Results 1 to 23 of 23

Thread: Vacuum Gauge Reading , What Does It Mean ?

  1. #1

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Exclamation Vacuum Gauge Reading , What Does It Mean ?

    More help.



    Connect Gauge to either #6 or #20 depending on which vacuum port isn't being used... an unused vacuum port should have a vacuum 'Cap' or 'Plug' over the port. Remove the air cleaner to gain access to the ports... but reinstall the air cleaner before doing your testing.


    Last edited by A20A1; 06-09-2012 at 08:29 AM.
    - llia




  2. #2

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    # 11 Choked cat or muffler more like
    - llia


  3. #3
    LX User
    Join Date
    Apr 2007
    Vehicle
    1988 Accord LX 5spd
    Posts
    198

    What could this be?

    Idle 900-1000rpms vaccum needle 19/1/2 to 20''
    Off idle 2300rpms 21 to 22''
    what could the needle be fluctuating from possibly to lean a mixture setting?

    The reason I say this is because my plugs usually look whiteish too light gray.
    and at about 2000rpms up there's no real power.
    I have to mention that I have replaced the air filter with a K&N .
    Also the exhaust is maybey 1/2'' bigger from the cat back.

    This is my source of irritation.

    Please Help.

  4. #4

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    1 point off the guage isn't something to worry about though.
    There isn't always a suction wave, and sometimes their may even be some reversion.


    If you're not getting enough fuel Check for:

    Vacuum Leaks
    Booster Venturies Loose
    Fuel Filter Dirty
    Float Level Low
    Carburetor Dirty
    Fuel Pump Dying, or Electrical Power to Fuel Pump Low.
    - llia


  5. #5
    LX User
    Join Date
    Apr 2007
    Vehicle
    1988 Accord LX 5spd
    Posts
    198

    Re: Vacuum Gauge Reading , What Does It Mean ?

    I think out of all of the things listed it could be possibly Fuel Pump power or Voltage at the pump or a dirty high speed jet or something. All the other things have been replaced last summer. and or adjusted I just last weekend Tightened up the primary booster and replaced the O ring gasket. Secondary booster leg was tight with no apparent leakage. Also the fuelpump was replaced about 2 years ago.

  6. #6
    LX User
    Join Date
    Apr 2007
    Vehicle
    1988 Accord LX 5spd
    Posts
    198

    Re: Vacuum Gauge Reading , What Does It Mean ?

    Hey what about a faulty carb adjustment as stated in pic 3 although not a wide fluctuation as stated above?

  7. #7

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    Their might be something wrong with the solenoids or sensors for the carb and the air suction system.

    Have you checked the O-2 Sensor?

    You could also try adjusting the float a little, becareful because if can break an o-ring easily and begin to leak.

    Don't touch the A/F screw unless it's falling out or something.
    - llia


  8. #8
    LX User
    Join Date
    Apr 2007
    Vehicle
    1988 Accord LX 5spd
    Posts
    198

    Re: Vacuum Gauge Reading , What Does It Mean ?

    I've checked the O2 sensor last year from the control module under the seat and it checked out ok. The air suction system I'll have to look up in the manual too see what's involved with it. Unless your talking about the PCV valve.

  9. #9
    DX User
    Join Date
    May 2007
    Posts
    5

    Re: Vacuum Gauge Reading , What Does It Mean ?

    hey guys i have a reading of #6 and what could be a #9 , the car idles in #6 just about point 10 and then it goes up it keeps constant about 15 and 20 and then it goes down to 10 and then up again. it says valve springs are weak, but on #9 it also says it vibrates while idling, what does this mean?? and the needle does keep steady as the speed is increase, hope i get some feedback thanks ya

  10. #10

    LX-incredible's Avatar
    Join Date
    Sep 2006
    Vehicle
    88 LX-i Coupe Twins/89 SE-i Coupe/88 Suburban
    Location
    Tucson, AZ
    Posts
    2,495

    Re: Vacuum Gauge Reading , What Does It Mean ?

    Rapid needle fluctuations are the result of valves sitcking / not properly seating. Is the needle fluctuating or not?
    88 LX-i coupe auto (241K DD), 88 LX-i coupe 5-speed, 89 SE-i coupe auto.
    Quote Originally Posted by stat1K View Post
    who is tim and where can i get naughty pictures of him?
    CARDONE SUCKS.

  11. #11
    DX User
    Join Date
    May 2007
    Posts
    5

    Re: Vacuum Gauge Reading , What Does It Mean ?

    fluctuating? you mean if the needle is constantly moving up and down from 10 to about 20 yes it is, if valves are sticking what can i do?

