My 89 efi running rough

Can anyone shed some light on this one for me? my Range Rover is running very bad, when cold after the auto choke has gone off the engine hunts, ie revs up and down on its own, this dissapears after a while but my main problem is it seems to be over fueling itself, it backfire's all the time after acceleration and generally missfires all the time, so far i have changed the plugs, leads, distributer, air filter, and the usual fuel and air sensors, but no joy!!!!! the car lacks power and sometimes cuts out. any ideas?

Hi have you checked the pipes going to the Plenum chamber? my Range Rover was doing the same, it turned out to be the breather pipe going from the "Special air valve"(love that title) to the plenum and the other side one going from the "Special air valve" to the brass coloured pipe on the otherside of the plenum chamber. Also the small pipe plugging between the "Special" pipe and the Servo pipe.

Have you have the Timing checked ? (Will backfire if the timing is wrong)

Check for leaks around the Plenum chamber and the inlet gasket (Warning this is long job and the gasket is steel so fights back)

Hope this helps in some way

Charlotte

Just going on experience of new cars here. Mass airflow meter on the throttle body? Throttle body itself?

Hunting often caused by air leak somewhere. try clamping main air inlet just and see if it carries on running and if so can you hear the hiss from the leak?

I am no mechanic but have seen these faults cause hunting on several different vehicles. Also may be worth a try if its cheap are cam / crank shaft position sensors?

Might be cheaper to pay for a diagnostic plugin to make sure you get the right thing in the first place. Place by me does it for £35 and hes got shedloads of gear and is very rarely wrong. Not in merseyside are u?

Hi

I've just had to rebuild the top half of my EFi. There is a small flexible pipe (Around 6mm diameter which fits to the back of the Plenum chamber that goes to the vacuum ball in the passenger side front light box check that this pipe is connected and not split also the small flexi pipe which goes from the left side of the plenum chamber to the orange and black one way valve going the advance/retard on the distributor check that this pipe isn't split it has a tendancy to wear over time.

Check the servo valve and sealing ring in the Servo (pita of a job to do had to get two sealing rings lost one in the Servo)

At the extreme have the cylinder heads checked for pressure leaks (take out a spark plug connect pressure guage and crank the engine over with the coil lead removed)

Cutting out is air ingress (something is expanding when it gets hot) get some engine cleaner and spray/brush it on a warm engine to check condition of gaskets/seals. There is a spring clip on the servo pipe which corrodes causing air leaks.

Charlotte

If this doesn't fix it I will check mine tomorrow and see where the problem lies
I don't believe you can plug and play the Classic Range Rover (If you can let me know)

my old rangie efi had a similiar problem it took me weeks to figure it out! some times it would be fine others it would run really rough missfires as well. i found problem by accident i lent on bracket for flow meter and it livened up it turned out to be a bad connection on control unit? attached to bottom of bracket i just cleaned the contacts and slung a cable tie round it to stop it coming loose again!
Not to sure what this box does i think it controls power for spark or something!!!!
charlotte might know!

Hi the unit youre talking about is the mass meter

In real words it takes in air from the air filter diverts a small amount and anaylises it then opens the butterfly fly valve to suit.

It sends all this information back to the ECU so all the other components can work in sync.


charlotte

Hi, Ladys and gent's.

Well this seems to be an interesting one! i've checked all electrical connections ar in, i've checked and replaced lots of breather pipes, and still it's suffering from the same symptoms.

Had it on an emmissions tester and emmisions are quite high but MOT passable, tried to set the air/fuel mix when it was on the tester but turning the ajusting screw does noting at all to the emmisions levels and at the moment it only seems to run ok when the screw is turned clockwise all the way round till it stops!! any less than this then the engine starts to run lumpy again.

is it looking like it's an ecu fault? cant get diognostic equipment on it as its an early efi (89) and is not plug and play.

A few people have suggested MAF sensor?

is there any way of checking these work properly eg. tests

what are your thoughts people?

Many thanks in advance

Chris

Chris does youre Coil have a small black square thing connected to the negative side of it ? if so this may be faulty. Mine has started to come loose causing all the problems you have described.


The filter is around 1cm x 1cm on the top right hand connector to the coil, it goes to the fuel over run relay.


Charlotte

Bit late now to check i'll have a look tomorrow though!

rip the efi out and put a set carbs on she will run sweeter all these electrics aint no good £££££

No don't change the EFi to Carbs it will be expensive and loads of things will need changing in both the engine/tank and most expensively of all the Engine loom will need replacing

Charlotte