PLEASE HELP DEAD VR6

[Ciaran]

my vr6 P 96 OBD2 has been playing up for a while and is now dead.

it now turns over but has no spark and the fuel pump does not prime or run.
my mechanic believes it to be dead ECU please tell me it not.

the car for a while has started some times but not others and when it does it backfires and struggles to run. then all of a sudden it will be fine.

it has a had a vag com check and no fault codes related to the engine at all.
just want to see if it is something stupid before i take it to the stealers.

also the car has had it's immobiliser by-passed so that is not the problem

[Sammie-golf-cabrio]

i had a problem like this with my golf kept cutting out n would only go wen it felt like it, mine was the fuel injectors
try that?

[raylee25]

Connect your car back to the Vag com and measure the voltage to the ECU. Its should be around 13.7volts. Anything less could mean the ECU is shagged.

[EvilScotsman]

Ok, heres some food for thought and a possible solution:

no spark or fuel pressure would suggest an ecu failure, but could be a broken wire or bad/dirty connectors. The ecu is under the scuttle tray beneath the wipers so it is in a position to get soaked if the seals are damaged or missing etc.

REMEMBER - If you get an ecu from the breakers it will have to be matched to the car using vag-com or it will go into "tamper" mode and refuse to start the car. The current ecu is not a scrapyard replacement is it? If so thats why it wont start.

The other problem may be the key. The proper key has a small chip inside it that the car scans for an ID code, if its a copy and isnt matched to the ecu it wont run either but will crank. Your key signal may be low or intermittent. The chip is powered by an induction loop in the car and doesnt have a battery. vag-com may be able to read the key signal on the vr6 post 96 models, worth a try.

One final tale to tell you - I was working on a '98 Proton persona (mitsubishi colt) and fitted a new airbag/steering wheel. When i had the cowling off the steering column, the induction loop (was a pink single wire with a coiled end and a bit of tape to keep the loop together) slipped off the ignition barrel - I never noticed - its got to be looped over the barrel before it will work (the barrel goes through the loop)  - and no matter what we tried the car would not bloody start, no fuel / spark etc. In desperation I phoned a proton dealership and guess what - the service manager said "have you moved the pink wire loop off the ignition barrel? cos if u have it will never start...." - red faced - I stripped the column down and yes, it wasn't where it should be. I slipped it over the barrel and shazam, perfectly running car again.  Check this hasn't happened to you - I havent looked to see what the golf uses for this but i would assume its similar.

[EvilScotsman]

Update, I have found some info that may help, and has made me think twice about something i was going to do,

Uwe Ross, the creator of vag-com, has found in the past that 98 vw's with aftermarket stereos can have an adaptor fitted to the harness which (through bad design) allows 12v to get onto the K-Line (data line to the ecu and all other controllers) - this can blow certain test interfaces and the ecu as well. If you have a non vw radio, measure between pins 7 & 4 of the OBD socket with the ignition off, should be 0 volts and with it on, around 5 volts. if 12v shows here under any condition then your ecu may be already dead or in a coma! top left pin is 1 and numbers run to the right. If you do get 12v here, disconnect the adaptor lead linking the stereo to the cars harness and check that the 12v has gone away. Disconnect the battery for 15 minutes, then reconnect. Turn the ignition on for 15 seconds and then try to start the car.

Another thing I came across is several reports of people swapping or otherwise removing the instrument cluster and then finding the car wont start. The cluster (for a certain range of vw engine immobs) contains a chip for the immobiliser and can lose its info when removed.

If another set of clocks is fitted from another car, the cluster must be matched to the ecu and immob using vag-com but is a complicated procedure. Immo2 and Immo3 are affected by these issues,

thought maybe these could also be your problem but would expect vag-com to pick up a dtc like this article suggests:

Quote:
17978/P1570 - Engine Start Blocked by Immobilizer

Possible Symptoms
Engine starting but stalling immediately or not starting at all

Possible Causes
Key(s) not matched
Instrument Cluster not matched
Engine Control Unit (ECU) not matched
Engine Control Unit (ECU) Power Supply faulty

Possible Solutions
Match Key(s)/Instrument Cluster/Engine Control Unit (ECU)
Check Engine Control Unit (ECU) Power Supply (Relay)


If no other immobilizer related fault codes are stored and the immobilizer related meas. blocks are fine except Engine Start not allowed, try cold-booting the car's computer. Remove both battery cables from the battery. Short the battery cables together (away from the battery) for about 15 seconds. Reconnect the battery.

[Ciaran]

ta evilscotsman.
il try the bad harness thing as the car has a sony fitted although think it was a factory option extra.
will try checking for voltage when i get back from offshore if i remember my multi meter!!!

bought the car as a CAT c write off and never realy been write although think it is more due to bad luck than any accident damage as no wiring had to be changed.