Mechanics

WHY IS MY IDLE BECOME UP AN DOWN AFTER CHANGING IAC AN THE TRANSMISSION JERKING HARD ALL OF A SUDDEN ?

2003 Pontiac Grand Am • 120,000 miles

I just baught the grand am an noticed it needed intake gaskets we replaced the gaskets from intakes all the way up, after we changed them them the o2 sensor was reading bad, my first clue was the cadilac converter cause of the carbon build up that was in the throttle body, I cleaned it up, an flushed the engine twice due to the coolant being really nasty, brown. So when I took the converter off I noticed that it weighed aboout 60 lbs the honey comb inside of it was gone tons of sand. I changed that an the engine light went off. But noticed it had a slight of a idle issue when you started it it would idle extremely high at two thousand rpm. It would slowly drop down after a minute but sometimes wouldn't go down at all. No mind me the transmission had a little jerk a slight little jerk. But after I changed the (iac) for the idle noticed that the car don't idle up real high anymore it just idles up an down up an down now, an the transmissions jerk has become very seriously, where it'll jerk the whole car hard when shifting gears.
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Twinkiedelight05
March 6, 2012.




So do you have any codes now?Have you checked for codes since the idle is going up and down and the transmission is shifting hard?I would be looking for a vacuum leak also be checking the inlet air temp sensor.I have seen problems with the inlet air temp sensor connectors cause hard shifting.

Saturntech9
Mar 6, 2012.
No, what im finding with this car is eevery part I take off was a junk yard part, but i'll check them sensors an no no check engine light came on besides the evap one 102

Tiny
Twinkiedelight05
Mar 6, 2012.
If your talking about a P0102 thats not a evap code its a mass air flow sensor low voltage code.
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Saturntech9
Mar 6, 2012.

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