Low vacuum :(

[high c]

hey guys, so my car is running and i am extactic!! One problem, my car is only pulling about 19 in/hg of vac. It idles kinda rough, but doesnt throw any cel's...but revs when i give it some gas...i do have low comp pistons, and that would make the vac drop, but not 6-7 units...i researched this and came up with a couple good links, but i think i distinctly remember back in september when i was driving my car again, that i was getting 25-27 units of vac... i could be wrong but i think i remembered that part atleast~
timing is dead on, checked both the map and iac and both are functioning to the point where i unplug them and the engine stalls and dies...maybe they need a cleaning? Any ideas what would cause the irratic idle? Doesnt bounce up and down, more like only a couple hundred rpm's here and there, but not at a certain incriment, seems kinda random~

any ideas ladies and gents?

please let me know and thanks!

justin

[NAiL05]

Elevation and shit matters so i dunno. If you have a barometer you can compare it with the reading your getting to see if its right or wrong. YOu might have a leak somewhere if its reading off.

[chicago]

Idle Problems

someone help him because i need help with mine and mine bounces really BAD

THANKS!

[high c]

thanks for the responces guys...and the self interest comback, try your iac~

anyone else have anything else that they think might be effecting it? I am not in an overly high area so i dunno how that would account for the 6-7 loss...

[HondaFan81]

hey guys, so my car is running and i am extactic!! One problem, my car is only pulling about 19 in/hg of vac. It idles kinda rough, but doesnt throw any cel's...but revs when i give it some gas...i do have low comp pistons, and that would make the vac drop, but not 6-7 units...i researched this and came up with a couple good links, but i think i distinctly remember back in september when i was driving my car again, that i was getting 25-27 units of vac... i could be wrong but i think i remembered that part atleast~
timing is dead on, checked both the map and iac and both are functioning to the point where i unplug them and the engine stalls and dies...maybe they need a cleaning? Any ideas what would cause the irratic idle? Doesnt bounce up and down, more like only a couple hundred rpm's here and there, but not at a certain incriment, seems kinda random~

any ideas ladies and gents?

please let me know and thanks!

justin

I'm having similar issues as to what you described with my Delta 272 cam, H23 ported intake manifold and F22 headwork, other mods etc. My cold idle is at 15 inHg of vacuum, then it warms down to 13 inHg. Idle is not totally smooth and fluctuates within 100 rpm or so if I let the engine idle itself. However, if I blip the throtte what it is in its warm idle state, the idle rpms get finicky and goes up and down some

Some people have said to check for vacuum leaks and I haven't fully checked (i.e. spraying around, etc while idling). However, it is not something blatant/obvious as I hear no hissing sounds, etc. Most if not all the vacuum and coolant hoses in the intake manifold/head area have been replaced recently and all components are functioning. I'll have to spray around and finalize this diagnosis to find out for sure on the vacuum leak possibility.

Also, you can't expect to be at stock-like vacuum when you have modified your engine to a certain extent (i.e. cams, intake manifold work, headwork). Perhaps I am where I am because of this. All I can do is eliminate possibilities and if everything checked out, well it's what it should be most likely as long as everything is running alright.

Also I still am dialing in my cam timing and ignition timing which can make a difference in vacuum too. Advancing the cam should bring me back some vacuum.

Sidenote: The only area that may have a leak/if any on my setup is the EGR ports..if that's fine, then I'm confident in everything else. I think I may seal up the ports, just for the hell of it.

[high c]

cisco, i was running into teh same probs back a while ago that sounded like yours...try unhooking your egr vac source, when i did this i got 20+ right back because it was sucking out...

any my problem has pretty much cleared itself up, i dont know if the rings were not sealing good at all, but now at idle i have about 21 constant and when i let off it goes to about 25

new prob tho, check in technical~

[cb9tunerguy]

try sprayin carb and choke cleaner around the intake manafold gasket. becareful of any sensors. dont soak them. if the idle races slightly, narrow it down by spraying it at specific points around the gasket. when you verify that it is the manafold. replace the gasket with an oe gasket. if you dont find a leak there, try sprayin some vaccume lines. if not still, try a compression test. maybe you have a bent or hung open valve. also verify the timing is set correctly. good luck

[high c]

thanks bud, ya i think it is going to clear up once the rings break in a bit~
thanks
justin