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MG MGF Technical - Stalling, spluttering, stuttering.

Any advise will be much appreciated...

I'm driving a 1997 1.8 MGF and it has developed a intermittent fault. The car from time to time starts idling at around 1200 revs and when put under load, (pulling out a junction) the revs die and usually results in the car stalling. It can then take a few attempts to get the engine to limp into action again. When the cars idling at higher than usual revs as you dip the accelerator the car splutters and stutters until about 3000 revs. It addition to the above the car also sometimes starts up with the fan on, even when cold.

After the car has had a fit it will eventually right itself and run perfectly well. There seems to be no logical reason for the problem, i.e. hot, cold, dry or wet days.

I've read through some achieves and many talk about resetting the stepper motor etc but this seems to have very little effect.
Darren

Sounds very much like an electrical fault - most likely with one of the sensors.

The fact that the radiator fan (is this the fan you are hearing being activated???) makes it sound as though the water temperature sensor is giving false readings. The ECU sensor is separate to the sensor used for the instrument gauge.

Other causes to look at are worn distributer parts (replace the dizzy cap and rotor arm as a matter of course), the ignition leads, and the crank position sensor.

More on the ECU temp sensor here: http://www.mgf.ultimatemg.com/hgf_pages/related_problems_overheating.htm
Rob Bell

Almost certainly the brown temp sensor:
if the temp sensor is known bad, or there is a wireing fault the ECU defaults to both HOT, (run fan) and COLD (run rich) because these are the failure safe modes (never will over heat, never will run lean and pre-detonate)

>The car from time to time starts idling at around 1200 revs
The car is running the engine slightly fast, like a choke

>and when put under load, (pulling out a junction) the revs die and usually results in the car stalling.
The engine is running rich

> It can then take a few attempts to get the engine to limp into action again.
due to being too rich it has flooded

> When the cars idling at higher than usual revs as you dip the accelerator the car splutters and stutters until about 3000 revs.
The overrichness tails off at higher RPM.

>It addition to the above the car also sometimes starts up with the fan on, even when cold.
Default fail safe mode
Will Munns

Yup. Had that one. Blooming scary pulling away from roundabouts not knowing whether the engine would fade just as I pulled out. (And pulling away from roundabouts is one of the things I love about the MGF - but its obviously a surprise to other road users who don't expect me to arrive quite as quickly as I do!) It would flood on starting, too, so it was fingers crossed when turning the key. Local MGR dealer didn't have a clue and faffed about changing plugs and leads and stuff but my favourite AA bloke had it spot-on. Temperature sensor.
Steve Madden

Would agree on the temp sensor circuit. Replaced mine already.

But I've still the same low frequently intermittant and usually only need to rattle at the cable leading into the ECU to cure for a longer time.
Mine had a loose main harness, beeing not correct attached to the ECU bracket and this obviously led to bent connections inside the main connector to the ECU.

below rear not visible on this pic
http://www.mgfcar.de/mems1.9/harness_loose_sc02513.jpg
30 KB pink-black (earth)
33 KG pink-green (temp sensor input)

I'm still investigating. Not 100 percent sure though.
Dieter K.

Opps, hit enter to early....

If it's a problem with the pink-black (sensor earth) then ALL other sensors are affected, cause they all get earth with this wire. (IMO)

Will ??
Regards
Dieter
Dieter K.

Problem solved.. I hope.

I had a play with the ECU sensor. When I disconnect the sensor the fan kicks in straight away, which I believe from the web site Rob attached means the sensor is faulty. I also found that the wire to the sensor was stretched and if waggled the engine would falter and the fan would kick in again. I've re-routed the wire so the connection is not being pulled in the wrong direction and I intend picking up a new sensor. The car seems fine again now, touch wood.

Where's the best place to pick up a new sensor, is it Rover or will a Halfords do??

Cheers for the help.

Darren
Darren

I don't think that Halfords carry this sensor in stock - so your best bet is Rover.

Sounds as if it is more a problem with loom/ poor connection than the sensor itself?
Rob Bell

Sound like you have 90% of the answers

Unplugging the sensor just proves the fan works, you have a fault within the wire leading to the sensor, by wiggleing the wire you ahve found the fault, now work your way along the wire running it over your thumb, at some point it will fold, this is where the break is, pull the wire sharply to break the outer plastic, if available thread some heat srink over the wire, strip and solder the two ends together, then heat the heat srink to cover the join. If you have no heat srink then use a very small amount of black tape.
Will Munns

This thread was discussed between 28/06/2004 and 30/06/2004

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