Hi,
I was vacuum testing my 89 RS earlier today too see where about it was standing with it's 140k/miles on it. I have replaced a few vacuum lines recently thinking it was probably about time. I'm averaging around 16-17Hg's idle (after compensating for being about 800' - 1k' above sea level). Now, I've read some people in here being around 20Hg's or so. Also, when I rev to around 2k/rpm's I'm around 21Hg's or so. Just wondering if this seems odd to anyone or normal.

Other thing I'm wondering, how hard is it to replace that plastic PCV lines that run fron that valve down to the dist and back up? Never bothered to tinker with it, but I figure it might help increase vacuum if I have any leaks in those areas.

Thanks
-Dan

 

16-17 Hg's is kinda low for a stock engine... My V8's pulling 16 Hg's at like an 800 rpm idle, WITH a cam. At a lower idle it pulls 14.

 

Read this post. I did some research for vacuum guage results and came up with the information in here

https://www.thirdgen.org/techbb2/sho...hreadid=200692

Somewere in there, it takes you to a site that was written for F150's but all the information is from places like haynes manuals and other general sources that apply to all cars. Hopefully this will help you out.

I know my car pulls about 17 at idle and all the way up about 25-27 at like 3000 rpm.

Hope this helps.
Jeff

 

I'm thinking I should just place the lines for the PCV system. Especially since their some of the last lines that have not been replaced yet. Anyone here had any trouble replacing the PCV system lines with just some vacuum hoses?

-Dan

 

Your vacuum readings are correlated to pressure on fuel demands & load of the surface (the Road!, uphill, down, level wind factor, too!).
You're doing fine.
Vacuum lines.
The back engine PVC line is 1/2" THICK WALLED heater hose, short section.
Reuse ALL the hard plactic lines as that keeps engine demands the required setting.
NOW ya can replace DAMAGED/Cracked hard plastic lines with 5/16" windshield wiper hose and that works perfect!
I've done both.
It takes a very good long day & a aching back later on to do a very through vacuum hose replacemnt.
It'll cost next to nothing (about $2+ in hose). You remove top manifold, all cables attached, roll/flip manifold toward passenger side, relax & lower on engine surfaces.
MOST damaged hose is the EGR one. Remove hose, LOOK AT EXHAUST SIDE! replace!
Results are dramatic & worth the long day.
It realy is simpple, very detailed.
PS Have NEEDLE nose pliers handy, use 'spit' to lube the plastic to slip on rubber hose easy! Distb. base hose takes longest! do first & use LOTS of motor oil for lube. Length is about 3/4" to 1 1/2", maybe up to 2". Previous hose shrinks so add about and 1". Yes, the hose CAN BE "too tall" and cause plastic pipe damage.
Final warning.
This plastic hose stuff?
NOT available from ANY ONE (even dealer!), except wrecking yard. And the stuff in the yard is more fragile! than yours.
Enjoy! I have twice! I missed some first time
This is an easy job.

 

Keds right, your system is normal. They will operate normally between aprox 17 inches at idle and 20+ inches at higher rpm lift. WOT will dorp it to almost nothing, then once you lift the throttle, the pressure biulds imediately to 20+ inches.

 

Hm, okay. I figured as much.

Thanks for all of the help.

-Dan

 

Heheh, yah. I noticed how cheap the stuff was when I bought a ton of different sized hose to replace all the hoses on my old AMC Jeep block that was doing poorly in idle Hg's. Turns out that two hoses had really small leaks in them and was throwing off the MAP sensor when the vac was jumping around.

Anyway, after that I was looking at the Camaro and tested the vacuum and thought I would ask you guys what you thought on the Hg rate for it.

Thanks for all the help once again.



-Dan