I've got a 99 Disco with a totally stock 4.0L

Most of the time, at higher RPM's I get a stutter. It's like a plug wire has come off, and I loose power. Then, after about 30 seconds, everything is normal again. Sometimes it will happen over and over, and other times nothing is wrong.

I have replaced the plugs (NGK), Wires (STI), and the VSS.

To make a long story short, I have found the problem in the wires. They jump spark to what ever metal they can find, i.e. valve covers, bolts, brackets.....

I have cleaned, sanded, and remounted all the grounding points at the motor, frame, and battery, replaced the wires, and even tried to wrap them in elec. tape. Nothing is helping.

Why is this happening? :mad3:

any codes?

If I take a long trip, I will get a mis-fire code. I can't remember the number...But, it has been doing this daily now with no light or stored codes.

Stuck valve?

If its jumping sparks.....you sure you have decent contact between the plug wires and the plugs.
Did you put some sort of grease or something on the wires?

Stuttering in a 4.0 is often syptom of stuck valves.

However, if you've seen it jump spark...than that's a different story. Is it jumping from all the plug wires or one in particular?

Has the truck been driven mostly in the city? Very little highway/4 wheeling/high RPMs in its life?

Sounding like stuck valves, a common problem in 96 n' newer rovers.

STI wires I have never heard of.

Magnecore (sp)

http://www.karlynsti.com/Folders/Karlyn_STI_Ignition_Wire_Sets.htm

I don't think it's a stickey valve because I can see the sparks jump off the wires when the truck is acting up.

This is a daily driver truck. It sees a 5 mile warm up to the interstare every morning and then a 12 mile trip down the interstate at 70-90MPH 5 days a week. It has never seen off-road.

I run the STi's on my 97 Discovery with no problems and even swapped the wire set's.

I'm out of ideas. I'm thinking of just changing out the coil packs now. I don't really know what it will do, but it can't hurt. Maybe the old packs are throwing out some supernatural wicked power, and the wires can't handle it. :confused:

If its jumping off the wires, then you're wires are crap. In general, at night, if you see a mini fireworks show under you're hood, you're plug wires are bad.

I know one guy who has worked on a coil pack. I will try to find the thread (on another BBS) and see what was going on there. But overall I seriously doubt that you're coil pack is dead. Oh, and when you see the price on the coil pack, severe hesistation will overcome you.

Did you gap you're plugs? I remember once a RR 4.6 was misfiring like a mofo. Had many of the guys at the shop stumped. Turned out to be a improperly gapped plug.

But what has me stumped is the wires work fine on my other truck. Both have the same motor etc....

Hell, the way Lucas is, I may just need to do some combination with the wiper switch, blinkers and open the fuel tank door while in low range to reset something. Damn land rovers.....I should have got a Kia.

They might be touching and grounding out on the engine. I doubt it, but you know, its always the stupid little crap.

Might want to think about looking into you're fuel system. Since the problem is at higher RPMs, that is where a lot of fuel issues come up. I doubt it, but there isn't any water or bad gas in you're tank? That just happened to my buddies rig. Bad gas will mess with you're rig.

Bad gas will mess with you're rig.


Reminds me of a Roy D. Mercer phone call to the auto parts store.

Reminds me of a Roy D. Mercer phone call to the auto parts store.

It was the damn oil filter, you sold it to me fair and square. I believe I am going to need a new motor cause of it.