engine refuse to REV - intermittent

[pcfnet]

That means your MAF is bad. And your TPS was bad too.
It does not use TPS info unless the MAF signal is wrong.

But how come it doesnt have any fault code from VCDS? The only code I got is:

00537 - Lambda (Oxygen Sensor) Regulation
11-10 - Control Limit Not Reached - Intermittent

Before I replaced my MAF, I did have the fault code from the MAF (Intermittent) as below:

00553 - Mass Air Flow Sensor (G70)
07-10 - Signal too Low - Intermittent

After the MAF is replaced, the code is gone (haven't done a relatively long term test though)

[pcfnet]

That means your MAF is bad. And your TPS was bad too.
It does not use TPS info unless the MAF signal is wrong.

I had tried a known good MAF from my friend's 968CS before, but still engine couldnt start at all.

[prj]

Then there is something else wrong.
If you unplug the TPS the car will always start.

The TPS is not part of the air-fuel calculation at all unless the MAF signal is incorrect.
Actually until the MAF signal is evaluated during start it uses fixed values for ignition and fuel based on altitude.

What could have been happening is your old TPS had the 5V supply short to ground inside. And if this happens a lot of other sensors also do not work, that rely on the 5V supply.
But that is easy to test - unplug the TPS.

The DTC you have now means your air-fuel mixture is incorrect, it is off by more than 25%. Running too rich. Probably because the MAF you have is not the right one.

[pcfnet]

Then there is something else wrong.
If you unplug the TPS the car will always start.

The TPS is not part of the air-fuel calculation at all unless the MAF signal is incorrect.
Actually until the MAF signal is evaluated during start it uses fixed values for ignition and fuel based on altitude.

What could have been happening is your old TPS had the 5V supply short to ground inside. And if this happens a lot of other sensors also do not work, that rely on the 5V supply.
But that is easy to test - unplug the TPS.

The DTC you have now means your air-fuel mixture is incorrect, it is off by more than 25%. Running too rich. Probably because the MAF you have is not the right one.

you are right, there is something else wrong. I restarted the car last night but failed again. Everytime when I am able to start the car, it was because I had unplugged the battery previously.. I guess this reset the ECU and so the car can start up initially.

I did tried unplug the TPS but I still cant start the car at all.

Before I replaced the MAF I did have some kind of contact issues of the plug to the MAF (Whenever I push the connector I can get the car run smooth and strong). But after I replace the MAF, I seem to get away with this issue initially.. even now if I push the connector it makes no difference at all.

Is there anyway we can run the engine without MAF deleted? I remembered there's a member (Neal, who sold his RS2 recently in this forum) had mentioned a custom map by you can run his car without MAF?

[ManiacuV6]

PRJ can make a maffless software. I strongly think that you can have an immobiliser or a factory alarm issue. Happend to me ( Audi Competition but with factory alarm). Use a 12 V 21W lamp and check if you have 12V for ignition coils when your key is in the starting position. GOOD luck@!

[pcfnet]

PRJ can make a maffless software. I strongly think that you can have an immobiliser or a factory alarm issue. Happend to me ( Audi Competition but with factory alarm). Use a 12 V 21W lamp and check if you have 12V for ignition coils when your key is in the starting position. GOOD luck@!

no I dont think its related to immobiliser because if this is the case the engine should be able to start briefly for a second or two before it stall. My problem is that either the engine cannot be start up at all (but the starter is turning at good power, fuel is feeding), or it can be started up but its extreme rough at very low rpm.

I am now suspecting the engine speed sensor, cam positioning sensor... or even the ECU itself. I might get a oscilloscope to check the pulse pattern from the sensor to see if they work at all...

[mike74]

My engine used to intermittently cut out while driving; when I pulled the engine speed sensor out there was a single length of wire stuck across the tip, presumably from a wire brush. I removed the wire and it never cut out again...didn't idle rough or refuse to rev though.
Did you ever manage to check the engine earths?

[pcfnet]

My engine used to intermittently cut out while driving; when I pulled the engine speed sensor out there was a single length of wire stuck across the tip, presumably from a wire brush. I removed the wire and it never cut out again...didn't idle rough or refuse to rev though.
Did you ever manage to check the engine earths?

I check with my mechanic, he has replaced almost all engine sensor (except the cam belt position sensor). He had gone through all the connection of the sensor to the ECU end, including the grounding, and everything is connected as it should. He suspect its the ECU the problem... I was thinking either this or the cam belt position sensor.

I got this sensor & the ECU (8A0997551BX)from audi tradition again... The car is now parked in a car park where its not easy to be toll by a toll truck, thus I plan to replace the ECU first to see how it goes. My question is how can I manage the immobiliser issue? Whats the correct way to do the ECU swap?

[pcfnet]

Just to update and share the result. I finally had my rs2 towed to my mechanic, within few hours he found the problem and it was the poor contact at the ignition. Problem fixed without any parts at all.

One of the symptom just before the car is towed is that the electric window operated intermittently. Once the poor contact issue fixed the window problem fixed too.

[Greg_S]

Glad you got it sorted. Was it on the multi contact on the fuse board or elsewhere?

[pcfnet]

Yes I am really glad its on the road again. I've been told its the electrical contact of the key/ignition. The car just think it is about to switch off and on. That explain how come it behaves kinda like miss fire but I couldnt see any fault at all.

Glad you got it sorted. Was it on the multi contact on the fuse board or elsewhere?

[Greg_S]

That makes sense, I have had a few problems with intermittent window operation and was going to start with the window relay but will check the contacts out too if it doesn't solve it

[macspring]

I know this is an old thread but came across it today, bumping it for others who didn't see it first time around or have forgotten it.

Prj is always right.

Hopefully the Rs2 is still running well for the op.