Engine-Man-Light baffled my mechanic

[zeratul]

Hi. I've had some trouble sorting this problem for the last 4 weeks. A4 1.8T Cab.

The Engine Management Light came one one day coming home, it still drove the same tho, but called the RAC and within 10 mins, arrived and said it was a sensor that controls the fuel mixture as it was reading that it was running lean ( along with another fault code, which he thought would be a knockon effect from the 1st code ).

The garage changed the sensor but the second code still showed so after looking into it, said the Cam needed changing to get to replace this part. After this was done (a second time as the 1st time he'd fitted it a tooth out!), I had it back and all was well until the EML came on again and was now struggling to get up decent speed and was not ticking over correctly.

So he's still got it and its still showing that its running lean on the mixture and runs ok initially but then starts to misfire later in the day when its run in a bit.

Its an independent BMW specialist, he has Vag Com, he's still having trouble finding out the problem.

I've not got the fault codes I'm afraid but does this sound familiar to anyone? He's had it some time and will have to collect it and take it to Audi next week and pay them also!

 

[mrjheeta]

hi mate, i've had this same code (running lean) for a while now on and off. yesterday i replaced the MAF, and i think it seems to have done the trick. it lacked a lot of power, and was very uneconomical! since replacing it, i havent been out on any very long runs, but have been on an A road, and it seems to be how it should be. maybe get them to check that out.

 

[zeratul]

Thanks for that - I'll check with him.

 

[aragorn]

aye sounds like the maf.

MAF underreads, the ECU thinks theres less air than there actually is so injects less fuel.

Lambda notices its lean and the ECU richens the mixture.

MAF is still underreading, so it enriches some more

Eventually it reaches the enrichment limit, and flags a code.

You've presumably already replaced the lambda so that rules out the only other possibility.

 

[zeratul]

I collected the car today and he said it still has the same faults. He thought it was sorted as after trying swapping around the fuel injectors it was working fine - but then the fault reappeared when driven in the afternoon.

So he suspects now that it may be a dodgy electrical connection.

He said he has changed the lambda sensor only so far. I told him about the MAF.

The fault codes that come back is always: 17544 (fuel trim - which is the original fault it went in for before he changed the lambda sensor some seal by the head which also meant cahnging the Cam Belt).

AND... in addition - code 16684 (random misfire) & sometimes along with 16687 (Cyl 3) and occasionally 16688 (Cyl 4) but not so much!

But it runs fine, not like when a coil has gone, but kind of half firing. He's checked Cyl compressions and they're all equally fine.

Anybody any ideas? Is the MAF still a possibility?

In addition! with just the ignition on, I heard a clicking sound comng from behind the drivers side headlight - when i wiggled the wire it occasionally stopped until it finally did and couldn't get it to come back! I'd not heard it before but can't see anything that could be behind there and think it is just a coincidence.

 

[BILKO1]

Check all your vacuum hoses as a small pinhole/split will cause the engine to run lean.

 

[adamss24]

In addition! with just the ignition on, I heard a clicking sound comng from behind the drivers side headlight - when i wiggled the wire it occasionally stopped until it finally did and couldn't get it to come back! I'd not heard it before but can't see anything that could be behind there and think it is just a coincidence.

Thats the evap. canister wich will click rapidelly after the engine runs a bit/warms up. Dont worry about it as its normal. I would clean the MAF with some electrical cleaner and see if it fixes it. If not, i would look for split hoses, replace the plugs, etc.

 

[zeratul]

Do you think its safe to drive it to wok and back ( carefully, 10miles to and from ) this week until the mechanic can look at it next week?

 

[zeratul]

As an update - the solution may have been found by Audi.

A couple of weeks ago my garage had another go and changed the MAF for a new one. Seemed to be fine and after he tested it a couple of days presumed mended. Got the bill for all the work carried out and agreed to pay 3 lumps of £250 over 3 months (£748)!

So last friday the Engine light came back on! Called, and told garage I'm taking it to Audi and will see what they say - then look at his bill then. (In all fairness he's spent some time on it)

Audi came and collected my car with a diagnosis and
a replacement 'breather valve' - they bring it back to me and it seems to be driving fine so far £82.

What are your thoughts about what to do about my bill with my garage?

 

[NHN]

Agree a fair rate & pay him as did check number of things that even audi might have done at 1st if he hadnt, but £748 is tad rich for what the fault was, maybe half or even a third

 

[zeratul]

The high price include having the timing belt changed. Audi charge £325 for this. But this was changed to remedy the fault which was not necessary, although may have been due!

So I'm thinking to pay the equivalent cost of the timing belt change or for all the parts only that he has had to pay but not the labour costs. With the evidence that I was still in the same situation when I gave him my car as to when I received the bill.