regular drop in the vacuum
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Fleet Mechanic
Joined: Mar 2005
Posts: 1,603
Likes: 1
From: St Louis
regular drop in the vacuum
I am trying to get my 91 bronco to idle down to less than 1000 rpms from the current idle of 1500 rpms. I pulled the codes on the truck using the KOEO test but could not get past this part yet. The code I got was 32 and another for 67. Well I am in the process of determining of the EVP has a fault in the wire or just a bad sensor. Anyway, I decided to attach my vacuum gauge to the vacuum tree on the upper intake. I found an almost steady 20 inHg with a slight regular dip to roughly 19.5 inHg with the engine idling at 1500 rpms. I had to go back and read about what this dipp would be an indication of and it seems that an old book mentions valve issues that need to be diagnosed with compression test or do a tune up.
So now for my question is this a concern especially since the motor sat for a few months, should I look to find any collapsed lifters or springs? I have not heard any ticking in the engine but I would not say that it is problem free. Does anyone have some suggestions for me to get this motor to slow down on the idle?
So now for my question is this a concern especially since the motor sat for a few months, should I look to find any collapsed lifters or springs? I have not heard any ticking in the engine but I would not say that it is problem free. Does anyone have some suggestions for me to get this motor to slow down on the idle?
Hotshot
Joined: May 2004
Posts: 12,170
Likes: 5
From: The hills of No. Calif.
I would look at the IAC. It's possible that there's some carbon buildup on the plunger which is holding it open and allowing too much air to enter. Look here for more info:
http://fordfuelinjection.com/index.php?p=39
I wouldn't be too concerned with the vacuum fluctuation at this point, that's really not a large variation.
http://fordfuelinjection.com/index.php?p=39
I wouldn't be too concerned with the vacuum fluctuation at this point, that's really not a large variation.
Last edited by TigerDan; Nov 5, 2006 at 11:21 AM.
