M.I.L Light, clutch slip.... connected somehow?

[ybt1982]

Hi folks,

I will start from the beginning, just in case there is anything within the story that might help in solving this rather strange puzzle.

I dropped my car of for a bit of work, including removing pre-cats and fitting my Clive de-cat Y Piece and fuel resistor. Upon collecting the car around 10 days later I took the car out for a spin. Everything seemed great, sounded brilliant and seemed much keener to get going. When I returned to the garage to pay we realised the the fuel resistor had been set on the 'white' tune, as it should be on the 'green' tune we quickly switched it over. Then the strange stuff started.

When restarting the car the M.I.L light came on and the revs were all over the place and not settling. We didn't have a diagnostic machine to hand so it was decided I would come back the following week when the diagnostic machine would be there. On the way home, all motorway, whenever I was in 4th or 5th gear and gave the car full throttle the revs would rise but the speed wouldn't, like clutch slip.

After a bit of research at home I decided to reset the ECU by unplugging it and leaving it for a while before plugging it back in. After I did this, still with the resistor set to the 'green' tune, the car started fine, revs were stable and perhaps most strange of all, I could not get the apparent clutch slip to happen again. No matter what I tried, full throttle in all gears, dipping clutch in 3rd while moving. All resulted in instant bite and the car took of like a very fast thing indeed.

Anyone wish to shed some light I'm more than happy to accept the theory that the clutch fairy has been to my garage, replaced my clutch to allow me to get the camshaft and other stuff done instead

[blitzracing]

The Mil light and clutch are not connected in any way. You have confused the ECU by switching maps between white and green tune, and it will go to the limp home map without an ECU reset that you have now done. I trust you have a correctly calibrated green map for your car? - The default one could be to be Range Rover!

[ybt1982]

It is the resistor swith that was supplied by Clive with the Y Piece, so that's all good. I realise the M.I.L light was probably due to that but would limp mode in any way cause the revs to rise like they did and make me think the clutch was slipping?

[blitzracing]

Fitting the green tune simply switches the fuel map you are using-so if TVR have not modified the non catalyst fuel map in your ECU for TVR use then it will be wrong....If Clive had made you believe that's all you need to do he's a very naughty boy, as its a real gamble what fuel map you will end up with unless he can confirm TVR modified both maps, and that seems unlikely as the chips are marked for catalyst or non catalyst use. There is NO advantage to running the green tune anyway unless your car is prone to shunting- you dont get any more power, and the ECU looses the ability to keep the fueling spot on. If you have a Tornado / Mark Adams chip, you will be fine as he calibrates both tunes in the one chip, if you are hell bent on the non catalyst tune.

As for the raised RPM- its been said that certain limp home conditions will raise the idle- but that's all, and Ive never managed to replicate this state however mean Ive been to the ECU!

[ybt1982]

I do not have the technical know how to answer that, Clive would be the best person...

CLIVE

From what I recall, the tune resistor had several settings and, the White setting was Cats still in and the others were non Cat tunes.

I am more concerned about the clutch slip anyway, is there a definitive test for this? I want to know if I should replace the clutch or go for the camshaft kit and other bits and bobs for more powahhh

[977]

Was it definitely the revs climbing or just the tachometer reading higher?

[SILICONEKID350HP]

Do you mean M.I.L.F light ? It flashes when you drive by a sexy mummy !

Edited by SILICONEKID350HP on Saturday 9th February 22:53

[ybt1982]

977 said:

Was it definitely the revs climbing or just the tachometer reading higher?

Now that I really think about it, I can't recall if the revs sounded like they were rising, but the tacho most certainly did.

SILICONEKID350HP said:

Do you mean M.I.L.F light ? I flashes when you drive by a sexy mummy !

Edited by SILICONEKID350HP on Saturday 9th February 22:17

I really thought a car like the Chim would help me in that department, but almost a year into ownership I am still relying on Mrs Palm and her 5 daughters for that kind of pleasure

Edited by ybt1982 on Saturday 9th February 22:23

[clive f]

seems to be some confusion here, supplied with the decat pipe Mark is a fuel resistor green for non cat, white for cat, nothing to do with maps or chips.

dnb who makes these will be along to explain shortly I`m sure if you need the technical answers.


as said earlier, clutch has nothing to do with anything you`ve done so far so dont know what is going on there?? did you pop round to see Colin?

[ybt1982]

clive f said:

seems to be some confusion here, supplied with the decat pipe Mark is a fuel resistor green for non cat, white for cat, nothing to do with maps or chips.

dnb who makes these will be along to explain shortly I`m sure if you need the technical answers.


as said earlier, clutch has nothing to do with anything you`ve done so far so dont know what is going on there?? did you pop round to see Colin?

Thnaks Clive, as I said, I do not have the technical know how to explain these things.

I did see Colin, car and ECU are fine, sill can't explain what happened with the apparent clutch slip issues though I thought it may be a limp mode type of thing to limit the amount of power sent through the drive train but that wouldn't let the revs increase.

[clive f]

so if you went and saw colin, did you ask him about any clutch problems?

