Hey, iv got a mk2 gti 16v with an abf fitted using the kjet system. Iv had it a few months now & has been fantastic until today. I started it up this morning to move it so I could change the clutch cable to the manual type, did the change over no problem at all. Then when I went to start it it wouldn't. I took a plug out to check for a spark & nothing, iv tested the voltage from the coil & it stays at around 12v with the ignition turned & also when turning over. Iv swapped the coil for a good one & no difference. I'm positive I didn't damage anything when changing the clutch cable although I probably did disturb a few wires. Iv checked all connections & can't find anything. I'm still fairly new to these cars & not sure what my next move should be, any advice is really appreciated!
Hello and welcome Do you hear the fuel pump priming with ignition and running while its cranking over?
ok so ecu is powering up, and it is seeing some kind of signal from the hall sensor. oil inside the dizzy means the internal oil seal has failed, good guide here: https://clubgti.com/forums/index.php?threads/190271 have a look at the spark module on top of the ecu, and have a general check over of all your wiring loom. the spark module has an earth back to the battery, plus it gets its live from the coil live side, though so does the ecu so if thats powered the spark module probably is too. have a look anyway, you should have a single black from fusebox for power (which is ok as you checked) then a spade with a black and a black/white which are the power feeds for ecu and spark module on the negative side you have a red/black for rev counter to fusebox, another red/black to a spade which is the feed back for the ISV contr5ol unit, then on the other side a red./black or green wire which is the trigger wire from the spark module. make sure non of these wires are earthed anywhere. another check, while cranking does the rev counter jiggle at all?
Thanks for the info, I'll check as soon as I get back over the unit. The last time I took the car out I do remember seeing the rev counter jiggle a bit but was running well otherwise. Is this a symptom of something? Incidentally a friend has his mk1 running a kr parked up next to mine so its possible for me to borrow parts to help diagnose what's wrong.
if the rev counter doesnt jiggle then you know the spark trigger from the module to the coil isnt there, which can help you narrow down where the issue is if it does jiggle while cranking then you know the ecu & spark module are at least trying to fire the coil
These are great tips, thanks. My distributor appears to be a Chinese one so I'm going to change that to Bosch while I'm on
So if I'm reading right, because my rev counter doesn't move, the fault must be the ecu or ignition module?
if you have no jiggling then this suggests spark module may be faulty, or the wiring to it. the fact the fuel pump primes tells you ECU is powering up, and if the pump runs while cranking this tells you the ecu is seeing a hall signal so would be trying to trigger the spark module. usually they're pretty much bomb proof and when they fail nothing works but it could still be the problem mind, keep it at the bottom of the list for now unless you stumble across one for peanuts or have a local member with a 16v you can try bits from. next step would be unplug ecu and spark module, check terminals are nice and clean and are tight. check the hall sensor plug and wiring under the rubber plug, and give the engine bay wiring a general once over looking for any random bits of tape on the wiring which hint at bodgery underneath. Other main points for the ecu loom are earth at the battery, earth to head, temp sensor on head with blue/white wire, coil connections and a 2 pin plug in the scuttle. spark modules are cheap and plentiful, same for all mk2 with electronic ignition plus mk1, cabrio and scirocco. you want later type ideally which is straight swap for mk2. mk1 type has heatsink separate so may not fit on the mk2 ecu bracket, though from memory I think the bolt spacing is the same? Spark module pinout: 1 - green or red/black - coil negative 2 - brown - battery negative 4 - black - coil positive 6 - brown/blue - ecu pin 12 peel the rubber boot off the plug then you'll see the pin numbers, check between pins 1 & 4 you should see ignition live, and continuity from pin 1 to coil negative, continuity from pin 6 to ecu. ECU pins: 1 - blue/white - coolant temp sensor 3 - brown - earth to head 5 - black/white - ignition live from coil 6 - yellow/black - idle switch (12v throttle closed, 0v throttle open) 7 - brown/white - hall sensor pin 1 9 - green - hall sensor pin 2 10 - red/yellow - fuel relay trigger 12 - brown/blue - spark module pin 6 15 - red/black - hall sensor pin 3
Really helpful thanks. Iv managed to get a spark to the plugs. Still won't start however. Iv marked up the bottom pulley so from what iv read the first cylinder should be at tdc? When iv taken off the dizzy cap I expected to see the rotor arm at 10 o'clock but it was at 4 o'clock, is that right?
the crank turns twice for every single rotation of the cams & dizzy, so line up the cam to TDC then check dizzy and crank
We have spark, we have fuel, we have the distributor rotor arm pointing at the notch on the housing (10oclock) when at tdc. But still it will not start! Its not even trying to, no cough splutter or anything.
They were soaked & stinking of fuel. Iv left them out over night as I think it may have been flooded. For a few weeks before this happened the car would start great but not rev without bogging down until it had warmed up. I put it down to cold weather, not so sure now..
Managed to get it running! Thank god. I think changing the distributor fixed the no spark fault but I'd tried so many times to start it that it had flooded the engine. Leaving it over night was all it needed. Oh & changing to manual clutch cable has made a huge difference to the biting point so a very happy ending
