Idle Speed

Hi, yesterday the idle on my p48 4.0 96 suddenly went up to 1500rpm. When in D its normal, but as soon as I put it in P or N it goes up - any idea?

punkassmofo said:

Hi, yesterday the idle on my p48 4.0 96 suddenly went up to 1500rpm. When in D its normal, but as soon as I put it in P or N it goes up - any idea?

Click to expand...

Clean your idle control valve.

I'd also check for loose vacuum pipes in case ones dropped off.

My Air filter is bollixed, could it be that?

punkassmofo said:

My Air filter is bollixed, could it be that?

Click to expand...

It won't be helping.

punkassmofo said:

My Air filter is bollixed, could it be that?

Click to expand...

could be filter, but I believe rojbarker is correct, check all the vacuum lines, they have a habit of developing split ends, and replace the filter ya tight bugger.

Right - air filter changed, what and where are the vac pipes I need to look at?

try the tps too.

I've googled vacuum line routing for 4.0 range rover but there's no pictures. Maybe someone on here has a haynes or other manual they can scan the page in for you. In the meantime, they are normally small black rubber or plastic pipes, about the thickness od drinking straws. They will be a multitude of places but all will start off from the intake plenum and throttle body area.

Had similar problem, ended up being the TPS that was faulty.

They can cause more trouble than you think , spent all weekend swapping bits :doh: