[SOLVED] Cylinder 1 Misfire - P0301 / P0300 Mystery

[GriffX5]

Have you tried cleaning the MAF? I was having misfires on my E46. Cleaned the MAF and it's been running great since.

[Toothbrush]

I have cleaned it, twice actually. Unplugged it as well with no changes other than getting a code.

[ard]

Originally Posted by Toothbrush

I have cleaned it, twice actually. Unplugged it as well with no changes other than getting a code.

Out of curiosity, was the code for an intake air temp sensor?

(MAF has a temp sensor in it, along with air density...)

[Toothbrush]

I honestly don't recall. It was one of the first things I tried, hoping for an 'easy' fix. As soon as I plugged it back it, the code resolved itself.

However, I just unplugged it and these were the codes presented specific to it:

P0113 - Intake Air Temp Sensor 1 Circuit High
P0100 - Mass or Volume Air Flow Circuit
P113B - "Manufacturer Defined" - Mass air flow (MAF)/volume air flow (VAF), 1 – incorrect signal


In other news, UV dye and light kit delivered yesterday, so will be playing around with those probably later this week or over the weekend to make sure I've covered all the bases for an air leak. At least, for my own peace of mind. Will try looking for leaks as suggested earlier and exhaust as well.

Also, I have had a replacement injector for some time, so that might happen as well. I've discovered it's much easier to have a part on hand and not need it than no part at all. Only reason I haven't replaced it already is I've never done that type of work (coding, index numbers, etc, etc...) and didn't want to go that route till I was certain or had no other options. Plus, most of what I've read and Indy's I've talked to suggest replacing the entire bank.

[ard]

Dont just concentrate on the big items- a hose leading off somewhere with a cracked elbow or split in the middle can be a hidden culprit

[pshovest]

N62 injectors don't need coding, they're plug-n-play.
Hmmmm.....now what possible motive would a shop have to recommend replacing all 4 injectors when only one cylinder has a problem.....

[Toothbrush]

I would assume I would need to reset adaptions at least?

Most of what I've been told is it's 'better' to do the extra work since you're already there and you may end up having to replace one or more of the rest anyway, depending on the root cause.

Probably not much gain involved for a shop only doing one vs 4 to 8.

[pshovest]

Adaption reset is not required. This is easily DIYable. For the most part fuel injectors are life-of-the-car parts. Replacing 3 or 7 functional injectors at $140 each is money down the drain.

[Toothbrush]

Just changed the fuel injector since it was a little warmer today and that was much easier than I expected. Thanks for the confidence boost!

Result: runs a little smoother but still same codes and same idle/driving issues as before.

More smoke testing and Compression test is next on the list. Is this something that can be done at home with a compressor and leak down kit? I've never done a compression test myself. Looked around online and not sure exactly how to do it still. Does anyone know of a guide specific to the 4.8i?

Also, took some pics of the intake valves for cylinders 1-3 since I had the injectors out.

[pshovest]

Congratulations on the repair, too bad it didn't help. Compression check should be next. How many miles?.