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vacuum readings + installation gauge

 
Old 12-14-2018, 07:58 PM
  #16  
GerritD
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Originally Posted by allan29 View Post
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 !
I will first position the vacuum meter permanently and make sure all tubes are tightened so that no vacuum leaks
occur.
Then I will run same test a little bit longer to make sure engine is warm.
I believe vacuum pressure will rise till 500mbar

Je te tiens au courant

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Old 12-15-2018, 06:23 AM
  #17  
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Originally Posted by allan29 View Post
I can't test on my car now because I "rebuid" my fuses panel and many wires , modified my CIS and put new parts on my car ...




Hi Alan, nicely done! I see that you are also a perfectionist in mechanics :-)
Coincidence occur when seeing your last photo : is this the resistance pack for the blower ?
Well I often, yesterday was no exception, get my blower running at full speed randomly.
Yesterday when turning on ignition to do my vacuum test, my blower suddenly went to full speed.
No way to turn it off
Is this related to the resistance pack 928.616.101.00? I suppose my 1980 928S has the same part?
What exactly is the function of this part? I thought it measured a temperature and when too hot, it switches off my blower....but at temperatures
of almost zero degree I find it strange....

Gerrit

remark : I also had my fuse of the blower melted twice : so fuse is still working but plastic holder melted


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Old 12-15-2018, 08:10 AM
  #18  
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Hi Alan,
here some pics pics of my car :



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Old 12-15-2018, 08:12 AM
  #19  
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The blower resistance pack is used , in stages, to control the blower fan speed - lose energy in heat! Is your hot power ok now? My car runs system of 5.1B, hot control 3.1B, and goes very well at any speed, from fully cold. Your vacuum will change with temp because when cold the extra air will let in air to lift the idle so it wont stall, and as it warms will close off the extra air and bring the idle down. Your fuse board looks terrific, I wish mine was as good!
Are there any problems left now?
I had starting problems once, 10-12 minutes after a shutdown. The temp sensor in post#8 (on mine its screwed into the heater water outlet, slightly different as the solenoid is separate) had resistance of 20 Ohm when closed, which was enough to stop solenoid from firing and lowering pressure. I replaced it with a 944 item (different thread) and all was fixed.
My car is a bit later - it appears in the Brian Long book


jp 83 Euro S AT 57k
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Old 12-15-2018, 10:12 AM
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Originally Posted by jpitman2 View Post
The blower resistance pack is used , in stages, to control the blower fan speed - lose energy in heat! Is your hot power ok now? My car runs system of 5.1B, hot control 3.1B, and goes very well at any speed, from fully cold. Your vacuum will change with temp because when cold the extra air will let in air to lift the idle so it wont stall, and as it warms will close off the extra air and bring the idle down. Your fuse board looks terrific, I wish mine was as good!
Are there any problems left now?
I had starting problems once, 10-12 minutes after a shutdown. The temp sensor in post#8 (on mine its screwed into the heater water outlet, slightly different as the solenoid is separate) had resistance of 20 Ohm when closed, which was enough to stop solenoid from firing and lowering pressure. I replaced it with a 944 item (different thread) and all was fixed.
My car is a bit later - it appears in the Brian Long book


jp 83 Euro S AT 57k
wow what a lovely car you have. I like the white interior, you don't often see this and it makes all the difference.
My car now starts fine when cold. I only need to adjust CO since fuel will be a little bit too rich when measuring CO values.
As for the resistance pack, currently I can only blow hot air since my AC is currently not working ( I removed AC pump, radiator and condenser
for overhaul)
What should I do with the resistance pack to solve my blower issue? Can it easily be fixed?

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Old 12-15-2018, 07:34 PM
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Try looking at this thread..
https://rennlist.com/forums/928-foru...full-tilt.html
Also note that if you have 'climate control' - there is a temp sensor in the alternator cooling hose (left front wheelhouse, in front of splash guard), and if this sensor loses connection to control head, moving the temp slide off full cold will go straight to full hot.

The all white leather interior is a bit hard on the eyes on a bright summer day here, and needs regular care , but it does look good.
jp 83 Euro S AT 57k
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Old 12-16-2018, 01:59 PM
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Originally Posted by jpitman2 View Post
Try looking at this thread..
https://rennlist.com/forums/928-foru...full-tilt.html
Also note that if you have 'climate control' - there is a temp sensor in the alternator cooling hose (left front wheelhouse, in front of splash guard), and if this sensor loses connection to control head, moving the temp slide off full cold will go straight to full hot.

The all white leather interior is a bit hard on the eyes on a bright summer day here, and needs regular care , but it does look good.
jp 83 Euro S AT 57k
Very interesting post about resistor pack. I will check this out with my resistor pack.
Problem with my AC is that PO removed everything but luckily put everything in a box. So I have the original parts.
I waited to overhaul my AC till my engine was overhauled. So now that this is fine, I can tackle my AC next year in spring.
Currently it is winter here in Belgium. (0 degree C and a little bit snow last night)
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Old 12-17-2018, 07:56 AM
  #23  
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My permanent gauge setup for vacuum + fuel pressure :


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Old 12-17-2018, 03:49 PM
  #24  
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Permanent fuel pressure gauge installations are often a bad idea.

The gauges don't always survive the heat and vibration under the hood.
If it breaks, you will have a high pressure fuel leak under the hood.

Those often result in fires. Not small ones either.
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Old 12-17-2018, 07:57 PM
  #25  
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Originally Posted by Wisconsin Joe View Post
Permanent fuel pressure gauge installations are often a bad idea.

The gauges don't always survive the heat and vibration under the hood.
If it breaks, you will have a high pressure fuel leak under the hood.

Those often result in fires. Not small ones either.
Joe, thanks for the remark. Due to heat, I chose metal gauges and also placed them near my viscofan blades, so that they will be cooled.
Luckily the weather here in Belgium is not one of high temperatures, except for couple of weeks in summer .

As for vibrations, it did not chose a glycerine filled gauge since vibrations are limited due too position and fixation, but I may consider to
replace them later when vibration issues should occur.

But I will surely check them regularly to make sure no leaks occur. thanks for the advice !
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Old 12-21-2018, 04:17 PM
  #26  
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So today I could take the Porsche for a test drive to check my warm pressure readings.
Vacuum : - 350 mbar (10,3 InHg) at idle
- 500 mbar (14,8 InHg) at 2000 rpm
Fuel : 4.1 bar (59 Psi) at idle

Are these correct readings? I myself find 4,1 bar rather high...
Engine was warm after driving 30 minutes. Outside temperature was 12░C (54░ F)

Last edited by GerritD; 12-21-2018 at 05:42 PM.
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Old 12-21-2018, 04:22 PM
  #27  
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Here are the pics



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Old 12-21-2018, 06:39 PM
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Mine runs VERY well at system of 5.1B, hot control 3.1B, but unsure of vacuum readings. Mine has two vacuum hoses connected - top, and base side.
jp 83 Euro S AT 57k
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Old 12-21-2018, 06:50 PM
  #29  
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Originally Posted by jpitman2 View Post
Mine runs VERY well at system of 5.1B, hot control 3.1B, but unsure of vacuum readings. Mine has two vacuum hoses connected - top, and base side.
jp 83 Euro S AT 57k
Any idea what your cold control pressure is? Mine is 0,8bar with vacuum connected and engine started.
normally the hose at the base is vacuum, and the one at the top is atmosphere pressure.
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Old 12-21-2018, 09:38 PM
  #30  
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Not really, never looked at it much, as long as it always starts from cold - <10C here in Oz, <20C in Saudi. Best guess is around 1B.
jp 83 Euro S AT 57k
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