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MG MGF Technical - HELP Please!! Car has Died!!

I'm stumped - My car cut out and now won't start, not a hint of it firing up.

Here's what happened - Started the car fine, first turn of the key as normal - Drove away from the house, car behaved as normal - Got to the junction ready to join the main road and had to wait for traffic. At this point, I noticed a hint of a misfire (hunting) which grew more and more pronounced. Went to pull away into the traffic, the car almost stalled, no power, kept blipping the throttle to keep it running but was unable to maintain the momentum and the engine died (almost as if I had run out of fuel - I have a quarter of a tank by the way).

Tried turning it over, no sign of it firing (although, when I let go of the key, there was a hint of it firing just as the crank is about to stop rotating). This same thing repeated for a couple of attempts, then even this stopped - now nothing!

Here's what I've tried - Pulled the fuel line off after the fuel filter, put a cup under it and switched on the ignition - Fuel flows freely. Pulled the high tension lead and tested for a spark by holding it close to the engine - Looks strong yellow spark(and I got quite a belt while holding the lead) but I don't know really if this means the coil is fine. Pulled a spark plug and checked the spark on that - Looks weak and blue??? (thinking about it now, it could be that I didn't ground the plug properly though....) Would any sort of imobiliser or engine management problem mean that I wouldn't get a spark?

Dissy cap and rotor arm are new (few thousand miles) and look clean inside.

Any ideas?? It had every feeling of running out of fuel, rather than some sudden electrical failure but the fuel is obviously being pumped around okay... How do I test it is reaching the cylinders? (plug was dry, no signs of fuel on it? - Thought I might have expected to see it wet?)

Help, I'm stumped!!!
Mark Clayton

Okay, just been out in the twylight and checked another couple of plugs - They are actually wet, so fuel getting through. Tried them and they are sparking but it just doesn't look that strong to me - quite a small spark but I've got nothing to compare it with. Can the coil just fail like that?
Mark Clayton

VVC or MPi engine? If MPi, check the rotor arm is still firmly glued into the end of the camshaft.
bandit

Sorry, mpi engine.

More facts - I've been away for a week so the car had been stood idle outside for 10 days. I've always had the slightest misfire when the car is idling, one missed beat every 10 secs or so, hot or cold (this had seemed to be getting worse recently). I improved it once by replacing the leads, dissy cap & rota arm but it's never completely gone.

Before I went on holiday, I added a Daytona exhaust (new cat & front pipe too) to the car. When I was waiting at the junction, I blipped the throttle to listen to the tone, that was when the misfire started as the engine returned to it's cold engine fast idle... one miss, then another, then another more pronounced, then I revved and slipped the clutch to dart into the traffic flow and woomfh - a distinct lack of power and significant misfire - Managed to dip the clutch and catch the engine before it stalled but couldn't get it to pick up and it ran for a couple of seconds more with me trying to tease more revs (by blipping the trottle) before it died.

I was surprised because it had initially started so easily and ran effortlessly up the road to the junction (perhaps 500 yards, engine still cold when it started happening). Not sure if my actions caused it?

Rota arm looks okay but I'll double check, thanks.

Seems I am getting fuel & a spark - Just can't tell if it's a weak one or not. No sign of it firing late last night but I suppose I could have flooded it as plugs were wet. (have left it well alone for the moment to dry out may just swap back to the old cat etc before trying again as conscious about the unburned fuel & new cat if it continues to fail to start). Have ordered a new coil just in case.

Am I right that if I hold the trottle to the floor, the fuel flow is cut off?

Also, ECU, coil, imobiliser or bad engine earth etc - These would mean NO SPARK at all right? Had a problem once before when the car wouldn't start after I had moved the ECU to get at a hydragas unit - Turned out I hadn't tightened the ECU to body connection tight enough (bad earth). Needless to say I have checked and cleaned that!

Any more clues?



Mark Clayton

Have you checked the cambelt ? it could be the belt that has gone ?
Percival

I must admit, that thought did go through my mind - I'm intending to take off the cambelt cover tonight to put my mind at rest.... There was no noise that I would associate with the cambelt but... !!!
Mark Clayton

I had a similar thing on our MPi many years ago and the dealer changed the ECU (under warranty) and that cured it!
Ted Newman

Check/clean the map sensor in the ecu.


