PDA

View Full Version : vacuum at idle


arjunior45
09-05-09, 21:17
Which is your car's vacuum at idle?
-670 mmHg {- 0,892 bar} or -550 mmHg {- 0,733 bar}? or maybe something else?

Nick
wrinx
09-05-09, 23:15
From memory it's about 0.7b but will check...probably Monday now before I drive it again.

wrinx
arjunior45
10-05-09, 10:45
as long as you do not have any air leak, your reading will be my guide.
Thanks Wrinx.

Nick
wrinx
10-05-09, 20:38
Ok, took the car out, looks like it's 0.5 at idle and 0.7 on over-run.

Hopefully someone else can add their readings to be sure.

wrinx
arjunior45
11-05-09, 08:21
0.7 on over-run.
wrinx

what's this 'over-run'?

Yes, having other readings might be helpful to.

Thanks wrinx.
wrinx
11-05-09, 10:47
Lifting off the accelerator from speed.

wrinx
arjunior45
11-05-09, 12:43
Lifting off the accelerator from speed.

wrinx

ok, thanks

Nick
arjunior45
12-05-09, 09:54
Ok, took the car out, looks like it's 0.5 at idle and 0.7 on over-run.

Hopefully someone else can add their readings to be sure.

wrinx

this 0,5bar is +0,5bar or -0,5bar. I believe it should be -0,5 bar, right?

Well, I measure my vacuum this morning, with a gauge going from - 760 mmHg {- 1,012928 bar} up to 0 mmHg {0 bar} attached to the throttle body where goes the tube for the EGR valve. And guess what;
I have 0 bar {0 mmHg} at idle. I hate that!!!
Is it possible to have this vacuum {0 bar} or even positive pressure at idle {did not measure any as my vacuum meter goes up to 0 bar} if something is wrong or with wrong connection {ps pierburg valve} or if blow-off valve is gone?

Nick
Juan AR155Q4
12-05-09, 12:28
Nick,
You should measure with the gauge connected somewhere between throttle body and cylinder head.
If you?re reading 0 mmHg is becaues you?re measuring between the throttle body and turbo.
arjunior45
12-05-09, 14:43
I used this 'red marked' tube in the first picture, which according to the manual is the 'vacuum intake for the thermovalve {placed on the thermostat} of the EGR solenoid valve'. As a 'vacuum intake' I thought it should indicate the vacuum, but I might be wrong. Am I?

The day after tomorrow I'll try some other hose, maybe the 'vacuum intake for the servobrake' right after the throttle body {see second 'picture'}. Do you think it's ok with that hose?

Or do you think it will be better to use the tube for the APS?
AlfaJack
12-05-09, 14:56
I would use one of the small bore hoses to the mid to left of the intake.
arjunior45
12-05-09, 16:20
these points are much better, thank you.
I think I'll use the hole from the 'oil vapour delivery hose' which does not interfere with the ecu signals at all. I can do this tomorrow. Hope to get a different reading.
wrinx
12-05-09, 18:11
this 0,5bar is +0,5bar or -0,5bar. I believe it should be -0,5 bar, right?


Sorry, I should have been more accurate, yes it's -0.5.

wrinx
Ditlev
12-05-09, 20:16
I read around -0.5 on idle and -0.7 bar in over-run.. :)
arjunior45
16-05-09, 09:55
thanks guys.
I still have 0 bar at idle and already found an air leak. It was from the blocked hole of th egr valve vacuum intake. Fixed it but still need to check all the other tubes. I'll probably mount the blow-off valve too, I've bought a year ago, and hope to finally fix the vacuum at idle.
arjunior45
17-05-09, 06:57
fixed the air leak yesterday evening and I have - 0,5 bar at idle, measuring vacuun from the 'fuel vapour recovery hose', as indicated by AlfaJack.
And Juan AR155Q4 was right too. I still 'read' 0 bar from the 'vacuum intake for the thermovalve {placed on the thermostat} of the EGR solenoid valve'!!!

Tomorrow I'll replace the 'blow-off valve' and if something change I'll post it here.