Range rover classic over fuelling

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Philip Townsend

Member
Posts
24
Hi all need some help and ideas for my classic, she is over fuelling and stinks. The parts I have replaced:
Fuel pressure regulator
MAF Sensor
Coolant Temp sensor
Both Lamba sensors
Fuel rail temp sensor
Stepper motor
Also checked TPS sensor and check fine tune resistor, Last week purchased a Diagnostic lead and downloaded Gauge which all readings where correct apart from the Lamba on 100% more fuel on long term. The map at 1100 was 14/2C but not sure on the mapping side of things, not sure where to go from here.
Best Regards Phil.
 
Hi Phil,

I had this on my 1990 Vogue SE at the beginning of the year, went through everything you did.

does it idle ok, then get to about 2000 RPM then misfire ?

pull the distributor cap off, and see how much slack there is the rotor arm. after doing everything you did, and more, it turned out the distributor was worn.. new distributor and its spot on !!
 
Get yourself Rovergauge put it on a laptop and you can run diagnostics from the white 3 pin plug under the drivers seat.

It will give you fault codes and live run data.

You'll be able to see exactly what it is doing rather than parts chase..

Check the fuel ECU under the drivers seat as well one part number was a notorious fail issue and there is a company on the Isle of white that repairs them they updated the fuel ECU to a later PN.

That's just clutching at straws though.
 
Thanks Phill,

As Adam says check the dizzy and if you can get the Ecuador checked or swap out for a known good one.
The wire harness can go quite britLle with age and start to fail, have a look on the TVR owners site or google ecu check, quite a complex process but worthwhile checking the lambda and AFM circuits.
 
If I understand what you have said, I think you have an O2 sensor problem and it is likely you have replaced loads of bits unnecessarily. I know you say you have new lambda sensors but have you checked they are actually working? The Lambda 100% trim is the clue. I recently helped a guy with a Westfield with a similar (the same) problem, it turned out that 1: The lambda sensors were failing and 2: Somebody had put the wrong relay in the loom so there was actually no power going to the lambda sensors which is why when they were powered up they didn't work due to contamination.

I would recommend checking the fuel pump relay is a 5 pin with diode and 2 pin 87's. If it has a standard 4 pin relay in it you've found the problem. The lambda sensors receive power through the fuel pump relay so that is why you need to check it has the right one in there. It would also be helpful if you put up your location, that way if somebody is close by they might be able to pop over and take a look or help out. HTH
 
I had the lambda sensors on mine going to 100% also.

on idle they sat even, when the throttle was blipped, they slid up to 100% and stayed there.

I changed the O2 sensors also with no change. in my case the distributor arm had slack in it rotationally and up/down. so when the rpm increased, the rotor arm was, I presume, moving with centripetal force and throwing the timing out.

the lucas hotwire system is pretty basic, MAF, O2 sensors, rudimentary fuel ECU, fuel pressure reg, HT leads, distributor, distributor amp and coil.

as a question for the OP.. how are you timing it up ?

I did mine static, then dynamic to 6 deg at 750 RPM with the vacuum pipe removed.
 
An ignition problem could cause a lambda problem but there would be other running problems. The OP doesn't say if there is a notable misfire or stumble or even if it idles well or otherwise so it is (like so many) a bit of a needle hunt in the proverbial haystack. I would have to admit that often if the lambdas don't work the engine will ultimately stall when warm, it will run fine when cold because the ecu won't look at the lambda output until it warms up but once it switches to lambda correction for fuelling it will throw a fit if the sensors are not working properly.

That said, the lambda sensors can be checked with a volt meter. I also wonder if the OP has the EFI warning light on? I would expect it should be. Hey ho, that's the joy of old Rangies!
 
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