intermittent mpi starting issues - starting to become a big problem.
Turbo Mini Forums

Hi, I have been having an intermittent starting problem with my mpi Cooper. I was wondering if anyone has any expereience of this problem and what the cause may be? Firstly, it’s a pain due to the intermittent nature – the engine will crank but not fire up

The battery is in good condition. The terminals are clean and clamps tight
There is fuel and a spark.
When the car starts it runs really well.
I have cleaned and replaced the crank sensor with another good used one – the prolem persists.
I have checked the condition of the wiring, plugs and fuses and all seem fine as far as I can see.
The engine earths are good and I have more than one fitted.
The spark plugs and ht leads seem to be in good condition


Basically I am stumped now as to what this can be. I have bought a replacement wiring loom, (which I thought came in sections but is one large integral car loom), I was going to change just the engine loom if this was possible. I can change the lot if needed but it seems a fairly big job

Im having the ecu plugged in later today to see if that shows anything.

The next steps I can think of are

Ecu check
Adjust fuel regulator (though car has done around 30k set as it is)
Change wiring loom
Maybe change the coil pack
Pull engine and clean flywheel/change oil seal.

I really could do with a bit of guidance with this one, cheers, dan

just had it plugged in, there were faults on nearly everything where we have had the engine in and out over the last few years. he reset it, if the problem persists it will hopefully show when i take it back. i have a feeling it wont be as straight forward as this...

Not ever had a play with an mpi (well technically...) but id also check your coolant temp sensor

Could be a failing coil pack might be worth swapping if you have a spair or no some one with one could still produce a spark but e weak. My old v twin bike had a dud coil pack but still worked to a just was temperamental and hard to start

"Tuning should be a compromise between what is possible and what is necessary"

10)Thou shalt always quest for more power

Schrödinger's cat - so which one am I ???

thanks for the input. basically the guy said there were too many faults to look at, and asked if i had been unplugging sensors - i did this when changing the engine. said reset it and see what i have got. i think two came back up straight away, oil temp and ambient air or something, which he said were nothing to worry about. i think that the best thing to do is see how it goes and let him plug it back in when the fault occurs again. hopefully this way it will narrow things down a little. i think that the codes shown were in relation to the different sensors and componets being unplugged during engine removal/fitting.

the coil pack seems to be a valid thing to look at. im not sure about water temp sensor not allowing the engine to fire though? however i will leave these as they are until the guy looks at the ecu again. cheers

Have you looked at all the vacuum lines?

Jean

http://www.jbperf.com/

I don't know how the mpi ecu works but from experience temp sensors are pretty important when it comes to starting a fuel injected car. Reading too cold and you could be injecting too much fuel and flooding it, or opposite, too hot and not enough fuel to fire.

Thanks for the input. I decided to have the errors wiped from the Ecu and start again. This was around two weeks ago and all has been good since.

However I tired to start the car this morning and the same problem came up. We tried to start if off a bump but it wouldn’t. It finally started off a bump via a tow but it took some doing. It seemed flooded – stank of fuel and bogged down when the throttle was pressed.

I got it on the diagnostics and this is what showed –

Ambient air temperature circuit
Oil temp. Circuit
MAP sensor – replace
Water temp sensor – replace

It was wiped of errors and only the top two appeared when restarted, which im not too concerned about.

By this time the car was starting normally. I got it home, replaced both sensors with good second hand ones – I will replace the water temp one with a new one which I have ordered.

The next problem is that it overheats badly now – the temp goes into the red and the expansion tank pops its cap. The car is high compression but have done 30k on the engine with nearly no problems. I have had problems with the MAP sensor in the past – this effected how the car ran, but it would start with the sensor disconnected. So im looking at the water temp sensor as the starting problem.

So basically it now overheats

I have ordered an 82 degree thermostat and a new expansion tank cap. I will change these in the next couple of days when im not working. If this does not work I will change the head gasket and water pump. If that doesn’t work I may look at an uprated rad. The car could do with having the fuelling set on the rollers. Does anyone have any ideas on what else may be causing it to overheat so badly? I don’t think there are any air locks after changing the sensor. I will test the old thermostat.

an 82 thermostat won't fix an overheat.

The top two faults are common on the Mini since it has neither of these sensors, they show as a false fault. The bottom two are the ones you should worry about.

Personally, I haven't been getting involved with these sorts of faults anymore as more often than not its corrossion in the wiring itself, and that is impossible to diagnose over the internet, and extremely difficult when you are infront of it. If it is the wiring, it could be anything anywhere, and there is a good hundered meters of the stuff on those looms.

First check the wiring loom down around the back of the manifold that feeds both the coolant temp sensor and the MAP sensor. It can sometimes get trapped between the bulkhead and manifold especially when the engine bushes are worn.

Cheers for the input sprocket. With both of these problems it s case of elimination. At the moment the overheating is my priority. Tomorrow I will compression test it, change the thermostat and change the header tank cap. As far as I understand a non sealing cap and/or faulty thermostat could contribute heavily to the overheating. I will reduce the fuel pressure when changing the thermostat for the 82.

I will have to see how it does regarding the intermittent starting fault – after changing the water temp sensor this may now be resolved? As I understand it the ECU takes the water temp reading as one of the parameters of how much fuel to put into the induction?

I realise that the wiring on the car is getting older, and to be honest it wouldn’t surprise me if there is a problem with the loom. As I said it’s a case of elimination and I want to start by changing the easier/cheaper components first.

As the errors have been wiped from the ECU is it trying to run the engine on the standard settings? When I first put the engine in over a year ago it overheated on the first run, and though it has been a warm engine ever since, it hasn’t overheated to such an extent as the first time. If I can get on top of things for now I think it really needs the fuelling sorted on the rolling road.

At the moment I run bpr6e spark plugs – does anyone have any suggestions on a plug that may help the engine run a little cooler? Thanks

Dan

thanks for the input on this. i changed a few parts a few weekas ago and things have improved with the car.

I removed the thermostat which when I tested was stuck shut. I changed the expansion tank cap. I changed the water temp sensor.

The car no longer overheats – it comes up to temperature very quickly (within a few minutes), then sits between 1/3 and ½ on the temp gauge. Before it used to sit between ½ and even up to ¾ on this gauge (on a motorway run). The oil temp also used to sit at as high as 120 degrees, this now only goes up to 90 derees and that’s on a motorway run. In traffic the water temp would creep up before, it now drops slightly to around 1/3 – ½ on the gauge.

The car itself drives much better – it now has even more torque, and will wheel spin 1st and second off the mark if im driving it as I previously would. Economy also remains good. It pulls really well through the gears (it always did but now even more so)

I will leave the thermostat out for the time being, and keep an eye on things as the weather gets colder – though as I said the engine starts to warm within a few minutes anyway. So I do not see a problem with this?

Also the intermittent starting problem has not returned yet – maybe it has been solved by changing the water temp sensor, we will have to wait and see.