OK Spike I normally don't like to disagree with people on here because I like a peaceful forum and people take things to personally but I know your better than that so I am going to put in my 2 cents. I have no idea what his problem is so I can't say your wrong, but I do believe it could be a few different issues so I would hesitate to say one thing or another is for sure his problem. So my disagreement isn't what you posted but how you posted it, I just would hate to have him come back pissed that he spent time and money on his VSS because he was led to believe that "IS" his problem just to find out it is not.

 

My truck drives the same way. Has for years. Never really tracked it down. My ONLY assumption at this point, it's the valves. My symptoms are exactly the same:

- Stumbles/pukes fuel while driving normal throttle...
- Suddenly boggs on the highway like the VSS is toast...
- Let off gas/re-engage gas and problem goes away for a while...
- Can also press gas pedal down until it either downshifts, or hits a magical part of the throttle range and clears right up (right before it would downshift)...
- Can manually drive truck and avoid annoying misfires...

Codes have always been a couple individual cyl misfires, one random misfire, and a downstream O2 code on passenger bank.

I started with Mike's 60K service including vacuum lines/pcv etc...
Replaced fuel filter..
Then replaced 4 O2's (O2 code cleared)
Installed Magnecore 8mm wires and +4 plugs (have tried at least 3 plug types though)
Replaced VSS (figured why not...)
Replaced TPS (again, why not...)
Replaced coil packs (what the hell right?)
Cleaned MAF (also tried known good one)
Fuel pressure/leak test (no issues)
Replaced cats/exhaust (unrelated, but they were old anyway)
Removed/Cleaned/re-installed ECU...
Run 91 or 93 every tank. Every other couple tanks I run seafoam.

Despite chasing down the stupid misfires with the easy stuff, they still exist. I've learned to live with it actually. I drive the **** out of the truck and it's never let me down. Just never really ran right either. Bought it with 90K, now has 123K.

If it's not the valves, it's some chewed up wiring somewhere. Sometimes it'll have a really good day where I'll only have to mess with the throttle a couple times to get past the stumble. Other times, it's pretty constant. Oh well! Good luck.

 

Just a thought, you may want to try cleaning both battery terminals, the connection at the back of the alternator, and the main ground point. detach each one individually and clean them with a wire brush. I know it sounds a little weird but think about this: the engine needs electric spark to run and if you have a little corrosion at one of those points with a relatively weak connection and then the perfect exhaust vibration at a specific RPM causes that connection to worsen just a little more and all of a sudden you are losing power! I would assume this is a very uncommon cause but it is possible, and 15 minutes could save you some headaches (and 15% on your car insurance!)

 

That's actually very good advice. I've checked the LR and it's good to go, but thanks for the input! Maybe the OP will have some luck.

 

Thanks a lot for the input on my engine faltering problem.

The disco was using oil and coolant so I had the head gaskets and valve cover gaskets done about 4 months ago and that solved that problem. I believe the new plug wires I put in are a Rover brand, but I will check on this. As for the spark plugs that were replaced when the head gaskets were done, I have to check with my mechanic. The work was done in a Rover shop, so hopefully he could at least get the plug wires right.

For now I am going to triage the time and money on this by starting with the less expensive fixes first. Clean battery and alternator connection, check to see if the misfire cylinders point to a bad coil, possibly change the engine speed sensor, and well, think about the valve cleaning job.

I do really like this truck, but love would be a stretch so I am not sure how far I will take it before giving up.

I will keep you all posted on the outcome.

 

You're no longer my friend!!!


No worries mate, I dont know all the answers even though I like to think I do.

 

Well I just upped my AAA tow insurance so now I have 200 miles of free towing. I am kind of hoping it will just die completely so the diagnosis will be completely transparent.

I drive the truck a lot and I need it to work, especially in December when I spend 3 weeks in Baja, way south in Baja. Only saw one Landrover there in 3 weeks this year. Lots of Dodges for some reason, but no Rovers. I need to get it back in shape by next December. Plenty of time for that one would think.

FYI engine codes the first time were misfires on cylinder's 3 and 6. According to my mechanic this is not the same coil. Oh well, taking it back to him soon to have the second set of engine codes revealed.

 

You do know you can go to a parts house like Advanced Auto and read the codes yourself.

 

Thanks for the suggestion and no I did not know that I could take my disco anywhere to read the codes myself.

I guess the reason I have stuck with my mechanic is that he does not charge to read the codes.

 

Autozone will read them for free, unfortunately though alot of the other ones have stopped doing it.