2000 grand am gt 3.4 engine studdering [Archive] - GrandAmGT.com Forum


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09-29-2013, 10:41 AM
So... this has been a headache for a few weeks now on "how to" fix this issue.

Work done (myself):

Fuel Pump
Fuel Filter
2/3 Coils
Ignition Control Module
Spark Plugs
Spark Plug Wires
Idle Control Valve
Cleaned MAF
Cleaned Throttle Body

After all this, my car is hard to start and I have to give a lot of gas to kick it over. I have double checked my spark plug to make sure they fire and double checked my fuel getting to the rail. Both are fine.

My OBDII reader gives me a 300 misfire code before and after. I've checked around the web for "possibilities" of my situation and comes down to

Fuel Injectors

ANY advice would be awesome right now because I need my car for work
Thanks in advance

09-29-2013, 11:35 AM
What is your fuel pressure?

Which cylinder is misfiring?

Have you checked the compression on all of the cylinders?

What kind of vaccuum readings are you getting at idle?

09-30-2013, 03:29 AM
Don't rule out the possibility of your EGR Valve being partially stuck open. Though mine eventually quit starting since it was stuck open, it did misfire a lot the 20 miles I drove it until I got it back in my garage. I had misfire code, but no EGR code. I completely overlooked it being the EGR valve, which resulted in me replacing the same parts in your list BEFORE finding out it was the EGR. It's worth a check. Good luck.

09-30-2013, 05:57 AM
@ris_boy: I don't have much of my tools on hand so I can't check those right now

@darkwave: I'll check the EGR valve soon as I get a some time.

09-30-2013, 07:53 AM
A misfire can be caused by a lot of things, and will definitely make the engine run rough, and can make it hard to start also. I'd check the catalytic convertor first. A plugged cat could cause all those problems you mentioned.

Also could be a problem with one of the two crank position sensors (control ignition timing), or the cam sensor (control injector timing), although you would normally get a DTC code for those if there is a problem.

If you are getting a P0300 code (general misfire), there should also be a code stored in the history for which specific cylinder(s) are misfiring. That could be useful info to have. Some scanners will allow you to look at current misfires for each cylinder while the engine is running also.

10-01-2013, 01:38 PM
alright... after a lot of time and testing came down to fuel pressure regulator and fouled plugs.

10-01-2013, 03:49 PM
Dammit!!!! that was what I was thinking, wish I'd have read this last night.

Glad you got it tho