Branko

Tried turning it over, no sign of it firing (although, when I let go of the key, there was a hint of it firing just as the crank is about to stop rotating). This same thing repeated for a couple of attempts, then even this stopped - now nothing.
As the starter takes around 200amps as the drop off of the crank position the voltage rises giving the coil a small voltage boost.

All seems to point to the Ht coil i know you have one comming but to put the mind to rest check the input volts to the coil with a meter or solder an old stop lamp bulb to the two terminals if it just glows you have a low voltage power supply problem.

RJ Rowlinson

Tried turning it over, no sign of it firing (although, when I let go of the key, there was a hint of it firing just as the crank is about to stop rotating). This same thing repeated for a couple of attempts, then even this stopped - now nothing.
As the starter takes around 200amps as the key drops off of the crank position the voltage rises giving the coil a small voltage boost.

All seems to point to the Ht coil i know you have one comming but to put the mind to rest check the input volts to the coil with a meter or solder an old stop lamp bulb to the two terminals if it just glows you have a low voltage power supply problem.

Let us know how you get on regards Roger
RJ Rowlinson

Wow, thanks Roger - That really makes sense, I'm keeping my fingers crossed that the coil does the trick! That would also explain why the spark appears weak.

Thanks to the others for their suggestions too. I couldn't help myself and took a peep under the cam belt cover - all in tact (phew!) - plus the rotor arm is firmly attached to the camshaft. I had a chat to Mike Satur, he thinks too that it sounds possibly electrical on the HT side (although he's only working from my description over the telephone) and suggested trying a new rotor arm (at the price, it would make sense to try this first) plus make sure I have a good power boost/fully charged battery when trying to start again. Haven't tried to start it again yet, will wait for the coil to arrive, replace the arm and charge the battery first - I'll let you know how I get on...
Mark Clayton

Okay - So the coil came today, great! Managed to get the old one off with a struggle and then tested the two of them with an OHM meter - The readings were identical (had a bit of a sinking feeling at that point!).

Nevertheless, put the new coil on, plus a new HT lead that I had spare and a new rotor arm & cleaned the dissy cap (no sign of any tracking etc). Charged the battery and then used jump leads to give it an additional boost and turned the car over - HEY PRESTO, it started first couple of turns of the engine.... Problem solved - OR SO I THOUGHT!!!

The car ran really smoothly, I left it ticking over as I put the engine cover back on etc.. then decided to take it for a spin... The car was nippy and smooth as I headed up the road BUT the moment I put my foot down, instant loss of power & misfire - Keep the throttle light and it (appears to) run fine - Gentle increase in throttle pressure, car accelerates (not that smoothly) and a rattle through the exhaust indicates misfire. Sniffed the exhaust after a 5 minute drive - rich, unburned fuel smell

I don't want to keep shelling out on parts I don't need but what do you think my next move should be? Distributer Cap, leads & plugs? or could it be something else: Air? Fuel? Timing? (not sure how that advances on a modern engine). Again, any suggestions would be greatly appreciated...

Now here's the WEIRD BIT - Got the car home and turned off the engine, waited for a few moments and then cranked it over - No sign of it firing - released the key and the engine kicked into life???

Read about a similar problem with a Rover 216 which did this same trick of firing only when the key was released and it was put down to a faulty IGNITER MODULE... Is there such a thing of the MGF?

Mark Clayton

Plugs, leads and distributor cap always seem to solve my problems, although this spring the original rotor arm has been replaced too.
Graham Martin

Graham - I think you're spot on - This morning (after leaving the battery on charge all night), I turned the key and the car started on the first turn of the engine. I took it for a run and it drove perfectly, no problems at all.

I thought about it this morning and realised the problem had started after the car had stood for 10 days in a mixture of warm weather & heavy downpours (the one thing I failed to mention in my previous threads what that I had found condensation on the inside of the dissy cap which was still there last night - I wiped dry with a cloth but perhaps didn't eliminate the damp). I came to the assumption that as I had got the car up to temperature last night and then left it on the drive, the warmth from the engine had probably helped clear the dampness, so by the morning all was working fine again.

