GenVibe - Community for Pontiac Vibe Enthusiasts

OK so...had and exaust leak, took it in and they put from the manifold back to the muffler including the cat, a couple days later the engine light came on, cyl 1 and 4 misfire, I have never changed the plugs so I did that, ran better, then on idle light comes on Misfire code cyl #4, found bad intake gasket, now it runs a lot better, but it still has a slight mis on idle and if it idles too long the light comes on cyl #4 misfire. changed all 4 coils and all 4 injectors, LTFT is at -17.2 on idle or light throttle when driving, if I step on it it seems to clear up an drive fine, my gas mileage has recovered after the intake change, it almost sounds like there is some kind of leak near cyl 4. compression test is cyl 1-2 135 psi dry and cyl 3-4 150 psi dry, all cylinders held 100 psi on leak down, I'm tired of changing parts. so is it MAF or an O2 or WHAT!!!!! lol TIA



2009 Vibe 1.8 229,000kms

*update*

so MAF looked clean but after reading on this forum I sprayed it with Electrical Contact cleaner because I had some............noe both trim are in the negative -16 and -17 respectivly so I'm to assume it was the MAF sensor, or is it reading correctly and telling me I have a vaccum leak somewhere?

Yep, let's get back to the beginning and then worry about throwing extra parts in later. Are you the original owner and if so, are you saying you have never replaced the spark plugs nor the ignition coils in this 142,000 mile car? That is always the first place to start on these small, reliable, Japanese engines. You did say that you ultimately replaced both recently. Did you put in Denso plugs and Denso ignition coils? These small, reliable, Japanese engines are VERY finicky about cheaper parts, with repeat error codes coming back soon after installation.

denso coils yes and NGK top of the line plugs yet has made no real change, intake gasket made a big change yet it still has a misfire, maybe I can video record it and post it, almost sounds like the intake is leaking internally on each #4 intake stroke, unless the mechanice screwed up or didnt really do a leak down test and thats the sound I hear

the misfire cyl 4 code only comes up if I let it idle for 10 minutes if I start it and drive it doesn't come up

Are there any vacuum lines that hook up to the intake manifold runner that goes to your cylinder number 4? If so check for vacuum leaks on those lines. If you have a vacuum leak there, it is going to lean out cylinder #4 and mess up the fuel trim.