no boost

jay22s3

jay22s3

2nd gear sorts em out
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hi after some help if poss please last week driving home on the motorway my car suddenly had a problem I was driving along at 75mph and when I tried to accelerate the car just bogged out managed to get home but it wanted to cut out at the traffic lights I had to keep reeving it slightly , the man had gone but I've changed it now and the car has no boost its just flat the only code I got was the maf 16487 what could be wrong ? any help would be much appreciated
 
I've tried that tuffty I bought a second hand maf of some one on Facebook starts up fine ticks over ok but just no boost its flat when you drive it
 
I assume its a genuine Bosch sensor? is the correct sensor for the year/engine code of the car?... known working before?

Have you actually just tried driving with the MAF unplugged?

What did you use to scan the car?

<tuffty/>
 
I was told it was a correct maf and working but my car is an APY originally1999 S3 but the engine has been changed to a BAM so which maf should I be using ? as I know the APY is narrow band and the BAM is wide band, and it is a BOSCH MAF that I got but it could be goosed , and I have tried running the car with it unplugged and there is no difference
 
Need to use a narrow band MAF so the one for the APY...

On the sensor itself it will have a part number... if it ends in 040 its a narrow band sensor... if its 049 then its a wideband sensor... you will need an 040

20131019_143442.jpg


<tuffty/>
 
jay22s3 said:
so could it be just as simple as the maf being incorrect that theres no boost ?
Click to expand...
If you have a wideband sensor instead of a narrow band one then it could explain the fault code you had...

Like I said... unplug the MAF and see if you get boost again... ECU has fall back tables in case the MAF goes faulty in this way but currently it cannot determine that the fault is the MAF just that its seeing more airflow than its expecting...

This normally happens when a MAF sensor over reads but if you are using the wrong sensor then this could also cause a problem... not something I have personally checked out and tested but the response curves between the sensors are different and the table for calibrating the MAF in the map are different between narrow and wideband ECU's

If you have no boost after unplugging the MAF then you have another issue...

<tuffty/>
 
jay22s3 said:
could the actuator be sized ?
Click to expand...
If it was seized you would probably have all the boost in the world...

When you say 'no boost'... do you mean literally no boost as in you have measured nothing over vacuum or some boost but not what you normally get?

Actuator pressure will give you at least 0.5bar/7psi boost pressure... if you are not even getting that then sounds like the turbo is goosed...

<tuffty/>
 
Take the TIP off the turbo (obvs engine NOT running) and see if you can spin the turbo by hand...

You could also have a pipe off somewhere of course... maybe check for that first... would need to be one of the main charge pipes for it not to make any boost at all...

What did you scan for codes with?

<tuffty/>
 
just an OBD SCANNER I have , I'm sure theres no pipes off but I will check there is play in the turbo shaft in and out and up and down but it does spin freely as I checked that when I had the tip off today
 
Ideally needs a scan with VCDS in case the generic scanner is not picking up all the faults (they don't always pick up every VAG code)..

Other than that dude not sure what else to suggest...

Smoke test, logging with VCDS and an experienced eye to look over it would be the next thing tbh

<tuffty/>
 
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