2000 996tt engine being funny

[niceguy]

Having installed a new MAF 996.606.124.00 + reset ECU, the problem didn't go away.

Car has the following

Throttle body cleaned & New stock spark plugs, Injectors cleaned with Redline Si-1 3000km ago

Billet DV

UMW remap

200 cell exhaust

Stock hollow wheels n tires

My car has developed 3 symptoms recently

1. engine rev hunting @ idle (almost stalled feeling) &

2. engine rev rising and dropping (bouncy rev) under 2000rpm

3. ABS/PSM comes on @ off throttle + bouncy pot holes.

To better describe symptom #2, the car drives perfectly at WOT or with a slightly heavier right foot. There is no boost leak or power loss. It sits at 1.1 bar at peak boost and no vibration or engine rev rising or dropping during WOT. All bouncy engine happen rev below 2000rpm at cursing speed.

Does symptom #3 suggests new a ABS sensor kit?

What should I do to cure symptom #2 the bouncy rev?

Edited January 5, 2014 by niceguy

[niceguy]

Symptom #1 Just been out driving and found the car to idle at a around 800 rpm and whenever it drops to around 750 rpm, it revs up to nearly 950-1000 rpm. The whole process simply repeats itself most of the time at traffic light.

Symptom #2 happens mostly on highway in 5th gear under 2000 rpm. It does so in 2nd, 3rd and 4th too. The rev counter just goes up and down between 1700-1900 rpm.

[RFM]

Check if all the disassembled parts, connectors and hoses, put back flawlessly and without any risk of airleaks. I suspect symptom # 3 could be the cause, anyway it would not hurt to scan the car with a diagnostic device such as PIWIS, it's useless to guess what needs to be done without a scan.

[niceguy]

Failing to get my hands on a compressed air pump, I decided to spray some crab cleaner onto those accessible vacuum and boost hoses to see if I can any suspected leak.

It is funny to say that even with the suspected vacuum leak, the boost shown on the dash is stable at 1.1 bar and power delivery is smooth. I do not feel any power loss and the car is still as fast as before according to my accelerometer.

Since the new MAF, I have done just over 100km. The car has been occasionally throwing ABS/PSM CEL on the dash and the P0102 Factory Fault Code 115 - Mass air flow sensor, below limit was read. Furthermore, No other fault codes with engine, tiptronic or abs/psm were read by the durametric. Have you got any idea why it had caused the P0102 code?

In the attached photos, the 2 hoses that I circled in red are in fact linked together with part of it linking to the great black metal y-pipe that connects to the throttle body. Having sprayed some crab cleaner to these 2 hoses, I found that the rev counter definitely dropped and therefore I suspect there to be leaks. Fortunately, I was told that hose is the breather hose from the oil tanks mounted on the turbochargers. I also sprayed some crab cleaner onto the F hose that connects the 2 DVs, the Intercooler hoses and the hoses on the N75 boost solenoid but found no rev dropping. Do you think this breather hose is the culprit? And should I go out and datalog any particular value to narrow down the issue?

Thank you very much for your help :p:

[RFM]

P0102 - Either the MAF or the wiring is bad.

[niceguy]

Dear RFM,

My MAF is brand new bought from a local reputable bosch dealer and it came in its original box sealed. I had a vacuum leak that caused the rev to run high and unstable rev at under 2000rpm. Can I possibily datalog the MAF and post it here for your guys to see if my new MAF is faulty or not? What do I need to datalog?

May I ask which wiring are you referring to?

Thanks a lot for your help

[RFM]

http://www.renntech.org/forums/topic/45735-idle-speculation/page-2 read Loren's diagram conserning the error code. Hope it helps.