In 4th Gear - under full throttle - as the car gets to approx 4,000rpm there is a sudden rise in boost to 1.0 bar from 0.6 (car is totally stock) and then the car hesitates or dies off. In other gears theres a slight flat spot, but 4th it's very noticeable.

Car has had major service with plugs/coils/MAF approx 4k miles ago.

ABS & PSM light came on as well on one occasion.

Any ideas anyone?

Thanks

Jim

 

I'm saying faulty MAF

Unplug it and go for another drive
The PSM and ABS lights will remain lit
If the car drives smoothly again the MAF is at fault

Where in England are you?

 

Its on its 3rd MAF - the OEM one that I thought was faulty so replaced with a new Bosch one (which made no difference so I assumed this was also faulty so swapped it for another new one - still no change!) so ruled that one out.

Any other ideas? - Could it be a DV or air leak - no idea why a spike in boost and then loss of power..

I'm in Warwickshire BTW..

Cheers

Jim

 

I had (possibly) the same problem and was convinced it wasn't the MAF
The garage told me it would need to be hooked up to diagnostics to solve it

I spoke with Marek and told him what was going on and he told me to disconnect the MAF and the car ran fine, I swapped it again and it was fine

Try disconnecting it and see what happens
If it still doesn't cure it you could have a boost leak
First place to check would be the hoses from the turbos to the intercoolers

BTW - I'm in Kenilworth, let me know if you need a hand

 

Sounds like classic bad MAF behavior, but it could also be a boost leak.

 

Yes - might just take you up on that! - If you recall we PM'd ref local specialists (Shirleys & AB)? Would be helpful to be taken for a drive in another 911TT to see how mine compares in terms of smoothness and performance?

Jim

 

Ah yes, of course I remember - I'm just useless at recalling names

My car is a stock '01 manual car with about 50k miles on it
I guess it "should" drive very similar to yours

Let me know when you're free if you want to meet up to compare performance and to check your car over

 

Update - unplugged MAF and get the exact same results as above.

Also car starting to loose performance in all gears - boost reading is OK (in fact higher than normal as now .9 or 1.0 instead of normal .6 or .7) but performance is way down..

Almost convinced its a boost leak or leaking DV somewhere - going to book it in for them to have a look at.

Anyone else got any ideas?

 

It sounds like you have a boost control issue. Nothing to do with the MAF.

 

Sounds like the e-throttle is kicking in and preventing an overboost. Have you read the codes?

A boost leak could maybe do it except that this is still occuring with the MF unplugged so I do not think it's a leak. what would happen with a boost leak and working MAF would be the ECU reading the incoming air properly and fueling for it but much of the air escaping which would lead to a full rich condition. In this case though it's seeing higher than normal boost and we know the ECU protects the motor from overboost - it has an e-throttle it will close as part of those protections. Read the codes, you will likely find that the boost solenoid is flagged and likely an overboost. Could be wiring to the solenoid, could be hoses to the solenoid, could be hoses the the W/G cans, could maybe be a broken W/G rod. Check codes first and then go down that list looking for issue. Bad hoses might show with a boost leak test.

 

If disconnecting the MAF didn't help the next thing I'd look for is boost leaks
(check everything that you can do for free, that's the way i'd go about it)

I had a problem with my car overboosting to 1.4 bar and the car was running horridly
I tracked it down to a boost leak at the lower intercooler connector

 

Someone's going to have to explain to me how a boost leak causes overboost. Overspinning turbos I can see but a leak in the hoses doesn't cause boost to go higher than it's supposed to... How exactly would that work?

 

Boost leaks cannot cause overboost, fact.

 

Seems logical - but could a sizeable leak on the intake side that adminsters unregulated air (not past the MAF) mixed with additional fuel injected by the ECU to compensate for the lean condition cause an increase in boost?

Pressure test is worth a punt IMHO - just read the DIY thread and seems straightforward.

 

A pressure test might reveal the issue, if I were you, I'd check the wastegate actuators