very rough surging idle HELP...

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Jan 5, 2012 | 06:01 PM

rlwilson2

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From: Nevada

very rough surging idle HELP...

A friend came over to change front bearing in 94 f150 4x4 5.0 AT. we changed bearings and he complained of it running odd occasionally. My multimeter was bad so we jumped the OBDI EEC to watch the codes on CEL... well check engine light is out.. started to check for belt noise no problems.. then we took off the belt to check for belt noise found steering pump bearing as problem put belt back on reset cpu by disconecting positive temrnal for 10 min. when started the truck runs awful... Idle is rollercoaster surging the exhaust is very rich, engine makes ping sounds, and hesitant to start. Any ideas? My buddy is stranded here?

Jan 5, 2012 | 08:47 PM

Ext. Cabh

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I had similar problem with my '93'. My truck when cold started and ran fine until it got warm, it then started running rough and very rich and if you shut it down it was difficult to start. It ended up being the Thermostat Coolant Sensor. I do not want to miss guide you since you are unable to pull codes. I would fix the CEL before throwing parts at it or wire a 12
v bulb into your jumper to read codes.

Jan 5, 2012 | 08:51 PM

Ole' gray

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From: Missouri

Quote:

Originally Posted by Ext. Cabh

wow, im so glad you posted this. it sounded like u were talking about my truck. Ive taken it to a garage in town, and they couldnt figure out what was wrong, they didnt even know where to start. At least i have an idea on whats wrong

Jan 5, 2012 | 09:02 PM

rlwilson2

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From: Nevada

I have a 92 4x4 5sp 4.9 that has no temp sensor in it so I understand that. This is quite different. The motor is surging at idle almost like a miss running so rich it will burn your eyes to stand near the exhaust. Idle smoothes out in reverse will not shift in od can not get to 3k rpms... Could the ecm be toast?

Jan 5, 2012 | 09:12 PM

Ext. Cabh

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It happened to me about a month ago and I believe it was on this site that I followed a thread that helped me figure out my problem. I did get a code 116 ECT sensor when I replaced it, problem gone.

Jan 5, 2012 | 09:27 PM

Ext. Cabh

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Someone else may be more knowlegable about your ECM. Are you able to pull codes? I am unfamilar with the 4.9, but I am surprised it does'nt have a ECT.

Jan 5, 2012 | 09:55 PM

rlwilson2

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From: Nevada

the 92 is supposed to have the ETC but the redneck boy I bought it from decided not to put it back on when he broke the housing tube on the thermostat cover. I need to put one on it actually runs great 99% of the time just always idles high and floods occasionally when starting a warm engine.
This 94 is driving me crazy! Buddy took our family van home tonight and will come back tomorrow... I'm going to set up a light on it to check codes.