Random Stalling, hard to start and EPC light

[beale187]

Dubbers,

My 4motion stalls at random (whilst driving) and can be hard to start whether it's warm or cold.

When it stalls the battery and EPC light come up on the dash.

I've tested the battery (and swapped batteries) still no luck.

I've tested the alternator and it's charging at 14.1V and about 13.5V when under load.

I've swapped out the fuel pump relay

I can hear the fuel pump prime when I open the door

I've scanned it with VCDS and it's not showing up any codes. Mind you when it's been scanned it's been stationary and no lights on the dash (hard to scan it whilst I'm driving and it randomly stalls)

I'm thinking... It could be a Crank Angle Sensor. Anyone have any other suggestions?

Also is there anyway in VCDS to see historical DTC's? Like when a DTC is logged but clears itself, anyway to check that even if the error is not present at the time of the scan? Hope that makes sense

Cheers,

[jmcc]

Could be the cam position sensor? I had a similar issue on the 1.8t, got a good price buying both cam and crank angle and replaced both and it fixed it.

I've previously looked into if there is a code history and as far as I found once they are cleared they're gone.

[beale187]

Did you have any DTC's on either sensor? Any suggestions on diagnosing either?

[LeStig]

Air flow meter .....
Unplug it and try it.
Car should run better than what you’ve got now.
If the symptoms remain then prob not the AFM but sounds like what mine was doing when mine failed .... only genuine Part fixed it.

[beale187]

Sorry swapped that also, forgot to mention.

[beale187]

Hazard of owning 4 MKIV's, part swap frenzy.

[LeStig]

Unplug it and try it ..... my symptoms were identical

[beale187]

Thanks mate, I'll give it a run over the weekend with it unplugged. Too risky during the 350km a week run to work.

[beale187]

No luck running without MAF. Stalled twice and was still hard to start occassionally

[HaydEn]

Crank sensor will typically only happen when car is hot, once cooled off will start back up without an issue.

Checked battery terminals?


Sent from my iPhone using Tapatalk

[beale187]

Crank sensor will typically only happen when car is hot, once cooled off will start back up without an issue.

Checked battery terminals?


Sent from my iPhone using Tapatalk

Terminals, earth at Gearbox and under battery tray, swapped MAF, removed MAF, alternator charging battery at 14.1V, no fault codes.

Little stumped, tbh. Typically stalls around 20km -60km, revs just slowly start dropping and throttle becomes unresponsive. When it stalls the EPC and battery light pop up.

[HaydEn]

The battery and epc light coming on is because the key is still in the ON position with nothing happening. Unrelated.

I have seen something like you’re describing due to a dodgy accelerator pedal. Could equally as well be the TB but they are a fair bit more resilient.


Sent from my iPhone using Tapatalk

[beale187]

mm.. good point Haydo, didn't think about those as a possible issue. If the accelerator pedal sensor is tied into the ESP system, might also explain another issue I'm having with the ESP light flashing every time I do a roundabout at low speed.

The accelerator pedal would not impact the vehicle starting up though, would it?

[HaydEn]

Won’t effect start up as ecu leaves the throttle body open a smidge ~6%

I’ve started cars without the pedal connected.

ESP thing I’m not sure if the pedal can be related, I would have thought that would be the abs controller detecting a wheel slip situation.


Sent from my iPhone using Tapatalk

[beale187]

Won’t effect start up as ecu leaves the throttle body open a smidge ~6%

I’ve started cars without the pedal connected.

ESP thing I’m not sure if the pedal can be related, I would have thought that would be the abs controller detecting a wheel slip situation.


Sent from my iPhone using Tapatalk

RE: Pedal - Good to know! Makes sense how else would it obtain idle!

RE: ESP - Figured the same, assumed wheel speed sensor haven't diagnosed yet. Didn't think the 2 problems were related though but you've got me thinking now..

Will dig deeper... Thanks mate.