randomly increasing revs or when braking hard

[dvkpajero]

anyone with diesel turbo knowledge I need your input

Iv got a 4m40t paj 2.8dt after a day playing in the mud my power steering pump had died which was ok was tired when i brought it so just replaced it.
But over the next few days i noticed every time i was hard on the brakes the revs jump to 2k and stay there for awhile then drop to normal, also happens when driving thru town now and then you feel the truck try speed up and when you push the clutch in the revs stay at 2k until you get on the brakes for abit or drive it off then it goes back to normal. When the revs lift i can leave it in gear and itll just keep driving till i do something then it drops.

Have put another vacuum pump in the truck made no difference, have checked for vacuum leaks carnt find any, throttle cable moves freely and so does the throttle on the pump, bleed the brakes twice no change, checked for loose plugs hose all seem good. Only done 4000ks since buying the truck but motor has been mint on or off road till now only thing done motor wise is a single mass flywheel and new clutch.
Gas pedal doesn't move when the revs jump can lift foot off and it returns to fully out revs stay at 2k have tried pulling it up no difference.

Anyone had this before or have any ideas? have talked to couple mechanics but they just said check for sticky cable or air leaks\

Cheers
Brian

[diogenese]

Is there any free play in the throttle cable when it's at idle? It could be the engine moving and pulling on the cable. Has the cable been routed differently when you swapped the ps pump?
I have also had the whole pedal box come adrift on our Paj but only under severe abuse!

[dvkpajero]

Yep theres abit of free play in the cable didnt touch the cable while swapping pumps as it not in.the way. Problem started after ps pump died but before swapping to the new one had to drive it for a day while the new pump turned u. Had the problem once maby twice before swapping p/s now its become a common thing can make it do it on que with braking hard.
wouldnt say i was abusing it haha but was deffintly getting work out.

[dvk-kp]

wouldn't say i was abusing it haha but was deffintly getting work out.

Maybe you should have been abusing it! Haha

[Cameron]

truck got ABS? my old v6 had some whack issue i could never find that caused the ABS pump to run sometimes, and increase the engine revs at the same time. felt whack through the brake pedal too.
If it's ABS, unplug the two abs plugs on top of the abs pump and go for a burn and see if that stops it

[dvkpajero]

yeah it has abs i want to say its something with the abs but no bugger all about abs and the fact it does it just driving along not using the brakes makes me wonder.
when the pedal goes hard it does feel weird to push on kind of a crunching feeling like it has air in it. Will try unpluging it tonight and see what happens.

Haha yeah least then itd have an excuse for breaking on me,ill make up for it next outing if i ever find the problem haha

[Cameron]

yeah man exactly the same problem as I had.
When I was trying to sort it, I replace G sensor, checked wheel sensors and changed the ABS ECU and everything. Only thing it could've been was the pump (you're meant to clamp the brake hoses and crack a bleeder before you push pistons back on the calipers when doing brake pads or it ##### the pumps) so i just ran most of the time with it unplugged.
I'll try find my spare g sensor, and ecu next time i'm in the shed. i had a big flood go through a few montsh back though so it might have been turfed out.

pedal feel is exactly what I experienced!

[dvkpajero]

And cameron wins haha you nailed it unplugged the abs plugs and truck runs flawless now thanks heaps. Will just leave it unplugged till i.can find a new one. Mate had a v6 auto with abs but it all looks completly different so will keep hunting

[Cameron]

yeah man I never got to the bottom of it but I changed/checked everything but the pump itself so surely it's that hah.

I ran mine unplugged for offroad coz I hate abs on slippery surfaces so meh.