pcmhacking.net

Hey guys.

I'm having some problems with the vt 304 in my gq patrol. The car is running std ecu with an eBay memcal to bypass the vats and do away with the bcm

The story goes i had it running fine and pulled the motor out to fix a couple if oil leaks and make a few changes.

While it was out i spliced in some plugs for the adaptronic computer which I'm hoping to get running soon.

Anyway got it all back in and hooked up went to start it but no spark. Checked the coil and it was missing ignition power. Forgot to hook a wire up so connected that back up to the efi relay and still no spark. Ecu is triggering the fuel pump relay still and smells like the injectors are still firing. I've got ignition power at the ignition module. Earths are connected. I've tried a different coil and a different ignition module but still no spark. Negative side of coil seems to be pulsing correctly on a test light

I should mention that while running a lead straight of the coil with a plug earthed to the engine i could feel a slight pulse while i was holding it but not enough to see a spark.

It's usually something that has changed that will give you problems but i went over my loom where i spliced the adaptronic plugs in and everything looks good.

One thing i found od was the coil has zero resistance between pos and neg when checked with a multimeter. Is that correct?

I'm also wondering if i can still run a check engine light and or a diagnostic plug without the bcm? Pins a3 and f14 on the pcm according to my diagram

Hoping if i have a diagnostic plug i night be able to get some codes?

I appreciate any help


Calvin

Just a stab here, you havent mixed up the coil plug for one of the injector plugs? The coil plug is blue from memory.

As for the coil, do you have the range set correctly on your meter? Seems strange that the coil was fine prior and now shorted?

Yeah defs got the right plug.

I went and bought a brand new coil and still nothing. I'm hoping to install the diagnostic plug and see if any codes come up on a scan tool

thats unlikely to help...

you need 3 things for the spark to work. ign module, hall effect pulsing in dizzy and coil. you can unplug the pcm and still get a spark, the module fires spark independently of the pcm during cranking.

Ah yeah the EST takes over once it's started ay. I read that before. I just don't see how i could have a hardware failure as everything was fine a couple weeks ago when i pulled it out.

Do you have any advice on how to test the ignition system more extensively?

Cheers

Turned out to be low voltage at the coil

How did that happen?

Well done for finding it

After i 'tidied' some wiring i couldn't get it started. Turned out i cut the coil power wire coming from the efi relay. I then just hooked it up to the injector power wire coming from the same efi relay. Put a separate bigger wire from the relay and i got spark

BUT

now it runs like crap and won't pulse number 8 injector. I think i might have cooked the ecu or my ebay memcal

probably just a stuck injector. try swapping them over to check.

Yeah its boy the injector if i swap #6 plug onto #8 it fires in 8. Injectors were all cleaned when i built the motor. I've got bigger problems unfortunately