MAF not the answer - help needed

[Imola]

Hi all

I had a problem that I posted here and on advice, I disconnected the MAF sensor which appeared to cure it.

Today I fitted a new MAF and it is as bad as before I disconnected again

Only fault code was a disconnected MAF

Symptoms:
AMD tuned S3 7 years on the remap and it has been great. Huge toque spurt at 2500rpm and then shoots off 3500ish like a rocket. Always ' tickle the accelerator under normal driving. Awesome.

With the MAF connected (old or new) it feels flat, no torque spike at 2500 and it goes at 4000 but hesitates a bit 3500-4000. Pulls hard, but not as hard. Now I have to push the accelerator down rather than tickle it too.

Disconnected MAF and it is back to the previous great performance.

help!!! Not sure what to do or where to look next - will log the MAF readings tomorrow as a start

 

[vivalacoulter]

Possibly a dud new maf? Did you buy a genuine one?

 

[Gops]

Need to do some logs I guess. I'm no expert but logs on airflow might help determine your problem.?

 

[Imola]

That's

Yep, genuine Bosch part from vag.

Will try logging the MAF and expected airflow (i think one can do that) tomorrow, but really have no idea where to look and pretty worried

 

[slowcoach3]

Check the actual plug that goes into the maf itself, i was having similar problems, fitted a new plug at the very costly 3.50 and all is good. Well worth checking

 

[Gops]

I think it was blocks 002 118 030 iirc. Tuffty might correct me in a minute though because he told me ages ago but I forgot :|

 

[Imola]

Slowcoach, did you replace the entire cable bakc to the EUC or just resolder the plug?

 

[Imola]

Update

I went to my local garage who have been looking after the S3 for the past 5 years.

We plugged in his universal diagnostics machine (for all makes of car) and looked at blocks. MAF was reading only a few g/s and after we fiddled under the bonnet, we read 168 g/s which is seriously low as far as I am aware (especially chipped). At one point it read mg/s!!!!

I tried a run down the road once we saw 168, but it was 'flat' as described above. When I got back (2 minutes) we looked at comms and got an ECU error and the traction light was on alone with no others, so not traction error (cleared easily).

We also saw an intermittent brake light switch error which cleared OK and did not return during testing.

There are no audible leaks on the boost side. When all is cool I am going to check a hoses and the Forge DV incase it needs a re-seal.

What can cause the low MAF readings other than a duff MAF? I don't have a full VCDS, only shareware and am concerned that registering for £60+ will possibly give me more info, but it will mean nothing and not help with the problem?

What about the N75? (lots of people post about that) How do I know if that is a problem?



This is getting worrying and I am concerned about throwing more money at it as it has just had 4 new tyres, 4 sets of pads, 2 new disks, new rear suspension arm (bush moved and wore into the arm), new wheel bearing and one or two other bits - all wear and tear, but still a large outlay

 

[Broken Byzan]

What fiddling was done to 'fix'the maf to allow the 168 run

 

[Imola]

Fiddling was that we checked pipes etc. unplugged and replugged the MAF sensor (I am going to check the connection pins more carefully in an hour when I've finished fixing my daughter's laptop).

Maf connector looked fine, but I am hoping to find out if slowcoach replaced just the plug (how?) or the wires back to the ECU

 

[Gops]

Just the plug, it opens up and you push the wires out! You need a smoke test, you could have a boost leak.

 

[Imola]

Been searching and still no idea what a smoke test is. Could give me a run through please?
We listened carefully for a leak on the boost side, but could hear nothing

I paid for VCDS tonight and thought about a new N75, but will wait until I can log the car when the serial number (or whatever) arrives

 

[slowcoach3]

Sorry dude, busy working! I replaced the plug itself, none of the wiring was touched, my plug had broken up a bit inside so wasn't making the correct contact. For me it was a simple fix for a change.
A smoke test literally puts smoke using a lightly pressurized machine through your TIP and the charge system, any leaks will be very obvious whereas listening for them won't help as much as you think.
Don't fit your n75 ( and void the return policy ) until you've done lots of logging to check other options first because n75 being faulty is relatively unlikely compared to other faults