3.6L S/C Low Boost Pressure Problems

Hello Everyone,
I am the owner of a 2001 Toyota Tacoma with a 1st generation supercharger, TRD headers and a AEM Brute force intake. I have recently noticed some degradation in boost pressure over the last few months and was wondering if you all had some insight into some areas to look for problems. Currently the boost gauge is only registering about 4-4.5Lbs of boost when I push it as hard as possible. I was pretty sure when I got it that is was putting out more like 5-6psi when I got the Truck. The car is equipped with the TRD dynamic tensioner and I just replaced all my belts, washed and rinsed all my pulleys, and checked all my lines for vacuum leaks when I noticed the low boost pressure. The TRD installation manual claims that it is supposed to put out 7lbs psi. What kind of boost ratings are you all getting and where else should I look for issues? The PO claimed that they had the whole supercharger warrantied approximately 30,000 miles ago but there was no paperwork to prove it. The truck runs/drives/idles just fine. Any help or suggestions would be great.

 

I don't think Toyota made a 3.6L.

 

Did you put on the headers after you had 5-6lbs or before? Also are you running the proper fuel upgrades for the supercharger?

 

You right it is a 3.4L my bad

 

The headers were already installed when I purchased the truck.

 

Maybe there is a boost leak in the gauge line

 

I checked that as well.

 

The truck does not have any fuel upgrades on it and is running the stock size pulley.

 

Does anyone know how to check the boost bypass valve to see if it is leaking? I can tell that the mechanical arm changes from one side to the other when the engine is turned on and off. But how do I check and see if it is leaking? I called magnson superchargers. The way I described it to them they seem to think that the vanes are worn out and at this point cannot be replaced because they are no longer produced.

 

After further investigation this weekend I have come up with the following. I used a mighty vacc vacuum pump to find out there was a cracked vacuum hose and a line going to the boost gauge was slightly leaking. After fixing those problems I see that my max boost output is around 4.5-5psi. I also can see that the boost bybass is opening and closing when I turn the car on and off. However if I unplug the boost bypass actuator attach it to the mighty vac while running and plug the vacuum port, I see the bypass actuator moving and holding a vacuum with a mighty vac but not really any noticeable difference in idle? Does this mean the flapper/valve inside the supercharger is not working correctly?

 

So the actuator works in this way: at idle the valve should be open to let the boost bleed off and not load up the engine. Then when accelerating the supercharger should be creating boost causing the valve to close and not bleed off the boost, correct? So does anyone know how to properly adjust the end points of the boost bypass valve?

 

I wanted to close the loop on this problem as I finally figured out another issue. As basic as it was, the EGR block off plate had lossened off due to the fact that whoever installed it (Supposedly Toyota) used bolts that only went at most a 3/16in into the supercharger body causing it to strip the threads and appear to be locked down, I litteraly unscrewed the bolts with my hand. There was no sealent/gasket installed on the block off plate either and obvious signs of leakage. The only reason I discovered it is becuase I was installing my 7th injector kit. Now boost pressure is around the 5-5.5 Psi mark (7th inj not functional yet), Which is where is was around when I purchased the truck.