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Idle surged, ran rich, now won't start

maddog440

CEG'er
Joined
Apr 10, 2007
Messages
48
Location
NW MN
OK, wife's '95 SE 2.5 ATX idle had been getting progressively worse. Car would die at stop signs and when switching from rev to drive etc, and was difficult to restart. It seemed to start much better cold than when it was hot. Car has 130k miles.

First I swapped the IAC with another car. No change, but I can't guarantee the new IAC is good. Next I tried blocking off the EGR, idle still surged. Changed plugs, same problem.

I then noticed that the car is running extremely rich. There would be a black spot in the snow/ice under the tailpipe when warming up. It got to point where the car wouldn't start at all, so I towed it to a buddies, pulled out the plugs, cleaned them with a propane torch and eventually got it started and back home. I ran KOER and KOEO tests. Now the plugs are fouled again and I can't even get it started by cleaning the plugs.

Results of the KOER and KOEO tests (1995 EEC-IV - pre-OBDII):

KOER
116 ECT higher and lower than expected
129 Insuffecient MAP/MAF Change Dynamic Test
167 Insuffecient TP change dynamic test
173 Lack of HO2S switch, rich bank 1
225 No knock sensed during dynamic test
332 insuffecient EGR flow detected
653 TCS did not change states

KOEO Keep Alive
176 Lack of HO2S switch, lean bank 2
332 Insuffecient EGR Flow Detected
543 Fuel pump circuit open-battery to PCM
556 Fuel pump relay primary ckt failure


KOEO On Demand
111 System Pass


I checked the O2 sensors on streaming data and both were 0.8V - 1.0V when engine was warm. I may have not ran to WOT fast enough on the KOER test and this may have resulted in the three dynamic KOER test codes.

Any ideas of what's going on here?
 
TPS (Throttle Positioning Sensor) may be bad, locking it closed, had that happen on my probe with a Zetec.

If it doesn't even turn over it's possibly hydro locked.
 
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Car turns over fine. I've had to charge the battery a few times from cranking w/o starting. I also thought that I may have a stuck injector, but it is not hydro locked.
 
I cleaned the plugs again tonight and managed to get it started. I checked the datastream again and bank 2 O2 sensor (front side) was reading around 0.1V, leading me to believe sensor is bad and is showing lean condition. Computer is giving extra fuel to compensate, causing the rich condition and subsequent poor idle and plug fouling. I'll put in a new O2 sensor tomorrow and recheck.

Anybody seen a car run this poor from a bad O2 sensor before. I have not seen a bad one affect an engine this much.
 
OK, I replaced the front O2 sensor, both sensors were around 0.9-1.0V, indicating a rich condition on both. Car still idled poorly. I pulled off the boot to the throttle body to check if the plate was dirty and if there was fuel present, sure enough, the UIM was soaking wet with gas! I suspected a ruptured fuel pressure reg., so I pulled off the vacuum line to the regulator and cycled the ignition switch to on. Fuel squirted out of the nipple on the regulator confirming the diaphram was bad.

I removed the UIM, cleaned the IMRC butterflies and runners, throttle body, and MAF since they were all accessible, replaced the regulator and UIM gasket. I pulled all the plugs and cleaned them as well. After about 2 hrs of work it runs like a champ!
 
I am having similar issues, especially after the car has warmed up. Was your idle not steady and rough on occasion? Did the engine ever misfire randomly and did you notice a loss in power once warmed up?
 
Yeah, as I said, some of the KOER codes were from an improper test. I replaced the O2 sensor as well.

greasemonkey, the idle got progressively worse over the course of a few months. At first it surged, then the car would sometimes die, then it wouldn't idle at all. It usually ran OK when it was cold. The best way to check for sure if it is a ruptured FPR is to pull the vaccuum line off the top of the regulator and cycle the key to on. When the fuel pump energizes, it will squirt gas out of the nipple on the top of the FPR if the diaphram is bad. Its a pain to get to the regulator though, as it's under the UIM. I could get the vaccuum line off with a long flat screwdriver, but you'd probably have to take the UIM off to get the line back on.
 
I'll be sure to check it out, thanks. Mine is an MTX so when I roll up to a stop and disengage the clutch, the engine rpms will rapidly drop to 400 or so then jump back up to a little over 500. I have changed the IAC, plugs and wires are good. I have replaced only one O2 but that was because of a check engine light. I was interested in this post because I had very similar issues (running well when cold, surging idle, misfire etc..).
 
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