Darren Roberts

Range Rover Classic 3.9 Overfueling

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Posted (edited)

Hi Guys,

 

I've got a 1992 Hard Dash 3.9 Auto SE, been bobtailed by the previous owner. When buying it I think I recall the owner saying it originally had cats that were now removed. So I have the lamba sensors in it, but no cats (and no back box either).

Its running very rich (so much the mrs won't come out in it with me!). I've invested in an ECUMate, it says I have fault codes 14 - water temp sensor and 17 - Throttle pot, it's also saying I'm in limp home mode (ticket about 1500 rpm) and the ECUMate is saying I'm running white tune with cats.

This problem seems to have been getting worse since a mate replace the valley gasket for me and I had a new temp sensor, so got him to swap that out at the time.

Before I start buy-in new parts, should I also consider putting the correct tun resistor into the loom? Is having the resistor with the tune for cats causing issues because the fuel map is wrong? Or should I swap out the water temp sensor and the other parts first.

And when they say throttle pot, do they mean the idle control valve on the side of the plenium, like ERR5322 or is it part of the MAF? I have a spare MAF so is it worth fitting that? Or could it be a wiring issue with the loom into the MAF...

thanks in advance for any help......

 

 

 

 

Edited by Darren Roberts

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Quagmire    18
Posted (edited)

If the doodah says you have a knackered water temp sensor then that will definitely make it run rich, so I'd change that as a first step.

*Edit- just re-read your post again. So you have changed the water temp sensor and it's still overfuelling? 

Edited by Quagmire

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Ally V8    17

Make sure the fuel temp and water temp plugs have not been swopped,seen this done several times...

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Bowie69    382

Yep, also check the wires aren't broken - check the reading of the temp sensor is working at the ECU plug.

Hotwire diagnostics in the tech archive.

Tune resistors won't make that much difference, certainly won't make it run that rich. But do swap once you have sorted the other issue.

Throttle pot is on the plenum, connected to the other side of the butterfly, this has 3 wires going to it. Very common they break off, loadsa money new, find a second hand good one if you can't find a wiring fault elsewhere, again check at ecu plug if seems ok at the throttle pot.

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Thanks guys. Didn't know there was a fuel temp sensor. I've got the old water temp sensor somewhere so I might put that back in and see if that cures the water temp fault....

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God, Bowie, now I know what you mean about the throttle pot......why did they stop making them? Might be a bit of a bitch to get one of them.....

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L90-v8    3

green tune resistors are a job to find I popped to maplin an got a 470 ohm resistor for less than 50p I got the 2 watt one as there easier to handle i had a spare plug kicking around ard soldered it to the existing wires wrapped it in shrink wrap job done

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Update.

 

Today changed the water temp sensor (new) and Throttle pot (second hand un-tested). Same faults still showing although it appears tp be running and sticking over better, Used my ECUMate ti clear the faults, stopped and started the engine again. Same faults came back (14 temp sensor and 17 throttle pot).

Not sure what my next port of call should be? Suggestions?

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Bowie69    382

Check signal at ecu using hotwire diagnostics in the tech archive. 

 

 

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