Idle drops then surges.

baddmove · Feb 3, 2011

I took it to O'rielly's here in town and they did the code check but could not come up with anything that helped, one guy said EGR valve,another said O2 sensor..this is on my 89 Bronco II, anyone have any ideas? I don't have much cash and this is my work truck..Thanks..

TimR · Feb 3, 2011

baddmove said:
I took it to O'rielly's here in town and they did the code check but could not come up with anything that helped, one guy said EGR valve,another said O2 sensor..this is on my 89 Bronco II, anyone have any ideas? I don't have much cash and this is my work truck..Thanks..

check all the vacuum lines.

IRKillroy · Feb 3, 2011

the IAC.... clean out your Idle Air Control valve... then readjust your idle per the Manual. If it's still happening then you need to look into your TPS for issues. Read the Manual to find out how to test it. After that, with no codes, I'd guess EGR. But those first two are easier then messing with the EGR.

That and what Tim said.

Nathan123 · Feb 3, 2011

Could try cleaning the throttle body. +1 on the vacuum lines and IAC. The IAC costs about 70 bucks so hope that cleaning it works. My bii actually had some bad vacuum lines, the ones that come off the manifold and go to a three way plastic disk over by the blower motor.

voodoochylde · Feb 3, 2011

89's don't have an EGR system, do they?

birddog321 · Feb 3, 2011

My 84 did that and it was the coil going bad.

headhunter257 · Feb 4, 2011

mine did this my old one and 2 things could have bin the problem 1 was the in take fuel pump witch only had 90xxx km on it and the other one witch happen down the road was the inursha switch the roll over switch for people who cant spell that word aka me was broken it would reset its self over night then cut out on the road then wait 20 and it would be fine that took a lot of money to fix i jut ended up cutting that dam thing out and hot wiring it in and put it back in when i went off roading then flipped my truck 27 feet down a cliff and the dam thing did not shut the truck off,,, laugh

Idle drops then surges.

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