Rough idle, running rich.. ugh | Ford Explorer Forums - Serious Explorations

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Rough idle, running rich.. ugh

drstein

Member
Joined
December 17, 2004
Messages
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City, State
Justin, TX
Year, Model & Trim Level
1994 XLT
94 XLT.. 160,000 miles on it. I just replaced the plugs and it's still doing the same thing. Rough idle, doesn't really smooth out, feels like NO power. Exhaust is black (but not thick.. just wispy black smoke) and smells like I'm pouring straight fuel out of the tailpipe.

Plugs had a little bit of black soot on them but otherwise looked fairly clean.

This problem came on suddenly. No other symptoms at all. The vehicle was sitting outside parked for several days.

I'm going to: replace the plug wires and clean the MAF.

Can anybody think of any other issues that could cause this? While running, the Check Engine light does go on but the code reader I have is a piece o' crap and is difficult to get information from. (It's a cheapie that just beeps instead of displaying numbers on a screen)
 



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My '92 recently had a bad idle (surging) and was down on power at more than 3/4 throttle (would slow down)

KOEO test didn't find anything helpful
CM tests showed 173 which is o2 not switching.

I took out my o2 sensor and it had black soot on it.

I checked my fuel pressure and found it way way high.. 58psi with the engine off (key on) but once running (and surging) it was bouncing from 100 to 110psi (off the scale).. I wasn't leaking fuel into the vacuum line but my fuel regulator wasn't regulating anymore.

Soo.. I'd check for a CM codes (and even try the KOER test).. and definatly check the fuel pressure.

~Mark
 






Your "cheapie" reader should be fine. It takes some practice and patience.

No KOEO codes typically means you don't have an electrical problem (bad sensors, wiring, etc.). This means you have a real mechanical issue when the engine is running.

Could also be the computer, but I would check the KOER and CM codes and diagnose the other potential causes first (such as fuel pressure). As mentioned, O2 codes are normally indicating issues "uphill" since they're in the exhaust.

I would definitely replace the plug wires and clean the MAF, as you mentioned. I would also clean the IAC and check for leaking vaccuum lines.

Hope this helps.

Mike
 






Update!

I cleaned the MAF and the problem persisted. I finally took it to a shop and they tested the MAF and found that it was in fact dead.

Replaced the MAF and things seem better.
 












I am having the same type of problems, replaced Fuel Pressure Regulator, no change.
 






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