Audi A3 1.8 8 T Fuel Trim DTC code & loss of power

[aljrose]

Hello and Happy New Year to all forum members, please help if you can:

I have a A3 1.8 T Sport (x) Registration (2000). It is the 150 BHP model. Recently it has the following problems:

- At speed on motorway noticeable loss of power in that the throttle is no longer as responsive as it should be. Car then has loss of power problems in just about every gear - some lurching.

- Fails to idle at a consistent level of revs. Revs fluctuate and fall low enough to bring the car close to stalling.

- Loss of power will eventually continue until the point of breakdown recovery. Car is recovered and DTC fault codes reset and car returns to normal capability.

- Before long (perhaps 150 miles) cycle starts again

- The only warning light on the dash relates to the yellow warning symbol for brake light failure. The brakes lights work without a problem.

- The DTC codes are P0170, P1114 and P1128 - All of these codes appears to relate to the Fuel Trim Add Air Bank 1 System.

PO170 = Fuel Trim Bank 1 Malfunction
P1114 = Bank 1 Sensor 2 Internal Resistant too High
P1128 = Long Term Fuel Trim mult. Bank 1 System too Lean

- However, I wonder whether, if I have a faulty blake light switch this is causing the ECU (computer) to believe there to be problems with the fuel trim and/or is causing the car to revert to limp home mode?

- The emissions from the car are as they should be. There is as I understand it 2 oxygen/lambda sensors - one before the cat and one after. The 1st lambda sensor has been checked and is fine, could the fuel trim problems be down to the second lambda sensor?

- And/or might this be a problem with the hoses regulating fuel pressure and turbo pressure and a possible air leak?

If anybody can shed any light on this conundrum I would be so grateful.

Cheers

[T-Sport]

Have you checked the MAF which are prone to failure on the 1.8T and could put the car into limp home mode ??

Coil packs are another big cause of power failure too,even if one has gone down it will affect the engine running correctly...

[aljrose]

Thanks

I am suspicious of MAF because when I disconnect it car runs a lot more smoothly. Coil pack has gone in past and replaced free by audi as a known fault.

Will sort MAF this w end and let u know how i get on.

[karlaw]

Hi I am new to this forum but have a similar problem with my Audi A4 1.8T Avant. Sorry I am not too mechanically minded what is a MAF...if anyone can help it would be appreciated. Cheers

[MickCheese]

MAF = Mass Airflow Sensor.

Here is a good link that explaines what it is. It does apply to a Scorpio but it gives you an idea.

http://www.fordscorpio.co.uk/cleanmaf.htm

Mick

[MickCheese]

And here is a link to an Audi tech Bulletin, it's not for the A3 but again useful.

http://www.wak-tt.com/vagcom/maftecdoc.pdf

Mick