Airflow count at idle?

[Girvin]

Im currently having some idle issues(as many of us have had) and will be trying to diagnose the problem tommorow but need some insight.

Im wondering how much air flow (in Hertz) are you guys seeing at idle and @ what rpm?

I just recently installed a set of 264s and my idle issues have gotten worse. Im seeing up to 60-70Hz at idle and my vacuum fluctuates between 11-16inHg. But will sometimes rev high to 20inHg while coming to a stop(clutch in obviously). Upon initial startup of the car my idle will hold steady with 15inHg, but once warm will start to surge with vacuum fluctuation. So far the only thing Ive checked was the valve timing and ignition timing. I'll most likely do a comp test when I have the time but I installed a new head less that a couple months ago with a bottom end that has only 18k on it. Anyone have any ideas??

 

[olmytsi]

31hz in the 800 rpm range stock motor and stock head just boltons.

 

[EclipseTrbo420A]

750 Idle 39 hz warmed up and vac is between 15 and 16. mods in profile

 

[Girvin]

hmmmm.......weird......Im still having the problems. Seemed to have got worse since my 264 install. Didnt quite have time to do and checks on the car......if i can sneak out tonight I'll do a compression test ......cause I wont be able to sleep otherwise.

Guess I should add that the car pulls strong under boost and has no drivablility issues....Im seeing good vacuum on decel to. A vacuum leak would mean lower airflow counts correct? if so, WTF would make the counts higher?

Any more insight would be greatly appreciated.

 

[Girvin]

well........found one of the problems

good ol' McDonalds drive threw tonight......pressed the brake in a couple of times while in line and the idle dropped then reved. I'll pull out the brake booster hose tomorrow, hopefully its just the check valve.

 

[EclipseTrbo420A]

I was drivin last night and rememberd your thread so i looked at everything. My intake at idle is only 35 Hz, 750 idle. and my vac jumps around when i hit the brakes in too. is there a way to fix that. ? let meknow what works for you i want vac at 20 like normal.

also would removed balance shafts have anythingt o do with it ? thanks

 

[Girvin]

Im pretty sure a BS removal will not affect vaccum in any way.......unless the timing belt was put on wrong and your cam timing is off. I'll let u know what the outcome is...

 

[EclipseTrbo420A]

OK thanks , let me know

 

[gsxtacy]

My gsx has always "pulled" or metered 32hz at 750 rpm. 16-17 vacuum. All accessories off.

since bone stock to now, no change.

gsxtacy