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MG MGF Technical - AAAAAAAAAARRRRRGGGGGHHHHH

If anyone remembers I posted some weeks back that my F was suffering from bouts of a kind of 'power-stutter' making the fall off and then come back and repeat at random.....
Well, it was sugested that it sounded like rotor arm trouble and because I don't know my rotor arm from my elbow I took it to the dealer. Dealer checked it out, replaced rotor arm, reset stepper motor ecu (showed as a testbook fault). I collected the car, paid, got as far as nearly leaving the forecourt and the stutter was back! Left the car with them. Next day they said they'd checked the ignition system, cleaned the loom (very dirty) and "its all ready Sir". This time I got 5 miles away before it stuttered. Back I limp. So this time they say they'll need to check the whole wiring in the ignition system and they have the car for 4 days: At the end of which they say they found an intermittant fault with the crank sensor (and duly replaced it). I was told that the technician was very confident this time. Took the car for a nice run to celebrate. Tearing along a few country lanes. Lovely. After 25 miles I was sat in a traffic queue for about 5 mins. As soon as I cleared the queue the damned STUTTER came back.

If anyone has come across this problem in an F then PLEASE HELP ME. It would be a big help to be able to suggest something new for the dealer to look at...............
John Philpott

John,

This sounds identical to mine, except I have problems starting as well and the revs dropping a lot as well as this stutter and eratic idling.

First attempt was to replace HT leads dist cap and rotor arm, no change.
Next was to dealer for a diagnostic check and there they found the stepper motor needed resetting.
Car drove fine for a couple of weeks then it started playing up again.

When it happened again took it to a non MG dealer to try and save money and they came up with crank sensor needed changing. Still no change so took it back to main dealer who swapped everying like ECU etc and still could not find the problem, but they did reconise it had a problem. They where thinking of changing the wiring loom next but not sure if they have.

I then decided to take it to Techspeed for its 72000 mile service and to see if they could fix it. Well I never made it and the car broke down on the way and that was last wednesday and my dealer have had the car since and so far have been unsucessful sorting it as the car has started behaving it self. I am suppose to be off to france with it next month.

I have told the garge they can do as much driving in it as possible to get the fault to reappear as I am getting desparate with just over 2 weeks to go and a car I have no confidence with for long trips.

Hopefully one of our garages find the fault and it is excatly the same problem.

Tom

Tom Randell

I'll be taking mine back in to the dealer as soon as I can and will definitely post the results on the BBS. It does look like we have the same trouble - I only have trouble starting after the problem has caused the car to stop. Then I get it started. It revs very strangely and finally cuts out completely.

Fortunately I've got a reliable Land Rover because it will be a long time before I'm confident enough to travel far in my F : (
John Philpott

Long shot, but have they checked the distributor itself? Had a not-disimilar problem with a Mazda MX-6 which turned out to be dizzy related - after they'd spent several days messing with other things...

Best of luck.

Chris
Chris

Jeepers, nightmare fault! :o(

Keep us posted John, and let us know what the solution eventually turns out to be. On occasion, this kind of problem has been solved by replacing the ECU (although this did not help in Tom's case).

If your car is a 1.8i, then checking out the dizzy would be sensible as Chris suggests - but VVC's of course use a wasted-spark, distributorless system.
Rob Bell

My bill for the first visit says:
carry out testbook health check
reset ecu and stepper motor
check ignition system plug leads and cap (would that be the distributor - excuse the dunce)
replace distributor rotor arm

The next bill says:
stripped all wiring and plugs, checked connections
found intermittant fault with crank sensor
replaced sensor, road tested now OK (someone should have told the car)

Back to the drawing board for the dealer.....
John Philpott

John that really is a tale of woe. I fave since cured mine simply by replacing the plugs and leads. Only cost 40 so was worth doing anyway. Good luck and don't get too dis-heartened
Jas

Tom
Did the diagnostic box that S&J installed in your car reveal anything ?

Steve
Steve

Probably a dum suggestion, but could it be the MEMS? Or has that already been checked and discounted as a possibility? I ask 'cos a friend of mine had some problems which sound similar to your and it was apparently, the MEMS itself that was stuffed. It took 8 weeks and 1 day to get the replacement part shipped to Australia.

phil
Phil

Steve,

The Diagnostic box did nothing and apperently ever since the car was towed in has not replicated the fault and has been starting and driving with no problems.

