intermittent missfire [Archive] - GrandAmGT.com Forum

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blk_grn_97GT
02-20-2007, 05:25 PM
i have a 1997 GAGT 3100, 223,000 miles and i am having a intermittent problem.
it is fine in park at idle but while i am at low rpm and cruise it has a slight sputter that to tell you the truth is freakin annoying. the thing about it is, is that it doesnt do it all the time, most of the time it does it when i am under half a tank of fuel, i have a new fuel filter, air filter, and all fluids are correct, and i do not have any trouble codes, i haven't been getting but 20 mpg as opposed to the 32 mpg i usually get, probably because when it does its miss i get mad and run the crap out of it, but anyways if anyone has input i would be glad to listen.

blk_grn_97GT
02-22-2007, 05:53 PM
follow up, has anyone had problems possibly with a timing chain slap causing the car to retard the timing possibly causing a slight miss, just throwing things out there because i have tested the fuel system(ok) and found in my manual that timing could be a cause of my symptoms, and also i have never changed my timing chain and i have 223,000 miles on my 3100.

blk_grn_97GT
03-04-2007, 05:16 PM
another follow up, the missfire has gotten alot worse, i am really down on power and i finally got a check engine light, it gave me a P0303 which is a cylinder #3 missfire, i pulled the plugs and checked wires and didn't find the problem, i even checked resistance on the coils and they were fine and made sure i had good spark using a spark tester and couldn't come up with anything, so i am still waiting to see if anyone has an opinion on what to check next, currently still driving so a quick response would be great.

Sprucegagt
03-05-2007, 06:45 AM
I think it's time for a compression check on all cylinders. Given the high mileage, you may have a cylinder worn out.

blk_grn_97GT
03-06-2007, 05:29 PM
ok, thanks for the feedback, i broke down today and took it to a shop and they confirmed that i have a dead cylinder, burnt exhaust valve is my problem they said

gectek
03-06-2007, 07:27 PM
wow, now the only way you could have found that out would be one of 2 tests, the compression test and the cyl leakage test, well also a cyl power balance test, but those are usually run with a scan tool or a special engine analyzer, burnt valve sounds about right. i would watch out because the piston can get the valve pieces stuck in it if the valve started to chip from the heat