idle is messed up?

[cj_92Bronco]

OK so i have a '92 xlt. 302 5.0L and the other day, all of a sudden, the check engine light came on and the RPM's just started jumping up and down. I was only going about 25 mph but even if i tried to give it more gas, lets say to 35 mph, it would do the same thing. once i got to a stop sign it completly stalled out, after spurting for about a minute, doing the rpm thing. at first i thought it just did it AFTER the engine warmed up, but after replacing a few things today (PCV valve and serpentine belt) it did it when i started the engine up when it was cold as well. Any thoughts on what i can do?

 

[Broncobill78]

Yeah, the ck engine light came on so pull the code(s) and see what it's telling you is wrong. That's where *I'd* start anyways.

 

[BroncoJoe19]

Yeah, the ck engine light came on so pull the code(s) and see what it's telling you is wrong. That's where *I'd* start anyways.

FYI... one can get some codes without expensive testing equipment. Pick up a Haynes Repair Manual for your vehicle, or a Chilton book and read up on it. I just did it with mine. Essentially all you have to do is to insert a jumper wire, and count the number of times your "check engine light" flashes on the dash board. Pretty cool

joe

Note to BroncoBill, and other posters,

IMO especially as a newbie, I was thinking that an instructional piece on how to pull codes might be worth putting together and pinning it to the top of this forum page. I havn't been around long enough to know how often the obvious starting point and suggestion is to pull codes, and the guy asking the question, hasn't a clue about how to go about doing it.

Just a thought.

joe

 

[4WHEELIN]

the same thing was happening with my rig, it turned out to be the iac motor. start your truck and put a flat head up to the iac and giver her a few wacks with a hammer and see if that helps level out the rpms, if so replace the iac, which takes about 5 mins.

 

[miesk5]

Note to BroncoBill, and other posters,

IMO especially as a newbie, I was thinking that an instructional piece on how to pull codes might be worth putting together and pinning it to the top of this forum page. I havn't been around long enough to know how often the obvious starting point and suggestion is to pull codes, and the guy asking the question, hasn't a clue about how to go about doing it.

Just a thought.

joe

Joe.

Some Info; unfortunately some manuals do not cover all the aspects of a self test using a jumper wire on non OBD II Broncos

Self Test for Codes;

Self Test - & Connector Location & pics, Bronco & Ford BEST PROCESS WITH DIAGRAMS! Source: by Ryan M (Fireguy50) at fordfuelinjection.com

http://fordfuelinjection.com/?p=13

and;

Self Test - A technician that is unfamiliar with the EEC Self-Test can mistakenly believe that continuous Memory codes are not present when they really are. He may run KOER Self-Test and get a pass code (111) and not realize that KOEO Self-Test must be run to receive any Continuous Memory codes. He may run KOEO Self-Test while counting MIL flashes and misinterpret the repeated hard fault pass code (111) to mean that Continuous Memory does not contain any codes. The engine temperature must be greater than 50