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Misfire like no other

MTXGTP

MTXGTP

New member
ok today i finally hooked up a scan tool to look at all my sensors and stuff and just to check on it plus i had what i beleived was a misfire well it is misfiring and its just one cyl, but it only misfires at idle. #4 is the only cyl. misfiring. well i think it might be a manifold gasket. any other ideas would be well appreciated.
 


MTXGTP said:
ok today i finally hooked up a scan tool to look at all my sensors and stuff and just to check on it plus i had what i beleived was a misfire well it is misfiring and its just one cyl, but it only misfires at idle. #4 is the only cyl. misfiring. well i think it might be a manifold gasket. any other ideas would be well appreciated.
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Plug, plug wire, coil pack?
 
ive seen it where a manifold will not seal and allow unmetered air into the cyl. causing a miss fire.
 
MTXGTP said:
ive seen it where a manifold will not seal and allow unmetered air into the cyl. causing a miss fire.
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sounds like you know what the problem is, yes?

ok let me backup you have a leak at the exhaust manifold gasket, and that would cause a misfire? Wouldn't running open headers cause a misfire on all cylinders then?
 


no at the LIM no im not sure cause i did a coolant pressure check and found out that im losing pressure but i have no leaks externally. im wondering if coolant could cause an miss fire.
 
I had this problem today actually...on a local's car. A slight coolant seep was killing one cylinder. Bad gasket in his case.

Is your plug wet from coolant?

Test to see if you have any spark at that plug. Pull it, and then put the boot on it and hold it with some insulated pliars. Have someone crank on it while you watch for a spark.
 


MTXGTP said:
ok but last time i tried this i got a not so very nice shock.
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That's why I said insulated pliars.

But if you said that you pressurized the coolant system, and it's bleeding off....you will need to find the leak. It could be going into the intake, or worse going into the block. If you think that you have it pegged at which cylinder it is, then pressurize the system again, wait for it to bleed off and check that plug. If it is going into the cylinder the plug will be soaking wet, and you have found your problem.

New intake gaskets could be in your future.
 
If this much coolant was going into the cylinder and fouling the plug to where it won't spark, I would imagine it would be very difficult to start. Do you find it hard to start at all?
 
I'm laying money on a plug going dead. I had the same problem were a plug just went dead all of a sudden. is the car running rich? One sure fire way to tell if your burnning coolant with the car running smell the exhaust gas's if they smell sweet then the cars burnning coolant. Keep us posted on whats going on
 


ok well today on the way home i started to get a miss fire during boost so plug has fouled. so would you say a intake or a head gasket if its an intake ill start on it tomorrow.
 
MTXGTP said:
ok well today on the way home i started to get a miss fire during boost so plug has fouled. so would you say a intake or a head gasket if its an intake ill start on it tomorrow.
Click to expand...

Don't you have to pull the LIM to get to the heads off? My vote is LIM gaskets. But that is just going by historical data.
 
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