Starter

MARPET

MEMBER
1999 PONTIAC SUNFIRE
2.2L
4 CYL
FWD
AUTOMATIC
111 MILES

My check engine light comes on sometimes, but then goes out after awhile. My ground wires are ok. Any suggestions?

Thursday, March 24th, 2016 AT 7:17 PM

5 Replies

CARADIODOC

MECHANIC
33,741 POSTS

There's over 2000 possibilities. Half of them refer to something that could have an adverse affect on emissions. Those are the codes that turn on the Check Engine light. The place to start is by having the codes read and recorded. That will indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition.

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Thursday, March 24th, 2016 AT 9:06 PM

MARPET

MEMBER
3 POSTS

I read the codes, said it was misfiring, but it wasn't. That's when I noticed someone had loosened the valve cover. So I put a new one in the other night, cause there was oil all over the engine. I also put in new NGK wires and plugs. There is a threaded bolt that sticks straight up from the starter, should it have a nut on it

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Thursday, March 24th, 2016 AT 9:24 PM

CARADIODOC

MECHANIC
33,741 POSTS

I don't know what bolt that is or what it's for. The misfires are often not felt. The computer detects them by the rotational speed of the crankshaft slowing down very slightly when a power pulse is missing. A scanner can show how many misfires occur in a specific period of time. A single misfire won't set a code. There has to be quite a few to do that.

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Thursday, March 24th, 2016 AT 9:57 PM

MARPET

MEMBER
3 POSTS

Thanks for your help, but I fixed the problem. At one point it was misfiring because someone had loosened all my spark plugs and valve cover and 1 bolt on the fuel pump. Oil was on everything. Check engine light came on because of a bare spot on one of the ground wires. I do appreciate your help though.

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Friday, March 25th, 2016 AT 7:16 PM

CARADIODOC

MECHANIC
33,741 POSTS

That doesn't make sense. A ground wire bolts to the engine or body sheet metal so it can be bare and touching since it's going there anyway. Any chance what you found is not a ground wire?

If the oil was causing the spark plugs to short out resulting in a misfire, that would set a diagnostic fault code and turn on the Check Engine light. You have to know which code was set to figure why the light was on.

Regardless, if the problem is solved, I'm happy to hear that.