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blue62 · 03-31-2021, 06:44 PM

Thought I would add that if your only pulling 9-10 inches of vacuum that is very low.
Your looking for 18-20 at sea level steady needle. look for around 1inch less for every thousand feet in elevation. So if you are in say Denver (a mile high). 13 inches would be like 18 at sea level.

So low vacuum like you have is a good size vacuum leak or late valve timing.
What is the action of the needle at idle? Steady? or????

A smoke test is a good way to find a vacuum leak but they are not absolute.
If you have a Vacuum leak it could be in a system like the EVAP system. One way valves in that system can prevent finding leaks with a smoke test.

No Oscilloscope at the dealership? Wow whats the world coming too????

03-31-2021, 06:44 PM	#9
blue62 Registered User Join Date: Aug 2018 Location: Woodland Wa Posts: 1,309	Thought I would add that if your only pulling 9-10 inches of vacuum that is very low. Your looking for 18-20 at sea level steady needle. look for around 1inch less for every thousand feet in elevation. So if you are in say Denver (a mile high). 13 inches would be like 18 at sea level. So low vacuum like you have is a good size vacuum leak or late valve timing. What is the action of the needle at idle? Steady? or???? A smoke test is a good way to find a vacuum leak but they are not absolute. If you have a Vacuum leak it could be in a system like the EVAP system. One way valves in that system can prevent finding leaks with a smoke test. No Oscilloscope at the dealership? Wow whats the world coming too???? Last edited by blue62; 03-31-2021 at 06:49 PM.