vacuum readings + installation gauge
12-14-2018, 07:58 PM
#16
Rennlist Member
Thread Starter
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 !
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 !
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
12-15-2018, 06:23 AM
#17
Rennlist Member
Thread Starter
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
12-15-2018, 08:12 AM
#19
Rennlist Member
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
Attachment 1344509
Attachment 1347256
jp 83 Euro S AT 57k
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
Attachment 1344509
Attachment 1347256
jp 83 Euro S AT 57k
12-15-2018, 10:12 AM
#20
Rennlist Member
Thread Starter
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
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
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?
12-15-2018, 07:34 PM
#21
Rennlist Member
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
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
12-16-2018, 01:59 PM
#22
Rennlist Member
Thread Starter
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
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
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)
12-17-2018, 03:49 PM
#24
Nordschleife Master
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.
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.
12-17-2018, 07:57 PM
#25
Rennlist Member
Thread Starter
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 !
12-21-2018, 04:17 PM
#26
Rennlist Member
Thread Starter
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)
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.
12-21-2018, 06:39 PM
#28
Rennlist Member
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
jp 83 Euro S AT 57k
12-21-2018, 06:50 PM
#29
Rennlist Member
Thread Starter
normally the hose at the base is vacuum, and the one at the top is atmosphere pressure.