I will be picking the car up propably saturday morning unless the problem comes back and they lend me a car.

As for a problem with the ECU they have swapped it and it made no difference.

John,

The starting problems when cold is minor compared to the other problems. What happens to the revs as mine keep dropping to 0 rpm yet sometimes the engine is still going over times it does die. This happens at any speed, revs or gear and was the main problem when it got towed in as had alrerady had to stop a couple of times on the hard shoulder to restart the car but when it finally stopped it wust would not start that was until the AA came out after about an 1 hour of it stopping it did start but that was just to get to a lay by as it was still struggling.

Tom
Tom Randell

Hi

I had very similar problems with my yr 2000 VVC, the dealer changed everything over many visits (MEMs, sensors, stepper motor etc, etc) Everything worked for awhile but fault always returned after varying periods Eventually I tried another dealer and they changed (after a lot of prodding) the Engine bay loom!!! Fixed all faults and six months later all ok

JR
John Roach

Engine bay loom? That's a new one - thanks. It's going back to the dealer on Monday morning and they're as keen as I am to hear ALL suggestions for a fix.

Tom - I hope yours IS fixed just make sure you drive it A LOT and under varied conditions before you go to France. Remember, mine ran like a dream for 24 miles of open road and then packed up after being stuck in traffic for just 5 minutes! (Hmmm... temperature seems a possible factor)
Best of luck

I should be able to update this thread next week when the dealer's had another go......
John Philpott

Garage have just rung to say the fault has at last re occured while the technician was driving and they have come to the verdict that it is the engine bay wiring loom causing the problem although they cannot guarantee 100% it will fix the problem. I have mentioned the BBS to them and that it changing the loom has worked before.

The only downside is it is about 320+vat for the loom and fitting but if it cures the problem I will be happy (although it should not need replacing in the first place).

I just hope this is not a part which MGrover cannot get hold of with the spares problems

Tom
Tom Randell

Fingers crossed Tom.
Rob Bell

>>The only downside is it is about 320+vat for the loom and fitting but if it cures the problem I will be happy (although it should not need replacing in the first place).<<
*gulp*
Have they got any idea what the fitting charge is ?
Will your 3rd party warranty cover this ?

I hope it fixes it - and there are no further surprises in the 72k service.

Steve

Steve

Many years ago, when my MGF went back to MG with damp starting problems - the garage gave up, the MEMS and engine bay wiring loom were changed. Luckily it was all done under warrenty. The "diagnostics" never reported a fault.
Jon Baker

Steve

Not sure if the warranty will pay for it but have left it in the hands of the garage as what ever happens it needs to be done.
The 320+vat does include 1.5 hours labour. Then I assume there the other charges like time spent finding the problem plus the service so it going to be an expensive bill, but cheaper than buying a new car.

Tom
Tom Randell

Tom
Well, that's sort of good news, hope they can get the loom in time for you.


I'm going to tell my dealer to check the engine bay loom on Monday. They've been very good about charging me so far: When they had the car for four days trying to trace the fault they billed me just 2 hours!

My only misgiving about all this is that nobody seems to be able to demonstrate what the fault is with the engine bay loom and why it arose in the first place.
But I suppose if both our cars ARE cured this way then it might save people some head scratching (and cost) in the future.
John Philpott

John,

I have spoken to garge this morning and they cannot tell me how long it will be before they can get a wiring loom, but they are looking into it as they know how urgent it is with france in two weeks time.

So be aware there could be a wait if a wiring loom needs to be ordered.

Tom
Tom Randell

tell your dealer to check the wiring on the rear of the crank sensor plug the wiring starts to break in the harnes wiggling the connection should reproduce the fault. keep me posted
joe

Replacing a whole loom seems like an act of desperation - maybe it is.

Tips such as Joe's should be more useful, in my early days of electrical fault finding a more experienced engineer told me always to check the connectors since they are much less reliable than the components they connect to. He was right then and has been proved right thousands of times since.
Brian

I just ran the problem past tech advice at the owner's club. They've suggested something new:

The MAP Sensor (Manifold Absolute Pressure)which reads the changing inlet manifold pressures to provide a core function in calculating the ignition and fuel requirements.

