Car won't run.

[UKAuto]

Bet there are several on here that could figure it out if you had your hands on the car, but being in Canada I will just have to throw this out there and see if any great ideas come back.

My 350i was running but cut out a couple of times. Now it simply won't run.

I have checked continuity of all wires from ECU plug to air flow meter
I have swapped in another air flow meter (told it works - but never ran with it)
I have put a brand new injector power resistor pack in (but tried with old one)
I have replaced all relays with new ones
I have checked the steering module with a meter, and all diodes and fusible resistor seem to be good
I have checked continuity from ECU plug to power resistor pack
I have checked that the fuel pump comes on when I twiddle the flap
I have checked that during cranking the king lead in place at coil end and distributor end off and near grounded surface I get rapped excellent sparks.

When I turn the key the car fires during cranking, as soon as I let go of the key it stops. If I hold the starter on for two or three seconds after it starts (not something I like doing!) it continues to fire until the key is released.

The voltage at all points on the ignition switch seem fine.

I don't have a correct relay diagram for the car, the ones in the Steve Heath book do not match, so I have figured some out, but not all yet; with that said I have eye-balled all connections for all relay sockets, and pushed them in from the back of the panel, they all seem good. Also, remember all relays are new.

In amongst the relays they are all identical with two exceptions, the steering module and the flasher unit - is this correct? are there any other 'special' ones, or are they all the standard bosch style five pin units?

I am finding myself testing in circles now, and it is raining today - so thought I would jump on here and ask for help.

At very least I am asking for sympathy.

Rob, isolated and alone, in Canada.

[SLB]

I would be suspicious of the ignition amplifier on the side of the distributor , but have you checked the spark at a plug during cranking? And are the plugs getting wet after a lot of cranking?

[ElvisWedgely]

Change the ignition module on the side of dizzy and possibly change the coil too. Sounds to me very much like an electrical issue.

Tony. TCB.

[UKAuto]

After checking at the king lead I did check one of the plug leads and getting a solid spark there two. Have put new plugs in, and cleaned up the wires, cap and rotor. Even if they were poorly the car would at least run poorly.

Your question on wet plugs is good, as in theory I could be flooding (unlikely as it fires on starter), or bond dry as new fuel is getting past the fuel injectors after the key is let go. I will need to pull a plug and see.

Thanks.

[Wedg1e]

Check for a bullet connector in the white/black wire from the ignition amp that runs across to the left side of the engine bay and joins the loom near the AFM connector. If that's pulled apart or corroded to hell the fuel ECU an't see the trigger signal and won't fire the injectors - any fuel in the engine making it cough is coming from the cold start injector.
You could thow a couple of capfuls of fuel into the plenum and crank, if it fires up momentarily but then dies it's almost certainly not firing the injectors.

[UKAuto]

Wedg1e said:

Check for a bullet connector in the white/black wire from the ignition amp that runs across to the left side of the engine bay and joins the loom near the AFM connector.

I remember checking that as it seemed a logical culprit, but worth another check. not corroded at all, but not the tightest of connections and it could have checked good as I tested it but has now moved back to its relaxed state...

work is wrapping up for the day, so once the rain lets up I am out back to take another look at things.

[2 sMoKiN bArReLs]

No help at at all....but 171 months is one of the longest memberships I've seen


sorry I've been no help

[jimburr]

might sound silly,and a bit of a long shot but is the keyswitch working right,are the oil pressure and ignition lights staying on when you let go of the key?

[UKAuto]

2 sMoKiN bArReLs said:

No help at at all....but 171 months is one of the longest memberships I've seen


sorry I've been no help

That was it! Thanks!!! Car runs fine after all, its me that's the problem, 171 months and the owner hasn't been properly maintained...

Oh, wait, just realized I got in my wife's car instead of the wedge and it started fine.

Getting old.

[UKAuto]

jimburr said:

might sound silly,and a bit of a long shot but is the keyswitch working right,are the oil pressure and ignition lights staying on when you let go of the key?

Not silly, and yes they stay on. I even jumpered a very strong 12 volts to that terminal just in case it was not maintaining voltage under load. (New battery this year too, and have been keeping its charge up).

Thanks - all suggestions welcome!

[UKAuto]

Wedg1e said:

Check for a bullet connector in the white/black wire from the ignition amp that runs across to the left side of the engine bay and joins the loom near the AFM connector. If that's pulled apart or corroded to hell the fuel ECU an't see the trigger signal and won't fire the injectors - any fuel in the engine making it cough is coming from the cold start injector.
You could thow a couple of capfuls of fuel into the plenum and crank, if it fires up momentarily but then dies it's almost certainly not firing the injectors.

I am assuming this is the one that effectively goes from the coil negative to pin 1 of the ECU. I checked it at those two points and the continuity is solid.

I am leaning towards the comments around the amplifier, even though the spark is excellent during cranking. Doesn't make sense to me, but I am still leaning that way. I think the one on my Griffith is the other connector type - otherwise I could swap them... Doesn't hurt to have a spare anyway, so I may buy one and see if it helps.

[UKAuto]

Wedg1e said:

Check for a bullet connector in the white/black wire from the ignition amp that runs across to the left side of the engine bay and joins the loom near the AFM connector.

re-reading this, perhaps my negative to pin 1 of ECU is something very different. I am going to have to have another look at that; in fact I think I have agonized over the fuel injection enough I have to go back over every aspect of the ignition circuit.

[V8 Fettler]

Start(!) with the basics.

All service items (eg spark plugs), HT leads, dizzy cap, rotor, amp in good order? Replace from a good supplier if in doubt to avoid going round in circles

Unswitched 12v to the fuel pump (make the shunt wire accessible so you can remove quickly)
HT lead spark testers on at least four leads.

A non-starting flapper with good fuelling will drench the plugs quickly, so an easy check for the presence of fuel in the combustion chamber.

HT lead spark testers will enable you to check if the spark is continuing after releasing the ignition key.

[mrzigazaga]

UKAuto said:

I am leaning towards the comments around the amplifier, so I may buy one and see if it helps.

Hi mate..I had a friend who's Wedge wouldn't run and that was the ignition amp..Worth a try seeing as you have replaced most other serviceable items...Ziga

[Wedg1e]

UKAuto said:

re-reading this, perhaps my negative to pin 1 of ECU is something very different. I am going to have to have another look at that; in fact I think I have agonized over the fuel injection enough I have to go back over every aspect of the ignition circuit.

No, you're correct: pin 1 of the ECU is the trigger input from the ignition amp/ coil negative side. You can't simulate the trigger with a 12V as the voltage present here actually contains back-emf pulses of as much as a few hundred volts, so the ECU input has a voltage dividing stage to knock it down.
Just a thought but are the earth terminals from the injection loom to the rear of the left-hand cylinder head in good order? Also engine to chassis and battery earths...