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Vacuum "pressure" at idle speed must be near 500 mbar (+/- 50 mbar ) cold or hot no difference .
The best , praticale , position for the vacuum tester is donwn the vacuum plug on the WUR .
When you accelerate , the vacuum pressure go down .
Connect anywhere BELOW the throttle plate - line to brake booster, WUR etc. Most such gauges read inches of Mercury, when you should see 17-21 at idle, less with throttle open, more backed off against the engine. Usually gauge is connected with a fine bore tube, to avoid seeing reading flutters at low revs.
jp 83 Euro S AT 57k
Connect anywhere BELOW the throttle plate - line to brake booster, WUR etc. Most such gauges read inches of Mercury, when you should see 17-21 at idle, less with throttle open, more backed off against the engine. Usually gauge is connected with a fine bore tube, to avoid seeing reading flutters at low revs.
jp 83 Euro S AT 57k
I just want to make sure that the vacuum and fuel pressure for my WUR are within range because I had some starting troubles as well as lack of power during driving
This electro valve can make trouble sometime .
His fonction is to down the WUR's pressure when , only during cranking , at hot start to help to start and can be leak all the time .
When it leaks , the WUR pressure is to low ... The electric command of this one is a thermocontact .
Vacuum "pressure" at idle speed must be near 500 mbar (+/- 50 mbar ) cold or hot no difference .
The best , praticale , position for the vacuum tester is donwn the vacuum plug on the WUR .
When you accelerate , the vacuum pressure go down .
Alan, I did my first test : cold start at temperature of 2°C (35°F)
Vacuum at idle of about 1000rpm is 220 mBar (165 mmHg)
After 2 minutes when engine warms up, it already rises to 260 mBar (195 mmHg)
WHen revving to 2000 rpm the vacuum goes to about 500mBar (375 mmHg)
Is this OK ? (My fuel pressure is still 2.7 Bar (39Psi) after 1 hour not running the car )
The position of the vacuum tester is at a good place .
May be I made a mistake about "no difference with cold and warm vacuum pressure" ...
Because , it's possible with auxiliary air valve open when cold , minimise the vacuum .
Try to see with warm engine , when the AAV is close, after 6 or 7 minutes at 20°C , more at less temperature , if you have the right vacuum .
When the engine is warm , you must find 3,4 to 3,8 bar with WUR pressure and when you disconnect the WUR vacuum , near 0,6 bar less .
2,7 bar of fuel rest pressure after stop engine during 1 hour is very good !
12-13-2018, 05:40 PM
vacuum readings + installation gauge
