Thread: D4 surge while towing uphill

If its a 3.0 then perhaps check that the inlet isolation valve's butterfly shaft is not having its movement restricted by grit between its shaft and housing. The valve is located behind the bottom right of the radiator where it can get splashed from puddles. Mine got to the state of causing faults and restricted performance/limp-home mode. The shaft area only needs a cleanup if it is the cause.



The vacuum chamber operates the butterfly with the linkages out of sight on the other side. Dealers use a test procedure involving temporary removal of the vacuum tube from its other end on top of the motor to check if its working.

Thanks Graeme
Will check it out, but wouldn't that cause it to surge all the time. Mine only does it with a heavy load towing and with a slight increase to the throttle when going up a hill.

Cheers

How many km on the D4? Sounds to me like symptoms of an automatic gearbox needing ATF changed.

Following on from Jonesy's post, is the surging caused by the engine changing revs / power output, which what it sounded like in your initial post, or could it be some sort of slippage in the transmission? Or is the transmission changing gears to cause the surge?

What sort of revs, speed etc is it happening at?

Also, what happens if you give it more accellerator pedal, rather than just a slight increase?

I assume from your post re the throttle body that Barbagallos couldn't work out what was going on?

Bob

Just a thought from left field, could this be the trailer stability assist causing this?

Originally Posted by rifi1

Thanks Graeme
Will check it out, but wouldn't that cause it to surge all the time. Mine only does it with a heavy load towing and with a slight increase to the throttle when going up a hill.

Mine started with the sensation of a bit of a sticky throttle when asking the engine to do some work low in the rev range on light throttle. No fault codes were registered with only the sticky movements until the butterfly spindle eventually got stuck fast which then triggerred MAF, MAP and turbo airflow faults.

Originally Posted by jonesy63

How many km on the D4? Sounds to me like symptoms of an automatic gearbox needing ATF changed.

Just done 11000kms

Originally Posted by BobD

Following on from Jonesy's post, is the surging caused by the engine changing revs / power output, which what it sounded like in your initial post, or could it be some sort of slippage in the transmission? Or is the transmission changing gears to cause the surge?

What sort of revs, speed etc is it happening at?

Also, what happens if you give it more accellerator pedal, rather than just a slight increase?

I assume from your post re the throttle body that Barbagallos couldn't work out what was going on?

Bob

It is a slight change in revs when it starts , usually only doing about 1200rpm and if throttled harder it gets worse. I can hold it in gear manually and it still surges.