Hi all I've had a no start no spark issue with my 91 GTI 8v for a few days now. I was driving along at around 40 when I lost all power and the rev counter dropped to zero. The engine cut out and I managed to coast off the road. The AA came and tried a new coil but that made no difference and they towed me home. I've been trying to find the issue without much luck. There is a spark when the ignition is turned to position 2 but nothing when cranking. The fuel pump can be heard to prime. The rev counter doesn't move when cranking. I've carried out the Haynes tests. Switch Unit (ICU): Battery voltage available between pins 4 and 2 Continuity between pin 1 and terminal 1 on coil Approx 4vs dropping to 0 between the coil terminals when the ECU connector is unplugged Earthing terminal 12 on the ICU connector gets zero volts. Haynes says to replace switch unit. I ordered a new one but it makes no difference to the spark or this test. Engine Control Unit: 5Vs available between ecu connector terminals 4 and 2 (Haynes says battery voltage should be available) Zero volts between terminals 6 and 3 Couldn't get a reading for the temp sender resistance Earthing the centre pin of the hall sender gets no voltage rise at the coil terminals, and the fuel pump doesn't operate. Hall Sender: Battery Voltage available on outer pins of hall sender When cranking voltage drops from to around 6-7 and fluctuating on the centre pin. I've cleaned up the earths on the head, coil and gearbox. There is continuity between the ecu earth pin 13 and the battery negative. There is battery voltage available at the relay feed pin 14, dropping to 8-9V when cranking. There is continuity from the hall sender to the ecu (pin 18) to the icu (pin 6) and to coil. Ive run a wire from the battery positive to the coil positive but no spark. I've tested the coil resistances and they seem fine. All this but still no spark when cranking. So after all that I believe I need a new ecu, but I'm reluctant to buy parts I don't need after getting the ICU and it making no difference. Any ideas?? Cheers Harry
Also my knock sensor cable is falling apart although I don't think this would be the cause for no spark
Not sure what ECU hay6nes was referring to with pins 2 and 4, pin 2 is the non existent lambda probe on a UK spec and pin 4 is for the knock sensor... PB ECU pin checks 1 - red/green - cranking live 6 - brown/white - common sensor earth back to the ecu (i.e. continuity to all the sensor brown/white wires) 13 - brown - earth to battery 14 - power from ECU relay 19 - brown/black - earth to head 25 - green - ICU pin 6 so you should see 12v pin 1 cranking on the starter, and ignition voltage between pin 14 and pins 13 and 19 for starters. Check the ecu relay can supply full voltage while cranking over as well
Hey thanks for the reply. I made a mistake with the ecu pins earlier, Haynes said 3 and 5 not 2 and 4. Not sure if I measured the right pins or just made a typo!! I've just done the following checks: Pin 1 gives around 9Vs when cranking Pins 14-13 gives battery voltage Pins 14-19 also gives battery voltage Pin 14 earthed to the battery negative terminal gives battery voltage and then 9Vs when cranking. So I am not getting enough voltage when cranking? cheers
ah, I think you were looking at the checks for the 16v electronic ignition unit, those pins are indeed power and earth You will see a volt drop while cranking, to rule that out you could jump the car and see if it helps at all
Yeah you're probably right, there are too many changes on models!! I'm already using a battery jumper pack (says 1000A and 7000J on it!) as the battery is basically flat now anyway.
did you check for continuity from ecu pin 25 and ICU pin 6? this is how the ecu triggers the coil to fire. Also does the fuel pump run while the engine is cranking? Worth checking ECU wiring for the dizzy side: 6 - brown/white - pin 1 (common sensor earth) 8 - red/black - pin 3 (voltage to dizzy) 18 - green/white - pin 2 (hall signal to ecu) while its all apart have a good look at all the pins on the ecu, spark module, coil and other sensors on the engine. Make sure the terminals are straight, clean and fully inserted into the connectors. peel back any rubber boots to check the wire condition into the back of the crimped joints. Look for any black tape covering your wiring loom, if there is any 9 times out of 10 bodgery will be uncovered underneath
OK so I have continuity between Ecu Pin 25 to ice pin 6 Pin 6 to pin 1 Pin 8 to pin 3 Pin 18 to pin 2 so ecu to dizzy connections seem ok I looked at the pins on the connectors for ecu, icu, dizzy, cleaned coil terminals, cleaned battery terminals and all connections on them. looked at lots of other sensors, Knock sensor is pretty ratty, the black and blue temp senders are a bit worse for wear but are connected, ISV connector was fine, cleaned up airbox sensor connector, looked all along the ecu loom, gave it a good wiggle. Checked for any stray wires around the ecu, didn't find anything suspicious. I took out the fusebox and had a good look at the connectors, there is a lot of black tape and bodging/ soldering under the dash going into the steering column. I pushed the wires going up into the steering column and I heard a whir and a relay clicked (ignition was on). Battery pack had run out so couldn't crank the engine to see if there was a spark!! So there may be an issue there but I'll have to wait a bit to test again. Maybe its the ignition switch? I tried connecting the battery positive to the coil before with no luck.
