Subject	Re: Ok, all of what you said is obvious.
Posted by	canyoncarver on April 22, 2010 at 6:49 AM
	This message has been viewed 84 times.
In Reply To	Ok, all of what you said is obvious. posted by inf on April 21, 2010 at 10:42 PM
Message	A misfire caused by anything, including a leaking fuel adapter, will cause erratic vacuum readings at idle. Vacuum pressure drops as engine speed increases, so you need to be at the correct stable idle speed to get correct vacuum readings. One of the keys to using manifold vacuum pressure as a diagnostics tool is to know what it is when everything is running good in your specific motor. Depending on the condition of the motor and other variables, 18-20 in/hg may be good. If you didn't have a fuel leak, and you were positive of no external vacuum leaks, yet struggling to find why your vacuum pressure is on the low side, you would need to perform a leakdown test to see if you have a valve, or a few, that aren't sealing well. What are your compression numbers? Cleaning or replacing the pcv valves couldn't hurt.
Follow Ups	What would cause low vacuum? - inf 13:10:09 04/20/10 Timing being off.. - Draker (Eugene, OR) 14:17:38 04/20/10 I know the timing is good... - inf 22:15:07 04/20/10 Well you've done a compression test.. - Draker (Eugene, OR) 00:19:13 04/21/10 as far as i know... - inf 02:15:01 04/21/10 Re: as far as i know... - canyoncarver 06:37:00 04/21/10 Ok, all of what you said is obvious. - inf 22:42:49 04/21/10 occasionally the vacuum will be in the proper range and hold - inf 22:46:21 04/21/10 Well, depending on where your idle is.. - Draker (Eugene, OR) 23:30:33 04/21/10 I used the boost leak tester and had it hit 5 psi - inf 01:57:52 04/22/10 Thank you - inf 13:15:55 04/22/10 I guess a leaking fuel adapter/injector would cause low - inf 23:21:50 04/21/10 Re: Ok, all of what you said is obvious. - canyoncarver 06:49:23 04/22/10 Thank you - inf 13:04:07 04/22/10
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