3.2 Di-D Fuel economy saving at last. A/T Line Pressure Mod
Posted: Thu Jul 26, 2012 8:57 am
I don't want to jump the gun but I think I finally found something on my pajero to alter in order to save on fuel economy.
I have tried the following methods with no success in saving fuel.
Full length bash plate for improved airflow
Cleaned out intercooler
Blocked EGR
Wastegate spacers to add a bit of boost
Advanced the diesel pump
Full fluid change of autobox, transfer and diffs
Checked rotating parts for binding
Swirly thing in intake removed
Pumped tyres a bit harder
Drive slower
Drive faster
Torque converter LockUp kit (helped a tiny bit)
Cleaned intake manifold
Free flow exhast
Catalytic converter delete
But a few weeks ago I upped the automatic gearbox's line pressure by about 14psi. (2.75 turns Anti Clockwise)

I have now done 426km and the needle sits here.

These miles include a morning's dune work and some light off roading valuating a farm. It usually was at 300km when halfway doing mostly highway work.

I believe the reason for this is that the clutches are pretty old (nearly 300'000km) and may have some excessive slippage that wastes energy and creates heat and wears the clutches even further. The pump may also not put out the pressure required due to age and the previous owner neglected the auto fluid which was brownish. Upping the line pressure makes the clutches engage firmly again. I have noticed since upping the line pressure that the gearchanges are more pronounced when accelerating hard but none of the smoothness has been lost. The factory torque converter lockup occurs easier now as well - I presume due to more power reaching the wheels and not being lost in slippage in the box.
I realise that my box may have seen better days but with 2 flushes in the last year and the line pressure upped a bit now I should get good life out of it. Some tow with it for thousands of miles without issues so I guess it's a tough box. The last time I dropped the sump the magnets in the sump were pretty clean so I'm not too stressed.
I'll try to give more feedback here as time moves on or just note today's date and check my fuelly in a few months time.
I have tried the following methods with no success in saving fuel.
Full length bash plate for improved airflow
Cleaned out intercooler
Blocked EGR
Wastegate spacers to add a bit of boost
Advanced the diesel pump
Full fluid change of autobox, transfer and diffs
Checked rotating parts for binding
Swirly thing in intake removed
Pumped tyres a bit harder
Drive slower
Drive faster
Torque converter LockUp kit (helped a tiny bit)
Cleaned intake manifold
Free flow exhast
Catalytic converter delete
But a few weeks ago I upped the automatic gearbox's line pressure by about 14psi. (2.75 turns Anti Clockwise)

I have now done 426km and the needle sits here.
These miles include a morning's dune work and some light off roading valuating a farm. It usually was at 300km when halfway doing mostly highway work.
I believe the reason for this is that the clutches are pretty old (nearly 300'000km) and may have some excessive slippage that wastes energy and creates heat and wears the clutches even further. The pump may also not put out the pressure required due to age and the previous owner neglected the auto fluid which was brownish. Upping the line pressure makes the clutches engage firmly again. I have noticed since upping the line pressure that the gearchanges are more pronounced when accelerating hard but none of the smoothness has been lost. The factory torque converter lockup occurs easier now as well - I presume due to more power reaching the wheels and not being lost in slippage in the box.
I realise that my box may have seen better days but with 2 flushes in the last year and the line pressure upped a bit now I should get good life out of it. Some tow with it for thousands of miles without issues so I guess it's a tough box. The last time I dropped the sump the magnets in the sump were pretty clean so I'm not too stressed.
I'll try to give more feedback here as time moves on or just note today's date and check my fuelly in a few months time.