AFM, cause of rouge idle? and cause of blown manifold gasket
05-19-2004, 08:30 PM
#1
Nordschleife Master
Thread Starter
AFM, cause of rouge idle? and cause of blown manifold gasket
Well i did something sorta stupid, i believe i may have over oiled my K&N filter the last time i cleaned it (last week). Over the last few days my car has been a little hesitant starting up, when it starts it idles very low hovering just over 500-600rpms. Its only stalled once, but started right up after i cranked it again. The idle smoothens out with the rpms raising too about 1200rpms and dropping back to normal idle, then going back up to about 1100rpms every so often in idle. When i put the car in drive (automatic car) the idle smooths out, but does run slightly rough. I figure i over oiled the filter, and maybe some of the oil may have clogged the AFM. Is it possible to clean the contacts on the inside of the AFM out with electrical cleaner?
I spent the day brainstorming as to what the problem could be, i thought it could possibly be the blown intake manifold gasket on the #1 cylinder. Which leads to my other question, this gasket blew out about 2 months ago, i sealed what i could with form a gasket which actually did a pretty good job at sealing the leak (but not fixing it completley). What could cause a blown intake gasket? I finally have time to replace them this weekend, wondering if anything else should be checked while i have the manifold off. I figured the blown gasket could be the problem, but ive been running the car like this over 2 months, these symptoms started around the time i changed the filter back.
Normally i would be pissed that i did something this dumb, but im really not as im hoping to sell this car in a few months. Its just a car and life goes on. I know i know, K&N doesnt do anything for peformance. Ive been running the stock Mahle filter for the last few weeks, other than the nicer sound being gone i really dont notice any difference at all. I think im gonna retire the K&N for a few weeks.
I spent the day brainstorming as to what the problem could be, i thought it could possibly be the blown intake manifold gasket on the #1 cylinder. Which leads to my other question, this gasket blew out about 2 months ago, i sealed what i could with form a gasket which actually did a pretty good job at sealing the leak (but not fixing it completley). What could cause a blown intake gasket? I finally have time to replace them this weekend, wondering if anything else should be checked while i have the manifold off. I figured the blown gasket could be the problem, but ive been running the car like this over 2 months, these symptoms started around the time i changed the filter back.
Normally i would be pissed that i did something this dumb, but im really not as im hoping to sell this car in a few months. Its just a car and life goes on. I know i know, K&N doesnt do anything for peformance. Ive been running the stock Mahle filter for the last few weeks, other than the nicer sound being gone i really dont notice any difference at all. I think im gonna retire the K&N for a few weeks.
05-20-2004, 08:11 AM
#2
Race Director
"The idle smoothens out with the rpms raising too about 1200rpms and dropping back to normal idle, then going back up to about 1100rpms every so often in idle."
A rhytmic up and down idle is typically caused by a leak after the throttle-body.
"Which leads to my other question, this gasket blew out about 2 months ago, i sealed what i could with form a gasket which actually did a pretty good job at sealing the leak (but not fixing it completley). What could cause a blown intake gasket?"
Yep, that's why your gasket blew out. NEVER EVER use any silicone sealants on parts that may see oil. The oil causes the silicone to get slippery and expand into a weak foamy mess. Could be coincidental, but perhaps you over-oiled the K&N filter and some of the oil found its way into our intake and started to mess with the silicone you used on the intake gaskets.
The only place that silicone sealant can be used on our cars is on the water-pump gasket. Buy some new intake-manifold gaskets, they're about 1.75 each. Install dry.
A rhytmic up and down idle is typically caused by a leak after the throttle-body.
"Which leads to my other question, this gasket blew out about 2 months ago, i sealed what i could with form a gasket which actually did a pretty good job at sealing the leak (but not fixing it completley). What could cause a blown intake gasket?"
Yep, that's why your gasket blew out. NEVER EVER use any silicone sealants on parts that may see oil. The oil causes the silicone to get slippery and expand into a weak foamy mess. Could be coincidental, but perhaps you over-oiled the K&N filter and some of the oil found its way into our intake and started to mess with the silicone you used on the intake gaskets.
The only place that silicone sealant can be used on our cars is on the water-pump gasket. Buy some new intake-manifold gaskets, they're about 1.75 each. Install dry.
