Running rich

Hey CANNON1349,

I would start by checking condition of all of the spark plugs, plug gaps etc.

With the two affected cylinders not being on the same bank or using the same part of the ignition coil it would first be good to see what you have going on in the combustion chambers.

Can you also please send a photo of the deposits on the old O2 sensor.
Also a photo of the spark plug condition would be great.

Heavy white deposits can be a sign of fuel contamination, coolant being burnt or silicone poisoning.

Has there been any more recent engine/ignition system work done?

Regards, Joe

Hello,

White powder on a O2 sensor is the engine is running lean and there is a good chance the spark plugs are white also could be from fuel contamination. Check for vacuum leaks and exhaust leaks this will cause engine to run rough. Too much fuel tank additives can cause white powder deposits also. The spark plugs and wires should be cleaned inspected inspected or replaced if needed. Let us know if this is helpful or if you need more info.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Thanks
Joe T.

Well after replacing the O2 sensor the lean code went away and so did a cylinder 2 misfire but a cylinder 3 misfire comes up immediately on the scan tool when started. So I got my test light and pulled the wires of the coil at cylinder 3 and cylinder 6 for comparison. No spark jumping to the test light at cylinder 3 and a consistent spark at cylinder 6. So I replaced the coil with new wires. So far no rough idle.

Good job, happy to see it's running good. Thanks for choosing 2CarPros. We are here when you need us.

Thanks again
Joe T.

Hey CANNON1349,

Perfect, seems like you have it figured out.

Did you recheck the spark plug condition and gaps etc?

I would say at this point if it runs and idles well I would check the short term fuel trims and make sure it is not still adjusting for a lean/rich condition.

If the short term fuel trims are now close to 0 or +/-8% max then the fault may very well have been the ignition coil and wires.

If the short term fuel trims are good at idle and 2,500 rpm's I would reset the long term fuel trims and road test. Recheck fuel trims and fault codes after road test and if all clear I would say you have found the problem.

Hope that helps, let us know if you have any further questions.

Regards, Joe