A6 1.8T Overfuelling

[soulsearcher]

#1 soulsearcher
One Post Wonder

Join Date: Apr 2008
Posts: 1

Rep Power: 0

A6 Over Fuelling
Hello
i have a 51 plate 1.8t, i am having major problems with the burning of excess fuel.
I noticed the cpu reading approx 16 to the gallon and a very strong smell of fuel, so i took it to my regular garage, who did a code read which said Mixture adaption too lean - Code p1128 and p1136
So they replaced the Lambda Sensor then they fitted a new MAF meter i then had a new Thermostat fitted and also the Throttle body cleaned and still the fault exists, MPG is awful.
So i got referred to an Audi/VW Specialist Bosch Service Centre who have checked everything possible relating to fuel and air, coil packs ,the new parts, all hoses etc check out ok, So the garage rang me to say theres nothing more we can do, so after having my car for 6 days I collected it today still with the same problem and a big hole in my pocket. Any help or advice much appreciated on this matter

[S E L Technical]

#1 soulsearcher
One Post Wonder

Join Date: Apr 2008
Posts: 1

Rep Power: 0

A6 Over Fuelling
Hello
i have a 51 plate 1.8t, i am having major problems with the burning of excess fuel.
I noticed the cpu reading approx 16 to the gallon and a very strong smell of fuel, so i took it to my regular garage, who did a code read which said Mixture adaption too lean - Code p1128 and p1136
So they replaced the Lambda Sensor then they fitted a new MAF meter i then had a new Thermostat fitted and also the Throttle body cleaned and still the fault exists, MPG is awful.
So i got referred to an Audi/VW Specialist Bosch Service Centre who have checked everything possible relating to fuel and air, coil packs ,the new parts, all hoses etc check out ok, So the garage rang me to say theres nothing more we can do, so after having my car for 6 days I collected it today still with the same problem and a big hole in my pocket. Any help or advice much appreciated on this matter

I too have exactly the same problems with a beautiful 2001 Quattro 1.8t and so does Steeley it seems ( see www.honestjohn.co.uk/forum/post/index.htm?t=62933 ). There is a serious issue with these vehicles that seemingly cannot be found without spending huge amounts of money- my car has only done 69000 miles. What has happened to the good old Audi reliability? Nobobody can fix it, and the only step next is to change the ECU computer- AT WHAT COST?-------TO THE METAL CRUSHER IT SEEMS. Contact johnsonsel@btopenworld.com to perhaps approach Audi direct with a possible litigation issue as they have made cars that seemingly have no second hand value now!

[Crasher]

Calm down, it isn’t that bad. At least it doesn’t have the Multichronic box and just because the garages you have taken it to have failed to fix it, doesn’t mean it needs a new ECU, ECU failure is extremely rare.

Let’s start at the beginning, what is your cars engine code and what fault codes are currently stored on the ECU.

If you approach Audi over this, they will not be interested as it is not a common problem and they will just say to take it to the dealer, two cases doesn’t make it common.

[S E L Technical]

Calm down, it isn’t that bad. At least it doesn’t have the Multichronic box and just because the garages you have taken it to have failed to fix it, doesn’t mean it needs a new ECU, ECU failure is extremely rare.

Let’s start at the beginning, what is your cars engine code and what fault codes are currently stored on the ECU.

If you approach Audi over this, they will not be interested as it is not a common problem and they will just say to take it to the dealer, two cases doesn’t make it common.

Thanks Crasher- the engine code is AWT 041191 from the log book- is that the one? Also the fault code was 17536 FUEL TRIM BANK 1 SYSTEM TOO LEAN (P1126). Note the MAF has been changed but fault remains. Also all oxygen/breather pipes and sensors checked OK and ignition OK. Turbo and exhaust OK. No fuel leaks but occasional strong smell of fuel mainly smelt in cabin when blowers are on (from back of engine?). Also very noticeable intermittent slight loss of power. Anything else Crasher- we bow to your expertise/thanks SEL?

[Crasher]

17536 (P1128) Bank 1, mixture adaptation (mult.*) system too lean

* mult. = multiplicative. This means that the fault occurs throughout the entire speed range and load range.

