What do these pipes under the plenum do?

[THEDAVINATOR]

Hi everyone,

I'm trying to sort general rough running and erratic idle issues on my Chim (following the excellent advice from people on here) with just the timing to check now - it miraculously passed its MOT last week - to say I was chuffed to bits is an understatement so it can't be running "that" badly...I changed the absolutely caked black BP7ES plugs to BPR6ES yesterday and the idle seemed to oscillate a lot between 1000 and 1500, before settling to a steady
900 - I haven't driven it yet though to see if the new plugs have improved things. Something I have noticed is two pipes under the plenum which ain't up to much...



I've noticed that on some cars they have little yellow caps blocking off the pipes. From what I've gleaned on here, these pipes are something to do with heating something in the plenum with coolant. My question is basically are they important, and if so should I block them off or join them together or something? Many thanks...

[phillpot]

Heated plenum for Range Rovers in cold climates.

In normal use the last thing you want is more heat in that area of the engine!

Edited by phillpot on Sunday 6th October 15:34

[lancepar]

Yours are already out of the cooling circuit.
You could reconnect them and add a fraction more coolant to the system..
But if you did you might discover why they are not being used, ie coolant leak.
They are connected on my Griff and will stay that way.

[Loubaruch]

After a body off I noticed them and asked the same question a while back,and received the same helpful answers. if you have the plenum off you can see that they just provide coolant heat to the air into the plenum. It is a sealed chamber so will not affect running at all. Best just ignored no need to blank them off.

[THEDAVINATOR]

Many thanks for your answers peeps. I'll just leave them then and cross them off my list of possible causes of my chim's iffy running...

[mk1fan]

The mounting bolts of the plate could be causing an air leak into the plenum. Note the use of 'could'.

IIRC the rear pair of bolts, those to the left of the pipes, are open to the plenum below the throttle butterfly.

Unfortunately, the plenum needs to come off to check them. You might be able to get to them insitu with a shortened allen key and patience.

If you take the plenum off for another reason then it is worth taking the plate off and plugging the holes with grub screws or shortened bolts (with some threadlock).

[Belle427]

Verify all the basics for rough running such as vacuum leaks, base idle and check tps is within range to name a few.
Afm is also a common culprit but can be difficult to diagnose, check the cleanliness of the connector.
Most of the info you need is here.
http://g33.co.uk/pages/technical-fuel-injection.ht...