94 D90, passed emissions finally, still fighting an bit of an odd issue. At highway speeds she runs about 3/4 up the gage. Also, at say 80mph there is no pick up, unlike my last D90 which would happily do triple digits. I mean I can get it to 90 but only barely and it heats up quick. I think it is related. What would you try? Vacuum advance? Fuel filter? Maybe mechanical advance in the dizzy. I am thinking either:

1. Bad fuel filter/pressure causing it to run lean
2. Plugged cats

I think the broken advance would make it run rich, not lean.

plugged cats are certainly a possible problem. The over heat may or may not be real. But sounds like it is in your case. But i will say, alot of d-90's dont really like to hump it over about 80-90, yours may be one of those. Might take a vavle job, and a few other things to get her up to speed.

checked the timing?

my rangie ran like complete ass with bad cats, fwiw

I have often thought that clogged cats could be determined by a vacuum test-but haven't had a means to confirm or deny this theory.

Let's go back to some basics here:
Compression test-it's an older vehicle and we aren't certain as to past treatment.
Ignition to baseline-new plugs, wires, cap/rotor, base idle, airgap, timing.
Vacuum test-might reveal all manner of conditions.
Leakdown-might show what the compresison and vacuum tests didn't.
Fuel Pressure-might be the key to everything, although, if it performs well up to 80 MPH, it's not likely to be fuel flow related.

Lastly, why do you feel the need to go so fast in a vehicle that was designed to go everywhere? I thought the whole idea about a Rover was that you didn't have to go fast, stop quickly, listen to the radio (or spouse :flipoff2:), remain comfortable (dry, warm, etc), IF you could go everywhere you really wanted to go...

PT

"Compression test-it's an older vehicle and we aren't certain as to past treatment."

Consistent across all (including #1 which did not fire for 20k) and good ~180 (I forget the number but tech said very good)

"Ignition to baseline-new plugs, wires, cap/rotor, base idle, airgap, timing."

All but timing checked. All new except plugs ~9k.

"Vacuum test-might reveal all manner of conditions."

No obvious vacuum leaks. All hoses fine, flame trap cleaned etc. Not sure how to do a vacuum test.

"Leakdown-might show what the compresison and vacuum tests didn't."

No equipment? NOt sure how to do. Doubt issue with good compression.

"Fuel Pressure-might be the key to everything, although, if it performs well up to 80 MPH, it's not likely to be fuel flow related."

Humm. Well I will put a new fuel filter on it. Not sure how to test pressure while running. I finally got it past Emissions test and with the 5k exemption I can never take another test so I may knock the loose stuff out of the cats and see what happens. They do rattle on occasion.

Wish me luck.

As far as speed, I need to do 90-100mph at almost all times to keep up with traffic.