They tell me that a cracked pipe or loose connection between the manifold and this sensor COULD produce this sort of problem when everything gets hot and expands....

Anyway, I've added this to my list (from this thread) of things to get the dealer to check on Monday

Tom
You may want to mention it to yours if they're just sitting around waiting for the loom to be delivered - you never know...
John Philpott

I have got the car back so I can at least get to work.
The garage have swapped everything to do with the engine petrol pump, ecu, coil, relays etc and have spent 14 hours loooking into the problem and have had the engine loom out and cannot see any problems but everything has pointed to the wire loom breaking down.

I will keep you informed whats happening.

Tom
Tom Randell

Suggestion:
Does the engine get enough fuel?
- Fuelpump
- Fuel filters
- Injectors

In the threads I only read about electrical tests.

Good luck,

Allard
A. de Graaf

is it possible that fuel hose from tank to engine is blocked by debris in tank? just a thought.

btw, i'm too lazy to check your previous thread.. but what's the milage of your car?



Jason

Car has done 71000 miles and the garage have checked fuel system and I beleive have swapped fuel pumps with no differenece. Admittedly since I have got it back it has been running better than before but I have not done any long drives.

Car will be going back in tomorrow for the wire loom which hopefully will turn up today.

Tom
Tom Randell

since most of usual fuel related prblms had been done, why not go ahead with draining/cleaning fuel tank to make sure that no blockage by debris.

anyone know the function of sensor at exhaust manifold?
Jason

The saga continues.

New wire loom fitted and still the problem continues.

I will have to suggest the MAP sensor.

I am getting desparate.

Tom
Tom Randell

Tom, you must be really p*ssed off.

Just looked up the MAP sensor in the workshop manual. It says

"If the MAP signal is missing the ECM will substitute a default manifold pressure reading based on crankshaft speed and throttle angle. The engine will continue to run with reduced driveability and increased emmissions, although this may not be immediately apparent to the driver."

Is this a diagnostic opportunity? What I mean is, you could purposely disconnected the MAP sensor forcing the ECU to apply its default state and see if the problem dissapears. Am I talking rubbish here or is this a valid test. It sounds logical to me from the manual, but then I'm no mechanic.

HTH

Dave
Dave

My dealer just called. They've had the car since Monday morning.
The guy says he's almost certain its either the MEMS or the engine bay loom or BOTH.... but maybe not i.e. no guarantees!
They then asked ME to decide what they should do.
I was tempted to say "do the loom" but after reading Tom's last post I don't think I'll bother with that - anyone reckon its really worth them changing the MEMS?
This is in danger of becoming a money pit.

Tom: Did you say your dealer had changed your MEMS already?

John Philpott

Tom
I'm sorry to hear that the problem is not yet resolved.
On the 1.8MPi isn't the MAP sensor integral with MEMS, and connected via a tube ?

The tube could be damaged or filled with fuel etc, so Dave's suggestions of removing the sensor / pipe sounds good.

Steve
Steve

Sounds like a good suggestion to me too Dave.

John, try the MEMS first. That'd be my gut reaction - then think about the loom (I've heard of more successes with ECU replacement than with changing the loom - Tom's experience being the double exception).

Tom, have a chat with Roy, and see if the car can't be looked over by an expert at Longbridge? I'm sure that the solution will be simple - but the identification is the difficult bit.
Rob Bell

The dealer has changed the mems as they had one lying around and it did not do anything but that was before they changed the loom.

I did ring them asking if they had looked into the MAP sensor and the tubing but not sure if they had or not. They where going to do a bit more swapping of components as at least the wire loom cannot be the problem.

Looks like I will give Roy a call as the car is booked into Techspeed for its second attempt at reaching them for its service on monday.

The garage may still solve it but will wait and see.

Tom
Tom Randell

I'll keep my fingers crossed for you Tom, and hope that the car will be ready for your French trip.
Rob Bell

Seeing as replacing the MEMS and engine bay loom didn't help Tom's car I've told my delaer NOT to replace these (they couldn't say they'd found a fault in either anyway).

What I've got them to do is disconnect the MAP sensor (thanks to Dave's post) so I can see if that is the problem. I'm just about to go over to collect it and then I'll go for a bit of a run (but not too far).
The dealer's best F man is on holiday next week so it would just be sitting in their garage in any case: I think I might have a go at a headlamp conversion to keep my spirits up : )

Tom: I'm VERY interested to hear what Techspeed make of this and/or Longbridge - please keep me posted
John Philpott

Well over the weekend I have done nearly 700 hundred miles without any major mishap but I don't think the car is 100% as it has shown signs of mis firing but it could be I am getting paranoid.

