Throttle Body Stuck Open (V50)

[Lion Heart]

Hi guys

2008 Volvo V50 2.0 diesel. The throttle body appeard to be stuck in the open position...

It is the single throttle body type with the throttle body at the front centre of the engine.

I pulled the pipe off, noted some oil residue (not burnt, oily) and the valvle fully open. Started the car and got my partner to lightly rev up and down, but the throttle body did not move at all.

There is no carbon build up at all, in fact quite the opposite. Inside it looks very shine and pretty much like new TBH.

Is there a way to test these, or should I just buy another one and pop it on to see if that solves it?

[Yobbo]

Originally Posted by Lion Heart

Hi guys

2008 Volvo V50 2.0 diesel. The throttle body appeard to be stuck in the open position...

It is the single throttle body type with the throttle body at the front centre of the engine.

I pulled the pipe off, noted some oil residue (not burnt, oily) and the valvle fully open. Started the car and got my partner to lightly rev up and down, but the throttle body did not move at all.

There is no carbon build up at all, in fact quite the opposite. Inside it looks very shine and pretty much like new TBH.

Is there a way to test these, or should I just buy another one and pop it on to see if that solves it?

Quite possible that the plastic gears in the actuator have stripped due to the flap getting stuck - common fault and the dealer remedy is to file the edges of it.

I think it might be a case of getting a new one. :/

[Lion Heart]

Originally Posted by Yobbo

Quite possible that the plastic gears in the actuator have stripped due to the flap getting stuck - common fault and the dealer remedy is to file the edges of it.

I think it might be a case of getting a new one. :/

Thanks for the input!

I looked online and they appear to be silly money new? Used ones are around £40, but the condition on most looks far worse than mine which looks almost brand new (literally zero carbon build up, very shiny metal flap etc).

I guess maybe get a cheap one to test. If that does not work then the issue is likely with power to the unit?

I mention this as this issue coincided with me changing the starter motor. NEVER had an issue before, change the starter motor and the next day the engine management light came on, scanned with VIDA and the fault states a common cause is the throttle body stuck open/closed, hence I checked it :-)

I have checked the electrical connections just in case I knocked on, and they appear physcially ok.

It could be coincidence, but seems weird that no issue, change the starter motor, immediate issue?

[Lion Heart]

A quick update on this and need some help...

Removed the throttle body and cleaned it up a bit. The flap is not physically stuck (moves bby hand).

So removed the throttle body position sensor from the end, which is the motor that makes turn open/close...

Looked inside throttle body and saw the gears (cogs, plastic) inside and those are working fine.

So plugged in the throttle body position sensor/motor and revved the car up and down, and this thing is not moving at all, hence it is not moving the flap.

So, put multimeter on the plug from this motor and receiving 5v no problem.

So I think the throttle position sensor is knackered, so I have order a brand new one £39.

HOWEVER, one question on reinstalling... Do I have to reset the position somehow? Concerned I may fit it and it not be in the same position (fully open for me!) and so move incorrectly and snap the plastic internals on the throttle body??? Any advice here much appreciated.

Also, right next to this motor is a cylindrical 'cap' into which a breather pipe fits. What does this do?????

[hansC30]

I'm not a car specialist here, but isn't it normal that when the engine is on, that the valve s always open? If it was shut, the air would be cut off and the engine would stall no? Or am I missing something here? I read that it only closes when turning off the engine in order to stop air from getting in and getting a "cleaner" stop of the engine

[Lion Heart]

Yes, you are correct. I've been doing quite a lot of research.

The throttle body butterfly valve has a very different purpose on a diesel to petrol car.

On petrol it opens and closes as you rev the engine to control the air flow into the engine for the combustion.

On a diesel you want as much air in as possible and so the valve stays always open, but closes when you shut the engine off which helps give it a smoother shut down (anti-bump I think they also call it).

To answer my own questions above, the domed cap with breather pipe is what closes the flap under vacuum pressure. The position sensor on the end is just a sensor, NOT a motor.

My issue it seems is with the vacuum lines in my case!!