All Vacuum, No Boost

[neonsox]

Tonight a friend and I installed an Autometer boost gauge in my Lebaron. I tapped into a vacuum line that runs between the throttle body and brake booster. The gauge reads -15 at idle and goes up to 0 if I floor it but never beyond. If I let off real quick, it sometimes drops to as low as -25. Did we tap into the wrong line? It feels like there is some boost when driving the car, but he gauge doesn't ever go past 0.

By the way, this is a T1 log intake if that helps. Where should I be tapping into under the hood to get the most accurate reading? Thanks.

[IROCNOROLL]

Quote:

Originally Posted by neonsox Tonight a friend and I installed an Autometer boost gauge in my Lebaron. I tapped into a vacuum line that runs between the throttle body and brake booster. The gauge reads -15 at idle and goes up to 0 if I floor it but never beyond. If I let off real quick, it sometimes drops to as low as -25. Did we tap into the wrong line? It feels like there is some boost when driving the car, but he gauge doesn't ever go past 0. By the way, this is a T1 log intake if that helps. Where should I be tapping into under the hood to get the most accurate reading? Thanks.

Sounds like you maybe found a "ported" vacuum source. Or the turbo is pooched and laying down with no boost. If you find a port right on the manifold itself, like the vacuum supply to the fuel pressure regulator, this is pretty much what you need. Or the MAP vacuum source hose.

[neonsox]

The turbo sounds ok and it feels like there's power, but no reading. Searching revealed that a boost environment wouldn't be ideal at the brake master cylinder and the line I tapped into might have a valve of some kind in it. Hence the vacuum only reading. Any verification on this?

[Darkside]

I added a boost gage to my T1 '91 Spirit in the same spot with no problems. Between the port on the intake and the brake booster. (lg vacuum line) The only time I lost boost on the gage was when I lost a hose from the turbo to the intake. But when that happened the car ran like crap. The vacuum runs at 20hg to boost of 12 to 15 lbs. under wot or 5 to 10 under normal driving.

[neonsox]

Quote:

Originally Posted by Darkside I added a boost gage to my T1 '91 Spirit in the same spot with no problems. Between the port on the intake and the brake booster. (lg vacuum line) The only time I lost boost on the gage was when I lost a hose from the turbo to the intake. But when that happened the car ran like crap. The vacuum runs at 20hg to boost of 12 to 15 lbs. under wot or 5 to 10 under normal driving.

Hmm... Well, the previous owner definitely had a gauge tapped into the very same spot since there was a tee and screw in the end of the nipple. So maybe I'm really not making any boost. Bummer. The car runs great, for the most part. Doesn't lose oil or smoke.

Any idea why I'm not getting any boost? I hear about a disconnected "wastegate actuator arm" a lot but I'm not clear on where or what that is.

[thedon809]

The wastegate is easy to see. If you look in the back of the engine where the turbo is you will see a little canister with an arm coming off of it, thats the wastegate.

[EvilcowRoland]

Before you go nuts tracking a boost leak, try moving the gauge to a different location. It sounds like you tapped into the heater control port. The vents are vacuum controlled and there is a small line going from the brake booster into the firewall with a check valve on it (so it's vacuum only). Try tapping into the main source coming out of the intake and if you still don't have boost then we'll start looking for the cause.

[glhman]

Quote:

Originally Posted by EvilcowRoland Before you go nuts tracking a boost leak, try moving the gauge to a different location. It sounds like you tapped into the heater control port. The vents are vacuum controlled and there is a small line going from the brake booster into the firewall with a check valve on it (so it's vacuum only). Try tapping into the main source coming out of the intake and if you still don't have boost then we'll start looking for the cause.

+1. Just because the previous owner has a T there, doesn't mean that his gauge was working

[neonsox]

So it should be alright to tap into the fuel pressure regulator? There is a small... I guess "canister"... that sits on the intake and is split in two. One line feeds the regulator and the other branches off in 4 or 5 smaller tubes that trail to the passenger side front fenders and the sensors there. What would give the best reading? What do I NOT tap into?

[neonsox]

Well I went ahead and tapped into one of the smaller lines and got 7 psi. Not bad. This weekend, I'll turn it up a notch or two and see how she does. Thanks to all who responded.

[EvilcowRoland]

7 is about right for a stock log intake car. If you're sure everything is in working order and you have plenty of fuel, you should be able to take the boost up to 10 psi with no issues. Some folks have even run as high as 12 non-intercooled, but that's playing with fire I think.

You'll be doing yourself a favor if you go through that vacuum system and double check everything. Remove that T with the screw in it and make it a straight line, etc. Just clean it up a bit and make sure all the lines are in good shape. 20 or more years does bad things to those rubber and plastic lines.

[detobias]

Quote:

Originally Posted by EvilcowRoland You'll be doing yourself a favor if you go through that vacuum system and double check everything. Remove that T with the screw in it and make it a straight line, etc. Just clean it up a bit and make sure all the lines are in good shape. 20 or more years does bad things to those rubber and plastic lines.

+1 replace all sh*t plastic vac lines with new rubber vac line (doesnt have to be $ilicone)

you will thank yourself later !

[IROCNOROLL]

Just make sure it is vacuum hose, and not windshield washer hose or the like.

[neonsox]

I did a little math and I figure...

93 base HP from the 2.2 + 10 psi @ about 7.57 per psi = about 168-170 horsepower with no other modifications. Not bad either. I figure I'll put a K&N filter in (negligible added horsepower) and maybe clean up the spark a little, and I'll be right at 175 horse. I can live with that. It at least gets me close to TII numbers.