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Discussion Starter #1
I just got done doing my full tune up on my d15 with mpfi swap. The cars idle is set at 750 and the timing is set at 18degress. I have never checked vacuum on it before but I did today and the gauge read 27inches at idle. During my tune up I noticed my cat is starting to come apart because it rattles when you tap on it, this may be my bad fuel milage concern, but when I saw the high vacuum that blew me away. I have been a tech foot over 7 years and I have never seen that before. I will say that both the throttle blade stop and the idle adjustment screws have been messed with. Any ideas? Is the throttle blade supose to be completely shut at idle? If not what's the stock setting?
 

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ministry of mayhem!
93 honda integra
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5,673 Posts
throttle blade isn't supposed to be closed shut or else the engine won't idle.

EDIT: but it"'s possible that yes, maybe the throttle blade setting was tampered with, and it's a bit more closed than it should be.
 

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Meat Popsicle
91 CRX Si
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throttle blade isn't supposed to be closed shut or else the engine won't idle.

EDIT: but it"'s possible that yes, maybe the throttle blade setting was tampered with, and it's a bit more closed than it should be.
Werd. See if you can see yellow paint on the stop screw and jam nut.
 

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Discussion Starter #5 (Edited)
The throttle blade stop screw is missing. Came loose and rattled out. Could cam timing. I will have to check it.

It seems most likely cause would be the cam is a tooth off. that would explain my poor fuel eco, poor performance, and high vacuum. even if the throttle plate is completely closed the air adjustment screw can be adjusted so the vehicle will run. Im pretty sure on this intake ( Y 8 ) that the throttle blade should be damn near closed and the throttle stop screw is only there so the blade itself is not slammed against the throttlebody. IF its not supose to be shut all the way whats the gap supose to be so i can readjust it?
 

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Discussion Starter #6
I found that the gauge is only reading 23 inches vacuum, which is borderline awesome and strange. the cat converter is coming apart so i ordered a new one to see if it helps my fuel eco. I check cam and crank timing today and reset ignition timing. all is good. vehicle still feels under powered. Im hoping the cat will help. Any other sugestions?
 

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Brokedick Millionaire
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I found that the gauge is only reading 23 inches vacuum, which is borderline awesome and strange. the cat converter is coming apart so i ordered a new one to see if it helps my fuel eco. I check cam and crank timing today and reset ignition timing. all is good. vehicle still feels under powered. Im hoping the cat will help. Any other sugestions?
22-23 vac is normal.....
 
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