Misfiring and hunting problems

Hi Guys,

Got a problem with a 97 disco V8.

Starts fine but within a mile or so starts to hunt and sometimes cuts out.

Always starts again and if you put your foot down pulls fine under load, and will rev smooth as anything at high revs when not under load.

I've checked for air leaks etc as best I can, but it's not easy when it won't idle.
I have a multimeter so can test sensors etc but where would I start.

The engine has done 160k, but apart from a bit of tappet rattle at start up seems fine.

Thanks for any advice,

Wookie

As you said id be checking for an air leak first off.All vacume hoses ,brake servo pipe etc
dont forget to suck on the dizzy vacuum unit for leaks

Is there a screw to wind in to speed tick over up so you can spay carb cleaner/brake cleaner around,to see if it picks up


Allso has your dizy come lose and alterd the timeing

Is it hunting or misfiring?

Peter

More hunting like 1k rpm+, but at low revs feels like it is misfiring a bit.
Brakes are fine but I'll check the servo as suggested.
From what I've read tick over is set by the ecu via sensors, but if I'm quick I might be able to vary it by hand. Got a tin of easy start which would do the job.
I don't think the dizzy is lose but if I can get it to idle I will check the timing.

Is it lpg?

yes but the tanks were removed a while ago for the sills to be welded.
Everything is still connected but turned off, so petrol only.

Are the MAF and stepper motor in good order?

If it is hunting, remove and clean stepper. Remove and clean plenum and ram housing, check throttle disc is set correctly.

Pop dizzy cap off and check inside the cap for corroded terminals - clean carefully with needle file or fine emery (or similar). Check condition of rotor arm. Also, if it stops when still a bit cold have a look for condensation in the dizzy cap - it does happen.

Put all that back together, fire it up and see how it settles. Once warm, check ignition timing. Assuming all that is fine, set base idle. That should keep you busy for a morning. HTH.

Hi Guys,

Went out the other day to check things out as suggested and couldn't get in.
Immobiliser light was on constantly, central locking not working.

Got in using a key and the green cl box was full of water, removed it, got it open eventually, dried and then cleaned everything I could with switch cleaner.

Connected it back up and hey presto all the faults went away.
I know this box connects to the engine ecu and probably others, but was the last thing I'd expected to be the cause of the problems.

Thanks for all your suggestions guys, I'm going to test everything I can when I next do a service.

Wookie