[Gipper]

Hi,

I have a 2000 Discovery 2 V8 here in Canada with 230,000 kms on the clock, it has recently developed a misfire on No. 4 cylinder at idle, ( I have a Bearmarch Hawkeye tool hooked up to it) but as the revs rise above ~1750 the misfire disappears. I have changed the HT lead and put in a new spark plug, (Bosch Platinum) it has a constant good strong bright blue spark at the plug. I am wondering if this is likely to be an injector issue or possibly a valve problem, any ideas?

Many Thanks
Grif
BC, Canada

 

[shpreetzer]

I had one with this issue changed spark plug, wire and swapped with another coil pack. It ended up being a block issue. If you are not overheating and not loosing any coolant I wouldn't worry about the block or head gasket and if you changed the wire and plug you may want to swap with a known good coil pack to try? Just my .02 cents and I'm
In Canada too our .02 cents arent worth much right now lol ?

 

[Gipper]

Thanks for the info, its not using coolant or oil, so Im thinking it is either a valve, injector or coil issue, not sure what the service life of the injectors is, but I might swop it out for a new/recon one, Ive put some Sea Foam into the tank, but its not improved the misfire so far.

Yeah 2 cents CAD doesn't get you very far these days lol

 

[James PS]

Your problem may be due to a worn camshaft. I had a misfire issue and chased down everything on the ignition side to no avail. It ended up being because of worn lobes on the cam. To check you can pull off the rocker covers, turn the engine over and watch to see if you have sufficient movement of the rockers; if not, it is a worn cam. Good luck.

 

[Gipper]

Hi James, thanks for the info, how many kms/miles are on your vehicle? was the misfire at idle only or did it happen at any revs?

Thanks!
Grif

 

[James PS]

Its been a few years, but I believe the mis-firing started happening around the 75K mile marker. It did start running rough at lower rpms and initially would do okay at higher rpms, but it degraded further to where it was bad across the rpm spectrum. Its my understanding that some of the factory supplied cams were made of softer material and that this failure is not uncommon. If you do end up changing the cam and want to upgrade to a high torque cam, the Kent 180 is recommended often; you can get them from Turner Engineering UK or Rimmer Bros, etc...