Pro cal

[Lieutenant]

Fix the speedo/odo setting so that you get a more accurate reading - I would think so, similar to the ScanGuage product a lot of TJ drivers have.

Fix the engine revs - I don't think so, probably need to look at ratios to fix that

[robbo1959]

Originally Posted by Lieutenant

Fix the speedo/odo setting so that you get a more accurate reading - I would think so, similar to the ScanGuage product a lot of TJ drivers have.

Fix the engine revs - I don't think so, probably need to look at ratios to fix that

I also have a scan gauge 2 fitted...

[tcf]

I have same car, went to 33s, but in 16x8" rim. I got a procal and it changed speedometer to spot on. Made bugger all difference to shifting pattern. Part reason your revs are up is because 100kmh on your speedo is really 107kmh. Therefore working engine harder. Plus obviously working engine harder to move bigger rubber.

[Macca2801]

Are you sure the speeds are correct as TCF stated above? Otherwise the only way the revs could go up is your torque converter is not locking now. The extra load on the engine to push the larger tyres is causing the TC to stay unlocked and hence a higher rev and more fuel consumption.

[SeaComms]

Yep correct. The procal will fix your speedo and odometer, and will therefor give you a correct reading on distance per tank, as they are currently both wrong. The tacho however is reading correctly and does change with tyre size. The only way to get the revs back up is to change diff ratios. As mentioned above though, possible your torque converter is no longer locking up (overdrive)

Basically you have gone from a 30.6 in tyre to a 32.7 in tyre. This will drop your revs to about 1,808 rpm at 100km/hr, down from about 1,930 rpm with the tyres you had on (figures based on calculated tyre diameter for 4 speed auto with 4.1 diffs).

However, I dont know enough about the diesel though to advise what the ideal rev range is.

[Lieutenant]

Originally Posted by robbo1959

I also have a scan gauge 2 fitted...

If he's got a scan gauge fiited, he should be able to use that to correct the speedo and odo. Shouldn't he?

Therefore probably suggesting that the extra $195 isn't worth it.

[SeaComms]

Na, the scan gauge only reads out stuff, it wont change anything. The procal will reprogram the electronic "speedo drive" to correct both the speedometer and the odometer, and will also reprogram the auto trans gear change settings to better handle the larger diameter tyres.

Personally I would say yes, it is worth the money.