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Discussion Starter · #1 ·
So, it's partly the same old problem I've been chasing for night on a year now, and it's REALLY beginning to do my nut in.

Reset all codes. Within 20 mins of driving, the EPC and ASR/ESP light come on simultaneously. ESP and 4Wd goes really crap, and the car understeers badly in wet conditions. CEr is jerky, unrresponsive, does 23mpg. basically, bloody awful to drive (bizarrely, it runs better once the warning lights come on, I guess that's because it ignores the MAF signal).

After a day or so, CEL comes on.

check with VAG-COM, Always the same code, MAF implausible signal. Tried a new one, worked for 2 days, then back to the same situation.

Now, I'd always been told that EPC meant "Emissions (and) Pollution Control", but after reading up in it it seems it could actually mean "Electronc Pedal Control", in other words, Drive By Wire! I'd always just put up with it as I know the exhaust is blowing, so I "thought" it was an exhaust related problem (i.e. lambda reading lean due to the extra air getting in), that was until I did a search on EPC on this forum last night.

Here's the latest symptom. For some reason, it does this the most when i drive the car away from work on a lunchtime!?!?! I have to go slowly across the awful roads around work due to the pot holes, but on a clear patch, if I try and put my foot down, the revs stick around 2500rpm and the engine backfires as though it's got some sort of launch control rev limiter going on. I can have my foot literally flat to the floor and it just will NOT rev any higher, the exhaust pops and crackles (pretty quiet though) yet if I dip the clutch and blip the throttle it'll rev cleanly. After a few seconds this clears up, and it won't do it again all day. Ye the next time I drive from work...same fault, nearly every day.

Would I be right in saying this could be related to the brake light switch??

Any help greatly appreciated as it's doing my nut in and making me hate the car. it's already ruined a nurburgring trip I was going to do, and the donnington trackday this sunday also. I've been putting off fixing it as I'm going to do a 3.2 swap again, but that is on hold for the time being, so the car has to be running right as a 2.8 sometime soon.
 

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ITS THE BRAKE LIGHT SWITCH..... honestly try changing... after all its only &6 and it is a known failure and the new one will be a revised part..

IF a 4motion thinks the brake is depressed it cuts the DBW ... try it yourslef... drive and left foot brake.. after 3 seconds the throttle will die and be disconnected.
 

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Discussion Starter · #3 ·
mint, will order one in the morning, and complain about the MAF whilst I'm at it. ?80 for 2 days use is not good value for money.
 

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The maf will be fine.... just change the brake switch.... the maf throws a cek with the switch. The only way to reliably test a maf is to do an airflow log in 2nd 3rd gear across the full range it should show a smooth airflow right trough to 2/3rds of theengine horsepower..

IE 175gm/s for a 210 bhp engine
 

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am i right in asuming you have a 2.8 4mo with r 32 gear box?

just a thought,but are you are using a non r32 rear diff ? sounds like the front and rear wheels are trying to turn at different speeds which would explain poor mpg and bad understeer.sounds like the final drive ratio of your gearbox does't match your diff ratio.also makes sense that it drives better with the warning lights on as the esp controler would reduce the torque sent to the rear wheels via the haldex which would be diong a lot of slipping and wearing out if this is the case(recomend an oil and filter change on the haldex)

just clutching at straws with the info i have but it seems to make sense.
 

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Discussion Starter · #6 ·
R32 rear diff is identical.

I've had the R32 box in since last year, the 4wd worked fine with the 3.2 in it.

It understeers becasue the 4WD isn't working properly, and not sending enough torque to the rear when it should.

When I reset the codes the 4wd and haldex functions fine.
 

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Discussion Starter · #7 ·
Well blow me! I think we've cracked it at last. 9 months of nightmare sorted for a few quid and next to no work.

Went to the dealers today, they had the brake light switch in stock, they sell a lot of them apparently.

Took about 10 mins to fit it.

Cleared all the error codes and reset the ECU.

Went for a razz up the road...it's like a different car! smooth as silk, barely have to touch the accelerator to keep it at 70mph (used to have to keep my foot down a little bit). No flatspots, no hesitation, no stuttering, better mpg, more powerful too.

Best ?6 I've ever spent!

Will see how it goes tomorrow, got a motorway run down to the NEC. Sould see an easy 30mpg+

Also, did some VAG COM data logging, and saw 140 on the MAF, so that says to me it's working fine.

Fingers crossed that's sorted it.

Setup the xenons too whilst I was at it. I'll be chuffed to bits if the warning lights stay off now, really need that ESP and 4wd working properly now the frost is here.

Cheers for the tips, sorry for ignoring you last time you said it was the switch, I didn't believe you!.
 

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hate to say it told you so......

I knew you didnt believe but I knew that was the problem.... but didn't quite know how to convince you..
 

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Discussion Starter · #9 ·
AAAAAAAAAAAAAAAAAAAAAAARRRRRRGGGGHH!!!!

soon.

10 miles later, EPC and ASR light came on.

2 hours later, CEL on. Flat spots have come back, averaged 28mpg sat at a constant 80mph (it actually does better mpg above 80 than it does below or around 70)

EPC turned itself off, but only for 30 seconds. Did this twice.

Bizarrely, before the CEL came on I had to refuel, and when I got back in the car, all the lights had gone out! I'd say this is the 4th time I've refuelled and noticed the lights seem to reset themselves, any idea why?

Just checked the codes. Same one, MAF implausible signal.

I'm going to torch it,

Just to add, the rev limit problem hasn't surfaced today, so I think the switch has at least cured that one.
 

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Looking at this logically, the car is telling you it can't read the MAF. You have changed the MAF and it was OK for a couple of days (first post).

It seems reasonable to me to assume a problem with the MAF connector or the ECU connector.

