Running rough, running smooth...
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Recovery Vehicle
Joined: Jul 2012
Posts: 978
Likes: 154
From: Mideast US
Running rough, running smooth...
Hi all.
Lately, backing from the driveway it is noticeable that there is some irregularity in the engine. After a few weeks, the 'check engine' light came on. Now it runs like a smooth dream. What is going on ?
The error code is for tired oxygen sensors. Erased codes and the story repeats, taking several rough weeks for the 'check engine' to show up and back to silk smooth running.
Lately, backing from the driveway it is noticeable that there is some irregularity in the engine. After a few weeks, the 'check engine' light came on. Now it runs like a smooth dream. What is going on ?
The error code is for tired oxygen sensors. Erased codes and the story repeats, taking several rough weeks for the 'check engine' to show up and back to silk smooth running.
Mudding
Joined: Feb 2022
Posts: 231
Likes: 112
Irregularity in the engine is probably from inconsistent fuel delivery. This could be caused by an O2 sensor having issues, or an O2 connector or wiring fault.
It could also be caused by any number of other items upstream from the O2 sensor(s). Example: If you have an injector that is sticking intermittently it will not be delivering the fuel the computer expected. This would result in an unexpected result to the computer from the O2 sensor which could result in an intermittent fault. Same goes for MAF, IAC, etc.
If it were mine, I would start with a visual inspection of the O2 sensors, validate their locking connectors are properly engaged and validate that there is no damage or kinks in the O2 Sensor wiring. If you have a code that indicates specific sensors, start with those. If the code indicates one specific sensor or sensor side, you might swap the upstream sensors across or the downstream across. The two upstreams are the same, the two downstreams are the same, but upstream/downstream are different. If the problem follows the sensor, replace it. If it stays in the same place, now with a sensor that was not faulting before, then you need to look earlier up the cycle at injectors, MAF, etc.
Another easy (ish) test is when the vehicle is running poorly, unplug the MAF. This forces the computer to use a RPM based, non-optimized, fuel mapping. If it starts running correctly, then the MAF is the problem. Replace.
That is about where my "expertise" would run out and I would be off to google, this forum and youtube hoping for some insight. Post up the codes like Extinct asked. That will potentially help the cognoscenti here a bunch.
It could also be caused by any number of other items upstream from the O2 sensor(s). Example: If you have an injector that is sticking intermittently it will not be delivering the fuel the computer expected. This would result in an unexpected result to the computer from the O2 sensor which could result in an intermittent fault. Same goes for MAF, IAC, etc.
If it were mine, I would start with a visual inspection of the O2 sensors, validate their locking connectors are properly engaged and validate that there is no damage or kinks in the O2 Sensor wiring. If you have a code that indicates specific sensors, start with those. If the code indicates one specific sensor or sensor side, you might swap the upstream sensors across or the downstream across. The two upstreams are the same, the two downstreams are the same, but upstream/downstream are different. If the problem follows the sensor, replace it. If it stays in the same place, now with a sensor that was not faulting before, then you need to look earlier up the cycle at injectors, MAF, etc.
Another easy (ish) test is when the vehicle is running poorly, unplug the MAF. This forces the computer to use a RPM based, non-optimized, fuel mapping. If it starts running correctly, then the MAF is the problem. Replace.
That is about where my "expertise" would run out and I would be off to google, this forum and youtube hoping for some insight. Post up the codes like Extinct asked. That will potentially help the cognoscenti here a bunch.
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