DaveW

Member

• Mar 29, 2014

• #1

Please help!!

My range rover classic with a 3.9 efi idles around 750rpm when start up, cold and when a gear is selected (auto box). Once the engine get to temperature it gradually goes up to 1100rpm. The things I've done so far:

Checked all vacuum pipes (three times!!)
Given the stepper motor a good lubing (tried another and the idle went straight up to 1800rpm!!)
Checked fuses on main board
Made sure accelerator cable is not over tight
Checked seal on oil cap and dip stick

Does anyone have any other ideas?

Thanks

Dave

 

classic kev

Well-Known Member

• Mar 29, 2014

• #2

Check throttle potentiometer for base voltage, then check scaling.

Clean and check operation and adjustment of throttle linkage.

 

DaveW

Member

• Mar 29, 2014

• #3

Thanks I'll give them a try!!

 

zen

Well-Known Member

Events Planner

• Mar 29, 2014

• #4

and check coolent ecu sensor

 

DaveW

Member

• Mar 30, 2014

• #5

Thanks! that's one thing I've not done.

On another note I thought I would go over the vacuum and other pipes again and thought I'd do a little test, whilst the engine was idling (also after making sure the throttle valve/flap closes fully) I pulled the pipe that leads from the inlet manifold into the stepper motor and bunged both ends assuming that the revs should severely drop due to a lack of air but it didn't at all. This makes me thing that the engine is getting air from another source, e.g. an air leak. Does that make sense?!!

Thanks again for the tips!!

 

jamesmartin

Well-Known Member

• Mar 30, 2014

• #6

DaveW said:

Thanks! that's one thing I've not done.

On another note I thought I would go over the vacuum and other pipes again and thought I'd do a little test, whilst the engine was idling (also after making sure the throttle valve/flap closes fully) I pulled the pipe that leads from the inlet manifold into the stepper motor and bunged both ends assuming that the revs should severely drop due to a lack of air but it didn't at all. This makes me thing that the engine is getting air from another source, e.g. an air leak. Does that make sense?!!

Thanks again for the tips!!

Click to expand...

very sound reasoning ,inlet manifold bolts often come loose amongst other issues

 

DaveW

Member

• Apr 11, 2014

• #7

Hi guys,

Quick update, I have now replaced the coolant temp sensor, the MAF meter, checked all bolts and seals to the inlet manifold, cleaned the stepper motor, checked the accelerator cable and throttle linkage, all vacuum pipes several times over and still when the engine warms up it the idle speeds gradually creeps up to between 1050 and 1100 rpm.

I'm running out of ideas so any other thoughts would be very much appreciated!! The only other sensor/ component I can think of looking would be the road speed sensor but I have a hunch that's not the problem. I guess the two other options are: 1 - the MAF base idle speed need looking at, or 2- run a diagnostic check ad the ecu?

Cheers

Dave

 

classic kev

Well-Known Member

• Apr 11, 2014

• #8

Did you check throttle pot?

Check ignition timing, check base idle.

 

S

smudge67999

Active Member

• Apr 13, 2014

• #9

hi have you done the base idle adjustment. also if you change the steppermotor you have to reprogramm it back. i did this with mine yesterday.my idle was high so i did base idle when you disconnect stepper motor clamp off the link pipe from the throttle body to the back of stepper motor .once you done that you then adjustthe allen key adjuster in the throttle houseing. adjust this down to about 550rpm then undo the clamp connect stepper motor plug and bingo.mine now ticks over on about 650/700 rpm .look in the rave it tells you how to do all this

 

DaveW

Member

• May 6, 2014

• #10

Hi Guys,

Just to let you all know, firstly thanks very much for all of your suggestions, the problem in the end was the oil breather pipe didn't have a restrictor in it so it was sucking too much air in from the oily bits!!

It's now on a proper idle setting so I'm happy!! Once again thanks for the help and guidance

Cheers

Dave