Lost boost?

Oh man. You can fit gorilla arms in there without even catching any of the hairs on anything. So much room.

 

So just an update if anyone is curious. I installed a new tensioner and a new continental poly v belt. Before the change i did a test and got 6.8psi, woth the old tensioner and the 70k belt. Put the new tensioner on and the new belt. 6.4psi. Slightly upsetting and not really sure what to do now. Basically now i know it is a slipping belt, but i wish the new belts would grip better lol.

I should just get a smaller pulley to compensate.....

 

Bypass valve must be culprit.

 

But i capped it off and ran a test and it didnt change anything? Maybe i didnt do it right? Im not sure, buti think for now i may leave it as is. I need a break from throwing money at it.

Edit. Assuming i can get a view of the valve, i should be able to view it opening and closing when i rev the engine right? I wonder is that will tell me anything. Not sure if i will be able to see anything definitive.

 

Anyone know the part number for the bypass actuator? Im finding a lot of stuff for the 3.4 system and not the 4.0

Also, wonder if its possible I damages the diaphragm when I first took it off by sitting there playing with it like an idiot.

Edit- i will borrow a vacuum tester tomorrow and check my valve for certain so i can stop asking so many questions. Wish i had done that before the tensioner purchase. Lesson learned.

 

So I did a check of the bypass valve with a vacuum pump, and there was no bleed down or leaking and it moved smoothly with no noise. Pulled 15inHG and it held steady there. So looks like the valve is not the culpret again.


And I'm out of ideas.

 

I have an idea......you won't like it though...

 

Well, im open to many options and considerations. The charger has 81k on it now and they are not east miles so i was thinking a completer rebuild, but i could be barking up the wrong tree.

Now remember before the ntire thing i was getting 7.5 psi, changed plugs and all that junk, then down to 6.5. Changed belt back to old and went back to 6.8. Changed tensioner and belt again, down to 6.4.

So changing the belt is having a direct effect. Sadly the best results are with a belt that has 70k on it and looks like it could explode at any moment.

All that being said, lets hear that crazy idea you have.

 

Ruling out the belt, since I just re-read the first page, my next questions are these.

The cap which has the CNC'd TRD logo on it. How was its seal? I have seen those get hard as stop sealing well.

The spark plugs. Can you double check to make sure all are tight?

Lastly, would be something with the rotor assemblies. Oil/gears/bearings/teflon rotor coating.

But since you pulled the s/c then immediately had the issue whereas you hadn't prior to, then it is something with the s/c.

 

Dumb question but are you sure the plugs you replaced are the part # for supercharged application?
Not sure that would make a difference lol

 

I wanna throw a question out there,
My supercharger sometimes seems like a light switch as if the bypass valve could be sticking then shutting... it's only got 8k on it and was deal installed last year... any thoughts
Sorry for crashing your thread

 

Giggle and lube it. Check your boost port vacuum hose.

 

The bypass valve?

 

My next question for @WOODEX M.E. is, did you install the Spec-U headers right before, near, during the spark plug change?

 

Yep, I checked online an when I asked the dealer the part number they told me matched up. They are the same ones that originally came with the kit.

 

No problem, we all need help. I agree with Tor, try lubing it. Also you can do what I just did and purchase a vacuum puller and you can gently cycle the bypass valve in and out to see if it is behaving properly. its $35-50 for the tool.

 

I know what you are thinking, good eye, but I have had those installed for about 18months. When I put on the headers it dropped from the about 8.5-8.7psi to the 7.5-8psi area. Which would be my current setup.

I sprayed soapy water on that area where the aluminum lid bolts on to look for a leak and its all sealed tight.

So far the only thing I have been able to make changes with is the belts. If I swap to the old belt, boost goes up to 6.8psi and if I use either of my new ones its down to 6.2-6.4psi. None of which are coming to the 7.5+ I should be seeing with my setup.

I could check the spark plugs at some point. I know if those are loose then boost could leak by. Are these threads they go into aluminum? or are the sleeved and tapped? When I was putting the new plugs in I was concerned about stripping the threads on the head because it didn't "feel" firm/right.

 

Belt change in design perhaps?

The lid might not show a leak, until under boost. However, having the immediate difference between belts shows it is something drive related.

Frictional differences. Tighter belt will increase that resistance. Makes me think that a bearing perhaps is not moving as freely as it used to.

Try removing the belt and spinning the pulley. Listen for any odd noises. See how much you can pull or move the shaft.

How many miles does your s/c have? Thinking oil perhaps?

You might have to pull it again and check over everything. There might be something hiding.

If you do pull it off, silicone the lid when re-installing.

 

Another thought (but doesn't account for the boost change with only belt change) is bypass valve adjustment. If you had s/c off, then re-installed you may have bumped the bypass valve enough to bring it out of alignment (possibly not fully closing under boost). I have not installed my s/c yet but I adjusted the bypass valve butterfly screw about one full turn to ensure I don't get any boost bypass when the valve is closed.

You can check/adjust easily without disassembling anything as long as you can get to the butterfly adjustment screw (allen head). The idea here is to ensure the bypass valve stop hits the adjustment screw "just" before the butterfly fully closes in the s/c housing which could cause binding.

Manually open bypass valve and let it spring back quickly. You should hear a definite metallic "ting" sound. This is the bypass valve adjustment screw hitting the bypass valve stop. Adjust butterfly adjustment screw IIRC counterclockwise in 1/8" increments and repeat the "ting" test. When the butterfly is actually fully closing against the s/c housing instead of against the adjustment screw, you will hear more of a dull thud instead of a metallic "ting" sound. Now turn the adjustment screw clockwise in 1/8" increments and listen for the difference in sound. You should hear the "ting" sound again. Your bypass valve is now adjusted perfectly. Repeat the manually open spring closed a few times to ensure no butterfly binding and a consistent "ting" sound and you are good to go. A perfectly adjusted bypass valve without any disassembly.

 

I did spin it when I had the belt off and it seems to spin freely. There is some backlash from the worn drive coupler, which is also apparent from the rattle when the vehicle is immediately started as when it is shut off. It doesn't slide in/out any so that's good. The charger has about 80,000 mile on it and I changed the drive oil at about 25,000 ago.

I am trying to avoid taking it off again as I may need to helicoil a bolt hole that got stripped. Fortunately I did silicone the lid when I put it on last and that has seemed to alleviate my fear of leaks, that and the soapy water and revving the engine. If it comes to that, ill pull it off and send it to get it rebuilt considering mileage.