Thread: What happened to your Discovery 2 today?

Worked out why I was getting more and more over boost issues, the boost reference pipe(?) from the metal boost pipe had cracked so the modulator wasn't getting any boost to open the waste gate. It looked fine until I was checking the modulator and knock the hose right off... Oh well, a pretty quick and simple fix.
On another note, I've noticed I get a speed mismatch (or something similar) error on the Nano since fitting the speedo correction unit. Is this normal? it doesn't seem to affect anything, cruise still works, speedo is within 1-2km and the odo seems to be reading correctly as well. Should I worry about this or just ignore it?

cheers

Redd

Originally Posted by Reddirt204

Worked out why I was getting more and more over boost issues, the boost reference pipe(?) from the metal boost pipe had cracked so the modulator wasn't getting any boost to open the waste gate. It looked fine until I was checking the modulator and knock the hose right off... Oh well, a pretty quick and simple fix.
On another note, I've noticed I get a speed mismatch (or something similar) error on the Nano since fitting the speedo correction unit. Is this normal? it doesn't seem to affect anything, cruise still works, speedo is within 1-2km and the odo seems to be reading correctly as well. Should I worry about this or just ignore it?

cheers

Redd

Where did you fit the Speedo adjuster?

Where are you getting the fault show up?

I think I reported some time ago that there can be issues using this unit at the wrong place in the wiring.

The autobox monitors output shaft speed, engine speed, selected gear ratio, TCC state, roadspeed (and numerous other things).

But if there is a speed mismatch you can get issues with gear shifts, cruise control operation, particularly when engaging it.

Other issues could be slip time and speed range corrections..

I'd fit it immediately before the Speedo, but that's just me!

Not only you, James, I've fitted several of them at the speedo to avoid those problems too.

Originally Posted by discorevy

Not only you, James, I've fitted several of them at the speedo to avoid those problems too.

Thanks for the confirmation Craig!

Originally Posted by shack

Where did you fit the Speedo adjuster?

Where are you getting the fault show up?

I think I reported some time ago that there can be issues using this unit at the wrong place in the wiring.

The autobox monitors output shaft speed, engine speed, selected gear ratio, TCC state, roadspeed (and numerous other things).

But if there is a speed mismatch you can get issues with gear shifts, cruise control operation, particularly when engaging it.

Other issues could be slip time and speed range corrections..

I'd fit it immediately before the Speedo, but that's just me!

I followed Slunnies write up, installed in the passenger foot well, coming out of the SLABS(?) unit. I remember now when I picked up the auto from Discorevy he mentioned about fitting at the speedo/dash. I'm not sure if the wire I've interrupted (pink/green trace) feeds the speedo as I thought it was the feed into the SLABS but I had to swap the input/output from the correction unit as getting no reading.

I'm away for another week or so, when I'm back I'll check again exactly what the error code is (I think it's something like 4-24 and 6-24)

Does anyone have a picture/write up of installing behind the dash? it actually sounds a bit better as easier power and earth points.

@Shack, once I get some other things sorted I'll reach out to discuss a bit of a tune etc

Cheers

Redd

Originally Posted by Reddirt204

I followed Slunnies write up, installed in the passenger foot well, coming out of the SLABS(?) unit. I remember now when I picked up the auto from Discorevy he mentioned about fitting at the speedo/dash. I'm not sure if the wire I've interrupted (pink/green trace) feeds the speedo as I thought it was the feed into the SLABS but I had to swap the input/output from the correction unit as getting no reading.

I'm away for another week or so, when I'm back I'll check again exactly what the error code is (I think it's something like 4-24 and 6-24)

Does anyone have a picture/write up of installing behind the dash? it actually sounds a bit better as easier power and earth points.

@Shack, once I get some other things sorted I'll reach out to discuss a bit of a tune etc

Cheers

Redd

Thanks Redd.

What computer on the car did you get the fault from?

Yes, for autos fit the SCU at the SLABS output and it will correct all systems and you shouldnt have any faults.

For manuals, the cars systems monitor shaft speeds etc and if there is a discrepency between what the engine/gearbox expects and the SLABS computers speeds then the cruise control etc wont work, so the SCU needs to be nearer the speedo.

Sorry, the wiring for the SCU re the autobox mentioned above is the opposite to what I was suggesting.

On the manual the ECM uses preset gear ratios and an error multiplier to calculate the current gear.

Speed is reported to the ECM from the SLABS unit (on a TD5 D2), then calculated for validity.

Altering the output enough, directly out of the SLABS can certainly wreck cruise control operation, but not much else.

On the Autobox however another controller is introduced, and it also expects ratios to be within certain ranges.

As pointed out above, this will cause a number of issues with the operation of the auto.

Sometimes they are very noticeable, other times they are not. The TCU however will know and it will mess up a number of things, as the auto itself monitors all speeds and changes shift pressures, shift times and a number of other things to prevent damage to the auto, and to provide smooth operation.

So you may end up with a slipping auto due to adaptive pressure control dropping back too far because it doesn't believe your have any slip, and you won't know. This will wreck the auto.

You may also have the adaptive pressure too high as it believes it is always slipping, and ramps up pressure to avert this. This is also bad for the pump, fuel economy and general wear and tear.

If you fit the SCU immediately before the Speedo, you avert this ever being a problem to begin with.

That's my tip.

Cheers