A3 not running so well!

[dave1709]

Hi guys, need some help to find out what's wrong with my a3.
It seems to hesitate when i push the throttle. it idles fine and once your going it seems fine its jst when you come of the throttle to change gear or slow of. anyone got any ideas?

 

[Econ]

Petrol, coilpacks and spark plugs......

Is it low in petrol? My R34 plays up when it gets under quarter of a tank.

When was the last time the plugs where changed?

Also check your coilpacks a very common problem on most cars

 

[dave1709]

spark plugs are fine, will check the coils. never let the tank get to a quarter. the car seems to be using alot more fuel for the last week or so??

 

[pgarner]

MAF might be dirty or knackered
disconnect it and take it for another drive see if its any better.
aslo get it scanned for faults. does the turbo stick kick in as much as it used to ?
diverter valve may have burst

 

[obi_waynne]

Are there any mods? My guess would be the MAF sensor. Has the battery been recently disconnected?

 

[pgarner]

please note that isf the maf is dirty it wont show up as a fault but you readings for airflow will be lower than expected

 

[dave1709]

Will disconnect the maf and see if theres any difference. the turbo does seem like it takes a bit longer to kick in.

could the problem be being caused by the wastegate sticking open or shut?

nah no mods as of yet, bit short on funds at the moment.

 

[pgarner]

if the wastegate has stuck closed it should put the car into limp mode and warning lights should come on as the turbo will overboost.
if its stuck open your looking at a lot longer than 8 seconds to get to 60 as there will be no boost - again the engine management light "should" come on.

id still go with the maf or a burst vacuum pipe as theres are the most common things

 

[Econ]

Is it holding boost?

 

[obi_waynne]

It could be a stuck wastegate or it could be a diverter valve stuck open. One stops the turbo spooling up and the latter will prevent the boost from entering the engine. Let us know how it runs without the MAF sensor.

 

[dave1709]

No warning lights and its not slow gettin to 60, its still holdin boost. will let ya kn ow if the lack of maf works.

 

[obi_waynne]

I got some slack in power after my battery was disconnected and that was around 3000 rpm. After 200 miles the maf readings had sorted themselves out and it runs fine now.

 

[dave1709]

Disconnected the MAF and the car seriously lacked in power. don't think the battery has been disconnected, had it in to get the timing belt done but that was a good 6 or 7 hundered miles ago.

 

[obi_waynne]

My guess then would be the diverter valve sticking open. It cuts in as you come off throttle and spits the pressurised air upstream of the intake instead of into the engine. Then when you go on throttle it is sticking a little causing a loss of power. A garage should be able to test this for you.

 

[dave1709]

Where about is the diverter valve so i can hav a look myself? or will i not be able to tell if its wrecked?

 

[herb]

Where about is the diverter valve so i can hav a look myself? or will i not be able to tell if its wrecked?

hi mate this will help you locate the dv http://www.forgemotorsport.co.uk/valve.pdf

and this tells you how to test the dv at the bottom http://www.forgemotorsport.co.uk/valve_service.pdf