P38 Gearbox Remap

Spongo · Post by **Spongo** » Wed Jul 22, 2015 11:56 am

So now I finally have the beasty running again does anyone know if its possible to remap the gearbox ECU on a Range Rover P38?, I know that Overfinch (allegedly) used to do it but there is no info around about what or how they did.

Reason I ask is that its a bit clunky going into top gear, it appears as it changes up the torque converter lock up does not release between 3rd and 4th initially causing a bit of a jolt through the driveline till it releases.

To be fair its always been a tad clunky but if I keep in position 3 then all is pretty well OK but when I use position D then it gets a bit clunky in the higher gears especialliy 4th....

And of course its running an MS2 so the ignition retard on gear change won't be enabled could that be causing some of the issue?

Any ideas?

DaveEFI · Post by **DaveEFI** » Wed Jul 22, 2015 12:33 pm

There is, of course, the 'MegaSquirt' auto transmission controller which talks to your MS via the CAN bus. But dunno anything about it.

Spongo · Post by **Spongo** » Wed Jul 22, 2015 1:27 pm

Yes trouble is I would have a christmas tree of warning lights on the dash if i disconnected the P38 controller and used a different one.

Was thinking of using the "flat shift" option on the MS and see if I can use the retard function from the current gearbox ECU to control it, that may help. The clunking is at low throttle though so not sure how much it would help.

unstable load · Post by **unstable load** » Wed Jul 22, 2015 4:09 pm

Contact Adrian at this address... support@blackbox-solutions.com
They manufacture the Nanocom OBD reader for Land Rovers and they can program the appropriate ECU's, so if the gearbox is able to be programmed he will know.

ChrisJC · Post by **ChrisJC** » Wed Jul 22, 2015 6:09 pm

Never heard of anybody doing that.

Have you compared it to a standard P38 to see if that keeps the torque converter lockup in when changing gear?, I'd be surprised if it did. I'll see if I can tell tomorrow when I run mine to work.

Chris.

Spongo · Post by **Spongo** » Wed Jul 22, 2015 9:49 pm

Cheers Chris much appreciated and I will ask those guys at Black box as well

Spongo · Post by **Spongo** » Thu Jul 23, 2015 10:15 am

Ok Blackbox state that a pre 99 GEMS based system cannot have the gearbox ECU re-programmed, makes you wonder what Overfinch did when it was converted?

He did say that the ECU may be at fault so as they are relatively cheap to buy a used one I might do that to see if it helps.

unstable load · Post by **unstable load** » Thu Jul 23, 2015 1:25 pm

They probably fiddled with the springs in the valves to get what they wanted from the box.

DaveEFI · Post by **DaveEFI** » Thu Jul 23, 2015 2:07 pm

Spongo wrote:Ok Blackbox state that a pre 99 GEMS based system cannot have the gearbox ECU re-programmed, makes you wonder what Overfinch did when it was converted?

He did say that the ECU may be at fault so as they are relatively cheap to buy a used one I might do that to see if it helps.

Thing is these boxes are a mixture of hydraulic and electronic control. You'd need an expert on that box to diagnose what is causing the symptoms you mention. In other words, it may not be a software problem.

ChrisJC · Post by **ChrisJC** » Thu Jul 23, 2015 8:46 pm

I couldn't be exactly sure what my box does, but it felt very much like it only used the torque converter lockup in 4th. Certainly it wasn't in when in 3rd, but seemed to go into 4th and lockup at the same time. The changes are so smooth though that it's hard to tell!
I couldn't get it to use lockup in 3rd.
Chris.

Spongo · Post by **Spongo** » Fri Jul 24, 2015 8:43 am

Dave

Yes its difficult to tell what might have been done, one thing for now I can just amend the driving style to suit the issues I have, think I may have a chat with the guys at Ashcroft as I believe they did the gearboxes for Overfinch.

Chris

Thanks for that, I guess its a testament to how smooth the P38 is that its difficult to tell.

One day maybe I will be happy with it and there will be nothing to fix

DaveEFI · Post by **DaveEFI** » Fri Jul 24, 2015 11:18 am

I had an early BMW E34 525 24 valve - IIRC the first car with the 5HP box. It was very high miles so the box perhaps not as smooth as it might have been. And you could clearly tell when the TC lock came in - it was almost like a 6th gear.

So I'd be surprised if an earlier box locked up in anything other than top. Although I believe it is more common these days. But I'd still expect it to unlock on a gear change - the TC will smooth that out.

Spongo · Post by **Spongo** » Fri Jul 24, 2015 1:15 pm

Well with mine if i put in in P3 and drive you can definatly feel the TC locking up, when its in D it feels as if when it changes from 3rd to 4th that the TC is locked mementarily then released and then re engaged giving the jolt through the drivetrain.

To be honest if I use P3 around town then its OK ish and given that its a 6.3L SBC engine its not going to make a huge difference on economy

Thinks it going to have to be one of those things I live with till I can find a guru