How many rotation's in a Mile on 31"

[Pipeliner]

Originally Posted by cmohr

Also, the auto gearbox makes a lot of its calculations on what gear to be in by speed and engine revs, .

I make all my calculations on what gear to be in by speed and engine revs.

[cmohr]

Originally Posted by Pipeliner

I make all my calculations on what gear to be in by speed and engine revs.

yes yes, but, I did say "auto" ..

Still, your ECU makes adjustments to timing and mix.



Yes, I know its a diesel, there are still adjustments to the rail injection made, depending on throttle position vers engine revs vers gear and speed. And if your speedo is reading low by 6% you will record 6% less km travelled so your litres per 100km will be wrong... Unfortunately for you that means it will be an even better result as if the speedo is recording the correct distance, that would mean you would be travelling further every litre.. ( bloody CRD's )

[loric]

Any thoughts on this?


http://www.marks4wd.com/products/tyr...orrection.html

I know it's not as good as the dealer pinion reset (and won't allow the ecu/bcm to calcuate dist to empty etc etc) but it looks interesting.

Or this from jaycar:

http://www.jaycar.com.au/productView...Max=&SUBCATID=
Eric.

[Pipeliner]

Both look as though they will correct the speedo only, so the ECU will still register the wrong speed as input into gearbox control, fuel injection, etc.

[cmohr]

Hmmmmm.. not sure, depends where it is wiring in..

If in the case of the speedo, and it is going between the primary sensor in the rear diff and the ECU, I would say yes, but, if it is between the ECU and the Speedo dial itself....no.

Diff ratios, would have to be changed in the ECU as there is no sensor telling the ECU that info, it is a mathmatical equation in the ECU.

So the little after market box would go between the ECU and the speedo dial only to make the speedo needle point at the right number, but, would not make any difference to the ECU as it would still be using the original setting to make decissions.



Let me say....


THE ONLY REASON I changed my speedo was to correct the data going into my ECU from the larger tyres. I knew that my speedo was out by almost 10kph before I had it changed , but, simply drove at 90km on the dial, which meant I was actually going 100km in the real world, but, the car ran like a piece of poo, had no power, was gutless on the highway, surged and hunted around the gearbox all the time changing up and down or the torque converter would lock up in top gear at 40kph and wouldn't change back down unless I stamped my foot to the floor. Petrol economy was woeful, average 20- 25 lts per 100. After I had the Pinion reset done properly, alll the power came back, gears held properly and only changes now when needed, ( if I'm cuising along in a 70 zone at 70 and I slow down to 60 in a 60 zone, the car drops out of overdrive by itself, I don't touch the accellerator, it just calmly drops out and alls good) fuel economy increase dramatically ( I still get 14-16lts per 100 on average, can get as low as 11 just on the highway), and the speedo read correctly so I just drive to the limit. Easy.. But, once again, I say this is my KJ, your experiece may be different, but, from all reports those that have done it have had the same benifts as me.

Thats about all the shrimp dishes I can think of.....

[cmohr]

OH>>>>>>>.


And if it is only changing the sensor reading from the Rear diff, that could also trigger the anti lock braking system to malfuction as they would be giving a different reading to the ECU, that would also effect the ESP as well one would assume.

Changing the setting in the ECU via the pinion reset alters all data received from all speed sensors.

[loric]

[QUOTE=cmohr;880628]OH>>>>>>>.


And if it is only changing the sensor reading from the Rear diff, that could also trigger the anti lock braking system to malfuction as they would be giving a different reading to the ECU, that would also effect the ESP as well one would assume. QUOTE]

Yeah - you're possibly right. I remember when the wires to my rear diff broke - i lost the odometer sense (but strangely not the speedo sense), the brake light malfunction light would come on and the ABS malfunction light would come on.

If you tweaked the speedo sense i don't think that you'd affect abs directly coz the abs will work on the differential senses from each wheel (on the front) and the diff at the back. It'd prob trip warning lighst all over the place tho.
But it's all academic really coz i don't think one would bother with all of this since the dealer pinion reset is so easy.
(shame it can't be done via the scangauge).

Eric.