Forgot.....The spark plugs I used, were in the top 3 recommended by Champion for the Discovery.

They're the Championpremium gold. But the thing is that Champion claims that the plugs are gapped to OEM standards which they say is .032. I know that LR recommands .037-.041 So I re-gapped the plugs to .041 Is that all right ???. That plug is built like a regular plug, and is not the needle headtype plug like the originals. Should I have gapped them smaller ??? Reason for asking, is that although the Idle is very stready at around 600 r.p.m, it idles lower than before which was around 700 r.p.m.

 

Your idle is too low, I know that Rover has a special plug made for the Rover engines which is good, I still like the Bosch Platium Plus 4's, just my choice. Gapping the Gold plug to a larger gap has probably effected their performance.
If you don't get it worked out, let talk over the weekend.
Mike

 

Re: cleaning the MAF (and Disco Mike and others might overrule me on this one)......if there's no evidence to indicate that your MAF is dirty or not functioning properly, you may not want to introduce another variable into solving the poor mileage equation. Better to eliminate variables, one-by-one, before adding more to the mix. I'd focus on decisively ruling out the cats andO2's first. Once those conerns have been confirmed or denied, then you can move on to other components.

Your truck has pretty low milage for it's year and,if theMAF has already been replaced, it should be okay.

I'm not criticizing the idea of cleaning the MAF, I justknow that it's easy tobecome overwhelmedby trying to attack potential causes and solutions all at once. You know?

 

Darover, having just read back through the chain of events that lead up to this, I can't help think that it might be worth your while to replace the pre-cat O2's.....especiallyconsideringthat you replaced the aft's, the acetone treatment, etc.Just because they aren't throwing codes doesn't mean they're functioning 100%.

I know I'm making a $200 suggestion but, of all the components being discussed, the pre-cats are towards the top of the list when it comes to impact on fuel mixture.

Replacing O2's is a little bit like replacing tired shocks......they're all working together as part of a system. You tend to get better results when you replace all of them at the same time.......rather than piecemeal.

Just my .02

 

This is not a spark plug issue. The whole spark plug speciality thing is a myth. A spark is a spark as long as it hits at the right time. He has issues outside of sparks plugs... I stand by my diagnosis.