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Premium Member
1995-2002 Range Rover P38A
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626 Posts
Discussion Starter #1
So I've searched quite a bit on this subject in the hopes of finding other owners report similar issues but no luck.
When i start my P38 and drive for the first 20 mins or so each morning it shifts really smoothly up through all the gears effortlessly
at around 2400 rpm.There are no warning lights of any shape make or description on the dash (except the book symbol comes up now
and again on a separate issue as i can hear the blend motors slipping upon AC start up so they need replacing).
Then it starts to change up at 3000 rpm or slightly higher after its heated up a while.
This seems high to me but the worst part is when on the highway and moving up from 3rd into 4th gear i have to hit 78mph (in excess of
4300rpm for it to change up every time.I'm afraid i might be doing damage by driving it like this as this is surely not right?
As i mentioned before when its cold and for the first 20 or so minutes it changes effortlessly up through ALL gears at 2400 revs.

Now i have recently dropped the transmission oil pan (fluid looked red and didn't smell but changed it and the filter anyway).
Replaced fluid with Dex/Merc topping it up until it began to run out the plug hole(was told it equivalent of ATF Dex iii),also replaced serpentine
belt,water pump (surprisingly easy ),thermostat,new oil & oil filter change,air filter etc but this high revs issue had been happening before i changed anything.Could it be a sensor of some sort telling the truck to shift at higher revs or am i looking at something a lot more serious?
Any help or suggestions would be greatly appreciated.
 

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JACK'S GRANDAD
Joined
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9,248 Posts
Test the throttle position sensor Tom.
Specs should be in RAVE etc, but count on 4.8-5volts at wide open throttle.
A bad TPS does some really weird stuff to engines and transmissions....

Martin
 

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Premium Member
1995-2002 Range Rover P38A
Joined
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626 Posts
Discussion Starter #3
Thanks Martin I'll get cracking on that as soon as Sandy blows through.
 

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Registered
1998 Range Rover P38A
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74 Posts
I would certainly look into electrical items first. My transmission was doing some weird stuff for about a month, occasional shifts at strange times in low speed traffic and then occasionally not shifting into fourth gear when it should and staying in third gear on the highway. It was not consistent and did not throw any codes but I knew something was not right. One day it shifted a bit more abruptly in stop and go traffic and the check engine light came on. The code was P0734, incorrect fourth gear ratio. I looked that up here on the forum and it sounded like many owners were in agreement that the MAF sensor was bad. I changed it out for a genuine Bosch MAF (mine is a MY 2000), cleared the code and it's been running like new again. It shifts into fourth gear as it should and other strange shifting is gone.
 

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Premium Member
1995-2002 Range Rover P38A
Joined
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626 Posts
Discussion Starter #5
I was thinking that the MAF could be the issue.I'll check the throttle position sensor today and go from there.How much did the MAF set you back and how easy/difficult was it to replace it?
 

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Premium Member
1995-2002 Range Rover P38A
Joined
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626 Posts
Discussion Starter #7
Well i tested both the TPS and the MAF today and the MAF seems to be working.I put a meter on it and when i revved the engine i got an increase in voltage.
The TPS however I'm not sure about because from what I've read on testing it with the ignition turned to the "on" position I should have been getting zero volts across the center pin,zero across one of the outside pins and then 5 volts or so through the other outside pin.
I did get zero volts across the center pin but one of the outside pins read 6 volts while the other read 5.4 volts?
I connected it back up and turned the engine on and then tested it with the meter again increasing the revs slowly up through the scale while observing the meter read out and it was a steady increase all the way with no sudden jumping of voltage.Don't really know what to think now am kinda back to square one.
 

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Premium Member
1995-2002 Range Rover P38A
Joined
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626 Posts
Discussion Starter #8
Does anyone on here have experience with their rig revving high through the gears like this when using a lower grade petrol/gas?Originally that's what i had thought may be the reason for the high revving every now and again but after running the 93 Octane in it for 1000 miles or so it didn't solve or seem to help the issue in any way.
 
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