p0171 and p0174 codes after header install

[FlyOn20S]

Hi i have a 03 z4 2.5i and i installed some long tube headers a while back and i have a p0171 and p0174 codes, i freeze framed the data and got +11.7 short term and long term fuel trims on both banks, at about 3800 rpms at 80 mph and i believe 24% engine load. The B1S1 and B2B1 have been moved to about 5 in from the B1S2 and B2S2 which are about the stock location. The headers were installed correctly and i have looked back over everthing. I have come tho some conclusions. :headbang:

1. That B1S1 and B2S1 are so close to the B1S2 and B2S2 that it might be causing this

2. The Headers cause the system to run this lean

3. I might have damaged the o2 sensors in install, but i highly doubt since there switching just fine.

If it is from the car actually running lean from the headers is there a way to solve this, add more fuel? I have yet to get a p0420 or p0430 code, the reason i installed the headers was from a burned out cat on bank 2 p0430 code.

Thanks for any help. :tumbleweed:

 

[ZetaTre]

Have you checked the intake boot: it tends to crack and suck in un-measured air... I'm saying that cuz you're running lean on both banks (all 6 cylinders); if it was a sensor issue it would be more likely to be on one bank only...

If the intake boot and all the vacuum line look fine, I would replace 1 sensor and see if one bank clears out...

The downstream sensor has no affect on fuel trim but is used only to monitor the cat efficiency...

Also, do you know that by law, cats have a warranty on their own that goes to 10 yrs, 100K miles?

 

[FlyOn20S]

i havn't looked at the intake to see for leaks yet, i have a aftermarket intak on it but i will look to see if its leaking anywhere.

Also i knew about the warrenty for the cats but just don't care about them any ways

 

[FlyOn20S]

i found a small hole in the intake tube by the throttle body gooing into the intake tube, going to fix tomorow.

 

[ZetaTre]

i found a small hole in the intake tube by the throttle body gooing into the intake tube, going to fix tomorow.

Good catch!!! A good way to track vacuum leaks is to use a propane torch (with the flame off... :? ) and rund it around the intake area (runners, manifolds, rubber boots and hoses) and notice if the idle speed changes (if it does it's sucking in propane which, ultimately, burns...)... The autoignition point of propane is 842F (432C)...

If it is on the rubber boot before the MAF, it's common to crack with age...

 

[FlyOn20S]

well i'm a service technician just havn't had chance to look or try with our smoke machine, great for vacuum leaks. I was at the gas station and stuck my hand down real quick and found the hole. its the little hose that splits off the rubber accordian hose at the throttle body. right now its just electrical taped up, ghetto but holding, till i can get a new one or make a replacement from aluminum.

 

[ZetaTre]

Was it a air leak then?

If you get a nice alu one you might get my business...

For what is wortch, the rubber BMW used appear not to deal so well with heat. Even if you get a new one, it will eventually end up the same. Something that works quite well is to patch the hole with some black hight temp RTV...

 

[FlyOn20S]

yeah it was sucking in lots of air , half the little tube was split