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#1 |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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Hey guys,
My vacuum pump (under the pass. headlight) cycles on for a moment every 4 to 5 seconds, when the ignition is on with the car not running. I've come to understand that this indicates a vacuum leak somewhere under the plenum. A no-brainer, right? BUT, on page 19 of the latest HOTB, Marc says in his troubleshooting tips: "If the pump cycles on and off the vacuum connections up to the secondary port solenoid are tight. As long as the pump will turn off for one second, the secondary port throttles will operate normally. If the pump shuts off for longer than five seconds it indicates that the vacuum system connections are tighter than average." So, according to Marc, my vacuum system connections are tight? Am I misunderstanding what I've just read? Anybody willing to help confuse me further? Thanks! Chris |
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#2 |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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Also, forgot to mention that my car idles normally...no high idle.
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#3 |
![]() Join Date: Apr 2013
Location: Eastern Missouri
Posts: 773
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Mine cycles like yours. Runs for 2-3 seconds, off for 4-5 seconds. I took my car to Marc last fall for injectors, coils, radiator clean, and tuning - he said mine was perfectly normal. He drove it with his laptop hooked up to it as well - and all was good....
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[LEFT][SIGPIC][/SIGPIC][/LEFT] [CENTER][COLOR=Indigo][SIZE=4][I][B] **Now Sold** 1990 ZR-1 #2093, Black on Black..[/B][/I][/SIZE][/COLOR][/CENTER] |
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#4 |
![]() Join Date: Aug 2013
Location: Crystal Lake, IL
Posts: 10
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Mine does the same. I also thought I had a leak. Glad to know otherwise.
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#5 |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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Thanks Racinfan, good to know Marc gave yours his seal of approval!
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#6 |
![]() ![]() Join Date: Feb 2010
Location: Pendleton, IN
Posts: 3,904
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A good working secondary system is a good setup. My 95 works fine...for now. My 91 has no secondary hardware and will never have a leak from that area.
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1988 KOH Prototype EX5023 sold 1990 ZR-1 #444 Convertible 1990 ZR-1 Black #966 1991 ZR-1 Quazar Blue #296 1957 Duntov SS Project |
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#7 | |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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![]() Quote:
The conventional wisdom (or my rookie understanding of it) is that a cycling pump means an under-the-plenum vacuum leak. Is that correct? Does my cycling pump mean that I have a vacuum leak? Or do I understand what I read from Marc correctly? If so, John and Racinfan and I don't have leaks. What are your thoughts? Everybody? |
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#8 |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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WOW, I'm kinda shocked...lots of views but not many replies. Anybody have any thoughts on this?
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#9 |
![]() Join Date: Feb 2014
Location: AZ
Posts: 860
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Thanks Brett. I'm with you on trusting Marc. I woke up today thinking I had a leak. Now I don't and I didn't have to pull the plenum...I'd call that a good day! LOL
Great night all! Chris |
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#10 |
Join Date: Aug 2005
Location: Scottsdale, AZ
Posts: 2,450
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Can you @ 3k feel the secondaries opening? A burst of power?
I think you are OK, but in the future just remove this stuff, no confusion just + 10 RWHP with tune |
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