the same problem and i'm stumped
Expert:  Tech Xpert replied 5 years ago.
Let me do some research and I'll get back to you.
Customer: replied 5 years ago.

Thank you

Expert:  Tech Xpert replied 5 years ago.

Did you replace the ignition module? That is the most probable cause. Otherwise I would clear all of the codes and start the engine. The first code that comes back is the one I would concentrate on.

 

The other thing that could cause this is the camshaft sensor.

Customer: replied 5 years ago.

the idi integrated direct ignition module has been replaced and i will look and see if it has a camshaft sensor but i don't think it dose.

 

Expert:  Tech Xpert replied 5 years ago.
Ok, let me know. Thanks.
Customer: replied 5 years ago.

no camshaft sensor crank shaft only and it has been replaced

Expert:  Tech Xpert replied 5 years ago.

The only thing I can do is list the parts that could cause this. Each one has to be tested manually. Otherwise, I don't know what else I can go to help you. Here are the parts that I have experienced this condition with:

 

Ignition coil

MAF

Powertrain control module

Throttle position sensor

Crankshaft sensor

 

Maybe someone else could give input.

Customer: replied 5 years ago.

The only one that i didn't replace was the tps at a closed position it is 0.35v the Haynes manual states that the closed voltage should be less than 1.25 volts and at 96 % (throttle) open it reads 4.27v

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