[ybt1982]

Yup, also confused by it. He told me a rather harsh way to test or clutch slip, I tried it and it was fine.... maybe I imagined it.

[clive f]

just enjoy it mate, whats the new sound like??

[ybt1982]

clive f said:

just enjoy it mate, whats the new sound like??

Sounds lovely. Still not getting any popping and banging on the over run though, but from reading up on it, I guess that's 'cos it's it is running so well

[clive f]

go up to approx 3000rpm back off, say when running down a long hill and gently feather the throttle a little this should give the desired effect.just have a play with backing off at different stages of rpm til you find the right range for this to happen.

[blitzracing]

clive f said:

seems to be some confusion here, supplied with the decat pipe Mark is a fuel resistor green for non cat, white for cat, nothing to do with maps or chips.

dnb who makes these will be along to explain shortly I`m sure if you need the technical answers.


as said earlier, clutch has nothing to do with anything you`ve done so far so dont know what is going on there?? did you pop round to see Colin?

The value of the resistor is "read" by the ECU to select the required fuel map- There are "Geographic" tunes available depending on the local emission laws and engine compression ratio for that particular market, as some areas the fuel grade is poor and the compression ratio is lowered. In the UK, there are two tunes normally used- the white where the car has Lambda probes and catalysts, and the green for pre 1992 cars where the emissions are not measured. Running a green tune does allow the engine a wider range of air fuel ratios, it runs leaner under a light load, and the idle is better as the Rover V8 likes to run a tad richer than the catalyst map allows. It can also reduce shunting as the ECU does not try to constantly trim the mixture, but that is all the possible advantages.

On the down side the ECU looses any fueling information from the Lambda probes, so 80% of the fault codes the ECU generates when something goes wrong are lost. You also really need to be sure the selected "green " tune is suitable for you specific engine, as its quite likely to be a bog standard 3.9 non cat Range Rover fuel map, that the TVR chip is based on. I dont have a definitive answer to this, as I cant tell simply looking at the map data, specifically as the map data changed over the years.Id suspect a Range Rover map would show up on a Rolling road, as it would run lean at higher RPM, (this is not recommended) as the map was never designed for the fuel requirements of a tuned motor. There is no reason to switch maps as long as you still have the Lambda probes fitted and the car does not shunt- the catalysts don't need to be present to run the catalyst fuel map. Any myths that the green tune is some sort way for more power is simply wrong, as the white tune switches to full power mode over 3400 rpm or 2/3 throttle anyway.

[clive f]

blitzracing said:

There is no reason to switch maps as long as you still have the Lambda probes fitted and the car does not shunt- the catalysts don't need to be present to run the catalyst fuel map. Any myths that the green tune is some sort way for more power is simply wrong, as the white tune switches to full power mode over 3400 rpm or 2/3 throttle anyway.

the reason I offered the green resistor in the first place with the decat pipes was because we found that some cars were liable to have shunting problems at low rpm, it was not done under the guise of gaining more power, just smoother running, some cars benefit from this, others have stayed on the white resistor with no problems.

[chris1972]

This is interesting because my 500 shunts around 2000rpm. What do I change in the ECU? I may try this for a couple of days.

[dnb]

The tune resistors were never offered as a means of making more power. They are simply a means of getting access to all the fuel maps so that a sensible choice can be made. Since we're dealing with hand built cars with no two the same, there's got to be an allowance for the variation:

Back in the day, my car was never particularly happy on a green resistor when decatted, but Clive's Griff was only happy on a green or red resistor. Hence why I made the rotary switches so we could figure out by testing and comparing which "tune" was best. Its' a simple idea, which seems to have been confused with a power upgrade in and of itself in some parts. In short, if the car is happiest on white, then use white. Otherwise there's a choice of one of the others.

I don't altogether hold with the idea that if the green tune was made by Land Rover then it's no good at all. The ECU is calculating fuelling based on mass air flow. If the engine consumes more air, then the ECU selects a different row in the table and it's still by-and-large correctly fuelling while the MAF sensor isn't saturated or it hasn't run off the end of the table. (For example, I know that my Jaguar ECU is tolerant of a significant SC upgrade without needing a remap, simply because the AFR requirements don't change even though the absolute mass of air and fuel change) Don't forget that the standard TVR maps aren't much to write home about in the first place, so remapping is generally a good thing with RV8 based TVRs.

[blitzracing]

The 1992 3.9 Ginetta's ran stock Range Rover non catalyst maps in the first place and ran horribly lean on rolling road sessions. Switching to the TVR 3.9 catalyst tune released no less than 18 BHP extra, hence my caution. I appreciate about the AFM and the load map, but I really cant see a Range Rover fuel map calibrated for around a peak power of around 160 BHP and peak fueling at 5500 rpm will have enough headroom in the map to fuel as far as 6000 RPM worth of airflow and 230 bhp plus for a TVR. I guess the Range Rover maps may have improved as the power outputs went up over the years if people are not loosing power in switching, or possibly TVR did alter both maps for any given engine size, but I really dont know on that one.