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Any fuel injection experts here?

I have a problem with a 1989 3.9 Range Rover.

It has developed a habit of cutting out at full throttle.

When it does this, if I hold it on WOT, the revs will drop to below 1,500 rpm, (it is an auto) then it will cut back in again, till the revs come back to 1,500, then it will cut out again, hovering at 1500, as if there is a rev limiter set to 1500.

If I back off the throttle by the tiniest amount, everything is fine.

I'm pretty convinced its something to do with the TPS, not in the switch itself, but in whatever the injection is supposed to do when it gets the signal for WOT from the TPS.

Any thought?

Thanks.

Reply to
SimonJ
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Not really my area but as it's an auto won't there also be a kickdown switch at full throttle? Maybe this is playing up.

Dave Baker - Puma Race Engines

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Reply to
Dave Baker

God this takes me back a bit. The good old Lucas effort. There is not a TPS as such on these- its a Throttle switch- not a potentiometer.

TBH I've not really worked on any at all, cos they were abit before my time, but i suggest first you check the switch for no continuity at WOT (sounds suspiciously like its signalling to the ECU that the throttle is shut) but as revs are above 1500rpm the ecu is cutting off the fuel altogether.- over run cut off.

Has the switch been off and replaced backwards? Some have the spindle hole on both sides!

If that all checks out (test at the ecu multiplug- the wiring was not very good on these!) then dont mess about any more - have the ecu tested by an atp modem dealer. The ECU's werent the best either.[1]

Tim.. [1] to say the least!!!!!!

Reply to
Tim (Remove NOSPAM.

Unlikely. The signal from the TPS doesn't have a vast effect on the fuelling.

Reply to
Dave Plowman

That sounds quite promising. The switch hasn't been disturbed, so it looks like a faulty switch or wiring. Would I be right in saying that the TPS on these is basically just two microswitches, one for WOT, the other for closed throttle?

Thanks for your help, will go do some checking on Monday methinks.

Reply to
SimonJ

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