Thread: 95 disco 3.9 v8 running like a dog

Hi Guys,

This is my first post so I apologise in advance if i leave any info out.

Recently purchased the above vehicle which had issues in starting and running but got it cheap so I took a risk. The vehicle does not like to start easily at any temperature. You can crank the motor with no throttle and it will not fire up. Give it a little throttle and eventually it might start but sounds like it is running on 4 cylinders. It will sometimes then stall and at other times if you can keep it running by pumping the throttle it will clear itself after 10-15 seconds and start firing on all cylinders.

I did find that it would generally start ok by holding the throttle flat to the floor and cranking for 5 seconds or so. However once you got it running it idles rough and has a huge flat spot around 1500 revs that makes driving it very uncomfortable. The idle also fluctuates somewhere between 600 and 1500 rpms.

Work done to date includes

Fuel pump replaced with new
Fuel filter replaced with new
Idle Air control valve replaced with new
Fuel regulator replaced with secondhand unit

All vacuum hoses checked and replaced as necessary. All the above made no difference to the behaviour of the vehicle. Finally decided to take it to my mechanics to no avail. They could not find any fault other than to say the coolant temp sensor was an open sensor and may not be reading right.

After two weeks with them and no answer the vehicle was sent to a supposed landrover expert mechanics shop. Spoke them today at length and they are none the wiser either. Apparently there are no codes showing from the computer. Their own computer readings when the vehicle was running indicated that the temp sensor and MAF appeared to working OK. Fuel pressure was 35psi and supposedly OK. They believe the vehicle is running lean which maybe explains the funny starting issues but cant remember how they came to that conclusion.

Can anyone help please. They are leaning towards a buggered ECU but don't have a spare one to swap over to test it.

In my searching of this (and other sites) I have been unable to find a similar starting issue where it runs on half the cylinders.

Any help would be muchly appreciated.

Thanks in advance.


Pete

Hi guys,

an update on my disco problems. The repair place had no idea what the cause of the problems were and resorted to pulling off the intake manifold to check lifters etc. The best explanation they could come up with was it was a tired motor as it had fuel and spark and should go otherwise.

After 5 weeks of this crap I picked up the vehicle and drove it home. They struggled to start it and it drove worse than when I took it in.

When I got home I started to think about the issues and what parts had been replaced etc. I took the dizzie cap off and to my amazement the rotor had the metal part missing. WTF???? And they had played with this car for 5 weeks and mucked about with the distributor and no-one noticed this????

Unbelievable!!!!!!!!!!!!

So I decided to replace the rotor, cap and leads. I had a mechanic mate come down to reset the timing as it was 18 degrees BTDC. But still the car did not want to start or run properly.

Whilst there was spark, it was weak. So, decided to replace the distributor and ignition module and bingo, started right up.

Was missing on one cylinder so checked those and changed over some plugs and leads and this thing is running sweet. Fires up with no throttle. Idles perfect. Drives well with no flat spots at all. All the supposed noises in the motor are gone. I think the noises were a result of the incorrect timing and not firing on all cylinders.

I just cannot believe that supposed expert mechanics could not sort this out in 5 weeks and gave up. What a bunch of clowns.

Anyway I am now happy as a pig in mud and many thanks to the contributors who helped give me some ideas on fixing the disco. At least I can use it now.

Cheers

Pete