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MG MGF Technical - Engine won’t start !!

Engine won’t start !!

Well I’ve re-built my ‘blown’ engine, in the end I opted for the used VVC block and my own MPI head ( skimmed, re-ground valves etc ) got her back together today but she won’t start…..
Any ideas ??
The valve timing is spot on and engine turns over well, I have good sparks at all the plugs and petrol flowing into the cylinders, I used all my old sensors, ECM etc all of which were working fine when the liner and piston blew so can’t make out why it won’t ***** start..

Help much appreciated..

Cheers

Rob
Rob Bristow

Mad idea, but may be you hit the emergency switch while working at the car.

The black box with rubber top on the far left in the engine bay. Can be engaged again by just push the button on top.
Dieter K.

Sparks and petrol but no power= valve timing out or maybe the valves are not opening, hydraulic followers not bled ,did you use the vvc followers by any chance?
mike

I used the complete head inc valves/springs and followers from my old MPI engine and the valves were opening ok when I turned the cams over to check before fitting the head to the block.
I didn't realise that you could bleed the hydraulic followers, how do you go about it ?
I have definitely not touched the inertia switch but there is a chance that it switched it's self off when the engine cut out at the time the liner / piston blew does that sound possible ?
But I would swear there is petrol getting through to the cylinders as when checking for sparks on all four plugs there was a flash back from one cylinder resulting in a flame about a foot high ( yes, I still have my eyebrows but only just )...

I wondered if it could be one of the sensors gone silly or maybe linked to the ECM and battery being disconected for just over a week.

Cheers
Rob

Rob Bristow

Cam wheels on wrong? 180deg out?
mike

Cheers Mike... I'll have a look at them !!
Rob Bristow

Rob
How's compression across all 4cylinders ?
How long are you cranking it for ?

Steve
Steve

Compression is good on all 4 cylinders and have cranked it over quite a lot for maybe a dozen rev's each time..

Not had chance to check the cam pullys yet but didn't think you could get them wrong because the locater pin is offset..

Cheers

Rob
Rob Bristow

Rob
Everything seems to be happening OK - perhaps just in the wrong order. Apart from the cams timing, then the obvious component is spark timing - but I'm sure you've checked the spark plug leads and the dizzy cap is on correctly, and plugs are correctly gapped ?

You could also try resetting MEMS back to default cold start setting (I think this is IGN on - but dont start and depress accelerator 5 times in 10 sec /)

I had one engine (in a Lancia) that needed all plugs removing - spinning the engine on the starter, and it would start easily once the plugs were back in - this was a problem in its cold start.

Good Luck !
Steve
Steve

Mike…And Steve, Thanks, you’re stars!!



I didn't know about the MEMS default setting, I had checked all ignitions side ( several times )and I kept thinking “it’s got to be valve timing” but of course it checked out ok until I took the cam pully bolts out to check the roll pin location
I had the cams on 180 deg out ( what a wally ). She’s running like a dream now, I’ve bled the coolant and hydro gassed her up then drove her for a couple of miles. Now I can have my lunch before checking the final ride levels.


Thanks again
Cheers

Rob
Rob Bristow

Nice one Rob! :o)
Rob Bell

My very congrats !!
Well done
Dieter K.

Rob
Great News !
It's horrible when the engine won't fire after all that work. But also great when it all drops into place and finally starts.
Makes you wonder what happens in all those dealer workshops ...

Steve
Steve

Rob, we've all done it hence the answers;-)
mike
mike

A question ...
If Rob's car was a VVC would it have started ?
The cams were 180degrees out, so think of a firing sequence of 4-2-1-3 instead of 1-3-4-2. Now, I know the injectors were firing at the wrong time but fuel is still entering the cylinder (wouldn't matter with single point injection or carbs).
For the MPi the sparks don't co-incide, but with the VVC's shared spark system, then all the conditions exist for the engine to run.
Has anyone seen this ?
How much power is lost because the injectors are firing 360 (crank) degrees early ?
No, I don't feel like retiming my cams to test this.

Steve
Steve

Steve,

I believe that the incorrect fuel injection timing would not make a lot of difference.
I have run a lot of V8 engines where the ECU only has four injector outputs, so a "group", or shared injector pulse is used.
These are however large cubic capacity engines. It would be more noticeable with a small capacity four cylinder engine.
All the same, I wonder how many people out there are driving their VVC with their injection timing out, squirting to the wrong cylinder.
This always a possibility with wasted spark engines (a spark on the cylinder compressing and one on the cylinder exhausting at the same time).
I use an injection timing light. Remove number one injector lead and insert light between the lead and the injector.
Ignition on. All plugs out. Thumb on plug hole. Turn engine over. Check injector fires on compression.
I test all four cylinders, in case the injector output leads are mixed up.

Mick
M F Anderson

The F only has two injector wires, so (at least) one injector is always fireing out of sequence anyway.

Will
Will Munns

I don't have a VVC. Can someone confirm that there are only two injector leads from the ECU to the four injectors?
If there are it it not a true multi point point (sequential) injection system.

Mick
M F Anderson

in the MPi there are only 2 wires
http://www.mgfcar.de/schedules/sb9.jpg

on the VVC there are four
http://www.mgfcar.de/schedules/sb11.jpg

but the point stands, if the injectors are not fired as the inlet ports are open then the charge will sit vaporized around the inlet valves. I would guess that the MPi gives a PWM signal to the injectors which is not timed against the crank.
Will Munns

My congrats Rob.

I've got big respect for this kind of enthusiasts.

Cheers
Erik

Like wise...

Just sounds amazing that you can do something like that.

Big thumbs up! For all the people who contributed (Mike / Steve, and the rest!) + Rob himself!

Hope it's trouble free from here onwards.
Hanah Kim

This may be a daft question, but, apart from the engine not starting, how do you tell if you have put the cam wheels 180 Deg out?
John Pugh

It was a process of elimination really, I checked there was a good spark on all four plugs and petrol was getting to all four cylinders so it had to be valve timing but like a fool I thought that the cam wheels only fitted one way and had checked the timing 3 or 4 times before Mike ( bless him ) pointed the problem out.. And that goes to show how valuable the support of the people who use this BBS can be.

I didn’t see any reference to the correct fitting of the cam pullys in the MGF workshop manual but later found one in an old Haynes Rover Metro manual, I used to have a Metro Gti years ago with the 16 valve K series engine in and went like a rocket powered roller skate !!

The ‘new’ engine is running like a sewing machine and singing like an Angel now so the “job’s a good’n “

The engine came out very well on my drive, I just un plugged everything, removed the main exhaust silencer and strapped the braked callipers up under the body behind the wheel arches then jacked up the body and wheeled the engine / sub frame etc out the back and into my garage.
I did find one thing which maybe of interest when bleeding the coolant system after re-filling it, which I did while the rear of the car was still elevated by about 12 – 15 inches… I opened the radiator and heater bleed screws, turned the heater to full ‘red’ and filled the system slowly turning off the front bleed screws as water ran full hole from them, when the system was full I lowered the car and ran it to warm checked each bleed screw for air then ran to full temperature.
I found it much easier to fill / bleed this way than with the car on the level..

Thanks again for the help..

Cheers

Rob

Rob Bristow

This thread was discussed between 20/03/2003 and 01/04/2003

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