i just rebuilt my 7a and now it is idling weird. it revs from 1500 to 2000 rpms back and forth. cant find a vaccum leak... any ideas?
7afe rebuild - 6G Celicas Forums
Most likely your engine is getting too much air which causes the ecu to dump more fuel in order to keep the AFR in check.
Have you driven it, does it have good power? Does it also surge under load or just at idle? Have you tried spraying around all the usual places to be sure of no vacuum leaks? If you close off the intake for just a second or so does it die quickly or keep running? (some cars you shouldn't cover the intake or you may pull the plenum O-rings out of their seats and if you already have a leak this could potentially make it worse just FYI)
Have you driven it, does it have good power? Does it also surge under load or just at idle? Have you tried spraying around all the usual places to be sure of no vacuum leaks? If you close off the intake for just a second or so does it die quickly or keep running? (some cars you shouldn't cover the intake or you may pull the plenum O-rings out of their seats and if you already have a leak this could potentially make it worse just FYI)
it only surges at idle.
and after i let off the gas it revvs for a second and then slows down
Have you tried cleaning the throttle body, a build up of carbon can and will cause surging. I think you need to keep looking for a vacuum leak though. Maybe the brake power booster diaphragm is leaking? Remove the booster vacuum line and plug it with a bolt to see.