jmacewen
12-10-2010, 04:31 PM
Hi Everyone,
Hopefully someone will read this and have an "Ah-ha" moment! I have a '94 Disco I 3.9, etc. Took it off road about a week ago and it did just fine. Drove it the next morning and all was fine until about an hour into the trip around town. It started idling super-roughly and hesitating. I pulled over and shut it off and it went back to normal for a few blocks when it started doing it again. Limped home and parked it.
After I got home I looked under the seat at the diagnostic display and didn't see a code. Went through the ignition system the next day, cleaned the MAF, checked all of the vacuum hoses and replaced a bad one, etc, etc. Started it up and it seemed fine until it got to running temp, when all heck broke loose. This time it threw a code, 44. I replaced both lambda sensors about two years ago when I replaced the catalytic converter. Took the driver's side one out after it cooled off, cleaned the connector and cleaned it. Put it back in, same thing but now it showed a persistent code 02 first. :confused:
This afternoon I did it right. I pulled the battery cabe and let it sit for about 30 minutes. Started it up and got a code 02 but no CEL. Turned it off and started it again, same thing - code 02 but no CEL. It idles fine for about three minutes below running temp. I revved it up to see what would happen and it went to and held 2,000RPM smoothly. When I let off, the idle drifted upward and stayed at ~1100 RPM. Revving it again doesn't fix it. As it reached running temp, the idle dropped back closer to normal. Suddenly, the idle gets super-rough, again, and it starts to sound like it's misfiring. Then, it really gets bad and sounds like some of the cylinders are not firing. At this point, the CEL comes up and the display says code 44 again.
I shut it off, wait for the relay to drop, turn the key to II and it still says 44. It displays no other code and the 02 seems to magically be gone. I have one of the old lambda sensors from the swap that seemed pretty clean, I will stick it in there. I worry, though. I had a '96 with the 4.0 and I lost one of the lambdas on it and it drove fine for months before I replaced it. Is the sensor really causing this or am I looking at a bad ECU?
I plan to go through the ECU continuity test procedure from the manual when time permits, but I was hoping someone might read this diatribe and save me a lot of pain with another solution.
Thanks in advance!! :thumb-up:
Hopefully someone will read this and have an "Ah-ha" moment! I have a '94 Disco I 3.9, etc. Took it off road about a week ago and it did just fine. Drove it the next morning and all was fine until about an hour into the trip around town. It started idling super-roughly and hesitating. I pulled over and shut it off and it went back to normal for a few blocks when it started doing it again. Limped home and parked it.
After I got home I looked under the seat at the diagnostic display and didn't see a code. Went through the ignition system the next day, cleaned the MAF, checked all of the vacuum hoses and replaced a bad one, etc, etc. Started it up and it seemed fine until it got to running temp, when all heck broke loose. This time it threw a code, 44. I replaced both lambda sensors about two years ago when I replaced the catalytic converter. Took the driver's side one out after it cooled off, cleaned the connector and cleaned it. Put it back in, same thing but now it showed a persistent code 02 first. :confused:
This afternoon I did it right. I pulled the battery cabe and let it sit for about 30 minutes. Started it up and got a code 02 but no CEL. Turned it off and started it again, same thing - code 02 but no CEL. It idles fine for about three minutes below running temp. I revved it up to see what would happen and it went to and held 2,000RPM smoothly. When I let off, the idle drifted upward and stayed at ~1100 RPM. Revving it again doesn't fix it. As it reached running temp, the idle dropped back closer to normal. Suddenly, the idle gets super-rough, again, and it starts to sound like it's misfiring. Then, it really gets bad and sounds like some of the cylinders are not firing. At this point, the CEL comes up and the display says code 44 again.
I shut it off, wait for the relay to drop, turn the key to II and it still says 44. It displays no other code and the 02 seems to magically be gone. I have one of the old lambda sensors from the swap that seemed pretty clean, I will stick it in there. I worry, though. I had a '96 with the 4.0 and I lost one of the lambdas on it and it drove fine for months before I replaced it. Is the sensor really causing this or am I looking at a bad ECU?
I plan to go through the ECU continuity test procedure from the manual when time permits, but I was hoping someone might read this diatribe and save me a lot of pain with another solution.
Thanks in advance!! :thumb-up: