 What is a safe vacuum value to test a MPS?, ...aka the value of looking at VW shows for teener stuff! |
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| 914rrr |
 Sep 7 2025, 07:00 PM
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Senior Member  Group: Members Posts: 1,995 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States  |
While cruising the swap meet section at a VW Show yesterday, I picked up an in the box NOS 049 MPS. (IMG:style_emoticons/default/dancinnanner.gif)
I did the :suck tongue" test and it passed. I'd like to test it with a pressure / vacuum tester to ensure it holds vacuum. I definitely don't want to overdo it and damage it. What is a safe vacuum value to test an MPS?  |
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| JeffBowlsby |
Sep 7 2025, 08:18 PM
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914 Wiring Harnesses & Beekeeper Group: Members Posts: 9,126 Joined: 7-January 03 From: San Ramon CA Member No.: 104 Region Association: None 
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18 in/Hg is used to calibrate.
Mouth suck test is no good, no where near enough pressure. Use a vacuum pump. |
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| 914rrr |
Sep 8 2025, 12:42 PM
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Senior Member Group: Members Posts: 1,995 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States |
QUOTE(JeffBowlsby @ Sep 7 2025, 10:18 PM)  18 in/Hg is used to calibrate. Mouth suck test is no good, no where near enough pressure. Use a vacuum pump. Thanks Jeff!! |
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| 914rrr |
Oct 30 2025, 09:02 AM
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Senior Member Group: Members Posts: 1,995 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States |
OK, it passed the vacuum text with flying colors.
What static electrical tests can be performed to check operational condition? |
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| Ron914 |
Oct 30 2025, 09:51 AM
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#5
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Member Group: Members Posts: 446 Joined: 19-April 22 From: Huntington Beach,Ca Member No.: 26,487 Region Association: Southern California
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QUOTE(914rrr @ Oct 30 2025, 10:02 AM) OK, it passed the vacuum text with flying colors. What static electrical tests can be performed to check operational condition? With a volt /ohm meter check the ohm readings for the primary and secondary coils then check each coil to case ground . The secondary coil should read around 350 ohms between pins 8 &10 and the primary coil should read 90 ohms between pins 7 &15 then check each to case ground there should be no continuity from case to either 7/15 or 8/10 |
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| 914rrr |
Nov 30 2025, 03:36 PM
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#6
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Senior Member Group: Members Posts: 1,995 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States |
QUOTE(Ron914 @ Oct 30 2025, 10:51 AM) QUOTE(914rrr @ Oct 30 2025, 10:02 AM) OK, it passed the vacuum text with flying colors. What static electrical tests can be performed to check operational condition? to each With a volt /ohm meter check the ohm readings for the primary and secondary coils then check each coil to case ground . The secondary coil should read around 350 ohms between pins 8 &10 and the primary coil should read 90 ohms between pins 7 &15 then check each to case ground there should be no continuity from case to either 7/15 or 8/10 OK, 8 & 10 = 360 ohms 7 & 15 = 92 ohms Not sure about how to check the pin to ground continuity. Is it simply touching neg lead to case and pos lead to each pin individually? |
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| Ron914 |
Nov 30 2025, 05:44 PM
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Member Group: Members Posts: 446 Joined: 19-April 22 From: Huntington Beach,Ca Member No.: 26,487 Region Association: Southern California
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QUOTE(914rrr @ Nov 30 2025, 04:36 PM) QUOTE(Ron914 @ Oct 30 2025, 10:51 AM) QUOTE(914rrr @ Oct 30 2025, 10:02 AM) OK, it passed the vacuum text with flying colors. What static electrical tests can be performed to check operational condition? to each With a volt /ohm meter check the ohm readings for the primary and secondary coils then check each coil to case ground . The secondary coil should read around 350 ohms between pins 8 &10 and the primary coil should read 90 ohms between pins 7 &15 then check each to case ground there should be no continuity from case to either 7/15 or 8/10 OK, 8 & 10 = 360 ohms 7 & 15 = 92 ohms Not sure about how to check the pin to ground continuity. Is it simply touching neg lead to case and pos lead to each pin individually? Check for continuity between each pin and the case of the MPS .If 7,8,10,15 have continuity to the case then the MPS is bad . |
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| 914rrr |
Dec 1 2025, 11:05 AM
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#8
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Senior Member Group: Members Posts: 1,995 Joined: 1-July 03 From: Knoxville, TN Member No.: 874 Region Association: South East States |
Thanks! No continuity found between pins and case.
I found a cross reference chart on Dr D-Jet website below. Q: can an 049 MPS be used on an 8/72 - 4/73 2.0 with the proper combination of ECU and MPS or am I reading the chart wrong?  |
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