Rough Idle problem 1992 Dodge Ram 50 (Mitsubishi Mighty Max) 2.4L 4Cyl

Problem goes like this:

- Rough idle, may stall in wet weather, exhaust smells rich, worse when in gear (Auto trans)

- not noticable when driving (doesn't misfire at speed or under load)

- When MAF sensor disconnected idle smooths out and exhaust leans out (doesn't smell rich)

- no codes in stored computer

- Idle Speed Control motor (Called Motor Position Sensor assy in Mitsu Speak)can be seen adjusting idle when warm causing a surge condition in idle speed (Up/down 300-400 rpm)

here's what I've tried

- Cleaned MAF sensor with fuel injector cleaner

- Tried 2 X MPS assys

- Tried 3 X MAF Sensors

- Tried 2 x ECU computers

- Checked values of following sensors IAW specs in haynes service manual - Throttle Position Sensor - MAF air intake temp sensor - idle position switch - O2 sensor - Motor Position Sensor function and resistance tests

It has also spent a day at the dealer with no results (and no bill luckily) and 3 days at a local "expert" with a $165 bill, a used MAF sensor and a cut MAF power wire to solve the problem (since refunded by garage with apologies for poor work by "expert")

looking for any input on what to try next or where to go to get accurate diagnostic info, wiring diagrams, troubleshooting flow charts, etc (free or at cost, I don't care).

Thanks in advance

Reply to
oconnor
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Have you posted the symptoms on

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? There is a good bunch of Mitsubishi folks there.

Reply to
MG

I'd check;

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I'm surprised at your comment of no codes. If it never had a new O2 sensor, I'd probably change that out. It wouldn't be the first time I tossed parts at a problem I couldn't otherwise solve.

FMB (only one B in FMB)

Reply to
FMB

More follow up. Just rechecked O2 sensor. Shows only 50-70 mV vice spec'd 600-1000mV. WOuld this cause the idle issue? Any thoughts, please help!

Reply to
oconnor

Reply to
orland

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