3.4 supercharger problems. ??Low boost?? (I've stumped everyone on T4R)

So ever since I installed my 3.4l Trd black second gen supercharger it's run good. No noices. Ping problems.

My set up:
Black second gen. SC
URD 7th injector
Urd 2.2 pulley
Boost gauge
AFR gauge
K&n CAI
4,400 elevation of you need to know.

so my problem is that I see others with the same set up showing 8-9 psi of pressure where as I am confused with different numbers between my URD and BOOST GAUGE.

My gauge will generally show 5-6 (6 while spraying from the 7th that helps seal the gaps in rotors for more boost).
BUT.....
my URD controller shows 3.5-4 psi when I'm WOT.

I feel like something is not correct. What is wrong and where am I loosing or just not making the boost I should like everyone else?

If anyone is free I'm out with the truck and got my computer hooked up right now and wants to compare their truck settings with mine on the URD 7th injector.

 

anyone have any input? my bypass valve rubber boot is working properly, it did not bleed off at all under vac and closes all the way. (could it be miss adjusted?)

 

You might want to consider disclosing the mileage of the vehicle or the mileage since the supercharger has been on vs. How many miles you have now.

 

Truck has 220,000 miles on it. Supercharger has been on for 15k of it.

The sc has around 50,000.
As far as boost its always been slightly lower than what it should have been.

 

Is the SC torqued to spec to the lower intake?

Intake gasket needs replacing? I know they are metal and reusable.

Install the check valve from the Throttle body to the bypass valve? is it in the proper direction?

Install the TB gasket for the SC? it's a complete circle inside not D shaped like stock.

cracks in the boost line to the FTC or gauge?

idler worn out letting the belt loosen and slip?

Excessive noise from the SC? worn bearings causing drag? There are the rear rotor bearings that eventually wear in addition to the nose cone bearings.

Nose cone coupler been replaced?

Have you checked the nose cone oil level? Use GM supercharger oil if you need to replace it.

Usually a low boost problem is the bypass valve going bad. it should be completely one way when the truck is off and all the way the other way when idling.

Has the adjuster screw been messed with? could be keeping the valve slightly open even at full boost.


My 2.1 pulley will pull 8-9 psi at 5500' here in Denver and go to 11 psi below 2500'

 

See your the guy I need to talk to.

I installed the sc in February with all new gaskets and correct ones.

As for the check valve what direction does it need to be? I'll check it.

I'm pretty sure the belt is not slipping. I'll try tightening the belt a little more or check it.

The super charger is in great shape. Little to no noise from the system it's self. A little from the nose cone plastic coupler up front. I installed new oil when I installed it on the truck.

Bypass valve works properly (as I know). I held a vacuum on it and it didn't breed off. As for the adjustment screw on top I don't know. Bought it used. No sticker on it ether saying don't touch like others.

I'm going to check the lines some more. Also the lines going into the URD controller. Also the torque again on the sc housing to the truck manifold.


I feel like I should have more pressure with this pulley than I did at my stock one. This is killing me tho!
Thanks for your input guys!

 

You could try and play with the bypass arm adjuster to see if it helps. My truck is at home and I don't remember which direction the TB check valve goes.

This is a PDF that shows were the check valve and boost gauge line go, Only 1 boost port on the black SC's

I have the PDF of the SC install instructions also if you don't have them. PM your email and I'll get it to you.

 

From the destructions

1. (Skip this step for 2001 and newer 4Runner) Cut the hose
leading to the IAC valve connector at the location shown, and insert
the kit’s one-way valve into the straight part of the hose. The black end
of the valve (see arrow, figure 25 and diagram on page 23)
is closest to the throttle body.

IMPORTANT: The IAC hose and the coolant hoses are similar in size.
Don’t cut the wrong one. The coolant hoses have clamps, the IAC
hose does not.​

 

Yeah I've got the instructions I'll look it over again for the check valve. It's currently pointing towards the engine. (Arrow is away from the throttle body.)

The valve is on the correct line. also my valve didnt have a black marking on it. it only has a triangle (arrow) pointing one direction. If i could get a direction on what way it should work (suck with vacuum from the motor but stop when it boosts and trys to push pressure back) that would make sense.


I just torqued down my supercharger bolts to the intake manifold. They were all at least a 1/2 turn loose from actually feeling some resistance or being tight. I torqued them back down again and see what happens next. I'm currently cleaning my air filter so it will have to dry.

My hoses for the URD and boost gauge are all routed correctly, no kinks or leaks from what I can tell.

Here is the routing if you want to know.

SC - t fitting - 7th injector - t fitting - boost and FPR.

 

Speedy says it best! "There is a one way valve discussed on page 11 step 1 of the TRD installation instructions. My one way valve was not marked as to which way it should be installed. After a quick call to Underdog Racing tech support, I learned you are to install the valve so that air flows from the throttle body to the engine. You can blow on the valve to see which way it flows air. This valve insures a smooth idle. "

 

No real changes. Still at 5 psi on my gauge while driving.

 

did you check that the bypass valve moves its full range?

Only other thing would be your rings are shot and causing a lot of blow by but with that much it would puke oil everywhere.

got a link to the T4R thread?

 

i can do a compression test to see what its like, Also ive never noticed any oil consumption nor loss from having the super charger on for those 15K miles and lots of highway driving and some towing.

as for t4r ive been asking this question for a while with no real help. most people dont even have any fuel upgrades nor know what their truck is doing because of lack of gauges like mine. no real specific thread just on the super charger thread. the discussion starts here and goes to the end of the pages (60-62 i think) how bad does my elevation of 4,500 ft change the boost pressure others are seeing. like the guy above with the 2.1 at 5,500, how come i am not seeing closer values like his.

 

Any chance the gauge could be bad?

 

thats the thing. ive checked my gauge against my fancy motorcycle gauges for carbs (see pic above by brake booster) and my URD is only picking up 3-4 psi of boost. where is should be a lot higher to activate my injector.

 

Engine bay looks clean as hell!

 

thank you! i take pride in my vehicles. ( it doesn't mean they dont get dirty once and a while, ill never go in mud holes tho)

 

Me either...ever...lol I'm looking to do same set up as you...supercharger 7th and 2.2 pulley

 

Did you get the line back onto the fuel regulator? is it seated well? I had mine come off once and it took a while to figure out since it's so hidden back there. I put a zip tie on all my boost lines and haven't had an issue since.