I'm going to replace the dissy cap with a proper Rover replacement (put a cheap one on last year), pull all electrical connections in the engine bay and give them a good clean and spray with electrical contact spray and hopefully that should be the end of it..... fingers crossed!!

Mark Clayton

My wife's Ford Focus has the same thing ! I've changed the plugs and leads so far at great expense, on the reccomendations of the RAC man, and its still not going. There is no spark at No 2 Cylinder.

Consequently she is commuting in my Beloved MGF.
Cedric

Mark, please post again if that fixes it, I imagine a new coil was more expensive than a good dissy cap first time round.
Leigh

One final note, if this is ever retrieved from the archives in the future - Some final interesting findings:

I had noticed at the time that the battery seemed to drain quite quickly - It is a new replacement, under 12 months old, replaced because the green battery condition light had gone out on my old battery (didn't know how old it was, so simply replaced it without bothering to test it - but kept the battery, intending to take it to the tip). A test of the alternator shows that, although it is providing a charge to the battery, it's barely over the 12.5v mark (I believe it should be 13.5-14v when engine is revving). Dark winter months, short trips & the load from the lights, HRW etc has probably meant that my battery has be running down slowly, rather than maintaining it's condition. This was further proven when I charged up the old battery only to find that the green light re-appeared... DOH!!

This probably explains the reason the engine fired once the key was released and the starter motor load was taken off the battery (as Roger suggests above).

When you combine a weak battery with a weakened spark (due to the damp, leading to the misfire) it's easy to see why the car wouldn't start once it had stalled.

Now that I have replaced the distributor cap, rotor arm and coil (all probably unecessarily) and cleaned all the important electrical connections in the engine bay, the car is running better than ever (even the slight misfire I used to have every now & again while idling has gone). I used contact cleaner to clean: Crankshaft Position Sensor, Throttle Position Sensor, low tension & HT coil connections, All distributor connections and plug connections, Stepper Motor connector, brown Temperature Sensor, plus I checked that the vacuum pipe running to the MAP sensor (which is inside the ECU on my car) was also firmly in place.

I'm due to service the car next month and will replace the alternator at this point - I've always been aware it was wearing out (as you can hear a slight grating from it's bearings as the engine comes to a stop after turning off the ignition and a bit of a whizzy whine from it when the engine is running). I thought failure would show up on the dash with the alternator light beginning to glow, or a more pronounced howl from the bearings but that didn't happen.

Thought it might be of interest...

Mark Clayton

...Sorry Leigh, I didn't see your post until after I typed my last message...

Yes, your so right - Although I think the cheaper dissy cap would have carried on okay with a clean (it was blue coloured by the way), the genuine black Rover one seems to seat better against the plastic shield (or is that my imagination) so perhaps it'll be better suited to keeping the damp out.

If I was a 'proper' mechanic instead of an (over) enthusiastic amateur, I would probably have taken a more logical approach and tested everything BEFORE jumping in with both feet and buying the first thing I suspected - Also, the 'proper' approach would have saved me the cost of a new battery 7 months ago!! LOL

Having said that though, the new parts should ensure peace of mind for the future and they weren't too pricy. I bought the genuine Rover coil new from an online seller on eBay (and because I had a £10 ebay voucher to redeem), it only cost me £25 including postage. The rotor arm cost just under £10 and the dissy cap just under £20 (both from local XPart).

All in all, the £55 (okay £59 if you include the contact cleaner) was far less than I'd pay a garage to diagnose the fault and the sense of achievement I feel in solving the problem myself is priceless!!

In fact, I was so chuffed that I wasn't going to have a garage bill to pay that I've ordered new plugs and blue silicone leads to finish the job off so that everything is new from coil to plug.

It's all down to having the confidence to give it a try.... something I wouldn't have if I wasn't for the help & support I've got from this bulletin board.

Thanks again for all your help!!

Mark Clayton

Mark
Nice to see your comments not all give feed back.

Just a quick note when you fit your new alternator make 100% sure it has a good earth path.

If your sure run a short bit of 4mm cable.

If you use a meter set to ohms and it should read the same as if you join the two lead together.

Regards Roger
RJ Rowlinson

Will do Roger, thanks, much appreciated...
Mark Clayton

This thread was discussed between 28/04/2008 and 06/05/2008

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