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Forum namePerformance/Engine
Topic subjectweird idle, IAT CEL, IAT readin -40 WTF!?
Topic URLhttp://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=127003
127003, weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by rshissler, Dec-31-69 06:00 PM
Ok so when i start the car it hardly even revs past 1k and almost dies but then idles around 1200, then after driving for awhile it and i come to a red light it will drop and idle around 2k. Heres the kicker it will idle at whatever rpm i push the clutch in at or take it outta gear at under 2k. Like if i let the rpms drop down to 1k then push the clutch in it will idle around there, but if i push the clutch in at 1500 it will idle around there. So im also throwing a CEL for the IAT input high. Tonight while driving i hooked up my scanner and went through the livedata and the IAT said -40!!!. I removed the IAT sensor and it looks good and the heads still there so i cleaned it and reinstalled it but nothing. Im gonna remove the manifold tomorrow and reseal it with new gaskets and see if that helps the idle cuz im thinkin the idle is from a vac leak. I sprayed carb cleaner around it but the idle didn't change. Any other help guys?
127005, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by phr0st187, Dec-31-69 06:00 PM
Check for vacuum leaks, change the IAT sensor, and also check the TPS and MAP. Because a 420a runs on a speed density system, a faulty IAT can have quite a negative effect on engine operation.
127024, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by rshissler, Dec-31-69 06:00 PM
well i fixed the CEL and put in a new IAT. still got a whacked idle ant cant find the vac leak. Livedata reads IAT at 111 with the car fully warmed up sittin still. TPS (%) reads 9.4 consent with the idle keeps goin up and done between 1200-2000k.
127025, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by phr0st187, Dec-31-69 06:00 PM
Did you ohm out the TPS and make sure it was within spec? Also you may want to pull the IAC out and clean it up a bit. Maybe it's sticking or something.
127027, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by rshissler, Dec-31-69 06:00 PM
well the TPS should be good i just installed a new one less then 2 months ago. I think my intake to engine gasket is shot. i made the mistake of reusing it since there were only 20k if that on it and it looked good. All i did today was crawl under the engine and check if all the bolts were tight. So sick of messin with the car and just wana drive it without problems for once.
127032, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by phr0st187, Dec-31-69 06:00 PM
If you need to check for vacuum leaks I've written a couple ghetto ways in this post

http://forums.2gnt.com/dcboard.php?az=show_topic&forum=5&topic_id=126945&mode=full

Scroll to the bottom. I've see those gaskets go out pretty quick usually due to the oil leak from the valve cover leaking down on it. And you should never reuse a graphite or paper gasket. Metal gaskets are the only reusable ones and some rubber ones as well but you even have to change them sometimes.
127229, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by rshissler, Dec-31-69 06:00 PM
alright so i just got done changin the gaskets and i still got a high idle. Change the TPS and still nothing. It now constatly idles at 2k and when i rev it and let the rpms fall it'll go down to 1.5k then bounce up too 2k again
127230, RE: weird idle, IAT CEL, IAT readin -40 WTF!?
Posted by rshissler, Dec-31-69 06:00 PM
FOUND IT!! took the TB back off and deicided to removed the IAC and clean it and when i took it out i found this


it deicided to come apart inside the tb. So i put it back togehter and now it purrs like a kitten.
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