My immediate thought with that code is pre cat lambda sensor failure but your comment about the fuel smell makes me wonder about a pre cat exhaust leak allowing oxygen to get to the lambda sensor. Another fault I had with a problem like this was the fuel tank evaporative emissions valve being stuck open. Where did the new AMM (MAF) come from? If that was with me, I would be suggesting a lambda probe next. Going back to the fuel smell, that should not get into the cabin anyway, have the plenum chamber drains been removed to stop water build up?

[S E L Technical]

Thanks very much Crasher for taking time to help, and it looks as though soulsearcher has the same problems and has replaced most things.

Your response has had me thinking that there could be several problems
1. The petrol smell 2. Supposed increased fuel consumption. 3. The ECU FAULT CODE/LIGHT.

Could it be possible the ECU light is coming on because the fuel tank evaporation emissions valve is stuck as you say (I have had trouble fuelling at garages with the automatic trip on petrol hose nozzles always switching off the fuel going in, with a very slow fill only possible)- how would you sort that problem anyway? One gagrage told me they had the latest systems and that there was a problem with my tank that was causing it- pressurised?

Then there may be a 'red herring' leading to the belief the car is over fuelling due to a fault on the petrol guage/cpu, since my fuel gauge is also behaving very erratically. It struggles to get off red even with thirty pounds worth of fuel in and then very quickly goes back to red after only a handful of miles! Today I had put in thirty pounds and the guage just came off the red. I then switched onto the cpu to see how many miles would be possible with the fuel already in the tank- THIS SHOWED ONLY 10 MILES. I then went to another garage and put a further £10-00 in. Nothing much more happened, but as I drove further the fuel guage started to creep up and over a period of 15 minutes went to half full, with the cpu display slowly increasing in increments of 5 from 10 to 145 miles. Could this be the source of the confusion over mileage per gallon, and would I be correct in saying Audi have previously recognised a fuel guage fault and issued a software modification to sort it out/ If so how much does it cost?

Thanks again Crasher

[Crasher]

The dash pods have a known issue with the fuel gauge which it may be possible to rectify with a flash update but I don’t think so on that year, normally it means a new dash pod.

If the tank vent valve was jammed open, this would not affect filling but the petrol smell worries me, it is not something I usually see on these. A jammed open tank vent valve has been known to actually make the fuel tank collapse under vacuum but as a test it may be worthwhile clamping the hose from the valve for a day or so to see what happens but relay this needs constant monitoring so it is not something I would recommend DIY.

Where did the new AMM/MAF come from?

Has the car ever suffered any accident damage to the offside front wing?

[S E L Technical]

Having tried on this site I try again, still not having solved the problems with an Audi Quattro A6 1.8T (only 69000 miles)which has the engine light on continuously despite having all the Oxygen sensors replaced, MAF replaced, plugs and runs OK but occasionally misses and intermittently there is a serious smell of petrol coming in from the vents into the car when the blowers are on. There is also an increased fuel consumption.

The code reads FUEL TRIM TOO LEAN BANK 1 - it also says misfire on no3.

Hope someone has experienced this and can help me thanks

[Crasher]

Fault code number, engine code and year old boy? I would not recommend posting your email unless you need some Viagra adverts.

[S E L Technical]

Thanks Crasher for advice (anyway if car cannot be fixed at least some other activity can be planned!). The year is 2001 (June! tax doubling also next year- wanna buy it?) and the engine number is AWT 041191 model A6T QUATTRO SE Variant LAWTQ1 Version QM5ABDR92P Vehicle category M1 , CHASSIS no WAUZZZ4BZ1N138104.

Hope this is enough Crasher- note am thinking now about changing the coil pack on no 3- the fuel smell does get really bad sometimes intermittentlly inside the car when blower is on, but strangely hardly noticeable outside or even in the engine compartment- strange? I did note that some time last year the previous owner had an ecu light on and the Audi garage,Lancaster Audi, recorded quote '' investigate and report on emissions light, attached test equipment and followed fault finding, checked lamda probe, sender and piping, locate fault to main fuel line cracked, reset systems and test- note technician reports eml light now gone out- if fault re-appears will require fuel pipe replaced and further investigation.''

No such code has re-appeared and quite frankly I am not totally convinced by that assessment, especially as further investigation is suggested after going to the expense of new fuel lines, which he suggested were cracked presumably as a result of the code received, but then allows the car back on road after the eml light is reset, so even he did not believe it and just reset the system. Also there would be evidence of a fuel smell outside the car and perhaps evidence of leakage under the car surely.

Perhaps one step nearer the breaker's yard?

Thanks Crasher