VR6 starts and dies - bunch of error codes

[emirc 0]

Hi guys, i have a problem that's kinda popular these days...

OK, after i had my cooling problems sorted out, and then heater core exploded due to overheating because rednecks at dealership didnt connect fan connector properly while changing some cooling components, i run into more Corrado woes.

Since i repaired cooling system, my car used to act funny when warmed up. I started to notice that when weather was very hot (40

[Yandards 0]

G28 is fine, that occurs on all VR's when the engine is not running.

 

You need a new MAF first up, the other two are probably due to the bust MAF as the ECU uses the signal from the throttle pot and the speed sensor to 'replace' the values of the MAF.

 

I would also suspect that your lambda probe is probably knackered too but change the MAF first.

[dr_mat 0]

.. but note that the short on the MAF could be caused by a wiring glitch, not the MAF itself. Check that out before forking out a small fortune on a replacement MAF. Otherwise, I would agree with everything Mr 'Dards said.. :)

[emirc 0]

THREAD UPDATE:

 

Half an hour ago i checked it again with VAG-COM, only this time i deleted old errors to see what's coming up. Turned the ignition, started engine, kept RPMs around 2000-2500 and then turned ignition off immediately (i didnt let it to cut off).

 

Now this time only 1 error:

 

00513 - Engine speed sensor (G28)

No signal

 

So i guess i will be spending 100 euros on new ESS :(

[Toad 0]

The engine speed sensor error occurs when the engine is off and vag com is plugged in. Because the engine isn't running, it assumes that there is an error with the speed sensor, when actually there isn't.

[emirc 0]

The engine speed sensor error occurs when the engine is off and vag com is plugged in. Because the engine isn't running, it assumes that there is an error with the speed sensor, when actually there isn't.

 

 

So how can i check this sensor properly? Download vag com codes while i keep engine running perhaps?

[Toad 0]

I don't think your car runs if it doesn't work. I'd ignore it for the time being and follow Yan, and Dr's advice.

[CrazyDave 0]

I don't think your car runs if it doesn't work. I'd ignore it for the time being and follow Yan, and Dr's advice.

 

Yep, thats correct. And you also get negative temp readings on AG ecu for inlet air and engine coolant until ecu sees a crank signal. No fuel pump either while cranking. All symptoms of crank sensor. CP ecu temps read correctly with just ignition on.

 

Start the engine. Reset the fault codes, drive the car and then read the faults before switching off is the only way to get accurate codes.

[Yandards 0]

The engine will not start if the crank pos sensor (G28) is bust or misreading.

 

As for the other fault codes not being apparent if you have an intermittent problem it may take some time and miles for it to be listed in the fault codes again.

[Yandards 0]

.. but note that the short on the MAF could be caused by a wiring glitch, not the MAF itself. Check that out before forking out a small fortune on a replacement MAF. Otherwise, I would agree with everything Mr 'Dards said.. :)

 

Very true but, sadly much less likely to be the case unless someone has done a recent air filter change and caught the MAF plug etc.

 

Still worth doing a continuity check on the ECU loom to make sure though.

[emirc 0]

I just wanted to report status if anyone may need it (hope it doesn't). To make sure i checked G28 sensor with ohmmeter and its OK.

 

Electrical connections between MAF and ECU were the problem though. The wires were corroded from the ECU side, and one was so bad that it actually break up. After cleaning and replacing wires, i got my idle now :)

 

But i still got the intermittent problem when car is at its operating temperature and under a little bit of abusing :oops: . It hesitates for a split second between 3000 and 4500 RPM, most noticeable and likely while shifting down and WOT. Could it be still MAF related, what you guys think?

[Benny 0]

I'm having the same problem emirc, and its really starting to annoy me now as it really spoils the whole car (especially as i'm a relatively new owner :( ) I recently changed the ECU (as it came with the wrong one when I bought it), so i'm thinking that could be the culprit if its faulty? But if someone has any other ideas then they would be much appreciated! :D

[CrazyDave 0]

If you found MAF wire problems it would be worth checking the throttle position wiring as the two are closely related to determine igntion timing and fueling.

 

I get a similar problem with my car at the moment (but caused by something very different, a dump valve!), but you'll get a similar thing for the same reason. An air leak would cause the MAF to read incorrectly during throttle closed at higher rpm. MAF is a major input for determining ignition timing so if it gives the wrong reading it'll make it rubbish to drive. Any popping from the exhaust?

 

An air leak would also cause an incorrect O2 reading, and as a result general bad running. Check for air leaks in the manifold / downpipe area and all of the inlet system.

 

Hope this helps? :)

 

edit: and yes it could just be the MAF anyway, but check the other stuff first.

[emirc 0]

If you found MAF wire problems it would be worth checking the throttle position wiring as the two are closely related to determine igntion timing and fueling.

 

I get a similar problem with my car at the moment (but caused by something very different, a dump valve!), but you'll get a similar thing for the same reason. An air leak would cause the MAF to read incorrectly during throttle closed at higher rpm. MAF is a major input for determining ignition timing so if it gives the wrong reading it'll make it rubbish to drive. Any popping from the exhaust?

 

An air leak would also cause an incorrect O2 reading, and as a result general bad running. Check for air leaks in the manifold / downpipe area and all of the inlet system.

 

Hope this helps? :)

 

edit: and yes it could just be the MAF anyway, but check the other stuff first.

 

Throttle position wiring and throttle body was checked and its OK, not as good as new but also not too worn out to cause any problems (at least my mechanic told me this :? ) . I mentioned that problem dont exist when car is cold, when you first start the car you can drive it very aggresively until oil temps reach 120

[CrazyDave 0]

Mmm sounds like lambda probe?

 

Closed loop control isn't active until engine water gets warm. Does your car have one? It should have. But some decat systems don't have a bung to screw the sensor in. Without the lambda probe it's a bit hit and miss as to if it run OK, I've had both with my car. The first time I unplugged the probe it ran great, but when I reset and tried again it ran like a bag of nails.

 

But keep in mind that it could still be an air leak. The lambda probe measures oxygen content, so if the system is leak free it's the mixture it reads. If you have an air leak the extra oxygen is being read instead. So the fuelling will be all wrong.

[emirc 0]

Now i realized my problem is not so intermittent as i thought. You guys that got same problems, should pay extreme attention on when exactly and how problems occur.

 

In my case,i realized im getting hesitating everytime i make hard right turns. Its also noticable when trying to pass the car in front of, when i make quick left then straight the car by giving it right turn, it hesitates. (we drive on right side)

Its also more noticable when climbing up the hill, when doing the actions above.

Less noticeable when gas tank is full.

 

However i still cant explain why is this happening ONLY when car is warmed up.

 

My best guess - fuel pump?!

[CrazyDave 0]

Now that sounds like the fuel pump.

 

It may have come loose in the tank? Check it out ASAP as this can cause a very lean running condition and you may do some damage if under heavy load at the time, even though you've got knock sensors.