Help me please!!!

[robby]

I have a 94 Countryman petrol estate auto, 110k miles and well looked after, its my 6th Monty and I thought I knew it inside out but - over the last 2 weeks its taken to stopping unexpectedly. This always happens at low engine speeds, mainly in traffic queues, no sign of overheating, no misfire or faltering, it just bloody stops as if you'd turned the key. It will then turn over quite normally but not fire at all. I then push the thing to the side of the road, swear, smoke a fag and after about 10 minutes turn the key and it starts as if nothing was wrong in the world. IT IS DRIVING ME CRAZY. I can't believe it is a fueling problem, I've replaced fuel and ign ECU, relay box, sensors, all from a running car and its made no difference. Everything else ign. is all top notch. The only other thing I can think of is that before all this happened the inhibitor switch on the trans stopped working when I started it one morning, i jiggled the lever and then OK - this is a red herring isn't it? Any ideas?

[G Force]

Hi There, I too don't think your problem is related to the inhibiter switch, as this just acts on the cranking circiut. I take it you have changed the crank sensor & checked the wiring to this sensor. Is your car a 2.0L Carb or Efi? If it is a carb version, the fuel pump is prone to overheating, causing cavitation if it is mounted upside down or just plain faulty. The wires should be at the bottom of the pump. Worth a check.

Cheers Gary :)

[robby]

Thanks Gary, its injection, i've changed the sensor but only a s/h one. Of course I suppose the same problem could exist on the donor car for the electrics I've swapped. I can't believe the problem is fueling, yesterday I tried running it out of fuel to see what it felt like, a lot different. The funny thing is that it won't happen at all once above 1500rpm or so, if I knock it out of gear when I stop and keep the revs up it's OK, trouble is I keep on forgetting and it gets me. Its not a tickover problem though, its steady at about 900, and only does this stopping business once or twice a day, no warning at all ,no rev drop, no hesitation, just stops. Does anyone want to buy a nice Montego?

[G Force]

Hi again. I can understand how it is driving you crazy. I would try leaving it idling in park and give all the wiring connections a good waggle see if you can make it cut out. If not when it does happen try and establish whether you still have a spark and fuel pressure etc.

Cheers gary :)

[e692wtt]

I would agree it's an electrical fault, as the engine just stops 'dead', kaputski and that's that...

I believe that when the Battery voltage available to the ECU drops below a certain value, the ECU shuts down to preserve itself and so the engine stops.

My thinking is that you have a fault with the Ignition Switch (the bottom bit, below the barrel, where the wires come out), and due to a bad intermittent contact (and maybe overheating and expansion?) the available voltage at the Ignition ECU drops below the critical level (at engine idle speed) and the engine stops. In the 10 minute wait before the engine will restart, the bad contact is remade (overheated parts that have expanded cool off and contract so that electrical contact can be resumed properly and the voltage at the Ignition ECU returns to its usual level). The voltage only drops 'critically' when the engine is idling - when the engine is at higher revs then the voltage at the ECU is still satisfactory (because the Alternator output is higher than when the engine is idling)...

Just a theory mind, but also do other systems on the car stop working as well, when the engine has cut out?

I'd say check for fuel pressure and spark, as G Force says, but also check for voltage at the Coil Positive terminal - ideally full Battery voltage (I don't think the system is ballasted at all)? It should be the same at the Coil + terminal as acros the Battery itself, I would say...

[mgdavid]

does your model have a rev counter? - if so then what does it do when the engine dies? If the rev counter dies first then it's ignition circuit (switch, or live to coil etc) , if the revs die away afterwards then it could be an overheating coil or the ECU or crank position sensor.
HTH

[robby]

Thanks for all the ideas - I've got plenty to do tomorrow. I especially like the ignition switch, I recall something similar on a m'cycle years ago. I have to confess that as to checking fuel and spark when its dead I haven't done that - I've either been caught without a tool to my name or so knackered with pushing it out of traffic that I can't be bothered. Next time tho'. The rev counter dies simultaneously with the engine, all other circuits work including cranking. Will let you know what happens next!! Thanks.

[jonhamil]

Hi there,

apparently my car had this exact same problem before I got it. The solution was to check the fusebox over, since it is renowned for the PCB (circuit board) to become cracked. I suggest changing the fusbox board, or try inspecing the tracks on the back?

On mine, it was apparently the main live feed through a 30A fuse which had to be bypassed for the problem to go away! Sounds strange I know, but that's what I've been told...

Cheers,

Jon

[MG1600S]

Fuseboxes, can and do fail on Montegos. Usualy headlamp circuit. With Montegos being ever harder to find in scrap yards, look for Rover Metro as well (K Series engine), all models have the same fusebox. Just swap the relays and fuses to suit your Montego....

[robby]

Hello all, thought you might like to hear about the results of the stopping problem. A couple of weeks ago I spent the whole day on it, went over every connection I could find, replaced the starter motor - it was beginning to suffer! the alternator (because I had a new one waiting around), did an engine service, and cleaned the contact block of the ignition switch. Filled with hope I took it out and it did exactly the same thing, in heavy traffic, and on a hill. Finally got it to go, took it home, locked it away, forgot it and went on holiday. Couldn't get it out of my mind tho' and spent a day at a breakers in Dorset collecting bits, prime suspect being the contact block (didn't have the nerver to pull it to pieces before - just used contact cleaner), also yet another relay pack, and more sensors to add to my collection. Got home this weekend, fitted all my bits and it's been fine for three days up until tonight! Just pulled out of Tesco carpark, it stopped but this time no power at all, everything ign.sw. controlled dead. It was pouring with rain but I had tools and no power to the back of the switch, wired the feed terminal directly to the battery, started instantly and took it for a half hour drive - no problem at all. This has to be it, I'm sure, as jonhamil says but although I can understand why this would stop the engine when theres an intermittent break in the supply, why wooldn't it restart, before the power has always come back straight away, maybe it's just enough of a break to make the ECU decide to have a rest. Anyhow, I'm feeling very relieved, will go into it more thoroughly tomorrow, and no longer planning to sign my life away for a Subaru Legacy. Many thanks for all the suggestions!!