50 replies to this topic

[greg.harvey]

So I took off a HT lead, held it against the block while my wife turned the engine over, no spark. If you're holding the HT lead practically to the block it should be really obvious if it's sparking, right? I mean normally there's a pretty healthy spark off a HT lead when the engine's cranking, AFAIK?

So it seems whatever happens when it won't start, it's not fuel delivery, it's not sparking at all - ECU/immobiliser not allowing it to?

[greg.harvey]

Looking at wiring diagrams (see http://www.theminifo...attach_id=68240 - page 14) and there's an "Oxygen Sensor Relay" in the mix while starting. I'm not very good at reading these things, but what I do see is of the major players, that's the only thing unaccounted for (starter cranks, instruments light and behave normally, can hear the fuel pump priming but no spark) so perhaps something with the oxygen sensor is stopping the ECU from allowing the car to fire? I have no idea what it even does, I'm just trying to see what other things are in the way via the wiring diagrams. Thoughts? I'm so frustrated, just want this car on the road!

[Juju]

When were the leads & plugs last changed?

[greg.harvey]

I have no idea, only just bought the car. It's done a shade under 50,000 miles. But remember, it starts sometimes and not others - it's not consistent.

[mark-tkm]

I'm not sure but it sounds like you might be having the same problem as me.
We used to think it was the level of the car as it mostly seemed to happen when the car was facing very slightly up hill but that doesnt seem to ring true any more.
Mine seems to do this mostly after it has been running for a while, for example went to get petrol about 4 miles away and after filling up stopped a few metres away and turned off the engine. After this it would not start and after several attempts over 15 minutes the battery ran flat so had to get it recovered.
I have also noted that 100% of the time after stalling, it will not restart for a good 10 minutes.
I'm going to check the injectors this week to see it they are clogged up and not atomising the fuel correctly.
It's a bit different to your fault but it may turn out to be the same problem.

This sounds very suspect to what I had on my 1997 MPI sportspack. I had exactly what you have said and then it progressively started to get worse. it turned out to be a wiring problem, after a while mine started to cut out every time i put the clutch down. mine was caused by the rubber engine bushes being worn and then when the engine rocked forward it distorted the wiring loomb! .. i put polly bushes on and got a auto leccy to fix up the wires as i know nothing of electronics (if you cant see it it doesnt exist in my mind.. but by god can you feel it )and i didnt have a problem since, im now in the middle of full restoration though! hope this helps.

sorry if this isnt very helpful to you greg

[greg.harvey]

sorry if this isnt very helpful to you greg

No worries!

One other thought - did crack the cat really hard on a bump around the time this started happening - just made a big dent in the cat, but didn't seem to upset anything else. Is it possible the impact dislodged some sensor somewhere in the exhaust manifold, something like that? Is there anything vaguely related to the exhaust system or located near enough to the cat that it potentially took a bang that could cause an intermittent fault like this?

[Mini mpi]

check your earth strap the starter will turn without this but the engine will not fire if there is a bad connection!!!

[R1minimagic]

If you pop a plug out and turn it over do you get any fuel mist coming out of the spark plug hole?

Also, you said the cat had received a large impact, are you sure it has not crushed the fuel pipes which run under the passenger side of the floor? If so, there may not be enough fuel flow/pressure to open the injectors....

Edited by R1minimagic, 17 August 2011 - 08:39 PM.

[greg.harvey]

Earth strap could be possible, I guess - remember though, this is an intermittent fault, so would've thought that would rule out something like fuel flow problems - it would fail to start all the time if that were it. When it does decide to start, it runs absolutely fine - that's a fundamental point here.

[liam_italian]

When you held the HT lead against the block did you stick a Spark plug on the end of it?

[greg.harvey]

I didn't, but I read that the spark from a HT lead is plenty powerful enough to arc over to the block without a spark plug? (I've never done this before... can you tell? )

[greg.harvey]

It started again today! First time, no problem! Put a new battery in one of the fobs last night. I'm not optimistic that's all it was, as this car can easily start one minute and not the next, but we'll see. I'm secretly hoping it was as simple as that, but I'm not optimistic.

[Blofeld]

the cut off switch is a ball bearing inside a 'holder' then creates and electrical contact. the inertia of a crash or big bump throws the ball out and cut the leccy to the fuel pump most importantly and engine stops. pressing the rubber switch down replaced the ball in the holder!!

i once had and found someone had bypassed the inertia switch with a paperclip across the plug and over time the paperclip rusted through and the car wouldn't start!!!

[greg.harvey]

I'm just back from a week away in England. Need to try the Mini again. Right now it's in the garage, blocked in by our Volvo, so I need to shift the old tank and try to get the Mini going again, see if these new fob batteries have sorted the issue.

My dad also reckons the crankshaft sensor is high on the list of suspects, because he had *exactly* the same problem with his car, (a H-reg Volvo 940 estate) - same symptoms and everything. Took months and three garages to work it out, but turned out to be a bad cable to the crankshaft sensor. So I need to check the wiring between that and the ECU if problems persist.

[greg.harvey]

Problems persist, wouldn't start yesterday, jiggled the crank sensor and the cable to it, made no difference. Joy. The local Mini guy thinks this could be a real b*stard to track down. As per usual in France, awaiting the right piece of paper before we can actually get him working on it... that, and the bugger needs to start so we can actually drive it down there!