VAG COM misfire/too lean

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Apr 22, 2008 | 09:08 PM

Apdl

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VAG COM misfire/too lean

Hi All,

It has been a while and finally got the old Audi checked out.
Here is what it told me...

Fuel Trim; Bank 1 (Multi): System too Lean
P1128 - 35-00 - -
Then some misfire stuff
P0300 - 35 -00 - - - Intermittent

P0301 - 35 -00 - - - Intermittent

P0303 - 35 -00 - - - Intermittent

P0304 - 35 -00 - - - Intermittent
Readiness: 0010 1001

The ceck engine light has been on for a while and when I cleaned the MAF it was gone for like 2 weeks now 6 mo later it is still on

I ordered new plugs and fuel filter
If that dosent work then check for leaks, Coil Packs, O2 sensor cleaning/replacement then I am going to need your help! what is your take on this?

Apr 22, 2008 | 09:39 PM

machetetooth

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RE: VAG COM misfire/too lean

I would start by testing your MAF sensor by running to 6500 in second gear while logging your air mass flow rate in the vagcom. Divide the highest flow rate by .8, and that should be around 170 hp. If it's less, somethings up. My xd45 goes bang louder

Apr 22, 2008 | 10:21 PM

Apdl

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RE: VAG COM misfire/too lean

Ok I will see what I can do with that
Thanks
PS. my P22 goes meow

Apr 22, 2008 | 10:32 PM

01AudiA4

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RE: VAG COM misfire/too lean

My fist goes faster than your bullets.

Apr 22, 2008 | 11:38 PM

Apdl

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RE: VAG COM misfire/too lean

Right...
Now for something constructive...

Apr 23, 2008 | 12:08 AM

cincyTT

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Joined: Dec 2006

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RE: VAG COM misfire/too lean

That is usually a bad primary o2 or vac leak.

Apr 23, 2008 | 02:13 AM

Apdl

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RE: VAG COM misfire/too lean

Vac leak would be a whole lot cheaper than an O2
BTW what is the formula for HP from MAF?

Apr 23, 2008 | 03:32 AM

david9999

4th Gear

Joined: Jul 2004

Posts: 4,354

RE: VAG COM misfire/too lean

I don't have my Bently with me, but in the usual germanic way of doing things AUDI reads out basackward. As I recall, "System too lean" actually means that the control system has exceeded the amount that it can lean the mixture in response to the engine running rich.

Made sense to someone.. Anyway, if someone can look up the P1128 trouble shooting procedure in their Bently, I would bet that it would tell you to change the oxygen sensor.

Apr 26, 2008 | 09:10 AM

Apdl

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RE: VAG COM misfire/too lean

Can someone check on this?

Apr 27, 2008 | 06:02 PM

#10

machetetooth

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RE: VAG COM misfire/too lean

Quote:

ORIGINAL: david9999

I don't have my Bently with me, but in the usual germanic way of doing things AUDI reads out basackward. As I recall, "System too lean" actually means that the control system has exceeded the amount that it can lean the mixture in response to the engine running rich.

Made sense to someone.. Anyway, if someone can look up the P1128 trouble shooting procedure in their Bently, I would bet that it would tell you to change the oxygen sensor.

Are you pretty sure about this? After a vociferous argument I just had with a 225 hp TT owner who has the same code, I really hope you're mistaken. Not to hijack the thread, but his MAF maxes out at 99 g/s, which is why I thought it was probably the MAF or vac leak making it lean.

Apdl, the hp formula is the one where you divide your peak air mass flow rate by 0.8. I got it from the 1.8t troubleshooting guide thread. GL