poor fuel economy

[dan_b]

@Andy no I don't think it's to do with your thermostat - I also changed that on mine recently. It's got to be something else. How's your idle speed? Does it tick over smoothly and pick up revs ok from low speed? I'm wondering whether the Idle Stabilisation Valve might be sticking or something, or are there other engine sensors that are involved in fuelling? Any thoughts Forum? Mine's a 3B by the way, Andy what do you have?

[T2Andy]

I was wondering about the ISV ,when i start the car it ticks over evenly from cold slightly above 1k but sometimes it hunts up and down nearly staling,for some reason when i have
just filled up and i pull away from the petrol pump to the exit ie starting then stopping in a short distance the car may cut out start it and the revs go up and down
Dan hope that makes sence.Mines an ABY with a chip and u\spring .

[T2Andy]

The motor does feel a little restrained at the bottom end and can have slight hesitation around 5k ,i do feel the fueling is out ,i always run it on super either shell or esso 5quid\gal.On the upside im running my van on cooking oil\deisel 200miles per 10 quid.

[Audi Parts Guru]

Yes i understand what your saying and having the injectors cleaned properly is on my list of things to do ,but ive also herd good reports on FORTE cleaners

I've also heard good reports on Forte products, having said that, any bottle of injector cleaner weather it's Forte or not will never be as good as an ultrasonic clean and flow test

[dan_b]

Well Andy we have exactly the same issue then! It had gone away with my car in Feb, but it seems to have come back. It definintely doesn't feel like the same problem as when the lambda went. What other components are there?

[neebover]

I thought my Idle Valve was the problem also.. on removal it was gunk'd up, full of allsorts.. after a good clean out and replace, MAF was the cause.. can't think what else it can be to be honest..

[dan_b]

Hmm, I'll give the ol MAF another going over I think, I guess it was a fair while since I last cleaned it come to think of it. I'll whip out the ISV too and give that a blast of WD40, shouldn't do any harm

[T2Andy]

I think the age of the car and components is the main cause if its not one thing its another, were do you start fault finding with out replacing every component and sensor.mine also can be intermitent dan .I can remember cleaning the maf plug\connectors and making a differance.

[martinjs]

Of course a dodgy thermostat can cause rich running, i've had this. If its stuck open slightly the engine will stay cooler for longer so the ecu will be dumping more fuel in thinking its still on the warm up cycle, im not saying this is your problem Andy, because i dont think this will cause the hesitation but i wouldn't rule it out if its not been changed.
Maybe try a maf from another car, yours could be on its way out.

martin

[alg]

My recent replacement MAF (old one 3 years old no fault codes clean wire) has solved my rich running issues. Did the PCV as well (old one pretty mucky).
I will report back when run the new setup longer but the whole car feels better.

[T2Andy]

How much for maf and has any one got one

[dan_b]

A new MAF is expensive. Clean it first. Andy if you can get yourself access to someone with VAGCOM they can diagnose any fault codes that might be stored in the ECU, or there's the "blink test" which I can't remember any of the details for.

[AndyP]

@Andy, give me a call and I'll hook it up to VAG-COM and see if you have any errors.

[T2Andy]

cheers Andy will try and get something sorted this week wont be using her much;just had a run from york which is mostly motorway and got 23\24 mpg holding at 80 and making the leg hurt with a few short blasts.Temp was half way between 50and 90 all the way and had no hesitation or tick over probs and that was on 95ron fuel.

[Billman]

Is there any Trick to have better fuel economy in the City! even to drive with less power??? Would it burn less i.e. driving with 4 cylinders or something more refined?? Would something like this Damage the engine?