M30 Motronic problem.

Post Tue Jan 10, 2006 7:15 am

I have finally got round to fitting my 3.5 into my sport,
all was going pretty well but after fitting all the wiring
its not starting. Ive double checked all of the wires to make sure they are
correct but there is no spark. There is a live feed to the coil, ive tried a different ecu and coil. Im so close but im stuck

I called the dealer and he told me to check some of the relays to make sure that they arent stuck as they engine and loom sat for about 6 months but they are fine.
Anybody got any ideas?

Post Tue Jan 10, 2006 1:24 pm

anybody??

Post Tue Jan 10, 2006 1:32 pm

dunno mate, have you got a dizzy or a coilpack? explain a bit more about the M30 injection, i don't know anything about it. its motronic yeah? with a coilpack?
if you have a coilpack, have you checked if the ecu coil outputs are doing anything? if you have power to the coil but no spark, this could be a good place to start. sorry i can't be any more help, i'm not familiar with the M30 at all.

Post Tue Jan 10, 2006 1:47 pm

king lead from coil to dizzy cap?

also these motronic dizzy caps can stop working completely and give no spark if they get a bit of condensation inside them

what engine is it, e28 type or e34/e32 type?

the e28 engine needs the flywheel sensors and the connections where they plug into the main loom to be working properly or it won't do anything

Post Tue Jan 10, 2006 1:54 pm

Right, here we go. Its an e34 engine with a coil pack. Im sure its all wired correctly and there is a feed onto the coil pack. It seem that the pulsed negative that comes from the ecu is missing. I am checking for a spark straight from the coil itself with a lead, missing out the dizzy etc. Ive had a thought that it might be the crank sensor. I will try the one from my 2.5 tonight but i dont know if they are the same.

Post Tue Jan 10, 2006 3:05 pm

have you connected the live wires on the loom near the ecu plug ?

Post Tue Jan 10, 2006 3:18 pm

yeah as derek says all grounds and power feeds needed! is the main engine relay (with all the red leads coming from its connector) in place properly and working? try bridging it with a piece of wire.

crank sensor is the same, but unlikely to be dead i'd say. unless you've knocked it during installation and it's not near enough the trigger wheel.

if there's no spark at the coil and you've swapped coil and ecu you've got most bases covered mate.

Post Tue Jan 10, 2006 3:22 pm

on the older e28 engine there's an immobiliser function that needs a separate plus feed to make the ecu work, but none of the later ones i've seen use this. did the car have a factory immobiliser?

does the fuel pump run when cranking? if not i guess or there's a wiring fault and the ecu isn't coming on

Post Tue Jan 10, 2006 3:23 pm

Thanks guys, i will try your suggestions tonight and update tomorrow

Any more ideas let me know.

Post Wed Jan 11, 2006 7:41 am

Sussed!! Cheers guys, it was the live feed beside the ecu. It was still connected to the joining block from the 5 series so it didnt look like it had to go anywhere. Just the exhaust, prop and cooling hoses to do now.
Thanks again lads.

Post Wed Jan 11, 2006 7:54 pm

Another 335 !

Where are you based ?

Post Thu Jan 12, 2006 7:46 am

Hi Andy, im beside Aberdeen. Im sure i contacted you before about wiring? I have a question for you, im using e28 m5 rubber engine mounts to give me extra clearence but it looks like my header tank is lower than the thermostat housing. Will this be a problem? I think in your tbmw article it said that you used these mounts but i think it was maybe wrong.

Post Thu Jan 12, 2006 10:10 am

to bleed it perfectly it will help to unbolt the header tank and hold it as high up as you can against its hose while you open the bleed screw. then once bled put it back in place and it can stay there!

i..e height not so important once its bled through.

Post Thu Jan 12, 2006 10:54 am

I did think about doing that. Cheers guys.

Should be on the road saturday, cant wait

Post Thu Jan 12, 2006 8:30 pm

I'm on M20 rubber mounts and header tank, i don't have any probs with air locks.

Have you got any pictures of the M5 mounts ?

Are they offset studs and how much thicker are they compaired to M20 mounts ?

Are you using the E30.de mounts ?

How is your clearance between the lower steering colum thing and brake servo ?

I need to gain a little clearance by the lower steering colum.

Post Fri Jan 13, 2006 7:45 am

Sorry, no piccies of mounts. The passenger side one is the same style as the m20 mount and about 8-10mm taller. The drivers one is a different style so it is hard to tell, tbh i didnt measure them before i fitted them.
The clearance looks pretty good so far, there is about 6-8mm gap at the servo and it looks like the frontpipe will clear ok, although ive not driven it yet to see if it will hit under load. They are both offset to the middle of the car so it raises the block a bit. Im using Karans mounts.

Post Fri Jan 13, 2006 8:06 pm

How is the bonnet clearance if the engine is raised slightly ?

Post Fri Jan 13, 2006 8:11 pm

must be close as i know my afm is into the soundproofing slightly

Post Sat Jan 14, 2006 7:15 am

It is close but i removed the studs out of the rocker cover, turned the afm upside down, removed the soundproofing and adjusted the hose so that the afm is hard down against the rocker cover. The inlet manifold is close but i think its going to be ok.