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?

 

among other things you probably have a vacuum leak... high idle is a usually the cause...
you need a pressure test up to 20 psi for 30 seconds from the two lower boost hoses... block one off and pressure thew other... if it holds for 30 seconds at 20 psi you will not have issues... trust me.. do this first...

this is what I would do.. and Ive done it all...

 

Thanks Markski,

My idle goes as low as engine shutting off, the car places some throttle automatically in order to save it from stalling. Could that also be caused by the idle control valve?

Should I follow the boost leak test according to this link? https://www.6speedonline.com/forums/...ig-w-pics.html

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.

 

In my experience, it was my O2 sensors.

I replaced my precats as a preventative measure. I must have gotten a faulty one.

My issue was that - at the stop light, my idle would keep on hunting.

Boost and vac leaked the car up the wazoo and still the same problem.

Put the old O2 sensors back on .. and problem solved.

Just my $0.02.

 

Hi Saint Ari,

what does it mean by leaked the car up the wazoo?

Did you not need to get new O2 sensors to fix your issue?

Were your symptoms similar to mine?

Thanks Saint Ari

 

What I meant .. I had the car vac and boost leaked checked until tight as a drum and idle hunting still existing. new MAF .. still the same.

It ended up the new O2 sensor was faulty. After the old one was put back on and its all gravy.

 

I see, thank you Saint Ari!

So did you have to fix any vac or boost leak before they were tight? Is there a way to check if the O2 sensor were the culprit with durametric or datalog?

 

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

 

I had that issue as well. Even though I had a new MAF, I still had vac leaks that would cause that error.

Like what Marksi said ... boost/vac check the car ... and go from there after.

 

you ned a compressor and a boost leak tester ... go to 20 psi and it needs to hold period.. mickey mousing this stuff is a waste of your and our time.. seriously...
markski