Passat diagnostics help.

[YZFAndy]

Hi all, Not sure if i've replaced a faulty part that wasn't the real problem.

The cars a 1.8T passat. Started the car and all fine then got a mile down the road then first cough that rapidly built into very bad kangarooing and at idle the engine was going from stalling to reving up to 2000 rpm. Had to get it from where it was and drove it about 5 mile by constantly varying the throttle which seemed to stop it cutting and missing as much but used easily 2 gallons in that distance.

First thought was the icm (1.8t aeb engine) but tested it and that was fine, then unplugged the MAS and tick over stabilised so ordered one. In the mean time i got a vag cable which also confirmed a MAS intermittent reading.

New MAS in and tick over normal but still a cough/ hesitation when gradually lifting off throttle at low revs and woolly power. Scanned it again and got this code:-

Friday, 11 October 2013, 19:15:48.

VCDS-Lite Version: Release 1.2

Control Module Part Number: 8D0 907 558 E

Component and/or Version: 1.8L R4/5VT MOTR HS D02

Software Coding: 04001

Work Shop Code: WSC 05314

VCID: 33199CCF122D

1 Fault Found:

00561 - Mixture Adaptation

13-00 - Adaptation Limit (Mul) Not Reached

---------------------------------------------------------------------------


Cleared that code, took it for a couple of miles then red lined it in first and second and again woolly and lacking in power until 5800rpm then sudden jolt of full power. Fault checked it again and now getting this:-


Friday, 11 October 2013, 20:17:37.

VCDS-Lite Version: Release 1.2

Control Module Part Number: 8D0 907 558 E

Component and/or Version: 1.8L R4/5VT MOTR HS D02

Software Coding: 04001

Work Shop Code: WSC 05314

VCID: 33199CCF122D

2 Faults Found:

16487 - Mass Air Flow Sensor (G70): Signal too High

P0103 - 35-10 - - - Intermittent

00575 - Shareware Version. To Decode all DTCs

08-10 - Please Register/Activate - Intermittent

---------------------------------------------------------------------------
Peak MAS reading is 160gs but reading Ross Tech website the suggest it should be around 120gs.

Also looking at the lambda sensor at tickover its all over the place. Does that look right or is it just the managment trying to find a mixture causing the erratic readings? though it should be 1 at tickover!
http://www.youtube.com/watch?v=B_BKfYB6jD4


So what you think, cheap and nasty MAS or does it look like lambda has gone too possibly by driving it when the MAS went down. Also seen suggestions of similar and throttle body cleaning needed?

Any help or suggestions appreciated.

 

[pepsilol]

Does it drive perfectly fine with the maf unplugged?

 

[YZFAndy]

Not yet tried it but will in a little while. Some one else suggested that but didn't see the point as its only going to go to a default map and ignore the sensors or will it just ignore the MAS and show up other possible faults?

 

[pepsilol]

Well if it drives normally on default values then the values your maf are giving are going to be incorrect meaning that the maf is at fault.

Your issues aren't really going to be caused by a dodgy o2 sensor. They're too severe.

 

[rodenal]

As above it could well be the MAF. Where did you buy it from? Its one of those things that unless you get an OEM quality part a new one can be a waste of time

 

[YZFAndy]

As above it could well be the MAF. Where did you buy it from? Its one of those things that unless you get an OEM quality part a new one can be a waste of time

Tried it now with a reset and unplugged Airflow sensor and runs much better so guessing it is just reading out of spec at higher air flows.

It was a cheap but new one from uk diesel but they seem to sell plenty of them without problem.

 

[MatteH Oxford]

The adaption limit would suggest a problem with the throttle body, check to see what sort of figure you have at idle. It should ideally be under 10%, any higher and I suspect it's dirty or you have an inlet air leak maybe. What this code means is that there is an issue with the idle control, the ecu can't correct it enough via the throttle body (presuming you have a fly by wire throttle, pretty sure the 1.8T has?).

Also check that all the pins and connectors are good i.e. clean, tight and contact properly.

 

[Fuzz]

Sounds like a boost leak to me!

 

[YZFAndy]

What this code means is that there is an issue with the idle control, the ecu can't correct it enough via the throttle body (presuming you have a fly by wire throttle, pretty sure the 1.8T has?).
.

No its AEB engine code which was the only one that didn't have fly by wire.

 

[MatteH Oxford]

Ah, bummer - there had to be one! .

Not sure how the idle is controlled on your car, on the good old mk2 golf etc there was a little black box behind the centre console that controlled a seperate idle speed valve.