The dealer found that the HT leads and plugs where shot so not bad going 2 months on a set of HT leads and 12000 miles on a set of plugs.

Techspeed thought it was okay.

Tom
Tom Randell

Tom
You probably are just being paranoid, like you say : )
So, sounds like good news.

Can the cure be attributed to anything in particular? What did your dealer do after they changed the loom (the problem was still there at that point)? Surely after all this time your dealer hasn't put it down to being the HT leads?!
John Philpott

John
They looked at the HT leads as they did ring me up to confirm what I had changed as when they started it up after the Wire loom change it still showed signs of a problem.

One HT lead was all burnt as well as the Spark plug.

I not sure what did the final solution if in fact it is okay as so much has been done.

Tom
Tom Randell

Let's hope that the problem has been cracked Tom :o)
Rob Bell

Tom,

Got your message :-(

As someone who knows nothing about cars, I feel your problem must be something on the HT side of the electrics. It should be a concern that the HT leads and the spark plugs have gone in such a short space of time.

Is the new coil still on the car - or was the old one put back on when it was found it didn't cure the problem?

Best of luck matey.

Paul
P9 VLS
Paul

Back to the drawing board

As you might have gathered the problem has not been fixed and have 2 days to find a car and sort out insurance, as I definatly cannot trust the car specially after thinking it was fixed and did about 700 miles before it played up.

Yesterday after work it struggled to start and then later on the revs just died and then took a bit of time to start, yet this morning no problems so it is just so intermittant I cannot trust it to take on holiday so have to find a MGF to use or I will be going in a Honda civic coupe.

Tom
Tom Randell

Sorry to hear that Tom.

I just called the MGR Helpline and explained that my dealer had come to the end of their ideas list. They told me they'd get their technical dept. to call my dealer about it.

I should hear back in 48hrs.

I've got the car this week though cos the dealer's top F guy is on holiday. The MAP sensor is disconnected so I can test how it drives. I just haven't had the bottle to get out there in it yet (plus I painted my headlights yesterday to cheer me up)

John Philpott

My dealer just called - they're having the car back on Monday 19th and have agreed to submit a technical report to MGR. They've also agreed that they will ask for a field engineer from Longbridge if necessary.
Just got to wait now.
John Philpott

Hi All

This might be going completely off track, but it's not the battery?? Perhaps the level keeps dropping and confusing every sensor in the car?? I seem to remember that before my strange starting problems, sometimes when changing gear, the revs would die and the car would almost stall. That problem went away, but soon afterwards I had the strange starting problem.

Tom ... you mentioned that you also had starting problems ... what happens??

Stefan
Stefan Gibney

Stefan

The car just cranks over without starting and then when it does start it is either fine or like this morning extremly lumpy and just would not idle properly.
The revs would be all over the place and the car mis fires badly which to me means the new plugs and HT leads are already knakered in less than 1000 miles.

Trying to find a car today to go on holiday with all looks like I won't be goi9ng.

Tom
Tom Randell

BUMP

sorry about this but my car goes back in on Monday and i'd like this thread to see the saga to its conclusion
John Philpott

John,
When your car goes back in, ask them to explain the fault. While they may not be able to find the cause, they should be able to describe what's happening - is it not fuelled correctly, does it have ignition problems ?
If they can't describe the technical details of the fault, how can they possibly hope to fix it ?

Steve
Steve

Steve - The best they've been able to tell me is that its in the ignition system rather than the fuel system. I'm a bit more hopeful now that I've got them (practically FORCED them) to agree to send a technical report to Rover: Then I'll have two sets of people to hassle about it!

I've been driving it a bit with the MAP sensor disconnected; The problem still appears but it seems to go away more quickly... That is, if I stop the engine when it happens and then restart it the car then drives normally?!
John Philpott

well, the dealer submitted their technical report to MGR on Monday - they tell me the SLA states a 48hr response so I should have more news Wednesday
John Philpott

This thread was discussed between 24/07/2002 and 20/08/2002

MG MGF Technical index

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