I have a 98 Disc. 1. It runs well around town but seems to lack power going up grades on the highway. It's new to me so I don't know if it's just the way it is or if something is wrong. It seems like a 4.0 V8 should have more power and torque and the specs say so too. I'm not looking to modify it but to possibly find something wrong and fix it.

It has 118k miles and should be in good mechanical condition based on how it's been maintained, but I do believe Land Rovers tend to need you to replace things occasionally.

It accelerates good on the level like from a stop light it has all the power I would expect from a stock motor. But on the grades it just bogs down and has a hard time going over 55 or 60. Ford Explorers are passing me. Like I said, it will speed away from a stop light with plenty of power... drives up to 75 or more on the level, about as fast as I'd want to go. But those hills kill it.

I wonder if it's clogged cats, O2 sensors, MAF, worn cam, slipping TC... looking for clues. Thanks

 

They are pretty sluggish. My 96 had a plugged cat and a loose throttle pressure cable going down to the transmission. Once those were corrected, it was a lot better... but a well running explorer, with the 4.0 or a v8 will probably still pass you. I'd think a dirty MAF could cause you grief too.

 

A well maintained engine is key to best performance, but remember these are 4500 lb trucks. All that weight is pushing it down hill while the engine is trying to push it up.

Another factor though is the stock diff gear ratio of 3.54 which means these trucks are geared a little high. Larger tires than stock make the situation even worse. Great Basin Rovers can supply you with 3.90 or 4.11 (depending on tire size) gears to fix this and make a significant improvement in power.

 

Mine runs fairly well and does struggle on grades, so I feel your pain. I used to take it up to the mountains to visit my brother, which is at around 4000+ ft., and I'm lucky to maintain 60-65 mph. I usually drop a gear to keep the revs up and speed consistent. I wonder how much of your mpg you'd be sacrificing with the shorter gearing.

 

I have the stock tire/gear ratios so it's not struggling from being undergeared due to large tires or anything.

I would like to replace the cats and O2 sensors but it looks like it'd be just under a grand for two cats, y-pipe (prefab or exhaust shop), and four O2 sensors. That's stiff, especially if it's not really clogged and I spend it just to find out it is just a slug no matter what.

How can I diagnose the cats?

4500 lbs? Did you put it on a scale? Mine is more like 5400 lbs running with fuel and the driver.

Adjusting the kickdown cable to the tranmission can help if it's not downshifting, but 3rd can be selected from the shift lever just as well. The problem is I'm trying to roll up the grade in top gear at 65-70 mph. I'm going 55-60 and Scotty says she can't give any more.

Again, I wonder how I can diagnose the cats. They're don't unbolt for inspection except with the whole y-pipe which is bent so as to not allow seeing in the cats. So I'd have to cut them out.

Some people responded their rover struggles on grades too. How do you know you don't have a problem as well? Did you have it since it was new? Do you know your cats are clear?

 

They're geared too high even with stock tires. 3.75 or 3.90 gears would make a big difference. It's a lot cheaper than dropping a 4.6 engine in.

Curb weight is 4465 lbs. Of course each one varies according to configuration.

Checking CATs for rattles, red hot CATs, or CAT inefficiency related codes are the only easy ways to check for bad cats.

If you live in an area without inspections you can cut out the CATs and weld in replacement pipe, do it to a used y-pipe to have a spare for inspections, or have a CAT-less y-pipe fabricated. The 2 downstream O2 sensors are useless for anything but emissions testing so they can be removed, unplugged, or ignored.

My entire truck is freshly rebuilt and runs like new. With slightly larger than stock tires it goes up hills just fine. It certainly has to work and requires more throttle but it gets up at a reasonable rate. Of course my opinion of reasonable rate and throttle input may be entirely different than yours.

 

You are comparing to toyotas and american cars. They are geared lower, usually, because they have a 1:1 high range transfer case. We have a 1.2:1 high range. If you do the math on it, overall reduction between a toyota with 3.90:1 or whatever is pretty close to a rover with 3.54:1.

 

I think they're geared too high for their power and weight. The transmission also seems eager to up shift early.

 

Tighten the cable.
I think the factory adjustment with the crimped on fishing weight is sketchy at best... and if the cable has ever been replaced, you can pretty much ignore the fishing weight.

Just keep tightening the cable until you get it to shift at the points specified in rave, section 4, page 7 of the workshop manual.

What's funny is that when this transmission is installed in a BMW, the cable is tight enough that when you floor it, you can actually feel a detent where the transmission will shift with maximum engine speed. I tried that in my 96 and it shifted WAY too high, but man did it have some power!

This is certainly one thing that is improved upon in the D2, with the computer controls... the shifting feels a lot better.

 

So they don't perform stoichiometrics and result in changes in the air/fuel ratio on a GEMS equipped vehicle? That would mean you could remove the cats and rear O2 sensors and there'd be no change in running, just ODBII codes for the AWAL sensors. There'd be no need for "O2 sensor simulators" or anything like that to get correct ratios, just to stop the codes which can also be ignored. That's the way the old carburretor-equipped cars were, with no sensors.

I don't intend to remove the cats unless I can confirm they're bad. I actually doubt they are. I just wish it was easier to confirm they're clear.