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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 15201
Experience:  GM Grand Master Technician 2007. 14 years experience.
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222mk, 2001 SSEI Pontiac Bonneville P0300 Random Multiple Cy

Customer Question

2001 SSEI Pontiac Bonneville P0300 Random Multiple Cylinder Missfire.
Submitted: 7 years ago.
Category: Chevy
Expert:  Dave Nova replied 7 years ago.
Do you feel the engine running poorly? Does it miss under acceleration?
Customer: replied 7 years ago.

Yes to all. See this car ran fine and has 247k on it. It was running at max oil pressure reading 120 psi and was leaking out of various seals when i bought it. I replace all seals and gaskets even the pushrods and lifters. Replaced the plugs and wires as well. Used delcos since they dont run right on anything else. Had the ICM tested it was good and the coil packs were withing acceptable range. Car runs slightly off and has no power if it is in gear. if you rev it up the service engine light flashes and i get the code. Compression runs 160-180. Replace the oil pressure regulator valve and spring oil pressure is around 60 at idle now. Supercharger seems to always stay in negative boost though rarely comes off negative 8 anymore.

Expert:  Dave Nova replied 7 years ago.
How old are the plugs and wires? Have you verified that the plug wires are correctly routed? Was the intake manifold removed?
Customer: replied 7 years ago.
Yes as mentioned before the plugs and wires are brand new yes to routing and intake.
Expert:  Dave Nova replied 7 years ago.
Have you made certain the injector wiring is routed to the injectors correctly. The injectors are close enough together that the wires can get swapped around, causing a misfire.
Customer: replied 7 years ago.
Yes, the injector wires are good. I verified it with a wiring diagram from gm technet as well. Also the injectors are new.
Expert:  Dave Nova replied 7 years ago.
Any other codes besides the P0300?
Customer: replied 7 years ago.
nope every time you clear it it comes back and like i said earlier the car has no boost anymore.
Expert:  Dave Nova replied 7 years ago.
Drawing a blank on this one. I am going to opt out and give other experts the opportunity to work with you on this question. No need to respond back to me, it will just force a lock on the question to me and will not make it available to other experts. Someone should be with you shortly.
Expert:  Dan replied 7 years ago.
I have an idea.....I see you said that your oil pressure was high which is making me think that alot of oil was pushed past the valve seals and pistons clogging up the converter. Remove a oxygen sensor before the converter and test exhaust pressure. It should be udner 5psi if you reve it a few times if it goes over replace the converter.
Customer: replied 7 years ago.
That has not fixed the problem either.
Expert:  Dan replied 7 years ago.
You already replaced the converter or tested it? Thanks.
Customer: replied 7 years ago.
Tested and removed
Expert:  Dan replied 7 years ago.
Ok, I"ll opt-out of this question and leave it open to other experts. Someone will respond automatically if they have some ideas. Dont reply otherwise question will be locked to me. Thanks.