ignition amplifier query

[chip-3door]

Looks like ours has packed up, car has no spark, and also the rev counter doesnt move when cranking, but fuel is getting through as you can smell it coming out of the exhaust.
Havent had a chance to dig around and find the amplifier yet (its dark! lol), it doesnt sit next to the coil like on many cars im used to, is it built into the ECU or is it a seperate module? if it is in the ECU are they available aftermarket?

Cheers in advance for any help


Chip

[Brianmoooore]

If you tell us what car and what engine it would help!

[chip-3door]

Sorry mate, 1989 325i, E30

[dasparkybad]

on this model it is built into e.c.u more likely to be crank sensor
check the wiring to it had a couple were the plastic cover that goes behind the waterpump pulley has come adrift and the pulley has gradually worn through the wiring to the crank sensor

[hoshy]

on this model it is built into e.c.u more likely to be crank sensor
check the wiring to it had a couple were the plastic cover that goes behind the waterpump pulley has come adrift and the pulley has gradually worn through the wiring to the crank sensor

On our early motronic m20 the crank sensor on the pully at the front is just connected to the diagnostics sensor. there are two sensors on the bell housing for RPM and Crank.

I think on the motronic engines the amp is in the ecu and the earlier cars (jetronic?) there was a seperate module attached to the bulkhead - I'm sure (and hope) Brian will correct us all on every account.

[chip-3door]

Crank sensor appears to be fine, and the fact that the ECU is firing the fuel injectors pretty much rules that one out anyway i should think.

Symptoms all seem to point to the ignition amp, (based on my experience on other cars), so i the one in the ECU an easily replaceable bit or am i better tracking downa secondhand compelte ECU?

[Demlotcrew]

Are you getting a spark at the coil?

Andrew

[chip-3door]

Are you getting a spark at the coil?

Andrew

No mate, wouldnt suspect the module if that was the case.

Tried a different coil too with a lead and plug straight onto it to take the dizzy out of the equation, still nothing.
Also if it was the coil or anything after it then it wouldnt effect the rev counter on cranking.

Im fairly sure its the ignition amp, all the symptoms point to that, just not familiar with replacing them on the 325, so after advice on how to do that.

[Turbo-Brown]

I've got a spare ECU (Motronic) you can borrow to rule it out if you like if you can pop over and get it (no idea where you are though)

Seems odd that the rev-counter's not working. Would've thought that with the internal ignition amp, it'd take it's signal from somewhere in the ECU instead of the coil.

Does anyone know for sure if the injector firing is linked to the crank position? I know it sounds daft to ask, but considering the way they're wired together, I don't think that the crank position really has much effect!

[Brianmoooore]

Ignition amp is all part of the ECU. Unnusual to fail, but a flashover from the coil centre pin to the neg. terminal would probably do the trick!
Don't pull plug leads off an E30 when it's running.
If the injectors are firing then I don't see it could be the crank sensor, although hidden in the depths of my increasingly confused brain, I half think I remember that a dying, but not dead one, can fire the injectors without the ignition working.
Rev counter on a motronic is fed from its own output pin on the ECU.

Have you checked for 12V (with a lamp,not a meter) on the + terminal of the coil, with ignition on and cranking?
I would try a new DME reay before getting to involved, as well.

[Mops]

I'm not an expert, but I'm doing megasquirt install, and I didnt come across ignition amp. coil is driven straight by the ecu (I think pin#1 to be exact). check ehether you have +12 on the coil shile cranking. confirm that coil- goes to ecu pin#1, if not post back, I'll go and get wiring diagram and check. confirm that ecu has some output on that pin. I believe that pin#1 just grounds the coil so you could possibly check with testlight... dont trust multimeters for measuring current spikes/singlan lines, they are very often heaveily damped and wont read anything.

[chip-3door]

Coil seems to have a steady 5v when ignition on wether cranking or not, which i must admit confuses the hell out of me!
That was on a meter though, so wouldnt react quick enough during cranking probably, will try a bulb when i get a chance to see if that helps show any life, i did try another coil though with a plug straight onto it from the king lead and that showed no life either, was a cossie coil though and not sure if they are the same resistance anyway.


Thanks for the offer of a loaned ECU, but i wouldnt want to trust someone elses property in a car that may have killed one ECU in case there is a fault present that kills another one, lol



Brian, where is the DME relay located?

[Brianmoooore]

DME relay is one of the three (poss. 2 only fitted) under the black cover on the inner wing near the air filter.
If you only have 5V on the coil +, then you are forgetting the basics, and looking for a non existant complex fault.
The + supply to the coil is straight from the ignition switch, but is often used by alarm installers for the immobiliser.
Any a;arm on this car?

[chip-3door]

DME relay is one of the three (poss. 2 only fitted) under the black cover on the inner wing near the air filter.
If you only have 5V on the coil +, then you are forgetting the basics, and looking for a non existant complex fault.
The + supply to the coil is straight from the ignition switch, but is often used by alarm installers for the immobiliser.
Any a;arm on this car?

Ive got 5v across the coil, but not sure what voltage ive got to the coil, i will check between the coil and ground to see if its getting 12v on one side and 7 on the other for a potential difference of 5 or if its 5v and 0v

Car has an alarm and an immobiliser, but both appear to be deactivating as normal and when the immobiliser is in operation it normally stops the starter working on this vehicle, but the starter is turning fine with the immobiliser deactivated.

[Brianmoooore]

Wit5h just the ignition on there should be 12V+ on both sides of the coil.

[chip-3door]

Wit5h just the ignition on there should be 12V+ on both sides of the coil.

Yeah and then drops to ground on the pulse to fire, but given that neither of two coils did, im pretty sure thats now whts happening, just for sake of eliminating it from our enquiries though i will go and take some more measurements next time im with the car.

[chip-3door]

Update:


First guess was correct it seems, was the ignition amp.

built into the ECU on our E30's, so i got a secondhand ECU on it and its fine now.