Try spraying the MAF connector with contact cleaner or WD40 and breaking/mating the connector a few times, check the contacts look OK in the connector.

Similarly check that the connectors are seated properly onto the engine ECU .

If you have a multimeter check the wiring between the MAFand the ECU.

Finally there is a small chance that either the new MAF itself is faulty or the ECU is damaged.
 

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Discussion Starter · #11 ·
I have logged MAF reading with VAG COM. it reads fine (well, according to the Ross Tech site it does). Which is even more annoying.
 

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Can you post the full error code for the MAF implausible signal, preferably the full VAGCOM scan for the engine controller.
 

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have you checked th earth leads fitted to under the battery tray? they corrode and casue a dodgy earth, save stripping the car back just add a new temporary earth from the battery to the gearbox or the engine block.
 

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Discussion Starter · #14 ·
yep, had the battery out, it was ok under there, but gave it a good clean anyway.

Monday,06,November,2006,18:24:44
VAG-COM Version: Release 607.3-UD

Control Module Part Number: 022 906 032 BG
Component and/or Version: MOTRONIC ME7.1.1 0004
Software Coding: 0000132
Work Shop Code: WSC 00517
2 Faults Found:
17550 - Load Calculation Cross Check: Lower Limit Exceeded
P1142 - 002 - Lower Limit Exceeded - Intermittent
16485 - Mass Air Flow Sensor (G70): Implausible Signal
P0101 - 008 - Implausible Signal - MIL ON

Readiness: 0000 0101

It only brings up the top code when I've done a reset on the ECU.
 

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yep, had the battery out, it was ok under there, but gave it a good clean anyway.

Monday,06,November,2006,18:24:44
VAG-COM Version: Release 607.3-UD

Control Module Part Number: 022 906 032 BG
Component and/or Version: MOTRONIC ME7.1.1 0004
Software Coding: 0000132
Work Shop Code: WSC 00517
2 Faults Found:
17550 - Load Calculation Cross Check: Lower Limit Exceeded
P1142 - 002 - Lower Limit Exceeded - Intermittent
16485 - Mass Air Flow Sensor (G70): Implausible Signal
P0101 - 008 - Implausible Signal - MIL ON

Readiness: 0000 0101

It only brings up the top code when I've done a reset on the ECU.
The 17550 Load calculation cross check basically checks demanded power against actual power. It looks at the throttle position and compares it to the air flow indicated by the MAF.

The manual says to check the throttle body, air mass meter (MAF) and the accelerator position sender for this error.

I would start with the MAF as it is also indicated by the 16485 error. As I said before check the wiring to the MAF as it is probably intermittant.

If you want a copy of the relevant pages on testing the MAF wiring from the V5 manual (V6 should be the same), I can email them to you. If you want them PM me your email address.
 

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Discussion Starter · #17 ·
i only get the load error if I've reset the ECU. it never ever comes back up if I just clear the error codes. the only one I get is the MAF signal error, and the corresponding error in the ABS module telling me to check the engine ECU codes.

I'll pm you my address.

if the MAF wiring was at fault then wouldn't that show up as an imtermittent error?

it's not intermittent , it's consistent. the exact same error, 10 minutes or so after resetting the codes. every single time, and it's done it for nearly a year now.
 

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Discussion Starter · #18 ·
Surprise surprise......the 2000rpm rev limt problem reared it's ugly head today.

Runs like a dog when cold.

Will run those MAF checks at the weekend. If I cna't sort it the engine is coming out and the 3.2 is going in. I've had ebough of this crap.
 

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Discussion Starter · #19 ·
Well, I think I've fixed it!!

I'd been putting off fixing the blowing exhaust as I was planning on swapping back to a 3.2 anyway. But since I've put the car up for sale I thought I'd be best fixing it.

Had to take all the bumper and front panel off to get the inlet manifold off, to get at the exhaust manifolds. Intake pipe was a bit oily, TB was caked in oil and muck.

Got to the headers, took off the drivers side one and I know it's bee blowing since I snapped one of the studs when renewing the downpipe. Well, I didn't realise quite how bad it'd got, the entire corenr of the gasket was missing!! there was a good 40mm hole in it, black soot showing just how much it'd been blowing.

Got it all back together with brand new gaskt and copper nuts (so they don't sieze again), cleared the codes and reset to factory defaults and went for a test drive.

Instantly smoother, bit lumpy whilst it was trying to work out the new settings, but it's smooth as silk now, and returned 28mpg even though I'd been giving it some stick. Did a good 20 mins, codes used to come up at 10mins so I think it could be safe to say it's sorted at long last. :)

Still go this code though

Saturday,18,November,2006,16:07:00
VAG-COM Version: Release 607.3-UD

Control Module Part Number: 022 906 032 BG
Component and/or Version: MOTRONIC ME7.1.1 0004
Software Coding: 0000132
Work Shop Code: WSC 00517
1 Fault Found:
17536 - Fuel Trim; Bank 1 (Mult): System too Lean
P1128 - 001 - Upper Limit Exceeded - Intermittent

Readiness: 0000 1001

Just wonder if was having trouble settling down? will keep my eye on it.

Nice to have ESP and proper 4WD again, not to mention the possibility of hitting over 30mpg once more!

I might keep it after all.,
 

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I had that same 'Fuel to Lean' Code and my car was very hesitant when i pressed the throttle, in the end it was my injectors that were faulty - and dam they are not cheap!! Anyways here are some guidlines on what to check for that code:

fuel line
fuel filter
Fuel Pressure Regulator
fuel pump
fuel injectors..

manifold cracks
intake cracks
Vacuum lines

cat and pre-cat
MAF
O2 sensors

Good luck!
 
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