Hi guys, had a breakdown in december. Was driving along and the engine suddenly lost drive(?) and then eventually dropped revs till it stalled/cut out. There was a horrible electrical smell and then it wouldnt turn over or start. Fast forward to now, its had a new dizzy, crank position sensor and new plugs. The original ecu was definitely fried, one of the chips burnt out. Having put in a new ECU the problem is still the same. It will crank and crank but not turn over. Once you stop cranking it pops 2/3 times like its definitely combusting. Spark plugs smell of fuel so its definitely getting fuel, good healthy spark to the plugs and the throttle body has been cleaned. VCDS showed one code for the TPS but I think thats come from the car that the new ECU came out of. As after clearing it, it hasnt come back. Also checked the tps and its throwing appropriate values on the multimeter. Anyone have any ideas whats going on here? Thanks ///Scott
Pull a plug wire and spark plug, check for spark. My agg did not agree with the new crank sensor, had to get a different brand to work.
maybe double check the timing: https://clubgti.com/forums/index.ph...ose-and-tune-your-mk2-digifant-gti-8v.124949/ also check the trigger wheel inside the dizzy, it should have 4 windows not 1. the single window type is for AGG/ADY. Assume the ECU has same part number as the old one too?
I'll double check the timing tomorrow, thank you so much for the detailed link. I'll check that trigger wheel in a sec and get back to you Yes the ECU is the same part number as the old one
Fact it pops ignition off may point to you loosing voltage to coil while cranking, but you get spark when tested so seems to rule that out... If you have a multimeter unplug the coil and check voltage from black to brown ignition on and cranking. Also in vagcom check ECU voltage ignition on and cranking block maybe ECU relay is past it's best
Oh and the ignition timing procedure in my guide does apply to early 2e, later 2e there's a vagcom procedure but it's possible the early procedure might still work not tried it
The window on the trigger wheel has 4 slots. From what I gather, the engine should still be in time. However, I'll check that tomorrow when I get the chance. Too dark now haha For the vagcom stuff you're suggesting. I'm using vcds lite, would I need to register/activate to utilise that feature?
Ignition coil was reading 1.5V then dropped to 0.7-0.8V when cranking. New ECU relay was put in aswell as a new fuel pump relay. Had these lying around I might add that I am doing this at a slightly lower than optimal battery voltage (12.2V), however, this issue was the same even when cranking at 12.8V
Yeah you would need a registered copy but I would try the old way first, all that said the car should still start so long as the dizzy isn't a million miles off. The coil voltage is your issue though as between black and brown you should have 12v near battery voltage ignition and loose a couple.volt while cranking. Check ignition switch mad wiring from it, plus any alarm/immo installs might have been hacked in at some point
It does have a cobra alarm fitted from donkeys ago. I'll add ignition switch wiring/immo wiring to my list of things to check tomorrow. Anything I should be looking for in particular in regards to those systems? Your knowledge is amazing btw thank you so much
Are you using the original key with the replacement ECU? Does this model have an immo in the ECU linked to the key? Sorry if I’ve missed this bit and am stating the obvious.
also do you think a bad ignition switch/immo wiring would cause the ecu to fry? from what im aware, my year (1994 cab) doesnt have a factory immobiliser in the ecu?
It should be, part number is exactly the same and production dates are only a few weeks apart, with the original being 49/93 and the new 04/94
Really appreciate your help tho bud, thank you Electrical stuff is about the extent of my knowledge when it comes to cars haha. This is my first older vw, so I'm still learning!
Had the same issue with my 92 mk3 and my coil was burnt out,did exactly what your car did,misfire got worse then it stalled as I coasted to the side of the road. These coils don't appear to be very long lasting from folks I have talked to and from what I have read,my car only had 140k km's @ the time.
It did feel like i had a misfire sometimes. When driving along, putting the foot down the car would kinda bog down a slight bit then come to life. Perhaps a symptom of an ignition coil on its way out?
