Anyone know what the sensor inside the throttle body is and what it does
I'm trying to sort a boost problem and would like to be able to rule this component out.
Thanks in advance for any info.

Last edited by gasman on 21st Aug 2015 3:44 pm. Edited 1 time in total

Air Charge Temperature:
https://www.lrdirect.com/LR008852-Sensor-Air-Charge-Temperatur

If it's a boost problem, see that just above the throttle body, almost on the same location, is the MAP sensor.

Thanks Atlas.
That rules out that component.
Thanks also to Alex
I have already changed the map sensor. I have also checked most of the hoses and connections. I am going to take the bumper off to check the last two intercooler connections.
Any other suggestions would be most welcome.

A common issue related to the boost pressure is the cracking of the hose that connects the throttle body to the inlet manifold. I've already had this issue and I'll replace all the hoses with these:
http://www.dphsiliconehose.co.uk/index.php...egory_id=0

But if a hose or the intercooler is cracked it should be easily identified after the oil condensed from oil vapors spilled out of this crack.

Also temperature and boost pressure sensors can be clogged with a mix of ash (due to EGR) and oil vapors. Also it won't hurt if you can clean the MAF sensor located near the air filter. For cleaning isopropyl alcohol is OK but you can use sprays dedicated for this.

Thanks Atlas.
I've already changed the MAP and MAF sensors. I've fitted a restrictor to the egr where it connects to the throttle body and cleaned the throttle body. All the hoses have been chacked apart from the large one from the intercooler leading to the plastic adaptor near the throttle body, as I couldn't get to the connection. I also need to check the intercooler itself for any damage or cracks as you have mentioned. If the weather is better tomorrow I'll see if I can get the bumper off and have a look.
The silicon hoses you have used look the business. I could be looking at the same upgrade.
Forgot to mention the car had its MOT a couple of days ago and the emissions were perfect. In fact it got a 'fast pass' on the emissions as it only required one cycle to reach the target.

Up date.
Today took off the front bumper assembly to reach the intercooler.
I have now checked all the hoses from the turbo to the throttle body, no cracks or splits. Took off the intercooler connected the two hoses back up and immersed it in water to see if there was any holes in that, again OK.

My issue with the car is only between 2000 and 3000 rpm. This is when the boost drops and I get the p0299 under boost error message.
Could this be down to the turbo control unit on the side of the turbo ?
I'm now running out of idears.

Can you log the boost pressure?
If, during acceleration, it reaches a max of about 2.5 bars, then it's not a boost problem. The turbo can generate the required pressure and the air path can hold it and the problem should be looked elsewhere.

Alex thanks for the reply.
I do not have anything to check the boost pressure. I don't think there is a mechanical issue with the turbo itself because if you drive it hard the revs rise very quickly and the excelleration is excellent.Once you reach cruising speed its fine. The problem arises once you try and accelerate from there. Between 2000 and 3000rpm the engine appears to hunt for air. The car slows and jolts as it tries to find the boost again, its a this point it will usually go into limp mode.
If however, you shift down as you excellerate the car will generally skip past the flat spot. Although this is not a pleasant way to drive and I suspect will damage the car.
As I have already replaced the MAf and MAP sensors and the crank angle sensor I was wondering if it could be a problem with the turbos electrical actuator, possibly sticking at some point.
Sorry but just clutching at straw's now.
Any thought's would be appreciated.

When you've blanked the EGR have you cleaned the inlet manifold ? Maybe it is worth to check and remove the swirl flaps, and if you'll remove the inlet manifold is also a good idea to replace the glow plugs, even if they are OK, and all the gaskets.

Could be also a fueling problem or a problem with the crankshaft sensor.

For diagnostic purpose buy one of this or find a garage able to trace the issue.

Last edited by atlas on 29th Jun 2015 8:09 am. Edited 1 time in total

Sound to me like your Egr Valve is sticking or the Turbo Vanes are sticking, Try using some Egr cleaner spray that you spray in the air intake as this removes all the gum and varnish deposits that causes the egr valve to stick this will also clean your turbo charger.
Don't spray too much at a time 3 second bursts max or you will have a run away diesel engine!.

Wynn's Diesel EGR 3 Air Intake System Cleaner 200ml

Thanks for the reply Atlas
I have not completely blanked the egr, the plate I purchased has a small hole in it so as not to throw up a fault code. This is fitted at the flange just before the throttle body.
I have changed the crank shaft position sensor and fitted a new fuel filter.
I think taking the inlet manifold off is a bit beyond me at the moment.
Thanks for the tip for the diagnostic tool though, I'll have to get one of them as mine is a cheap generic one.

Thanks also to Turboextreme.
That stuff sounds good. Won't do any harm to try that as well.

Its all good information.
Thanks Guy's Now at the point when I learn something new something old is lost out the other side !
Now retired so it doesn't matter anymore.
Freelander now gone.

On my car, a 2007 model, I have the EGR pipe blocked and everything is fine, no error codes and the car is more responsive at lower RPMs. Models built before 2010 shouldn't throw errors if the EGR pipe is blocked. Maybe that restrictor is the real cause for this issue.

Hi Atlas
I fitted the blanking plate after the issue started.
 Now at the point when I learn something new something old is lost out the other side !
Now retired so it doesn't matter anymore.
Freelander now gone.

I've seen a car with symptoms like yours and I couldn't believe what was the real reason....
On the return pipes from injectors, there is a pressure valve that will help keep a constant pressure of 10 bars on the return line, pressure needed for proper functioning of injectors. That valve was defective.
As soon as it was replaced - it comes together with the return lines -, all returned to normal.
Doesn't hurt to verify it...
And yes, strange thing, the ECU used to throw the P0299 error code, a low boost code...