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Discussion Starter #1
2003 BMW M62 Range Rover.

When the engine hasn't warmed up and the colder it is, the more the symptoms show up.

Rough idle, almost wants to stall.
If you press on gas, it sometimes will stall or sometimes will rev up.
If you put it in gear, the load will cause it to stall somwtimes.
Sometimes it backfires in the exhaust (Or atleast I think it is, making bangs in the exhaust)

Once engine warms up, all symptoms goes away.
When it's cold and you rev it up to 2100 rpm, symptoms also goes away.



Any thoughts of where i should start to look?
 

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2002-2005 Range Rover MkIII / L322
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I'm away from my RAVE, so can't be precise, but this sure sounds like a temp sensor issue. Not giving accurate temp to ECU. It's not compensating for the cold. That's why it settles down after warming up a bit.

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Would that be an engine oil temperature sensor or coolant temperature sensor? If it is an oil/coolant temperature sensor would you have a high temperature warning alarm? For coolant the gauge would move to the red right? , not sure what happens with engine oil temp sensor failures...
 

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2002-2005 Range Rover MkIII / L322
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Check the Mass Air Flow Sensor. I have a spare one somewhere in my stash that I keep just to trouble shoot things like this. Check the idle air control valve flap too to make sure it sits slightly at an angle and not completely closed. That's how I would approach the issue.
 

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also quickly clean your TB... it sounds like something else might be going on, but this would cause similar cold start issues.
 

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The MAF also has the intake air temp sensor, so cleaning could resolve. Earlier, I was referring to the engine coolant temperature sensor located topside front just below and right of the air duct. Definitely seems temp related.

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Would that be an engine oil temperature sensor or coolant temperature sensor? If it is an oil/coolant temperature sensor would you have a high temperature warning alarm? For coolant the gauge would move to the red right? , not sure what happens with engine oil temp sensor failures...
It would be the coolant temp sensor.. and no body said anything about a sensor failure just that it is not registering fast enough. No you would not have a high temp alarm because your rig is not overheating. Could be as simple as your coolant temp sensor has corrosion at the connector.

Brad has the most likely cause. Being 16+ years old it most likely never had the throttle body cleaned. As carbon builds up where the butterfly rests it fouls up the TPS
 

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Discussion Starter #8
What is the best way to diagonse which sensor is faulty?
 

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What is the best way to diagonse which sensor is faulty?
If it's not throwing a code plug it into a diagnostic on life stream and see what value makes no sense. Tho... you should really take a look at your TB, as rrtoadhall said junk will accumulate around the blade. The car will be loopy at idle, stall randomly but smooth out once warm or loaded up.
 

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Agree. Why not start by getting a can of throttle body cleaner and cleaning that? It's relatively easy, fast, and could be a quick win.

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Agree. Why not start by getting a can of throttle body cleaner and cleaning that? It's relatively easy, fast, and could be a quick win.

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Mine was so horribly fouled at 100,000 miles I had to remove the thing. Took carb cleaner and a wire brush on a dremel to restore it fully. Trashed was caked on there really thick.
 

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I had the same It was thr Vanos system. Clean HUBs and solonoids and reset cams .While open replace guides and chain and tentioners if engine done more than 160K Miles
 

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+1 on the throttle body. Cold mornings were the worst, I had to feather the accelerator for a few seconds and it never properly idled above 1000 rpms at startup. No faults either. I exposed the throttle body, cleaned the black build-up with a toohbrush and rags and it has never run better in the 2 years I have owned the truck. Immediate fix and self gratification too.
 
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