P38 Idle Problem

I Have A Range Rover P38 4.6 Petrol / Idle Speed Increases Up To 2.5 Thou Could Any Body Help On Solving Problem As Am At End Of Me Tether Cheers

This is a rather tentative idea, but if it does this after starting in the morning it may just be that your battery is not charging as well as it should; possibly its getting on a bit or hates the cold. The engine is trying to charge the battery asap, and thus doing this off its own bat, as it were.

Not that a new battery is a cheap option - i have just forked out £65.00 for one!

My RR used to do this, but a change of battery has cheered it up a lot, and it is behaving a lot better in the mornings.

I have this exact same problem

did a new battery solve it ?


Can anyone else help ?

Big Advice ...
Don't Change The Battery By Yourself If You're Not A Technician ..
Check The Battery Power Before You Go Changing It ... Maybe The Problem Is In Somewhere Else .

Cheers .
Charbel .

whats the big deal with changing a battery on a p38?

woody47 said:

I Have A Range Rover P38 4.6 Petrol / Idle Speed Increases Up To 2.5 Thou Could Any Body Help On Solving Problem As Am At End Of Me Tether Cheers

Click to expand...

Check that there is free play on the throttle cable,if it does not return fully the Ecu will not see a voltage equal to or less than the stored closed throttle voltage.If this is what is happening the Ecu will keep the idle air control valve jacked open to allow it to slow the engine down in a controlled manner - ready to accept loads like PAS and the A/C compressor.In other words it still thinks you have your foot on the gas.The only other thing you can doing is to clean out the idle air control valve,it could be stick ing if its badly gunged up.

Thanks guys

I think it is solved (fingers crossed)

The Idle control valve is a new one so I discounted that.
It occurred to me that the batterry replacement mentioned was a red herring and that in fact in changing the batterry the previous poster had re-set the ECU.
so I disconnected the battery for a few minutes and re-connected it and hey presto the idle went back to normal. I guess some condition while driving had caused some confusion. I have gas and I wonder whether the gas ECU had got upset and then sent a signal that was confusing the main ECU

anyway I have not driven it much since the work but so far so good.

thanks for the tips, I will post again if the problem returns

Nevyn

Oh and to reply to rodent's comment

the big deal with changing the battery on a P38 is that you have to be careful

make sure you do not have the keys in the ignition and I generally leave the door open too.
If you do not then when you re-connect the battery the car is likely to lock itself and initiate a key-code lockout
which if you don't have the keycode can be a real pain
you can oly get the keycode by taking your logbook to a dealership and asking them really nicely to give it to you.

so yes it can be tricky to change the battery on a P38

Nevyn

thanks Nevyn, i have only recently bought a P38 (my first range rover) and i don't have the codes for radio, keys and whatever else.
i was looking to change the oil, filter and fuel filter and the manual i have downloaded says to remove the battery negative lead to do these jobs.
think i had better speak to local LR before disconnecting.

Did i read somewhere else that if you do disconnect battery, you have 17 seconds 'grace' before all the electronic gadgets reset?

I wouldn't count on it
if the security systems detect any "messing" with the electrics it will likely "secure" your vehicle

best to make sure you have the key code before you mess with anything

and be aware that if your battery runs completely flat
(kids leave the interior light on AArrrgh!)
and you get the AA/RAC etc. out to give you a jump the likelyhood is you will have to enter the code

you have to have all the doors and the bonnet shut before it lets you enter the code so this can be a little frustating for the recovery guy because you have to put some charge in, close everything up and then wait (sometimes up to 10 minutes) for the system to tell you to enter the code.

I have my code stamped on a dymo in a secret place in the car so i always have it to hand. don't leave it on a card in the owner manual in your glove box !

The code is a four digit number lets say it is 1234

have all the doors, bonnet, tailgate closed
when the screen on the dash tells you to "enter key code"

first lock the car with the key
then turn the key from centre to right (unlock) the number of times indicated by the first number (in our examle - 1)
then from centre to left (lock) the number of times in the second number (2)
then right for the third (3)
then left for the fourth (4)

then you should be able to unlock with the button

if you get the code wrong then lock the car and start again (you may have to wait for it to allow you to enter the code if you make a mistake.
The time you wait increases each time you make a mistake)

This process can also be found in your handbook

Hope this helps
nevyn

cheers Nevyn. Do you know if the harmon kardon/Alpine hi fi system has a code too?

Hi

I think it does
i have replaced mine with a HDD MP3 unit but i am sure I got the code for the original head unit from the dealership also

(Note for a future discussion)
Changing the stereo head unit on these is frought with problems and not to be done unless absolutely necessarry!!

Nevyn

Right Nevyn This Is The Big Deal !!!