• The site migration is complete! Hopefully everything transferred properly from the multiple decades old software we were using before. If you notice any issues please let me know, thanks! Also, I'm still working on things like chatbox, etc so hopefully those will be working in the next week or two.

Noooo boost

A

ayeb

New member
I recently found out that I'm not getting any boost. A while ago i removed the lower hose going to the bypass solenoid so that's not the problem. I'm getting about 18psi of intake pressure @ idle sometimes it goes to 20psi. I checked the vac/boost via torque and a manual gauge. So maybe I'm thinking its the bbv? I also have the p0442 code don't know if that matter.
 


i would replace the Bosst control valve, Ive had that problem before, also replace all of the vacuum hoses that go to it. Before you do that though i would hold the boost plate closed and have someone rev the car and see if it boosts.
 
Is your supercharger belt attatched/not broken slipping a lot?
did your sc tensioner fail?
Do you have a supercharger? (lol just have to be sure ;-))
 


I don't know if the belt is slipping. The tensioner.....I didn't check. There's no rattling at idle. Only when I press the boost plate down I hear a bit of rattle. Within the housing
 
So my boost kicked in today I was wondering where that power was coming from. So I connected the torque app and yes I was seeing boost. I also noticed that my map pressure was around 5 to 8 to 14 psi is that normal? I thought it was suppose to read something like 20
 
That phone app can't read map/boost correctly.

Engine vacuum is anything under 0, so -20ish to 0. Idle is at-19 to -20in/hgs aka vacuum. Anything above 0 is boost and because it's a 2 bar map it would read in KPA or psi depending on what gauge you watched or what scanner you run.
 
I wish there was like a data sheet of normal readings somewhere on the net that the torque app displays so people can compare to see what sensor is not functioning properly
 


I've been battling this no boost situation for the longest. I wedge a screwdriver between the fuel rail and the boost valve to keep it open and still don't get any boost. Does the p0442 code have anything to do with this situation I'm facing?
 
ayeb said:
I recently found out that I'm not getting any boost. A while ago i removed the lower hose going to the bypass solenoid so that's not the problem. I'm getting about 18psi of intake pressure @ idle sometimes it goes to 20psi. I checked the vac/boost via torque and a manual gauge. So maybe I'm thinking its the bbv? I also have the p0442 code don't know if that matter.
Click to expand...

Pull the vacuum line that leads to the bottom of the boost bypass valve and plug it with something. Let the bottom of the bbv be open to the atmosphere.

I once had a problem of making less than 4 lbs of boost despite being on a 3.5 pulley and it being -15 out... a bad bbv was the culprit. In that weather, the car made 10.9 lbs under full boost after plugging.
 
Is the arm on the boost actuator suppose to be retracted withe engine off? Also does the arm suppose to move kind off freely when giving it some gas? In park I have to do quick jerks on the throttle cable to get the arm to move then it closes quickly and forcefully
 
Ooook last statement about this problem. I forgot to connect the Map line to the t fitting under the snout and drove the car for a day and didn't notice any difference in drivability. Sooooo could the map sensor or for need replacing?
 


The bbv is a little spring-loaded thing that's supposed to open and close when needed. If you take the blower apart the incoming air will come through one or the other outlet hole, depending on whether you need the air compressed or not.

If you forgot to connect the MAP line you had a big ole vacuum leak most likely. Depending on the car, it may or may not have affected drivability. When I had a vac leak in front of the MAP sensor it didnt drive any different, it just ran pig rich (a quarter tank of gas in 40 miles).
 
Fivefingerdeathpunch said:
That phone app can't read map/boost correctly.

Engine vacuum is anything under 0, so -20ish to 0. Idle is at-19 to -20in/hgs aka vacuum. Anything above 0 is boost and because it's a 2 bar map it would read in KPA or psi depending on what gauge you watched or what scanner you run.
Click to expand...
An L67 should be -19 to -20in/hgs?
Mine, before being cammed, would idle -16 to -17 at the lowest and after the cam is more around -13.9 to -15.6 ish which a lot of people said was normal. I assume elevation plays a factor into what the car would be at? And mods of course, but even stock here in MI mine wasn't as low as -20 ever that I saw. Just wondering
 
You must log in or register to reply here.
Back
Top