Hi Timbuk2
Sounds like you have checked the most obvious culprits already.
A couple of other ideas....Stalling is often put down to a bad coil.
Surging is normally fuel related, or the electronics that control the fuel.
It often is a bad sensor or dirty sensor. When were the oxygen sensors last changed?
You could try just removing the sensors from the exhaust, cleaning them up (usually covered with carbon deposits or even rusty if you have a tiny crack in you head gasget from coolant being blown out the exhaust) put them back in & run for a while. If the surging / stalling gets better then you have found the problem & you should plan to change for new.
Another idea is a good brand of fuel cleaner / injector cleaner (do you use premium or regular gas?) Newer RRC's dont like regular gas, the higher the octane the better for any electronic contolled Range rover fuel systems.
Because all parts are expensive, best to try cleaning parts first, (plugs, rotor, connections etc) then if you see a improvment it confirms that the part you cleaned is the culprit & then its worth replacing that part for new.
One last obvious thing to check is the ground strap from the battery to the frame, then the frame to the engine.
good luck,
let us know when you figure it out.
Andy
Surging + Rough Idle 93 Range Rover 4.2
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ANDYD
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sailourboy
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surging
My 92 RRC 3.9 also suges after warm up and no one has found the cause yet, though it doesn't seem to be as extreme as yours yet (no tach). I will be interested to see what you find.
Cheers
Ted
Cheers
Ted
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HeadDamage
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My 87 RR had a problem where it would rev up on starting then stall, it would then not restart untill it had sat for quite awhile. The problem got worse over time and I tried all the fuel system tricks but it didn't get any better. In the end it turned out that the TPS was out of adjustment, 5 min with a screw driver and a mulitmeter and she was good to go again. Don't think that this is your problem but thought I'd add it to the tread.
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sillysod
sounds like a possible stepper motor. I would suggest going here, there is tons of valueable information on your rover.
http://rangerovers.net/rremedies.htm#surging
http://rangerovers.net/rremedies.htm#surging
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bclandrover
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timbuk2,
The white three prong diagnostic connector is under the passengers seat most easily accessed from behind with the seat moved fully forward and up.
Did you fix the vaccuum leak in the PCV system?
Have you set the base idle and timing??
Can you check the O2S, MAFS, TPS, TEMP sensor output with a scope? A check at the sensors and at ecu will help eliminate wiring issues. Check and clean all ground wires and connections. This is cheaper than throwing parts at it!!!!
Later,
Don
The white three prong diagnostic connector is under the passengers seat most easily accessed from behind with the seat moved fully forward and up.
Did you fix the vaccuum leak in the PCV system?
Have you set the base idle and timing??
Can you check the O2S, MAFS, TPS, TEMP sensor output with a scope? A check at the sensors and at ecu will help eliminate wiring issues. Check and clean all ground wires and connections. This is cheaper than throwing parts at it!!!!
Later,
Don