Used octane boost now car won't start :-(

[Asiangunner]

Hi guys,

I've never had any issues with my 83 Lux starting but i filled up a full tank of 95 ron and i had some Millers octane boost in the garage so though id put some in, the car was running fine but then i didn't drive it over the weekend so went to start it today and it's not starting.

The battery is fine and no alarm or immboliser issues. The engine is turning over but doesn't fire up as if its being starved of fuel.

I tried EasyStart which make the car almost turn over but it doesn't fire up and stay on.

I've done a search on octane boost issues and fuel starvation and can't find the right answers.

Any advice guys?

 

[Lowtimer]

The octane booster is almost certainly irrelevant to your problem: merely a coincidence.
Start with section 2 of this page:
http://www.clarks-garage.com/shop-manual/eng-15.htm

... and it sounds like you need to work through section 2f to find out what is and isn't working.

 

[Asiangunner]

Cheers buddy i'll start going through the list.

So you thik there is no way the octane boost could have contaminated the fuel in some way?

I did notice a cranking noise when trying to turn it over..

 

[Lowtimer]

Assuming it was actually what it said on the tin, and you added it in some vaguely sensible ratio, there is no way it could prevent the engine from firing. In any case, if there was something drastically wrong with it, it would have shown up when you were driving the car on it earlier.

 

[Asiangunner]

ORIGINAL: Lowtimer

Assuming it was actually what it said on the tin, and you added it in some vaguely sensible ratio, there is no way it could prevent the engine from firing.  In any case, if there was something drastically wrong with it, it would have shown up when you were driving the car on it earlier.

Yeah that totally make sense mate, i suppose i was clutching at straws.

I'll work through that list and let you know how i get on, thanks again mate.

 

[Peter Empson]

I'd be tempted to try pulling the fuel pump fuse out and try to turn it over for a few seconds, it often helps me in similar situations with the 944S. This assumes it's running too rich, but worth a shot, you hopefully will find it'll try to catch as the system runs out of fuel, if you have a helper get them to put the fuse back in at this point, if not then put fuse back in and try again. I'd also put the battery on charge for a bit if it's more than a few months old, they can lose power very quickly in the cold over a couple of days, and these engines take a lot of work to start.

 

[Asiangunner]

Cheers Pete I'll give that a go in the evening, is there a guide as to which fuse is which in the Haynes manual? My fuse box has no cover , not sure if it's ment to have one.

 

[Super_Marv]

Does the 944 lux have a DME relay? Sounds like the classic symptoms of a failing DME to me.

 

[Peter Empson]

I can't remember which fuse number it is now, but can check tonight.

I thought of the DME until I read that it seemed to want to start with some Easystart, which I guess would rule this out.

<Edited to add> Of course checking the fuse on mine will be pointless as I have the later fuse box, but here's the Clarkes garage page which might help.

 

[Mike_Pollock]

Anything will start on easystart!

Would guess electrical - 1st choice DME

 

[Asiangunner]

Really silly question but what does DME stand for?

 

[peanut]

ORIGINAL: Asiangunner

Really silly question but what does DME stand for?

its a bit misleading really as it can mean either the ECU (engine management unit) or it can refer to the DME relay

I prefer to refer to the ECU as ECU and the DME relay in full so that there is no misunderstanding.

The ECU's pulsed outputs controls both the Fuel injection system and the ignition system using both built in 'maps' programmed and stored in a processor and feedback from all the various sensors around the car.
The Ecu works in conjunction with the DME relay to power the fuel pump and the ignition system via the ECU

First thing to check on a non starting car is always have you got fuel on the plugs and is there a spark at the plugs . Either or both of these absent will tell us where you should start looking

 

[Asiangunner]

Thanks Peanut, that does help mate.

i've not got round to starting my checks tonight so hopefully i'll get round to it tomorrow.

 

[Wardy 944]

Good luck getting it sorted, theres no worse feeling than when your car won't start []

At least you didn't use NOS fuel additive http://www.gixxer.com/forums/showthread.php?t=226570 []

 

[Asiangunner]

ORIGINAL: The Game

Good luck getting it sorted, theres no worse feeling than when your car won't start []

At least you didn't use NOS fuel additive http://www.gixxer.com/forums/showthread.php?t=226570 []

LOL damn that original poster got roasted and so he should have, he was actually trying to defend what he did...

 

[944turboS]

ORIGINAL: peanut

The ECU's pulsed outputs controls both the Fuel injection system and the ignition system using both built in 'maps' programmed and stored in a processor and feedback from all the various sensors around the car.
The Ecu works in conjunction with the DME relay to power the fuel pump and the ignition system via the ECU

I had similar issues when the crank sensor failed on a 220hp Turbo.

 

[Frenchy]

The DME relay looks at the aforementioned crank sensor which is situated passenger side back of the engine, when 45 rpm cranking speed is seen it pulls in and allows fuel and ignition to come on and hence starting fuel and ignition to be in place.
HTH Jim.

 

[robwright]

The DME relay is actually two relays in one. Ignition fires the rleay which in turn provides power to the fuel pump and also to the DME unit (ECU). When the DME (ECU) sees 200 RPM cranking speed from the crank speed sensor it will ground the coil and thus allow for spark generation. When the DME relay fails it is generally the heavy duty side of the relay that controls the fuel pump. No fuel - no start hence why many carry a spare relay or 3 way bypass cable like I do. Like Peanut said it could be many things. Fuel pump, fuel pressure regulator, poor coil, poor leads, crank sensor, ECU, DME relay need I go on??? You just have to be methodical and work your way through the list. The obvious place to start is fuel. Crank the engine then remove a plug. Is it wet??? You have fuel. Next do you have spark? Crank the engine with a plug earthed to the engine should tell you if you have spark or not. Good luck mate []

 

[Frenchy]

Rob, was always told 45 RPM ? apparently soldering joints in the relay breakdown, probably the current drawn from the pump finds it out.

 

[peanut]

ORIGINAL: Frenchy

The DME relay looks at the aforementioned crank sensor which is situated passenger side back of the engine, when 45 rpm cranking speed is seen it pulls in and allows fuel and ignition to come on and hence starting fuel and ignition to be in place.
HTH Jim.

Jim I'm afraid that is inaccurate. Its 225rpm not 45rpm and the DME relay and ECU do not work as you state either. Your description is far too simplistic I'm afraid and rather misleading.

Rob's description is more accurate but the Bosch system is very complex especially on later cars. The description of the Motronic fuel and ignition system runs to many pages in the manual and can hardly be described adequately in a few sentences .

When the ignition is switched on the DME relay coil is energised for a second or so only allowing the fuel pump to build up sufficient pressure to operate the solenoids in the fuel injectors (and cold start injector if fitted ) the relay is then de-energised cutting the +12v supply to the fuel pump

When the engine is cranked the ECU looks for the correct information from various sensors on its inputs before it re-energises the DME relay which feeds a continuous +12v to the fuel pump. At the same time the ECU uses its program to pulse the fuel injectors , pulse the cold start injector and pulse the ignition amplifier (which provides the regulated HT spark from the coil )