About a week and half ago a code popped up on my ecu saying that the Left side was running lean. First I took off all the setting I had on my VAFC 2 to see if that was a problem but the code popped back up. So I checked the injectors on the left side and they were all working properly. Next I switch out the MAF (a spare one I had) and the reset the ecu. A couple of days when by and no code until today when this time it said the Right side was running lean. Any ideas what could be causing this? There are no vaccum leaks or exhaust leaks. The only other thing I could see is the fuel pump is going out but wouldn't that make both sides run lean and not just one?

 

I have heard of this problem before, if you can search I believe there was a thread on how to upgrade one of the lines going to the fuel rail.

 

Do you know when this thread was made or the title so I could narrow down the search.

 

could also be faulty O2 saying u have lean condition

 

Running lean is most likely O2 sensors, bad MAF or a IM leak..

If a MAF is bad, it will affect both banks... the fact that you switched MAFs and it switched the lean code to the other bank is strange... keep driving and check for codes again - see if the other bank reposts...

Or clear the codes and see what posts.. if you consistently get the same bank, then I would look into the O2 sensor on that bank first - how old are your O2 sensors?

 

I had this problem before I did the VI swap. Was always the left bank, even after changing O2s. Haven't pulled my codes in a month or so to see if it's still there or not, just used to the CEL being on frequently now due to swap & other issues.
Sorry I haven't got back to you after you called that night. Hit me up on IM so I don't forget again.

 

O2 sensors are probably the original ones (112,000 miles), I don't know because I purchased this car at 57,000 miles. Thats was my next guess if the MAF was bad but when it switched banks I was like WTF. Ok this all started when I repaired a hose that was split open, which fixed my idle problem. I also did a compression test and put some oil in one of the cylinders on the left bank to see if compression would go up. Lets just say I put too much in there and after starting the car smoke was coming out for a little. Thats why I figured my O2 got Focked up by this but when it switched banks I thought it might be something else.

 

It probably wouldn't be a bad idea to replace both O2 sensors - better mileage, etc. - especially at that mileage.

What hose did you replace? It is possible that the oil fouled up the O2 sensor(s).

I would start with the O2 sensors (since you've already swapped the MAF).

 

The hose I replaced was the bottom hose on the egr-bpt valve (looks like a UFO) which connects to the egr-valve. And I guess I will replace those O2 sensors.

 

Ok.. that hose won't make you run lean... so definitely do the O2 sensors.

www.oxygensensors.com, Bosch OEM sensors are 70 bucks a piece - plug and play. Takes an hour to replace both.

 

and most of that hour is getting the f-ing 02 socket on so use an open end wrench

 

I actually used an O2 sensor socket - and it worked ok - but I suppose an open ended wrench would be easy too... Just soak them in PB blaster for 10 mins..

1hr includes jacking the car up etc.