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Fluctuating idle?

(1999 Pontiac Grand Prix)
in Pittsburgh, PA on September 26, 2012
replaced iac, unclogged purge valve solenoid, disconnected maf(no change). still fluctuates
Displaying 3 answers & 6 comments
Popular Answer
on September 26, 2012
CHECK FOR VACUUM LEAK.
on September 27, 2012
replaced alot of hard brittle fittings and hoses. did a acuum leak test. all good. interesting enough though, I removed the pcv valve, cleaned it out and it appears the idle has smoothed out, but now the crankcase is building up pressure and not being released by the pcv. i must have done something to it while cleaning it out?????????????
on September 27, 2012
Replace pcv valve, check air cleaner box for debris or rodent nest. "Engine breather element and hose."
Clean throttle bore with carb. cleaner and tooth brush,get back side of throttle plate also. Engine will
run rough for a few seconds after cleaning. Just some random thoughts. Who knows, it just might work!
on September 27, 2012
already took the whole air intake system apart and vigorously cleaned it the throttlebody. cleaned the maf, iat, and the airfilter is clean and no sign of debris. at this point i really am leaning towards the pcv.
on September 27, 2012
Be sure to check engine breather as that is what helps purge crankcase pressure as pcv valve pulls vacum on it!
Good luck.
of Greg's Orange Auto on September 27, 2012
do u have any eng codes in pcm?
on September 27, 2012
got p0440....evap leak. checked fuel cap and its okay. tested and clened out purge valve solenoid and it tests okay.
of Greg's Orange Auto on September 27, 2012
poss vac leak
on September 27, 2012
Poss. intake manifold vacuum leak? Internal brake booster leak? Just some other possibilities?
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