MG Maestro cuts out when put into reverse!!

[bodgit0_0]

Since owning the salvage project maestro I have noticed it occasionally missed and farted randomly. The engine runs really sweet until it dies and misses.

If you keep the revs up then it will stay running but you can hear the misfire/missing in the exhaust.

The main thing noticed tonight whilst putting the wheels on after having new tyres mounted, once the car is put into reverse the misfire occurs! It's definitely related to the reverse lights coming on!

Anyone got an idea what or how to attack this fault.

I've also noticed alot of the dash illumination doesn't work, neither does the brake lights.

[bodgit0_0]

Just disconnected the tail light, fault has gone.

Will investigate it further tomorrow evening.

[mgt16]

Sounds like you need to clean up all your earth points

[hairyone]

I had the same happen to mine it was the reverse light switch on the gearbox a wire was touching the case so when put in to gear it was shorting and blowing the fuse for the same lights you have not working took me a while to find it

[bodgit0_0]

Cheers, will check the switch tomorrow evening. Then start investigating the earth's..

[bodgit0_0]

A little update from tonight's findings..

The circuits that are causing the engine to cut out are as follows-
Left indicator
Right indicator
Brake lights
Reverse Lights
Cigar lighter

No other switches cause it to cut out, my dilemma is now that there is no common earth across the problematic circuits. So apart from cleaning every earth any top tips on other causes.

Cheers

[E_T_V]

The earths to the front bumper bar on each side are the prime suspects.

Otherwise there is an earth point behind the dash high up on the passenger side which I think the ECU is earthed to (amongst lots of other circuits).

[bodgit0_0]

Today I cracked all the MOT failure jobs apart from the brake lights not working as they are related to this fault.

The alarm system has been pulled out completely as this was inoperative and wired in to the ignition system!!

To add confusion I removed the cigar lighter and ran a separate earth to it direct from the battery thinking that in theory I will have bypassed the fault.... WRONG..

Reversed the process and wired in a power feed and the engine wasn't effected.

The fault appears to actually be related to the power circuit?

[Jeff Turbo]

Today I cracked all the MOT failure jobs apart from the brake lights not working as they are related to this fault.

The alarm system has been pulled out completely as this was inoperative and wired in to the ignition system!!

To add confusion I removed the cigar lighter and ran a separate earth to it direct from the battery thinking that in theory I will have bypassed the fault.... WRONG..

Reversed the process and wired in a power feed and the engine wasn't effected.

The fault appears to actually be related to the power circuit?

Have you tried a different rear cluster yet?

[Sussex Pete]

The earths to the front bumper bar on each side are the prime suspects.

Otherwise there is an earth point behind the dash high up on the passenger side which I think the ECU is earthed to (amongst lots of other circuits).

I suffered this problem as well the first time I came to move my Turbo in the dark. Had lights on, engine running, engaged reverse and the lot died There was me in the middle of the road with a dead battery and no-one to help push! Anyway thanks for the pointers as to where the faults may be.

[bodgit0_0]

Have you tried a different rear cluster yet?

Have only tried it with the clusters removed, will swap out a spare set tomorrow.

Pete, does your car suffer from the other causes??

[Sussex Pete]

Pete, does your car suffer from the other causes??

Yet to check! The only thing I was aware of at the time was how dim the headlights were! The next time I moved it was in daylight and had no problems, so there is a good chance of a wiring fault at the front. Interestingly, when vacuuming the car (the seller hadn't cleaned it at all), I found a long unattached black wire running across the back of the car underneath the tailgate lock. I think that may be another earth that needs to be reconnected somewhere - but where I have yet to find!

[bodgit0_0]

Cheers Pete, I have checked the front earth's which looked clean but one was a bit loose.

Have also swapped the ignition switch as its new from the previous theft, no change..

More confusion today though, if I add my own direct battery feed from the positive terminal straight to the ignition switch I would of thought it would of supplied a good power supply. It actually caused the engine to die without any of my problematic circuits being switched on.

Are there any known problems with the fusible links found near the battery? I am really struggling with this fault now as its gone from a suspected bad earth to suspected power issue to, well... I don't know?

Any other good ideas please feel free to throw them across.

[Guest]

I would be using a test meter to see exactly whats going on here. Clip the neg. lead to the battery earth terminal. Then check that with the lights on you have 12v on the ignition coil. Also check from the engine block, should be 0 volts. If any voltage here, check the engine earth strap. My Maxi went through a spell of konking out when going round roundabouts. Turned out to be a loose engine earth strap.
Good luck David

[G Force]

You found a loose earth point on the front bumper? It might be worth swapping the ignition ecu as it could have been damaged by running with the bad earth point.