Crank engine.... Then it only fires when you stop cranking?

[RomanV]

Okay, so here's what's happening.
Basically, when I crank the engine over, it doesnt fire.
However, when you stop turning the key, that's when it fires once or twice.

A friend of mine was saying that this is caused by not having a type of resistor in line with the starter motor, that prevents it from draining all of the current from the ECU etc.
When I crank the engine over, things like the clock etc. look fully drained.
Could this be happening to the ECU too?
Or could this be an earthing issue?

My old man is convinced that my problems are due to cam timing being incorrect, but I would like to investigate this as an alternative possibility, before I go to the trouble of dropping the engine out to check the cam belt.

How would I eliminate this as a possibility?

I was thinking that getting a second battery to power just the starter motor, would show whether this is the case or not, as it would allow it to crank, while still having power to the ECU etc.

Or alternatively, if this was the case, Surely I would see a voltage drop at the power supply to the ECU?

Is there such a thing, as what my friend is describing?
If so, why isnt it already in the loom somewhere, and where would I get one? What is the proper name for it?
I think he called it a dwell resistor or something like that.

Any help appreciated.
cheers
Roman

[Alex B]

The clock/ headunit turn off when you are cranking. And a resistor? That would be one mother of a resistor to take 60-80A

[fangsport]

dodgy starter relay, if fitted.

[Lloyd]

Surely you dont have to drop the engine out to check the cambelt.

And the resistor idea doesn't sound right. Quite often the clock and everything else turns off during cranking to supply all possible power to the starter

[fangsport]

forgot to add :
bad or missing/unconnected earth wires.
bad power wire to starter.
dodgy battery.
dodgy starter.

[AE91Sprinter]

I have a similar problem, cept it only does that when its been sitting cold for a few hours (like, 8+).

You shouldnt need to drop the engine out to check the cambelt, you normally just unbolt the mount and swing it away on the side the cambelts on and unbolt the lot.

[matt dunn]

i would have to say from the symptom you describe that you have a bad earth from the battery to the block.

Check and make sure that you have a heavy cable from the battery to the chassis and another one from the chassis to the block.

Matt

[RomanV]

To all of the 'dont have to drop it for the cambelt' people....

Yes I do.

The VVTI pulley & the cover for it, is hard up against the strut tower... As the VVTI pulley sticks out about twice as far as the old one.

I've change the cambelt with the engine in the car with my old NA engine, and it was difficult but doable.

In this case, it is impossible.

Thanks to others, I will try and set up a few more earths or something.
BTW if the starter relay was bung, then surely it wouldnt turn over at all?
I cant see how that could be the problem. (But am interested to know how/why if this is possible)

[matt dunn]

BTW if the starter relay was bung, then surely it wouldnt turn over at all?
I cant see how that could be the problem. (But am interested to know how/why if this is possible)

it cant.

[RomanV]

Okay thanks.

I will perhaps get someone more knowledgable than myself to have a look, before I do anything major.

I will also... Hmmm make up some more earthing cables or something.

[SUBARUCONVERT]

Try and check things out first, check the voltage at the ECU while cranking, if the voltage was that low it would hardly crank, so maybe u can cross that off. Ur friend maybe thinking about a coil resister in points ignition cars, where it is bypassed during starting to get full voltage to the coil and the best spark. id doubt ur (coil on plug?) engine would have anything like that

[RomanV]

Correct, it is a coil on plug setup.

And yes, it cranks over excellently.

I've got a good 12v everywhere (including the ECU) when the engine isnt running.

(Well except for 5v at the sensors etc)

[vvega]

you have 2 power supplys in your car
one that has 12v when on except when cranking andon ethat has 12v whist cranking

do you have power to your ecu while cranking

just sounds liek youve hooked into teh wrong power wire to me

BTW
you all havwe to cheack coil and injector voltages whilst cranking

[Ae92typeX]

Its unlikely as you have not mentioned, but I'll suggest it anyway-
Ive come accross alarms wired up incorrectly, so they imobalise when starter is on, then are ok just with ign (as they have been connected to a bad power feed)- did exactly the same thing as yours

[RomanV]

you have 2 power supplys in your car
one that has 12v when on except when cranking andon ethat has 12v whist cranking

do you have power to your ecu while cranking

just sounds liek youve hooked into teh wrong power wire to me

BTW
you all havwe to cheack coil and injector voltages whilst cranking

Hmmm interesting to know, that makes sense, and sounds like exactly what is happening.

Will check with a multimeter tonight.
Will be happy if I dont have to drop the motor again.

[gepsk8]

check igntion switch, also sounds like the motors been out so check efi earth on th head as well.

[BBBrad]

Run a hot wire straight from the bat + to the ecu, just temp. See what happens.

[Leon]

totally fuxxored starter motor draining all the juice, so leaving not enough left for spark to fire engine.

Can you crash start the car easily?

[Zak]

It's one of your main big fuses just off the battery

[RomanV]

Okay after testing for voltage drop at the ECU, that was exactly the problem.

I cleaned the battery terminals, done them up tight, undid the earths, sanded the contact patches, and left the battery on charge over night.

Cranked it over the next day, and BOOM! Huge back fire and smoke out the intake.
Not just a gentle splutter like before.
So it's definitely a cam timing issue as well.
I hope there's no damage to the engine, will take the head off to see if everything is okay.

Engine is now stripped down with only two mounts holding it to the car, it will be out as soon as I can get access to a hoist.

Then will check cam timing, get someone else to have a look, and stick it back in. Will hopefully run after that. Fingers crossed.