Tune resistor \ lambda advice??

[lig]

Hi Chaps,

So after running my 500 with a green tune resistor for the past year, I thought I would revert back to remind myself just how bad it ran with the white resistor - so I plugged the lambda sensors back in, adjusted the AFM, reset the ECU and hey presto....

With the green TR it runs great very smooth throughout the rev range, although it does chuck out a lot of fumes because I guess it is running too rich.

With the white TR it feels like it has a twin cam, from standstill to about 3500 revs while cruising it shunts, I can feel the engine hunting all the time then if I put my foot down there is plenty of power but it seems to switch to a second cam at about 4000rpm, it really is ugly to drive.

Does the green TR just eliminate the lambdas and so the ECU adjusts its fueling accordingly?

Could it be that I have a faulty lambda sensor? would it be worth shelling out £150 for a new pair? I would expect the car to behave a lot worse with a faulty lambda, has anyone experienced this??

I just feel that it isn't right running the car with the green TR but I guess I will have to revert to this?

Any advice much appreciated - and I know someone is going to shout GET A TORNADO CHIP \ REMAP- !!!

Cheers,
Lig.

[trackcar]

you wouldn't know unless you could analyse the mixture under light running conditions. unless you can do that you'll just end up adding new parts until you stumble across the problem.

[rodbloke]

Does it produce a small (but very annoying) misfire on a very light throttle?
If so...I stumbled across a very long thread on things like this a couple of months ago and some people cured it by switching the tune resistor. If I remember correctly (and I may not, as i'm hungover) the light misfire is due to a lean mixture at cruise, and the Green T.R runs a lot richer so hides the problem. I think the down side is that it runs a lot leaner at higher revs, which could lead to problems.

I had the same problem with the misfire, a quick r.r. visit (no rechip) pointed out a couple of issues, (coil was knackered, and precat problem (now gone))..problem appears to be sorted.

[GreenV8S]

lig said:

Could it be that I have a faulty lambda sensor?

Yes.

lig said:

would it be worth shelling out £150 for a new pair?

No.

lig said:

I would expect the car to behave a lot worse with a faulty lambda, has anyone experienced this??

Ys. From the sound of it the 'closed loop' mode is completely goosed, and it could be caused by any of a dozen or more faults or any combination of them. Trial and error is liable to be a very slow and expensive way to track the problem down. You need to get the car looked at by somebody who understands the operation of the engine management system and can track it down methodically. These symptoms don't sound particularly unusual and can be caused by some common faults, but guessing is not the way to track them down.

[mongoose]

Hi Chris,YHM

[chassis 33]

If you want to have a less hit and miss approach than replacing each component in turn until the issue goes away, try the Range Rover workshop test sheets, they can be found here www.rangie.com/articles_topic.php?id=167&cat=7&subCat=51

Regards
Iain

[lig]

Cheers for the advice chaps,

Mongoose is kindly lending me a set of lambdas to try, if this doesn't cure it I guess It will be a RR day. TRACKCAR - could you email me your details as a little bird tells me that you have a Rolling road?????

Thanks,
Lig.

[trackcar]

lig, yhm.