2001 A4 B5 cel p0171

[powdirtjumpa397]

Hey all i have a 2001 a4 1.8t...has an apr stage 1 93 chip..if it makes a diff ...theres been a cel coming on latley..p0171 system too lean(bank 1)....this comes every time i clear the codes.....some times i get a p0300..p0301..p0302 ..p0303..p0304....since the light came on iv been try to get rid of it....i read that it could be a few things....i replaced fuil filter,spark plugs,cleaned MAF changed a vacume line and the suction jet pump because it was leaking...the car whisles when turbo is spooling...mabe secondary air injection?????some time the cell light flashes at cold start then either stays on or gose off but some time cel light is off but car still in lip mode...well ne info could help me out ....so ne post is good thanks

[Stampy]

I would VAG it man. The generic OBDII codes only do so much. You did the basics and its still a problem. Cleaning the MAF is a real shot in the dark. I have never really seen that Fix a MAF. What kind of plugs you running? What are they gapped to? I don't think its your coils cause the misfire isn't consistent within a cylinder or two.

[djwimbo]

If your CEL/MIL is flashing your ECU is recognizing that the misfire may be endangering the catalytic converter.

Is it misfiring more under load, WOT, or idle.
Plugs and gap are the first thing I'd look at.

As far as the P0171, if you've already cleaned your MAF, check your fuel pressure regulator, and the vacuum line going to it. If you're running lean, it's possible that the vacuum line going to it may be collapsed, not connected,... Fuel pressure also rises with boost, as the FPR is vac/boost assisted.

another suggestion, spell check and paragraphs.

[biketsai]

log it

[powdirtjumpa397]

Well what pluges are the best 4 are cars ....i read about copper plugs..Are thes better but there olny good 4 5000 miles?

[ARS267]

my A6 was throwing that code and it turned out to be a bad PCV valve that was sucking in un-metered air.

[Poopie]

its usually some sort of leak in the intake after the maf or a vac leak

[tdn]

I had the same cell on my 01.

Replaced ALL the vacuum/boost hoses and the CEL went away. I replaced my MAF shortly after because it was giving me low readings, so it is possible that it was my MAF but I didn't give it enough time for the cel to reapper. I'm 90% sure it was the hoses because they were badly tore up. Although some looked just fine, but were leaking when I tested them.

My advice, is replace all your hoses first, it's the cheapest solution. And completely worth doing if you haven't replaced them yet. Then replace the MAF because it's also resolved the same code for many people.. cleaning your MAF won't do anything if the MAF is simply broken. If you have a vagcom cable, get a reading.

[djwimbo]

....i read about copper plugs..Are thes better but there olny good 4 5000 miles?

Don't believe that 5,000 mile rule. Yes, keep a spare set in the glove box, No, you don't need to change them every 5K.
I've had mine in for 10K w/o an issue, all I did was recheck the gap at ~7K. Unless you're running lean and burning the electrodes off, or rich and fouling them you won't need to replace them for awhile.

I use NGK BKR7E (standard resistor type plug). Some people use the Iridium version of that plug w/o issues as well. Just remember if you re-Gap an Iridium plug make sure you use a wire style gap tool, not the $.75 wedge style from AutoZone.

To the OP. Still don't know when it's misfiring, but if you have a repetitive CEL for a lean condition you have a problem.
Make sure there aren't any cracks or tears in your TIP or vacuum lines. Sometimes you'll get lucky and be able to hear the hissing sound of the vacuum leak. We aren't usually that lucky b/c 60% of our cars tick.

[boostedup]

replace MAF. cleaning it does not always fix it........i had the same code, cleaned the MAF and nothing. replaced it now it's all good........

[Ewok_Fetus]

Take it from someone who's knows replacing MAF's all too well... Change it... There is one for sale in the FS forum... He is asking $130...

[Rau]

had the same CEL, turned out it was my MAF