vpc and base idle

[jdmawd]

just a quick one, should i really be trying to get this car to idle at 750 with the vpc. it does idle ther,e but the idle quality is horrible. the vacuum signal is super low -5. im thinking either my exhaust cam/intake cam is off a tooth. as stated in a different thread, i have never had a vacuum reading higher then -15. that was with the idle at 900. *no cams*

 

[rdrkt]

Give it up I don’t think you are ever going to be able to get a decent idle at 750rpms. My car had a “great” idle with my 272s but the car was still a lot more comfortable at 750 as opposed to 1000rpms. But I had a little help from a project that is being developed. When it does finally get released VPC and hacked MAS owners will be jumping for joy.

As an example I was getting 15 in of vacuum at about 850-900 rpms with 850cc injectors, non degreed Web Street cams, an obliterated MAS, a SAFC and this black box. That box was the only reason that car idled at all and what was pretty amazing is that it idled pretty decent. When I switched over to a pair of HKS 272s we unhooked the box and the car idled a little better than it did with the webs and the box. When we hooked the black box back up we were like “Cams? What cams?” If you are interested ask HighPsi91 and see if he has and finished units yet.

 

[NJGSX96]

I got a nice idle at 750-800 with 264s, 650s, VPC/AFC combo. Vacuum is at -14 for me. AFC is at -38, idle at fuel lean. This on as 550 chip with 650 injectors.

Pressure test your intake. See if yougot any leaks. If you can't get it to idle better, no worries. As long as you don't stall and the car is tuned for WOT... 2 out of 3 ain't bad.

 

[jw]

5inhg is horrible and something must be really wrong. Like you already said, it could be your timing totally off. Check the timing belt and also ign timing while you are at it. Is it a stock head? Did you rebuilt it and decked? If you do, it will throw off the cam timing also.

 

[jdmawd]

Give it up I don’t think you are ever going to be able to get a decent idle at 750rpms

im starting to agree, the idle was best at 900-1000

5inhg is horrible and something must be really wrong.

agreed -5" means there is a lot wrong somewhere. i have removed all the vac line thanks taboo the vac signal is still unchanged.

Pressure test your intake. See if yougot any leaks.

I was unaware, that a pressure check would identify any vac leaks. i was under the assumption, that with the throttle body door shut. the intake test would only show leaks from the turbo to the throttle body.

*keep in mind i have not installed the cams yet.*

car idles at 750 and shows -5"

at 900-1000 10-15'

 

[NJGSX96]

Aren't you supposed to open the throttle plate when you do a pressure test?

 

[jdmawd]

Originally posted by NJGSX96
Aren't you supposed to open the throttle plate when you do a pressure test?

i have no idea, i guess it would make sense wouldn't it

how exactly do i make this pressure tester.

 

[jw]

Not really, however, I do recommend you to crank it to TDC to avoid it leaking through the valves. My car idle at 750rpm/15inHg with HKS cams.