I wonder if anyone on this forum attempted to replace the speed sensor located on the side of the transfer box adjacent to the parking brake to repair the high idle issue in a Landrover discovery 2. See the following excerpt from RAVE:

"....Vehicle speed sensor
The vehicle speed sensor is located on the side of the
Transfer box adjacent to the parking brake. The
sensor provides road speed data to the ECM. The
ECM in turn detects vehicle movement from the road
speed input and ensures that idle air control mode is
disengaged. Should the vehicle speed sensor fail in
service the ECM idle air control would become erratic...."

 

Never gone the route. I just removed the idle air control valve and cleaned it with brake cleaner. It was pretty gunky. Idles perfectly now.


i am sure you’ve already tried this

 

Yes, I cleaned the IAC valve well with the expensive throttle cleaning spray fluid came in a spray can but the idle was still high. The engine got a code of PO505.
I replaced with another OEM used and cleaned IAC valve but did not fix it. Code came back PO505
I read many posts all over the internet and other landrover forums and found the followings:

1) reset adaptive value. I erased code with my "Launch" scanner but code came right back like clock work. It appears that IAC code does not truely get deleted with a regular scanner. I think I need to reset adaptive values (?) with OBD link and some android app which I am yet to learn how to do it.

2) I found the excerpt from RAVE from this Landrover forum which talks about the speed sensor on the side of the transfer box etc...See excerpt below. I have not heard from anyone about replacing speed sensor on the side of the transfer box to fix the high and/or eratic idle. Some people tried to reset the adaptive values but the high/eratic idle problem still came back. I need to know if anyone has tried replacing or cleaning the speed sensor on the side of the transfer box to fix the high/eratic idle.

3) i wonder if I need to clean my throttle body again and do a reset of adaptive values on the TPS ( i need to learn how to do this) . I really like to hear from anyone who has tried this

Has anyone here dealt with stubborn a high/eratic idle problem succesfsully? I need to solve this mystery and clear code to get smog check for the car.

FROM RAVE:
"....Vehicle speed sensor
The vehicle speed sensor is located on the side of the
Transfer box adjacent to the parking brake. The
sensor provides road speed data to the ECM. The
ECM in turn detects vehicle movement from the road
speed input and ensures that idle air control mode is
disengaged. Should the vehicle speed sensor fail in
service the ECM idle air control would become erratic...."

 

I had a throttle body that would stick slightly open of the pedal was released in any manner than suddenly, flipping throttle open and close suddenly would calm idle down. Had to replace the TB. Otherwise try disconnecting MAF to troubleshoot.

 

Have you checked the oil separator baffle at the top of the passenger valve cover? If it’s clogged or if has been removed it’ll cause idling issues.

 

I did remove the throttle body and IAC, and cleaned both and put back, but did not help. However, replacing the MAF with another good used OEM MAF did help but the engine now has a consistent engine code P0 505. I tried to erase the engine code P0 505 using a regular scanner but the code kept coming back. I read many old posts on this forum and learned that I really need to reset the adaptive value to truly delete the P0 505. I also understand that software GEMS plus apps to use along with using ODB link "dongle" is no longer available online for people like me and you to use it. I really need to know how other members on this forum are dealing with deleting the P0 505 code using the OBD Link dongle and which software (?) to use online. Disconnecting the battery posts to reset adapative values did not work.

P/s I did replace the oil baffle on top of the passenger valve cover with an upgraded PVC valve on the intake manifold and a straight hose to the passenger valve cover, and learned that it did not help and instead creating more problem with other engine codes. I ended up removing the upgrade PVC on the intake and put all the original components back including a cleaned oil baffle back onto the valve cover. My oil baffle was never a problem.

I can explain the reason why the original Rover oil baffle is a better engineering design than using the upgraded PVC valve on the intake and straight hose on the passenger valve cover, but this has to be another topic to discuss on the forum. Right now , i need to figure out how to delete the engine code P0 505 in order for my D2 truck to pass a smog test. My car would never pass smog with this engine code P0 505 !
Thank you in advance and welcome all inputs from members here on the forum. we had some members who have experienced with similar issue and posted on the forum in the past but unfortunately those members are probably no longer around to give me any feedbacks. That is why I am staring this thread to help those with similar problem currently. Not many of us are still driving the old Disco 2s ! I am trying really hard to keep mine on the road reliably.

 

Sorry man. I am out of ideas, sounds like the speed sensor thing is your best option so far.

 

Where are you located? Suggest you find a local with a good running truck and swap the entire upper intake.

 

Extinct, Do you think i may have a vacuum leak in the upper intake? I think I really need to learn how to do an adaptive reset while preparing for a smoke test. Thanks

 

If it was affecting the idle speed you most likely would have a fault code for lean 02's, they are very sensitive. You can rent the nanocom at my site and use it to do an adaptive reset.