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Discussion Starter · #1 ·
1999 4.0 Gems ~ code reader can't read! Having some running issues, took to my mechanic, he says when he plugs in the diagnostic machine, it shows nothing. And it's not his machine that ain't working. Second problem: engine stutters when running. Symptoms:
  • when cold, idle goes up to 1800
  • when cold, driving, press lightly on accelerator and engine cuts out completely for about a second, then with more gas pedal, it runs fine. Still has "cut out" problem when accelerator pressed lightly.
  • when warmed up, idle eventually comes down to normal (around 900 rpm). Engine still cuts on but for much shorter duration under acceleration.
Today I'm going to read up about the Throttle Position Sensor. Any other suggestions of where to look for this problem? Or ideas why the diagnostic machine cannot connect to the car's system.
Kevin in Minneapolis. Thanks much!
 

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what code reader was he using? you need to find someone with a p38 compatible reader, Did anything get fixed or cleaned prior to this? eg MAF If so you may need to reset adaptive settings, in the engine ECU before proceeding
 

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Discussion Starter · #3 ·
what code reader was he using? you need to find someone with a p38 compatible reader, Did anything get fixed or cleaned prior to this? eg MAF If so you may need to reset adaptive settings, in the engine ECU before proceeding

I did just put in a new MAF. How do I reset adaptive settings? Never heard of that...
 

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Water in the back of the OBD connector causes corrosion so no connection. Clean the idle air valve as it has two functions. It controls the idle speed and it also opens to raise the revs on very small throttle openings.
 

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Discussion Starter · #7 ·
Can you please direct me to where the OBD connector is found? Thanks!

Water in the back of the OBD connector causes corrosion so no connection. Clean the idle air valve as it has two functions. It controls the idle speed and it also opens to raise the revs on very small throttle openings.
 

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1995-2002 Range Rover P38A
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Can you please direct me to where the OBD connector is found? Thanks!

Water in the back of the OBD connector causes corrosion so no connection. Clean the idle air valve as it has two functions. It controls the idle speed and it also opens to raise the revs on very small throttle openings.
Connector is on the passenger side, near the passengers left foot near the center console.
 

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Discussion Starter · #9 ·
Duh! Of course the OBD connector location - I wasn't thinking. Will check that. Today I cleaned (with sandpaper) every single fuse tab, plus all the relays. Hoping I can solve this without having to spend $$$. We do have a local landrover place - Expedition Autos - so if nothing else, I will take it to them next week and see if they can use their LandRover diagnostic machine to read.

Any directions on how to find the Idle Air Valve? Or a picture of one? Thanks for your help so far.
 

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Discussion Starter · #11 ·
I'm now suspecting the Throttle Position Sensor - held in tight with two T25 bolts. Got one loose, but only just, still very hard to unscrew all the way, but of course the other one - I stripped it! So, if I want to go further, will have to drill it out, and find a replacement screw bolt. If I do that, is it likely I'd find a jammed plunger or something?
 

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Discussion Starter · #12 ·
Went to local Rover repair place - Expedition Auto - they diagnosed it fine and said to get a new TPS - I ordered it from BPUtah, will advise once it arrives. They said to come back when installed and he can "program" it. Thanks for all the advice! Kevin / Minneapolis
 

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Once you've changed it, the adaptive settings will need to be reset, so that is what he means by programming it. The ECM stores the voltage from the TPS at idle and after changing it, this voltage will almost certainly be different. If the stored voltage is lower than the new voltage, the idle speed will be high, if it is higher then you will have a hesitation when you open the throttle so it does need to be right.

It might be worth driving the car there and putting the new one in at their place. Trying to drive a car with an automatic gearbox and an idle speed of 2,000 rpm isn't that much fun.
 

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As you’ve replaced the obd socket, it sounds like possible water ingress at some point, it’s worth pulling both footwell kick panelsand soldering the wires, rather than leaving in the joints that are prone to corrosion
 
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