if the ignition loom has been hacked best bet is pop down the scrappy and pull one out of a mk3 golf thats in good nick, swaps right over while the knock sensor wont stop it starting, you need a decent one. while looking at mk3s check the engine bays for a decent knock sensor, they're all the same pretty much just wire length that differs. I had one off an old audi 2.0 on my digi or you can usually pick up new hella brand off ebay for cheap enough
Ok cheers I'll try find a new loom at the weekend, it'll only keep giving me problems otherwise. I've taken a couple of pictures under the steering column. The ignition switch connector looks awful. The green corroded wire is the lead from the battery, pin 30 I think. Tried to start it with the jumper pack but it keeps overheating and running out of charge, its supposed to be able to jump something like 10 cars on a single charge and its barely lasting 30 seconds. Maybe the crappy wiring is blocking the voltage and the jumper pack is working extra hard?? Also not enough voltage for a spark? The car battery is so flat the starter solenoid won't even click without the jumper and the mfa goes out when you try to crank. Any tests I could do on the ignition switch connector??
ewewew! get that binned asap. if the battery is royally stuffed it might be the cause, do you have a charger you can put it on?
I've got a battery charger I could try on it tomorrow. Looking on eBay at looms, would I just need the internal loom with the fusebox, saw one for a mk3.5 cab but it has no electric windows or central locking. Ill try get to a breakers at the weekend. Still wanna see if I can get it to run by wiggling a few wires first though !!
you litterally just need the loom from the ignition switch to the fusebox, if you get the complete stalk loom as well that might be handy depending on the state of the rest of it, but the gti type ones with the dual chamber headlights are a bit different. worst case you could strip wires out the donor mk3 loom to repair yours if different.mk3 dash loom is pre mk3 dash loom is pretty different to mk2, only bit thats of any use is the stalk and ignition section really. But you can strip bits out to repair a damaged mk2 loom, for example the stereo looms can be removed and swapped with a bit of effort to depin the fusebox pins etc
ahh ok so its just the 2 connectors and the wires between them. Ill look out for something suitable. So could this dodgy switch be the reason for no spark?
probably not no as you bypassed a faulty ignition switch/wiring when you jumped the coil with voltage straight from the battery, assuming the jump pack was man enough to power everything properly. Also assuming you left the original wires on there and used the spare terminal for the jump wire this powers up the coil and tci as if ignition is on, plus the power wire back to the fusebox will have back fed all the other ignition live feeds on the fusebox, i.e. ecu relay trigger, fuel relay etc. its definitely got to be sorted sooner rather than later regardless though, you know theres a bad joint somewhere on the ignition power since wiggling back here caused a relay to click and what I assume was the fuel pump to prime
I tried again just to be sure. Cleaned up the positive to the starter motor as it looked a bit corroded. Connected up the freshly charged jumper pack, connected the batt positive to the spare coil positive, ISV comes on, ignition lights turn on, cranks and engine turns over nicely, but still no spark. I just cant think what the problem is.
hall sensor would be a suspect, when you say fluctuating was it a pulsed signal? if you can find any old dizzy with a hall sensor on it you can plug it to the loom and spin the shaft to see if the coil sparks
So basically I plugged in the multimeter and when cranking it gave a voltage of around 6-7, it was just going up and down randomly I wouldn't say pulsating
Righto, heres a great video showing how to test the hall sensor while turning the engine over by hand that'll rule out any voltage drain issues and should confirm if the hall sensor is good or not https://www.youtube.com/watch?v=CuwqlfUD43c or as i say grab yourself any old known good dizzy and plug it in, spin it round and every time the trigger wheel passes the sensor you should get a spark from the coil
