Quote:
Originally Posted by Stl-986
1st....get the correct o2 sensors. You can get them on Amazon. Using the generic ones that crimp are known to cause issues.
Also, it helps to post the actual codes that are in the computer.
how many miles on the plugs?
What are you using to get the fuel trims? Standard obd readers are going to most likely give you the wrong pid for those and not be correct. Seen it myself using Torque. Correct ones can be seen in durametic/pwis. Fuel trims are going to be a symptom of your issue so I wouldn't bother looking at them for now, deep rabbit hole there.
With what you describe it sounds like an O2 issue and/or a vacuum leak.
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Thanks for the reply, some further information:
The generic sensors were all I could get at the time and that wasn't easy. I have now found a UK source for the correct ones and since all these problems started when the CATs were changed O2 sensors are the most likely culprit.
There are no fault codes stored. Prior to changing the O2 sensors I had 5 codes, two for pre-CAT O2 ageing, two unknown or vendor specific (turned out to be post-CAT O2 ageing) and a final unknown which was engine bay fan low voltage. Apparently this comes up if the battery voltage was low, which it was.
A couple of months ago when I had a random misfire and CEL, these would show up, but nothing since.
Plugs were changed with the coils, 2 weeks ago, so only 200 miles.
I have Torque Pro installed in an Android Head Unit and an Autel, both show the same for fuel trims, O2 sensors and pretty much everything else I can monitor. After a battery reset all fuel trims reset to 0% and the long term fuel trims then go negative from there. The old plugs confirmed it was running rich.
Is there an easy way to check for vacuum leaks? I have had a look round the vac lines and listened around the intake, but can't hear anything. The vac gauge on my scanner looks normal, but may be a small leak wouldn't show up?
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