1.4 AUA Throttle Cut Off with ABS and EPC lights
- Thread starter lavandism
- Start date
lavandism
Member
Robin, thanks for a reply. I looked extensively over your refurbishing thread searching for answers.
Voltages are OK, alternator has been changed two weeks ago, battery and ecu measure 14,2V strong.
No interference noise, but now thinking of that, audio does act weird, like changing tempo on CDs. It is not a stock radio, and it came with the car, so I do not know how good the wiring is, unfortunately. Headlight earth point seemed intact, I checked it two weeks ago too.
PlasticMac
Member
A VAG specific scan might be a good idea ...
Could give you a clue at least.
Edit: Might also be worth removing the radio, to rule it out.
Mac.
Could give you a clue at least.
Edit: Might also be worth removing the radio, to rule it out.
Mac.
lavandism
Member
Just as I was sending a message, @PlasticMac 
I've done a VCDS-lite check this morning while collecting the car.
Implausible Pressure Correlation and an Intake Leak, the ABS fault and a G202 Yaw Sensor. The ESP sensor has been acting weird for some time, but seeing people around here driving with these for months, I have not prioritized fixing it. I suppose the ABS may be connected to it?
Upon arriving in the garage, car started up with an extremely rough idle, running very very rich, almost a failed turbo smoke (1.4 aua, no turbo, I am coping with the situation through silly jokes). It makes me thing of a throttle body failure, since that was the only thing I fixed myself in the air flow system.
I've done a VCDS-lite check this morning while collecting the car.
Implausible Pressure Correlation and an Intake Leak, the ABS fault and a G202 Yaw Sensor. The ESP sensor has been acting weird for some time, but seeing people around here driving with these for months, I have not prioritized fixing it. I suppose the ABS may be connected to it?
Upon arriving in the garage, car started up with an extremely rough idle, running very very rich, almost a failed turbo smoke (1.4 aua, no turbo, I am coping with the situation through silly jokes). It makes me thing of a throttle body failure, since that was the only thing I fixed myself in the air flow system.
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How about the pre-cat lambda (related to mixture issue)?
the above description definitely sounds like the throttle body is involved in the symptoms, but the question is whether this is the cause.
On our AUA the oil cap on top of engine surrounded by oily residue, cap not really sealing. Fitting a new one with a better seal reduced incidence of manifold pressure-related errors, as did replacing the breather unit on the back of the engine block with a new one.
the above description definitely sounds like the throttle body is involved in the symptoms, but the question is whether this is the cause.
On our AUA the oil cap on top of engine surrounded by oily residue, cap not really sealing. Fitting a new one with a better seal reduced incidence of manifold pressure-related errors, as did replacing the breather unit on the back of the engine block with a new one.
lavandism
Member
Did that after reading your thread! It is double sealed now with some really high quality rubbers, hehe.
Breather unit though, never really checked it…
lavandism
Member
Pre-cat lambda gave me an error only once, during the old battery, and has never shown itself on the fault codes ever since.
Would it fault lead to a christmas tree and cutting off any response to accelerator?
Lambda problems more likely to just be heavy fuel use, smell of fuel around exhaust and poor economy. Your description is pointing at the throttle body, but we're looking for the reasons to explain why it is misbehaving, and why the lights are being triggered.
lavandism
Member
thank you, Robin.
it might have its part, as the exhaust always has been rather smelly. the fuel economy has been constantly around 40 MPG.
PlasticMac
Member
The faults you have, could, possibly, bring up EML ABS, ESP, and trigger Limp Mode.
Can you remember which lights you had at the Christmas Tree moment?
Mac.
Can you remember which lights you had at the Christmas Tree moment?
Mac.
when our one misbehaved it was exactly those lights - primarily the ABS & ESP, and the engine on idle fluctuating rhythmically from 900-1200rpm but no pedal response.
lavandism
Member
Started with losing throttle response upon engine breaking / reducing the push on the pedal. At a certain point I saw a rev needle dropping to zero and then turning back.
ABS + ESP with (!) three bleeps came on screaming, followed by EPC with EML.
lavandism
Member
Restarting the car saw rough idle, 900–1200 as @Robin_Cox describes, but it could keep going if I kept the revs high. Now thinking of that, a leak sounds very plausible and what I had been doing was effectively feeding loads of fuel to keep the mixture ratio. Until it was not enough anymore and the car cut the throttle.
I did notice the brake pedal becoming stiffer, but braking ability itself was unaffected, thankfully.
This morning the revving has been jumping from almost stalling to 2k, with attempts to stay still around 1100.
I did notice the brake pedal becoming stiffer, but braking ability itself was unaffected, thankfully.
This morning the revving has been jumping from almost stalling to 2k, with attempts to stay still around 1100.
lavandism
Member
Is it fixed? I thought we were just getting started!thanks for helping to get to the bottom of it
Ours did it again recently probably when the voltage dropped (cold night) - I managed to prevent it from happening through the winter by putting the CTEK battery charger on every 2-3 days when the same time and weather last year it was happening every few days, which is what makes me believe it is ultimately related to either alternator output or similar and low voltage after starting, with headlights and window defrost switched on, using the steering to reverse off the driveway resulting in voltage drop and unhappy ECUs. The other occasions when it has happened when I've been driving, it has always been on approaching a junction on the morning commute, put the car into neutral, indicators on and apply the brakes getting ready to turn and "ping", Merry Christmas!! Hence the other hypothesis I've had with it being triggered by applying the brakes with a failing brake switch (static electrical interference on radio when pedal pushed). Or possibly some combination of both!
lavandism
Member
But what was the reason of your Christmas lights, just battery?