Ok well I am the very proud new owner of a 2000 audi a4 1.8t quattro...

I had the car for about a week when I got a p1128 (system running too lean)
I started by looking for vacuum leaks . . . found a few cracked hoses. . . replaced them . . . code came back.

I then went and replaced the oxygen sensor . . went on a long trip about 1100 miles. The CEL came back on on the way down, after probably a few hundred miles. . .

the issue now is that when she first starts up its been running very rough. . . than after about 15-20 seconds she purrs like a kitten . . . its really getting to me . . . Im about to do some tests down in the garage to see if I can figure it out. Gonna test the injectors, maf, and look for more leaks. Any input and/or advise would be greatly appreciated.

o and the guy I bought it from had a turboxs (i think) blow off valve on it. . . I took it out and replaced the stock dv . . I believe I put it in right. . . the valve in the dv goes closest to the turbo right? . . . well please give me all your input thanks again !!!

 

Someone please help . . haha. Im not really sure where to go with this!

 

Altight well I was doin some research and talking to some people and came to find out my malfunctioning engine temp guage/sensor could be causing an issue atleast with the rough idle at start. So I ordered one and should be installing that tomorrow. Im still searching for a vacuum leak. I sure do with that I could get some imput from someone whom has experienced something similar to what I am. Please give some feedback.
Thank you

 

ok . . . . . well unfortunetly noone is helping me out here I was talking with some people and they asked me if my engine temp gauge works. . . It just so happens that mine does not work.
They suggested that this could be a cause for my rough idle at start. .
I dont think this has anything to do with my cel . . . however its worth the price to just throw that sensor in anyway. . .
Anyone have a good method on how to check for a vacuum leak?
I was thinking about hooking up a guage to a vacuum line and start from there. . .

 

Yes, the coolant temperature sensor has a lot to do with how the car runs. Also, try cleaning your MAF. Maybe run some Sea Foam, etc.

 

Alright, thank you. Is it best to a specific spray for the MAF. ?

 

Seafoam is not for MAF sensors...

You need a VAGcom to help you out here.

What is the primary O2 sensor reading when the car is warmed up?

Most common vacuum leaks are around the back of the block (EGR & PCV system hoses).

Check the boost hoses, DV pipes, and the MAF housing (airbox). If anything was modified then put back to stock, that's a pretty good place to start, but the code might tell a better story with freeze frame and O2 sensor info.

The code is P1128: multiplicative fuel trim too lean (bank 1). This means that the ECU is sensing too much air and will try to compensate with more fuel, but it's multi, which means off-idle/under load. The most common cause with Audi/VW for this codes seems to be a bad MAF, but sgsin, O2 sensor readings and freeze frame data would help here.

Try contact cleaner to clean it. It's more of a band-aid, but it doesn't hurt to try.

 

I didn't suggest to use it on the MAF sensor.

 

I know not to use seafoam on the maf. . . There is a spray you can buy for the maf. . .
Anyway, I replaced the Engine temp sensor. . It didn't help the cold start issue. . . I just dont see what could cause it to run rough for fifteen seconds than just smooth out and idle normally. . . ???
I have a mac tool scanner. . . it reads some data. . .
I think Im goin to search for a vacuum leak. . .

 

I still havent found any vacuum leaks. Does anyone know the best way to test for loss of boost? Anyone have any other thoughts on what could be causing a lean condition!?