I'm a long time lurker on this forum but haven't posted before. I've been carrying out an abf conversion to my mk2 golf but can't get it to start. The fuel pump primes when the ignition is turned on and vag com shows no errors. Ive verified with a meter that the fuel pump relay is been operated when cranking. I understand that this rules out the crank sensor which is new anyway. If I remove the ecu and place a jumper between pin 8 on the connector and earth I can produce a nice fat spark so there's no problem with the wiring or the coil. The ecu is not telling the coil to fire everything suggests a fried ecu but its priming the pump and talking to vag com? Help.
Should be able to see cranking RPM on vag-com/vcds measuring blocks to prove getting crank sensor signal. Are you using a no. 30 ECU relay (I guess if getting comms with vag-com you are) Are you using the correct distributor for the ABF too? Does it fire then stop? (immobilser not allowing engine start)
It's ce1 so I'm using the original relay, as you say the ecu is powering and communicating so I don't think the problems there. I'm still learning vag com but ill try measuring blocks next. Unless my thinking is wrong it can only be that the ecu doesn't know the engine is spinning or its b The dizzy is right as far as I know but I'm checking for a spark at the king lead anyway. No spark at all so it's not the immobiliser.
Go into engine measuring blocks, check rpm and injector pulse width and see if injectors are being triggered too.
I'm new to vagcom but rpm and injector pulse width don't change when cranking. Is rpm on block 001 actual as read from the crank sensor?
Yep, group 1 RPM is from crank sensor. If no crank sensor signal you won't get spark or inj pulse width either. Need to check rpm signal once connected to ECU in vag-com without turning ignition back off completely or you may lose comms with ECU. Only odd thing with it is, you're saying the fuel pump relay is being operated when cranking, so in theory there should be a crank signal.
I'm getting a value at rpm even when not cranking 378 it thereabouts. This doesn't change when cranking. If the engine isn't running shouldn't this be 0? I've checked the crank sensor again and wiring and all seems fine continuity wise but I'm getting 12v at both of the lines connected to the ecu and I'm not convinced this is right.
That test works except its at battery voltage and I'm getting a voltage between 2 and 3 as well. I think all I can do now is try and get another ecu
Have you disconnected the loom from the ECU and crank sensor and checked if continuity in the loom between pins 2+3 on the crank sensor plug? (short in the loom?)
You can check if crank sensor works by turning on ignition. Measure voltage between pin 2 between and earth. This should be a green/black wire. You need to get engine turning over slowly by hand. You should be able to see if the voltage changes between 12v and 0v. If this works then hall sensor is fine. Red/yellow wire should be hall supply and brown is earth.
That's definitely something ill check. No continuity between 1 and 2 in the loom but I lose earth when I disconnect the ecu. Ill have to try and locate a pin out because I'm not convinced it earths through the ecu.
It shouldn't earth through the ecu. Some sensor earths are on the block, there is a large brown earth in the loom to the ecu but this should be earthed anyway regardless. You may need to add chassis to engine block earth if its not there.
Yeah your confirming what I thought however earth was fine until I disconnected the ecu so I need to check my wiring again. Which is odd because the crank sensor wiring wasn't touched if I recall correctly.
Make sure you have all earths for a start chassis > engine. Battery > chassis. These should be large. I would say 4 gauge or even replace with new stuff. There should also be some little earth straps going from too of block to coil body too. Disconnect ecu make sure you still have them.
Yup.. There's a earth mounting point on the block near the dizzy and I ran a ground from coil. It was the only thing I hadnt tried and we went through the whole saga of no spark! If it is the crank sensor that's pretty much straight forward. For us, it wasnt until we changed ECU, then our's sparked and all good since!
