Mk IV Fault codes

[Stan 24v 0]

My mates 2.0 8v GTI has the engine warning light on constantly. He has been back to VW on 5 occasions, and they have cleared the fault and confirmed the fault is:

 

Bank 1 Too lean

 

However after 20 mins the fault reappears. He changed one of the pipes which had an NRV in it, but it hasnt fixed it.

 

They dont know what is causing the fault, as usual!!!

 

Does anyone have any ideas? ECU? MAF? Speed Sensor?

 

Ta

[dr_mat 0]

Lambda or MAF are the most likely culprits for mixture problems, I would have thought.

[Kevin Bacon 5]

You need to hook it up to VAG-COM (I cover the Norwich area if that's any good?) and get a better translation of the fault code....

 

What the Doctor has suggested is a good place to start though.... not much else to go wrong on that engine to be honest.

 

My mate's 8V MK4 ran like a sack of smelly stuff too....until he changed the MAF (only about £50 on that car, grrrrrrr) but I'm not saying that's defo what it is....

[Stan 24v 0]

Cheers guys, Ill tell him tomorrow.

 

Kev, hes up here in Lancs mate, the other place on my avatar ;)

 

Ive got Vag Com but no lead. I'll need to borrow yours again Gav ;)

[corradophil 3]

Pretty definate "Bank 1 too lean" was the error which showed up on my Seat Leon when the MAF gave up. Does the car feel more underpowered than normal :wink: If it is slower than normal try unplugging the MAF and running it. If the power improves that is a good sign it has gone. Also if you know someone with the full version of Vag-com who can do data logging you can check the flow reading which is quoted in g/s. As a rough guide IIRC the flow in g/s should be somewhere near max horsepower x 0.8. In this case I beleive 115bhp x 0.8 = 92. Have a look on http://www.seatcupra.net there is loads of info on there.

[Supercharged 2]

Would have thought VW would have tried swapping the MAF to test, they keep the mk4 ones in stock most of the time... but you never know!

[Stan 24v 0]

Cheers Phil will tell him tomorrow.

 

Supercharged No mate they didnt, they didnt have a clue what it was!!! They really are sh*t!!!

[h100vw 0]

I've got Vag Com but no lead. I'll need to borrow yours again Gav ;)

 

Is he back from his hols?

[Stan 24v 0]

Yes mate, back in today

[h100vw 0]

Update, got a code off the VAGCOM, 17536 "Bank 1 too lean".

 

VW reckon they tried a MAF but I bet if they didn't fit it in the inlet pipe it won't have worked properly.

 

RW1 you out there?? :lol:

 

Gavin

[RW1 0]

Not really enough info as this fault appears cos of several conditions.

 

Is the fault code the only one?

 

Has anything been done to the car in the last six months such as fitting an airfilter? eg. K&N (oil) type filter

 

What is the engine code?

 

The most likely areas that need to be looked at if the car hasn't been "disturbed" are fuel pressure and therefore the fuel pressure regulator.

 

or

 

An air leak somewhere.

 

The vacuum pipe connections are prone to deteriorating so check pipe ends for cracking (most likely) and examine vacuum pipe lengths for splits (less likely).

 

Check the intake ducting after the MAF for splits/seating.

 

Check secondary air feed piping for splits/seating.

 

Check the two lambda probes are working. Do this by looking at the active value fields (need the engine code to define). Check they are both oscillating in value and not rock solid.

 

Check crank case ventilation is properly connected so there are no leaks.

 

After this it will get very complicated to with diagnostic instructions.

 

Vacuum pipes are the most likely culprit as there was a problem with them right from leaving the factory.

[Stan 24v 0]

They chopped off the end of one of the vaccuum pipes due to deterioration.

 

Fitted new pipe behind the MAF (Big flexible one).

 

It was the only fault code, however the lambda was a bit erratic when we arrived at Gavs (Gav you got more info?)

 

The light was cleared down yesterday, and has come back today. VW have the car again now, but they say they had the same fault code and still dont know what it is.

 

He also thinks they changed the MAF.

 

Whilst looking yesterday, we could hear a slight hiss of air, but couldnt work out where from, may be a red herring?? All of the pipes seem ok.

 

Also, the car doesnt seem to run any differently.

[RW1 0]

however the lambda was a bit erratic when we arrived at Gavs (Gav you got more info?)

 

Need to quantify in value.

 

 

we could hear a slight hiss of air,

 

Hmmm... would like t see that identified/eliminated as this whole problem is more likely to be an air leak.

 

and has come back today

 

NAture of this code is that it is "long term" as some calcs go on so I would n't expect it to reappear straight away.

 

May be just worth asking the garage to do a fuel pressure check and see if it falls within spec.

[Stan 24v 0]

Theyve just told him they reckon its the MAF, and have changed it. He got a good deal though ;)

 

Also, if it doesnt prove to be that he can take it back. So dont go disappearing yet mate ;)

[RW1 0]

OK, the meter is running :)

 

£30

 

 

 

£60

 

 

 

£90

 

 

 

.

[h100vw 0]

On the lambda front it was running in the low teens %age wise for quite a while before settling down to around 1.

 

I felt this was strange at the time as the car had just done 50 miles and we had only stopped to boil a kettle.

 

I am not 100% about a leak, the noise in this pipe could have just been normal airflow being altered. We tried squirting some GT85 (better smelling than WD40) around all the joints but it didn't suck anything in that we could tell.

 

Could have done a pressure check except the pikey f**ks that did my garage over had my gauge away. Chris do you think it would be low pressure?

 

Can we talk about a discount for cash :lol:

 

Gavin

[RW1 0]

Cheers Gavin,

 

That looks like Lambda is OK on what you saw. It can be one of the causes. But with this fault there may be two probes, front and aft of the cat.

 

Vacuum leaks is the one I’d really check in detail.

 

I had a thought this morning that maybe the car’s had a bad shot of fuel and the filters become partially blocked thus reducing the fuel flow. A pressure check on the lower side of the spec would indicate that. Changing the filter (cheaper option) would leave the pump itself. Pressure after the regulator at the engine should be above 2.5 bar but no more than 3 bar. I only quote this as typical as some pumps run at different pressures/flow rates.

 

The other possibility is the exhaust is leaking.

 

There are so many variances in detail. Could do with which year the car is, mileage and its engine code. Also, is it stock or has any part of the induction or exhaust been changed? – air filter, cat removed, non standard exhaust.

 

 

Discount. Free this Sunday, one day offer only - 10 til 4pm. You’ve got to be 14 miles north east of York ;)

 

Chris

 

 

.

[Stan 24v 0]

Update:

 

The MAF was replaced, and fault code cleared down, on Friday. It is now Tuesday, and the light hasnt come back on. (Touch wood)

 

Cheers for your help guys ;)