  12. #12

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    it says springs are weak... so you replace the springs... might want to check your valve lash just in case.

    https://www.3geez.com/forum/showthread.php?t=39319
    - llia


  13. #13
    DX User
    Join Date
    May 2007
    Posts
    5

    Re: Vacuum Gauge Reading , What Does It Mean ?

    so the website you showed me shows me how to adjust the valves, is there another page were i can change the springs??? how much would i be spending on springs, would ya suggest me to just buy a new car? how much time i'm going to be spending on changing springs, adjusting valves, is it worth the time spend?

  14. #14
    3Geez Veteran ghettogeddy's Avatar
    Join Date
    Jan 2006
    Vehicle
    88 lx sedan (R.I.P.) / 89 LX sedan(sold) / 89 lxi parts car(towed away) / 87 lxi hatch
    Location
    Antioch CA
    Posts
    9,591

    Re: Vacuum Gauge Reading , What Does It Mean ?

    Quote Originally Posted by CAMARORZ28
    so the website you showed me shows me how to adjust the valves, is there another page were i can change the springs??? how much would i be spending on springs, would ya suggest me to just buy a new car? how much time i'm going to be spending on changing springs, adjusting valves, is it worth the time spend?
    prolly gona be a couple hunered bucks its like 360 or so for new spring rockers and everthing else in the valve train so springs arent to much heres a post from my own rebuild thread that shows the prices for some a18 parts thats are better then stock and fit without modificatopn
    https://www.3geez.com/forum/showpost....0&postcount=52

  15. #15

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    On another note I would try to rule out other possibilities like spakplugs or faulty carb adjustment or vacuum leaks that could be hiding behind an increased idle speed, if idle was adjusted to compensate over the years.

    .
    .

    BTW

    #9 vibrates at idle 800-1000 rpm
    But when you raise the rpm from say 1000 rpm to 3,000 rpm the flucuation of the pointer will begin to stop.

    #6 is steady at idle 800-1000 rpm, no fluctuation
    But when you raise the rpm from say 1000 rpm 3,000 rpm then the needle fluctuates.

    If it only fluctuates at idle 800-1000 rpm then that would mean #3

    If it fluctuates at any rpm then that would mean #12

    .

    .
    .
    - llia


  16. #16
    DX User
    Join Date
    May 2007
    Posts
    5

    Re: Vacuum Gauge Reading , What Does It Mean ?

    Quote Originally Posted by A20A1
    On another note I would try to rule out other possibilities like spakplugs or faulty carb adjustment or vacuum leaks that could be hiding behind an increased idle speed, if idle was adjusted to compensate over the years.

    .
    .

    BTW

    #9 vibrates at idle 800-1000 rpm
    But when you raise the rpm from say 1000 rpm to 3,000 rpm the flucuation of the pointer will begin to stop.

    #6 is steady at idle 800-1000 rpm, no fluctuation
    But when you raise the rpm from say 1000 rpm 3,000 rpm then the needle fluctuates.

    If it only fluctuates at idle 800-1000 rpm then that would mean #3

    If it fluctuates at any rpm then that would mean #12

    .

    .
    .
    ok the car when i first want to start it and its cold i have to step on the gas pedal to give a little gas, otherwise it will just wont to start until many attempt and then it starts without pressing on the gas. then when the car starts it starts to accelerate "without me pressing on the gas" , and it goes up to 2500 rpm and it stays there for a while, if i dont press on the gas sligtly it will not decrease from 2500 rpm, when i press on the was sligtly it decreases to about 1500 rpm, and then about 1 minute from beign in 1500 rpm it goes up to 1100 rpm, after a few minutes then the car starts to idle, from about 700 to 1000 rpm, then from about 500 rpm to 1000, and so for, and if i dont keep it steady at the gas "meaning feeding it gas so that it does'nt idle from about 500 to 1000" the car will shut off but it will start right back up.
    Last edited by CAMARORZ28; 05-20-2007 at 08:38 AM.

  17. #17
    DX User
    Join Date
    May 2007
    Posts
    5

    Re: Vacuum Gauge Reading , What Does It Mean ?

    Quote Originally Posted by ghettogeddy
    prolly gona be a couple hunered bucks its like 360 or so for new spring rockers and everthing else in the valve train so springs arent to much heres a post from my own rebuild thread that shows the prices for some a18 parts thats are better then stock and fit without modificatopn
    https://www.3geez.com/forum/showpost....0&postcount=52
    if that was the case, could i get the head from a junk hard and that way i dont have to do all the valve spring changing? i know i could be risking that the head is bad but could i give it a try?

  18. #18

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    So you're sure you don't have a vacuum leak then, it sounds like it not even looking at a vacuum gauge but then a leaky valve would do the same thing.

