Golf 6 GTI 2011 - ECU Flash Strange Fueling

[Miks22]

Hi All,

So I have been loving my GTI for the past 8 years, just an all-round great driving experience.

I recently decided to up the performance a little bit by doing a downpipe and ECU tune.
The performance boost is pretty amazing, a real pocket rocket now!

However, one strange thing that I have noticed is that now when I'm coasting (with zero pedal input) the car is still fueling.
Before the car would never do this, would get 0l/100 in this state but now between 2.4-6l/100.
The main issue for me is that the car feels like it has got reduced engine braking and almost feels like it got a fast coast.

Another observation is that in 1st and 2nd gear the car goes to a zero fuel state but from 3rd-6th the car is fueling during coasting. (got a manual box)

Anyone got any idea why this is or how can it be sorted?

TIA

[Callum229]

Got pops and bangs? That will cause fuelling when you lift off.

Maybe also mass airflow sensor?

Did you put a generic tune or was your tune specific for your car?

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[Miks22]

No pops & bangs mapping, I'm not a fan.

If it's the mass airflow sensor why the difference between gear 1+2 & the rest?

I assume that the shop that did the work used a tune specifically for the car, they specialize in German cars.
This shop has previously done great work for me.

Just an extra note, the downpipe removed both cats.

[THANAS]

Have you brought up the issue with the tuner? That would be the first place to start, get them to run a set of detailed logs relating to the fueling and load system.

[Miks22]

Hi Thanas,

Yeah, I have. He knows about the issue I'm having.
We went on a drive together with him monitoring the car.
There weren't any faults etc.

What he did notice was that the throttle was open 10% but the pedal was at 0% (3rd gear and above).
So he says the car (VW software side) was asking for the throttle and not the ECU tune he did.
He said before the remapping was done he updated the VW software to the latest version and believes that VW made a tweak to the coasting state.

To me, this coasting state doesn't seem right.
What are other MK6 GTI doing?

Look, he has worked on my car for many years and have never had any previous issues.
I'm totally happy troubleshooting the issues with him but at this stage, I don't know what is causing it or how we go about correcting it.
Is it a tweak that VW made or is it the ECU tune that is causing this?

[THANAS]

Well an easy way to find out would be to flash it back to stock and see if the problem persists. There are variations, but the standard procedure is for the injectors to turn off below a certain load threshold/after a certain duration off-throttle.

What manufacturers do is slowly close the throttle to prevent rich conditions and carbon monoxide emissions. This tends to manifest as rev hang rather than what you're describing, and even then that doesn't prevent the injector turnoff condition.

Flash to stock, and take it from there.

[Miks22]

Thanks Thanas, will suggestion that and see what the out come is.

[THANAS]

No problem, give me a shout if you need any assistance.