Expy 2002 Missing after warm up

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Dec 4, 2010 | 03:41 PM

sibcc

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Expy 2002 Missing after warm up

Hello,

My 2002 Expy has a miss/rough idle after warming up. It is smooth until it runs for a a while. It also stumbles on acceleration and gear changes under load. I can watch the engine and it begins a slight shake ater the warm up period when the idle drops to 600-700rpm. The Service Engine Light just came on. I'll have the codes pulled on Monday. Any ideas or possible suggestions? I'm thinking COP or the IAC.

Thanks,
Brent

Dec 4, 2010 | 07:09 PM

alloro

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I think you're right about it being a COP, perhaps more than one?

Dec 4, 2010 | 08:51 PM

rvbuilder2002

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I think this is also can be a symptom of of an EGR valve problem

Dec 6, 2010 | 08:49 PM

ronjeremy6

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My 99 just did this last week. Thanksgiving day actually. Check engine light didn't come on until the following Monday. I just knew it was going to be COP's, but I had the code pulled and it was the dreaded P0171/174 combo. Last time it was a vacuum line, so i looked up top and found ANOTHER vacuum line rotted in half. Drove it home, cut a piece of 3/8 inch fuel line, popped it on. So far so good. It did run rough for a few trips after fixing the vacuum line. But that may have been because the o2's were so out of whack.

Short answer, if you have the P0171/P0174 codes look for a vacuum leak near the firewall.

Dec 6, 2010 | 10:15 PM

sibcc

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The code was P0304. I tried just replacing the COP on #4 but it is still misfiring. I guess I need to pull the sparkplug and have a look at it. These were supposedly replaced about 6000 miles ago. I'll also switch injectors and see if that moves the misfire to another cylinder. Any other ideas and suggestions most welcomed.

Regards,
Brent

Dec 9, 2010 | 03:00 PM

sibcc

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I went ahead and checked and changed the plug on #4. There was evidence that at some point H20/coolant was in the hole. I'm utterly amazed at the lack of engineering that went into this head design from a design stand point. The plugs recessed in deep holes, the sealing of those holes, the hoses directly above the holes, the softness of the aluminum and the consequent plug blow out; the flimsy manner by which the COPs are attached. Just flat out stupid engineering.

RANT Mode Done

Anyway, changed plug and COP, but still misfirng. Checked IAC, Fuel Injectors, EGR, Elbow at rear, I was going to do a compression test, but decided against it due to the plug thread problems of these engines. Cleaned MAF. Cleaned up COPs and swapped # 1 with the new one from #4. Hooked up all the wires I removed plugged my vacuum guage in and started it up. Patiently waited for engine to warm up. Finally it's warm and to my amazement the misfire is gone. Vacuum is where it is supposed to be and not wavering. I'll be going for a longer test ride shortly.

Thanks for the ideas;
Brent