I'm looking for some help with my mk3 Golf. I bought this car recently, it started and ran fine - no reported problems from the previous owner. I hadn't had the car long when the diff broke and since replacing the gearbox I am having starting problems. The car originally was a 8v gti. In the past a distant previous owner converted it to OBD2 VR6 and turbo charged it. When attempting to start the car it turns over fine. Occasionally it will start, but after a short time will cut out. The first time the battery was reconnected since the gearbox change the throttle body performed some kind of calibration routine which I had never noticed before. When the ignition is turned on; -the fuel pump doesn't always run -the fuel pump relay can be felt to click -there is 12v going to the ECU -there is continuity between the ECU earth pin and ground -occasionally the secondary coolant pump can be heard to run I have tried connecting a code reader to the diagnostic port but fails to communicate with the engine. Any help/advise would be much appreciated.
Quick update Removed the transponder thingy in the key today and it did occasionally still start as before so the immobiliser side of things would appear to have been deactivated. Also on the rare occasions it does run (for upto about 10 seconds) it doesn't appear to want to rev. When I depress the throttle pedal it sounds like it backfires a little and seems somewhat hesitate. I don't remember this occurring when the car was running and in use.
I'd try a bigger earth cable on both the ECU and chassis. I think I had similar with my mk2 R32, I thought I had killed the ECU but luckily it was ok and ran with a meaty earth.
Hi 1990 - thank you for that advise, I'll give that a go this evening and let you know how I get on. I am not sure what the standard earthing arrangement is for the VR6, I fear mine may have been changed. Can anyone point me in the direction of a wiring diagram, haven't had any luck finding one online so far.
Well I've added two new earths, one on the block (to the rear earth point on the rear of the engine) and one to the chassis, both fairly meaty. It fired up first time - and seemed to be quite happy ticking over as it never cut out after the usual short period. I had a few cars to shift before I could take it out around the block and wanted some confidence that it would restart so turned it off, moved the cars out the way and then found out it was back to its old tricks and wouldn't start again
if you feel the fuel relay click but pump doesnt run thats where I would start, on the obd vr6 pretty much all of the engine electrics as well as the fuel pump are powered off the pump relay, so it has a fair bit more load on it than usual. try a 17, 18 or 100 relay in the pump socket and see if that gets it going reliably, if so try another fuel pump relay look at the socket and fuse holder for corrosion or heat damage while you're there, my fuel pump went a bit random and I found the fuse socket melted and pump relay socket had a bit of corrosion damage
Hi Rubjonny, thank you for your advice. Removed my fuel pump relay 167, it is in good condition with no signs of any untoward damage. The socket looked good too; My friends mk2 happend to parked next to my mk3 so I had a rummage in his fusebox (!) and found this; Installed his relay and upon ignition on things sounded good, and I was able to get a code read; 17908 - Fuel Pump Relay Circuit - Electrical Malfunction 17708 - Misfire Detected Reason : Fuel Level Too Low 00543 - Engine Speed Input Circuit - RPM Upper Limit Exceeded 16486 - Mass or Volume Air Flow Circuit - Low Input 16515 - O2 Sensor Circuit - Voltage Low (Bank 1 Sensor 1) 00668 - Battery Power Voltage Supply (Terminal 3) The engine then started. Again it would not restart, and has not restarted since so I've not been able to clear the codes (I'm guessing i should have done this after reading them..sorry). I had borrowed the reader from a friend and it was the first time I've used it. The following day I visited Eurocar parts and acquired cheap and nasty fuel pump relay; and crank position sensor; Swapped them out and still nothing I fear that it may have been coincidence the car starting after swapping of the relays. It may have started at that time with the original relay fitted... Can anyone give me a bit more information on the reported codes please? What would be the next step to take?
sounds to me like you may have a wiring fault, drop your fusebox down and have a good look for anything that looks suspicious. make sure all the fusebox plugs are fully clipped in and the lock bar is clicked in to hold all the plugs in properly. another thing worth checking is your engien loom plugs actually still have the round locating pegs on the back end, without those they wont lock in securely giving you issues like this. I've seen them ripped off by people who didnt realise you got to click the lock bar out first! also on a related note your mates mk2 has a couple nice bodges going on there with the wires shoved in the front, maybe he would like to start another thread so we can sort it for him
I have a very similar issue with my MK2 VR. It fires up off the key, runs for a few seconds without an issue then dies. When you crank it again, it won't go unless you give it a bit of throttle, and even ten it pops and bangs its way into life. Few suggestions so far have been: MAF, f*cked Lambda. It's almost like it dies when the ECU does it's pulling the timing back trick to warm the car faster before it drops onto a quiet idle.
Sorry for the lack of updates - I unexpectedly managed to get another project on the road recently which has thrown up a whole load of its own teething problems so I'm working through that at the minute. I will be returning to the Mk3 shortly though so updates will follow.
Hello folks, finally managed to get back onto this car - so am picking up from where I left off. The fusebox and relevant connections all seem fine - can't see anything untoward going on there Thanks for the suggestion - having had another good look at the engine bay wiring with fresh eyes there were quite a few questionable connections/plugs that certainly wouldn't have been doing me any favours. With the help of a friend these have all now been reinstated back to factory-esque condition, and replaced the lambda for good measure. This didn't make a damned bit of difference. I then tracked down the guy who built the car and was told about how trouble free it had been - just my luck! A while ago i aquired pretty much everything for converting a mk2 golf to VR6 - in a job lot sale, the haul included standard ECU, Keys, Immobiliser box and transponder etc. I had the idea of swapping out the ECU in my mk3, and wiring up the key/transponder ring/immobiliser box from my newly acquired parts stash. This resulted in a car that started off the key reliably as you like, would run for as long as you dare and drives like a dog as you expect. This lead me to believe that the problem must be an intermittent issue with the ECU. I had been told it was a United Motorsport ECU so after a bit of digging around the internet ended up speaking to Tim at The Phirm. I've now got the joy of trying to continuity check every leg of the ECU socket ... watch this space.
Have done a continuity check on the holder for the main chip and it all checks out fine.. I now reckon its the EPROM its self is playing up. Anyone else every heard of or experienced this?
Update - Fixed ECU was sent out to The Phirm (UK United Motorsport agents) to be checked. Turns out the encoder on which the chip sits on had gone bad. That was replaced along with the latest software loaded and the car now runs Initially it had a fairly major overfueling issue, but this turned out to be lambda sensor wire had a break. Sometimes the car has a fairly erratic idle, especially when you dip the clutch to stop at the lights, but that's another issue for another thread. Thanks to everyone who helped with this.
