318is wont start - HELP Please

[E30Mike]

Hi

My 318is refused to start this morning, It cranks ok just wouldn't fire.

Tried some easy start with no luck so checked for spark and appears to be none.

After reading several posts on the zone I have checked various things with success.

Green wire at C101 connector is 0 Volts

Fuel pump not working so short 87/30, pump runs but car does not start.

Checked for volts across 85 and 86 which there is so relay is faulty. No its fine as I checked it separately. Dont understand that.

Short out terminals on dme to make sure thats ok, which it is

checked voltage on green wire at connector block on steering column which shows 12v.

I havent yet found correct pin out for the 318is ecu to check that

If any one has any advice it would be Very Much appreciated

Thanks

[kam-325i]

Is there a CPS on the M42 ?

[jonesy318]

Sounds like possible crank sensor fault..

[Brianmoooore]

There is a CPS on most engines, including the M42, but it's not the prime suspect here!
If there's no voltage on the green wire in the C101, then that is likely to be the problem.
If there's 12 volts on the green where it leaves the ignition switch, but it doesn't reach the C101, then there's a break somewhere, and the most likely reason is immobiliser related.
Start your investigation above the glovebox, where there's a two pin socket with a green wire to each pin and see if power is reaching here.
If there's no immobiliser fitted, this socket should be fitted with a plug with a short loop of green wire, but if one (or more) is fitted, this is where they should be connected.

[kam-325i]

arh, the dred'd "Two Green wire plug fall out" symptom !!

[jonesy318]

Thank god for brian, otherwise we could of had you replacing all sorts of stuff. Proves the zone works as it's intended to...

[Brianmoooore]

With no voltage at the green wire in the C101, as far as the engine is concerned, the ignition is not switched on.

[E30Mike]

Hi Brian

Do you mean behind the black plastic cover which is the roof of the glovebox?

Half a ton wiring in there as it has a BMW immobiliser fitted (switched off via the key over 3 years) but no sign of a 2 pin socket with green wires

[E30Mike]

The socket you are looking for is just below the circled earth point.

Thanks Will but my car looks totally different to that

[Brianmoooore]

Yours will be the same if all the extra wiring was removed!

[E30Mike]

Even with the immobiliser out of the way there is no sign of the earth stud. will sort out how to post a pic

[E30Mike]

[img][img]http://i1295.photobucket.com/albums/b63 ... 65f2ef.jpg[/img]



I can't see any earth stud


I do rememder it as well as the loop on earlier cars I've owned though

[Brianmoooore]

Earth stud will be in there somewhere. Follow the brown wires.
The two blue connectors are part of an OE alarm/immobiliser. Are they connected to anything now?
Can I just make out the green loop near the top right of the accessories socket?

[E30Mike]

Looks like a loop but its blue green I think from when I was outside earlier. The immobiliser should still be connected. I just turned it of with the key under the bonnet when the remote broke.

I will have another look tomorrow in day light which will make it a bit easier.

Cheers and thanks for the help

[E30Mike]

Now have 12v at c101

Maybe I disturbed something in the glove box or I think more likely it was a case of operator error in the rain yesterday as it still won't start.

Tried to fire a couple of times along with a back fire this morning

Crank sensor reads 514 ohms, the cam sensor reads 1251 ohms.

anything else I'm missing??

Thanks

[Brianmoooore]

Check for sparks at a plug and that the fuel pump runs when cranking,

[E30Mike]

defo no spark, fuel pump does not run with ignition on

will enlist help to see if pump runs when cranking and get back to you

Thanks

[E30Mike]

pump not running when cranking either with no attemt to fire this time.

plug definitely smelt of fuel when I took it out earlier today so either it runs intermittently when it attemps to fire or else left over from when I bridged the relay terminals

[Brianmoooore]

Does the DME relay (five pin one, probably white, mounted at the back of the engine bay,under the wiring cover) click when you pull it out and push it in with the ignition on?

[E30Mike]

Yes it does and causes the 2 other relays in the abs (i Think) to click

[Brianmoooore]

Looks like everything is getting the power it should, but the ECU doesn't know that the engine is turning. It's told this by the crank position sensor, so this has to be the prime suspect.
This has three pins on its plug. One is just the outer shield of the screened cable, but the other two have a coil of fine wire connected across them, which should have a resistance of about 550 ohms. Check this resistance, and move the lead to the sensor around a bit while you are doing so.

[E30Mike]

514 ohms whatever I do to the wire,

However thought I'd try starting it again

it tried to fire so tried again but left it cranking and it started to pick up speed then died

tried again and this time it started to fire but kept it on the key until it finally had enough momentum to keep running.

not very good for the starter or battery I know,

stopped it and it restarted ok

Will try it again in a while to see what happens but certainly can't say its fixed.

Thanks for your help

[kam-325i]

Almost sounds like an old ignition system drying out !!!

[E30Mike]

Certainly old but not wet if you mean that in a literally

Tried it again a it starts without any real trouble

Very confusing

Will see what happens tomorrow when I put the glove box back together.

[E30Mike]

Still Runs and still none the wiser what caused it

Many thanks Brian for your help

Mike

[Brianmoooore]

That crank sensor resistance is definitely on the low side (assuming it's an OE sensor) and one with a few shorted turns could fit your symptoms, so if it happens again, I'd make it the chief suspect.