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Hi all
came across this interesting one.
car cranks no start. no spark NO trouble codes.
this is 4 wire COP design, so 1 power , 2 grounds and signal wire. Power and grounds tested (loaded) fine,
there is no PCM control on any of the 4 ignition coils.
2 things that could cause this bad input (crank sensor, if i am not mistaken , no cam sensor needed for spark) or timing issue
rpm is above 200rpm on scan tool, so there should be injector pulse and ignition control, right? but it is not
tested compression. very healthy compression of 180 on all,
no idea why pcm is shutting down coils with good rpm/crank signal.
what i also noticed is that high fuel pressure is only 30psi, instead of targeted 600psi.
is it possible that low fuel pressure in the rail could cause pcm to produce "no spark, no ignition control"
Does the scan data include injector on time? It would be nice to know for sure if the computer even intends to pulse the injectors during cranking.
I try not to work on VW if I can have it my way, so I'm not super familiar with the anti theft strategy, but I would probably start with a look at whatever output commands are available in scan data and confirm that the computer recognizes that you are indeed trying to start the engine and is authorizing the start.
You'd think 200rpm from the ckp would be all the indication it needs, but, VW....
Low side pressure should be 6 bar~90 psi. This would be enough to start the car even with a faulty hp pump in default mode. 30 psi measured on the high side could be default without any pressure present.
You may want to disconnect the low pressure feed into the hp pump, look for fuel flow and/or connect a pressure gauge. You also can try to start the engine feeding externally regulated pressure/fuel into the hp pump if there was nothing coming out of the low pressure side.
If the low pressure turns out ok you may have a problem with the hp pressure sensor and you could try to manipulate its reading using a potentiometer/variable resistor.
An expert is someone who knows each time more on each time less, until he finally knows absolutely everything about absolutely nothing.
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