strange idle

[01Townie]

when im in park or neutral, the idle surges every couple of seconds. not a high rpm surge, maybe 200-300 rpm surge from idle. its been doin this for a while but i really notice it now with the loud exhaust. any ideas on what it could be? i checked it with a scan tool and no codes were thrown from it. ill get a video of it once i get the time, maybe when im on my lunch break or something.

[miamibob]

Throttle body clean out or IAC??

[Ryan12689]

Possibly a misfire?

[01Townie]

Throttle body clean out or IAC??

I replaced the iac and cleaned out the throttle body last year

[01Townie]

Possibly a misfire?

That woulda thrown a code if it was a miss. I thought that's what it was at 1st but I checked it and only code it had was for the fuel level sensor which has been bad for a few months, and the problem started before that

[zoomie]

loud exhuast?....hmmmm id try looking at at the exhuast system, apparently the manifold bolt like to let go or break,as a well as the seal underneath just after the cats. a clean iac dont mean that it will work forever. i had to replace mine eventually becuase it would idle stupid at stop lights.

[miamibob]

Would get an OEM IAC. Don't know about anyone else but have seen too many issues with aftermarket ones - even new ones!!

[01Townie]

Would get an OEM IAC. Don't know about anyone else but have seen too many issues with aftermarket ones - even new ones!!

i went with a motorcraft IAC, i didnt wanna go with any other brand cuz i trust motorcraft over all of em

[01Townie]

loud exhuast?....hmmmm id try looking at at the exhuast system, apparently the manifold bolt like to let go or break,as a well as the seal underneath just after the cats. a clean iac dont mean that it will work forever. i had to replace mine eventually becuase it would idle stupid at stop lights.

i replaced the iac, i cleaned the tb. i think i might have a manifold leak

[sly]

it'll also do that if the MAF is dead/disconnected (found that out on my Mark one day - reconnected the MAF, all was well)

[wannabep71]

Not all misfires show a code I just dealt with a misfire on cylinder three that didnt throw a code, my buddies genesis found it though

[01Townie]

it'll also do that if the MAF is dead/disconnected (found that out on my Mark one day - reconnected the MAF, all was well)

i know its connected sly, but how would i go about tellin if its dead or not?

[01Townie]

Not all misfires show a code I just dealt with a misfire on cylinder three that didnt throw a code, my buddies genesis found it though

ill have to check into it, thanks!

[01Townie]

pulled the plugs...all SHOT! and have oil leakin in cylinder 4...im hoping valve seals, gonna kill myself if its the rings

[sly]

to test the maf, unplug it. if nothing changes... it's likely the problem. But it looks like you found the problem. Bad plugs.