    Check for leaks try to get it to idle without help from you.

    it's a lot easier to check for leaks then it is to replace the head... might save you a lot of work if it's just a vacuum leak and not the valve(s).

    high idle (fast idle) on startup is normal and so is pressing the gas to get the rpm to drop. If you need help getting the car to idle check out this thread,

    https://www.3geez.com/forum/showthread.php?t=46572

    .
    .
    .
    - llia


  19. #19
    3Geez Veteran lostforawhile's Avatar
    Join Date
    Dec 2002
    Vehicle
    86 hatchback, 1990 Lincoln Towncar
    Location
    nowhere GA
    Posts
    15,401

    vaccume gauge question answered,where is the thread?

    I finally scanned some info from a vintage chiltons book,this is the vaccume gauge readings question answered,now i can't find the thread. if someone can locate it,eithier move this,or add a link please. i searched with no good as expected. i'm really suprised they don't put this info in modern service manuals,the info is just as relevant on modern engines as on vintage engines.


  20. #20
    3Geez Veteran MessyHonda's Avatar
    Join Date
    Feb 2006
    Vehicle
    89 LX-i(5speed)
    Location
    Bay Area
    Posts
    22,201

    Re: vaccume gauge question answered,where is the thread?

    i believe a20a1 posted the link topic on vacuum....nice find Tim

    1989 Honda Accord LX-i
    B18c1 swap since 7/2011
    175whp and 132tq
    Redzone tuned

  21. #21
    3Geez Veteran lostforawhile's Avatar
    Join Date
    Dec 2002
    Vehicle
    86 hatchback, 1990 Lincoln Towncar
    Location
    nowhere GA
    Posts
    15,401

    Re: vaccume gauge question answered,where is the thread?

    that is from a 1962 mg tune up guide, there is also a lot of interesting general information on engine rebuilding,tuning,carb info etc. a lot of it applies very well to any carbed engine. also info on porting and ccing cylinder heads,etc. you just can't find this kind of info anymore. i will scan as soon as i get the chance. i need to make photo copies,they scan better.

  22. #22

    A20A1's Avatar
    Join Date
    Sep 2001
    Vehicle
    2006 Chevy Cobalt LS
    Location
    Kaneohe, Hawaii, United States
    Posts
    88,734

    Re: Vacuum Gauge Reading , What Does It Mean ?

    I like your diagrams more and the descriptions.
    - llia


  23. #23
    LX User lostscotiaguy's Avatar
    Join Date
    Apr 2010
    Vehicle
    81
    Location
    California
    Posts
    244

    Re: Vacuum Gauge Reading , What Does It Mean ?

    To : Camaror
    "ok the car when i first want to start it and its cold i have to step on the gas pedal to give a little gas, otherwise it will just wont to start until many attempt and then it starts without pressing on the gas. then"

    I second that response from A20A1.... High startup idle is normal in any carburated vehicle, and 2500 sounds about right. It will do this until it warms up and then it should drop automatically to around 750.... Your best bet is when you go to start it when it's cold is to push the pedal 1-2 times to the floor BEFORE turning it over, then just turn it over, it should start right up and then go into "high idle". If you tap the throttle and do the "Kick down" before the car is up to temp it will usually want to stall out and will feel sluggish. This is just because the fuel wont evaporate as easily/quickly on a "cold" throttle plate, and will make it harder for the engine to run properly.
    Anyhow i hope this helps and I'm probably telling you stuff you already know, but I figured I'd throw my 2 cents in...

    I feel old! I can remember a time before Fuel Injection when "Warming up the car"was just one of those hassles you had to deal with before driving somewhere. Now when I wait for my 81 to warm up I kind of enjoy it, but I do hate the idea that you have to rev the crap out of a cold engine.

Similar Threads

  1. How to read a vacuum gauge
    By Dr_Snooz in forum 3geez Accords
    Replies: 5
    Last Post: 12-20-2010, 05:33 AM
  2. New vacuum gauge
    By Dr_Snooz in forum Performance
    Replies: 8
    Last Post: 11-23-2008, 06:52 AM
  3. Vacuum Gauge
    By HondaBoy in forum 3geez Accords
    Replies: 14
    Last Post: 12-15-2006, 11:55 AM
  4. what is a vacuum gauge?
    By myaccord7 in forum 3geez Accords
    Replies: 6
    Last Post: 08-13-2004, 05:47 PM
  5. Temperature gauge reading low?
    By Poodlehead in forum 3geez Accords
    Replies: 3
    Last Post: 08-25-2003, 08:35 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
This website uses cookies
We use cookies to store session information to facilitate remembering your login information, to allow you to save website preferences, to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.
     
Links monetized by VigLink