1.8t very rough idle/miss

[SoVeReIgN]

Hey guys,
My car's idle has never been perfect, usually varying 50rpm while sitting around but lately i've noticed that it tends to seem like it missfires/drops a cylinder (and the revs) then comes back up.

It has gotten alot worse in the past few days!
Sitting there idling it will missfire/knock, revs will drop to 500 then it will compensate and hit 1000 then back down to 800. Rinse and repeat.

When coming off the throttle in gear or in neutral (at all, even just a tiny touch) the revs will drop as far down as 200rpm, then come back up to 500 then missfire - then hit 800 and then back down etc etc.

I reset the computer and it did its throttle body calibration and it was fine for a short while but after some hardish driving it went back to having dramas.

Can anyone suggest possible causes? It only has dramas when its idling it would seem, although last night it felt like it had a flat spot/struggled at about 1800rpm.

[DUB 20V]

Hey guys,
My car's idle has never been perfect, usually varying 50rpm while sitting around but lately i've noticed that it tends to seem like it missfires/drops a cylinder (and the revs) then comes back up.

It has gotten alot worse in the past few days!
Sitting there idling it will missfire/knock, revs will drop to 500 then it will compensate and hit 1000 then back down to 800. Rinse and repeat.

When coming off the throttle in gear or in neutral (at all, even just a tiny touch) the revs will drop as far down as 200rpm, then come back up to 500 then missfire - then hit 800 and then back down etc etc.

I reset the computer and it did its throttle body calibration and it was fine for a short while but after some hardish driving it went back to having dramas.

Can anyone suggest possible causes? It only has dramas when its idling it would seem, although last night it felt like it had a flat spot/struggled at about 1800rpm.

maybe maf? wont you need to data log it

[SoVeReIgN]

maybe maf? wont you need to data log it

Ah the MAF was replaced about 10~15ks ago but I guess it could have gone again aye.

It isn't going into limp mode or anything though, I might have to disconnect it and see how it drives.

[DUB 20V]

Ah the MAF was replaced about 10~15ks ago but I guess it could have gone again aye.

It isn't going into limp mode or anything though, I might have to disconnect it and see how it drives.

yeah maybe, or maybe o2 sensor?

[gpk_gti]

sounds like maf to me!!!


I HATE MAF's!!!!!!!!!!!!!!!!

[Fizz]

Stick it on the vag com and see if there's any errors, maybe reset the ecu and realign the throttle body. I doubt realigning the throttle body will help in this case but its worth a try

[gpk_gti]

maf doesnt come up!!! ask h100vw... our resident maf expert!

[Fizz]

maf doesnt come up!!! ask h100vw... our resident maf expert!

Can check Lamda figures though

[99gti]

Ah the MAF was replaced about 10~15ks ago but I guess it could have gone again aye.

It isn't going into limp mode or anything though, I might have to disconnect it and see how it drives.

Didn't you just pick your car up from having some work done to it?

Bugger to hear that.

[DUB 20V]

sounds like maf to me!!!


I HATE MAF's!!!!!!!!!!!!!!!!

hahhahaha i dont have a maf yay for me,

[BL33SU]

hahhahaha i dont have a maf yay for me,

how do you run d car without as MAF? can it be done for our cars?

[99gti]

how do you run d car without as MAF? can it be done for our cars?

Haltech aftermarket ECU/computer

Yes it can also be done to your's using the oxy sensor and knock sensor to calculate the air/fuel ratio etc.

[shami]

I think he had suspension work done to his car...

Sound like MAF mate...

[DubSteve]

Dave has done something to the car lol. Didn't you have some more work other than suspension done to it, I could have sworn you told me at the BBQ.

I'm not trying to disagree with any of the mk4 owners but what about the throttle body? Maybe dirty causing these problems?

[gpk_gti]

I went through many different scenarios and fault checking when I had issues.issue 1 was a faulty 10 month old maf and a very small boost leak.But I also changed the lambda probe sensor,very hard for that to be faulty..there were no codes coming up btw.....


ive still got a spare lambda if you want.....