changed MAF but now idling weird and.....

the car starts and idles from cold perfectly, but once warm it starts and dies/stalls straight away which is weird. it also idles a little unsteadier than it used to.

have run the car for about 150 miles since the MAF and let the initialisation finish before i started it first time after the MAF change.

it still feels like there is a tiny hesitation in power around 3k rpm and also the exact millisecond i let off the throttle power tails off quite suddenly which only seems since the new MAF.

im wondering if i need to be checking TBB or any other hoses etc to examine for tears or rips etc which from reading on here seem very common, but i dont know where to find the TBB on my 2000 a3 1.8 tsq

if anyones got any experiences of this, or advice etc then its greatly appreciated

thanks, dan

p.s - havent got an OBD for my vag com at the moment so cant plug it in for a code or anything

I would reset the ECU and perform a throttle body adaption if i were you. Disconnect the battery for 30 minutes or so. Turn the car on to the position just before starting. Let the car sit like this for 4 minutes or so. You should hear some clicking from the engine bay as the throttle body adapts. Make sure you have your radio theft code too.

tbb ???? I assume you mean throttle body or feed piping/throttle body butterfly plate? concentrate on the (IAC) idle control valve/stepper motor

1.8t's don't have idle air controls. They are electronically controlled through the throttle body.

that doesn't answer the question

it has a stepper motor and the throttle stop plate bends, difficult to explain

Citroen and other cars use this system, ill try to get some pictures of it

quote:

ORIGINAL: avant80@2.6

it has a stepper motor and the throttle stop plate bends, difficult to explain

No it doesnt, it is controled excatly the way Jestnomen explained it

There is a stepper motor that actuates the butterfly valve in the throttle body. On the non drive by wire the stepper motor only corrects the movement to establish a controlled idle. On the drive by wire cars it controls all movement from idle to wide open throttle (WOT). Typically rough idles are caused by the throttle body needing to relearn the settings for a smooth idle. This is also called an adaptation or throttle body adaptation (TBA). Readings from MAF are calculated in determining the correct idle speed. Thus if a new MAF is installed it is conceivable that the engine could idle erratic as is the case here.

As I mentioned before, when I had this kind of problem (engine revs erratic, lack of power and random stalls) it turned out to be the engine speed sensor which was faulty. I strongly recommend reading the ECU fault codes to see where the problem might be...

thanks everyone

it seems to be only on starting when warm that the car cant establish an idle speed and stalls instantly. the rest of the time things are perfect apart from heavy acceleration when there is a tiny stutter around 3k rpm

jest - if i had left the ignition on but not started for long enough after the airflow do you think i still need to reset the ECU?

thanks, dan

Well that I don't know, I doubt it. Reseting the ecu is always recommended. Better to start from square one.

my apology there its all one system and is built into the throttle body pity you cant take it apart? and yes you need to clear the codes in the ecu