All Things MK6 R and GTI > MK6 Modifications & Technical Area

ED35 CDL sudden poor starting, misfires, general poor running, no boost

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john_o:
no recent changes
car running great
54k miles

just went out to the car after work on Thurs, it started but misfired, i turned it off then it was ok and i drove home...
then went to use it again an hr later and it barely started, and i get EPC/EML lights on, and its barely driveable , just bogs down

VCDS scan shows me at least 4 things that now appear to have no power (which implies an upstream relay, fuse or cable issue , hopefuly not the ECU!)


--- Quote ---4 Faults Found:
008852 - Fuel Pressure Regulator Valve (N276)
               P2294 - 004 - Open Circuit
             Freeze Frame:
                    Fault Status: 01100100
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 88207 km
                    Time Indication: 0
                    Date: 2050.14.20
                    Time: 21:43:24

             Freeze Frame:
                    RPM: 756 /min
                    Load: 20.0 %
                    Speed: 0.0 km/h
                    Temperature: 66.0°C
                    Temperature: 41.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 14.224 V

001112 - Evap System Purge Control Valve (N80)
               P0458 - 002 - Short to Ground
             Freeze Frame:
                    Fault Status: 01100010
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 88207 km
                    Time Indication: 0
                    Date: 2050.14.20
                    Time: 21:43:25

             Freeze Frame:
                    RPM: 765 /min
                    Load: 20.0 %
                    Speed: 0.0 km/h
                    Temperature: 66.0°C
                    Temperature: 41.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 14.097 V

000052 - Turbocharger Bypass Valve Control Circuit
               P0034 - 002 - Low
             Freeze Frame:
                    Fault Status: 01100010
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 88207 km
                    Time Indication: 0
                    Date: 2050.14.20
                    Time: 21:43:25

             Freeze Frame:
                    RPM: 765 /min
                    Load: 20.0 %
                    Speed: 0.0 km/h
                    Temperature: 66.0°C
                    Temperature: 41.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 14.097 V

000581 - Solenoid Valve  for Boost Pressure Control (N75)
               P0245 - 002 - Short to Ground
             Freeze Frame:
                    Fault Status: 01100010
                    Fault Priority: 2
                    Fault Frequency: 1
                    Reset counter: 255
                    Mileage: 88207 km
                    Time Indication: 0
                    Date: 2050.14.20
                    Time: 21:43:25

             Freeze Frame:
                    RPM: 765 /min
                    Load: 20.0 %
                    Speed: 0.0 km/h
                    Temperature: 66.0°C
                    Temperature: 41.0°C
                    Absolute Pres.: 1010.0 mbar
                    Voltage: 14.097 V
--- End quote ---

Battery voltage is good (see above)
i have checked some fuses but not found any issues (so far), am i missing an obvious fuse thats just blown here ?
i have replaced the '100' relay to prove its not that (same behaviour),

Anyone on here had similar issues / fixed them ?  cant see 3 seperate components going at the same time so in my head it should tie to a single central issue.
which at this point looks like a fuse/relay ive missed , ecu or broken wire

pudding:
Have a look at the main harness under the vacuum pump.  It rubs on the pump housing and a wire might have worn through and shorting on the metal housing.  Two of your faults are short to ground, so that's where I'd be looking in the first instance.

john_o:
cheers for the reply @Pudding  , sounds plausable, Ive now handed it to a trusted local garage (who generally look after it) , lets see how it goes.

john_o:
Wiring all checks out
Fuse box replaced
Issue now permanent not intermittent
alas its looking very ecu related  :sad1:
Next up is an ecu swap with immob removed just to prove it.
Then its decision time on swap for 2nd hand and/ or get original repaired
I have an rtech remap , can get it redone but a pain tbh
No mention  of water damage
Car bang on 10yrs old this month
Let's see....

pudding:
Bummer.  Not a common occurrence for an ECU to pop but as so many sensors share the same voltage reference line, the fault codes are pointing in that direction.

What I would be investigating before getting a new ECU is what caused the reference line to blow in the first place?  Short circuit? Bad mapping/tampering? etc etc.

It is possible to copy your old ECU to a used one, but obviously both will need sending off to a specialist.

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