[rlc588]

Recently I did a tune-up on my car and now I am having a rather precarious problem.

What I did.

Replaced coolant sensor on the rear of engine.
Replaced spark plugs
Both pre cat o2 sensors
Pulled intake manifold, replaced gasket and cleaned all throttle body parts
Replaced PCV and hoses
Replaced fuel filter
Ran seafoam through tank and intake
Changed oil
Cleaned MAF

After the repairs, I drove the car for about a week and all was fine. I then drove it about 400 miles highway. Twice during the trip the car lost power for about a min or so, although still ran. The first time the SES didnt come on, the second time it did. I pulled P1083 only (Bank 1 Sensor 1 Lean) I cleared the code and went on driving. Yesterday, while on the highway and right at 60 mph it happened again for about a min or so. No SES light though.

The O2 sensors I used were not OEM and I will be replacing them with new Bosch sensors.

I am confused since only one code appeared and that it has not come back on. If I had a vacuum leak post MAF I would think that P1084 and others would also be on.

Any ideas?

Right now all I can think to do is to replace the O2 sensors on the off chance one of them was defective. Also, I am thinking of taking the intake manifold off again and running a bead of gasket maker for double measure (but I really dont want to do this if I dont have to).

Thanks in advance!

 

[Loaded325i]

You should measure your fuel pressure before you go on buying more parts

 

[travisn]

first I would try to switch the upstream o2 sensors and see if the code follows the o2 sensor or it stays with the bank. the o2 sensors have different part #'s but they might work interchangeably, or just switch where they are screwed in and leave them plugged in to the original plugs if they will reach.


then try to switch the fuel injectors to see if the lean code follows the injectors. ie: switch injectors 1-3 with 4-6.


Basically you are using the car to determine where the problem is.

 

[hummer]

Sounds very much like a failing fuel pump.

 

[rlc588]

Currently there are no codes being shown but I can feel the problem.

My build date is 02/10 so both pre-cats are the same part (and thankfully cheaper). I will switch them and see what happens.

The car starts and idles fine. If it was a fuel pump would it not be evident at all times??