Problems yet again

[s111Truck_cab]

Right, my 95 3.9 disco (sequential LPG) had new cats fitted last Monday due to a bad knocking from one of them( all is quite now) But on wednesday just after setting off from a garrage with the engine hot it started to miss-whole car shaking, so i put my foot down on the gas and it cleared. The same thing happend on friday, stopped at some traffic lights, then when setting off again it missed but soon cleared. Today while on my way back from filling up it started to miss again but did it for most of the trip back, some 10 miles. So took a look at it and found one spark plug quite loose and another not so bad, both on the drivers side. I have also cleaned the stepper motor and breather. Have yet to see if the loose plugs were the cause. Any other suggestions?

[TEMPL4R]

If you have coil packs, then it's a Wasted Spark system. If one plug has a fault, it can drag it's twin down with it. So you lose 2 cylinders.

Chris

[s111Truck_cab]

What are coil packs and how do I know if i have them on my disco?

[TEMPL4R]

If you have a distributor with 8 HT leads coming out of the cap, you don't have coil packs.

Chris

[s111Truck_cab]

On mine there are 8 leads going to the engine and one in the middle going to a coil. So 9 in total.

[TEMPL4R]

Yep, Distributor, 8 out, 1 in.

A loose plug is a common thing, they do wear the thread out in the head if they are loose too long. So be careful when tightening.

If you fit new plugs, tighten them up to compress the seal, then slacken them off again, then retighten. It helps to stop them loosening.

Chris

[s111Truck_cab]

Yep, Distributor, 8 out, 1 in.

A loose plug is a common thing, they do wear the thread out in the head if they are loose too long. So be careful when tightening.

If you fit new plugs, tighten them up to compress the seal, then slacken them off again, then retighten. It helps to stop them loosening.

Chris
Thankyou for your advice. I will see tommow if this was the problem.

[s111Truck_cab]

Well It missed all the way home today so took the header cap off and sure enough there were loads of bubbles and a brown scum around the outside. Bloody hell, one head gasket must have gone. It's going in for both heads to be skimmed and new gaskets fitted. Ouch £££££'s. Got to have it done as it is a fab car with only 95000 miles on it. What does anyone recon the cost will be for this job??

[s111Truck_cab]

Another question. Seeing as it has never overheated should the heads be skimmed(always stays at near halfway) Is there any harm in having them skimmed?