belt slip? boost actuator?

[darkagentL]

Ok. I research on this forum constantly. Here's my deal. I go WOT from dead stop or rolling and i see maybe 2lbs through first then it gains a tad into second then about half way through 2nd it jumps to 9 or 10lbs. I know about belt slippage but isn't that more of a high RPM thing. Once it gets up to 9 or 10lbs it stays there as long as I'm in it. I thought maybe the boost actuator wasn't adjusted right so I followed the advice on here for adjustment and when I loosened the bolts it kind of sprang up about 1/4 inch then I set the lever barely on the stob and tightened her back down. No change. Truck has 30,000 all stock(swiss cheese airbox mod) and I changed the belt at 20,000 gates green. Belt doesn't seem real snug but you can't squeeze it together above the idlers. A slight dusting on the underside of the blower snout. I never hear any squealing or such noise. Is there something I've not found yet that could be causing this lack of boost? Is it feasible to think maybe the gauge is hosed or the line to it maybe? Any suggestions here are greatly appreciated. Thanks.
Matt

 

[CHUXSVT]

if theirs black residue under the snout, then yeah its slipping. who gave you the belt size.

 

[203Cree]

I'm not sure how much I'd trust your guage. Does it pull smooth all the way thru the gears, other than the normal gear changes?

 

[darkagentL]

CHUXSVT.... I know it may be slipping a tad but wouldn't it slip more at high rpm than low?

203Cree... The truck pulls smooth and hard but the gauge jumps quickly midway through second from around 4 to 10 and stays there.

 

[darkagentL]

wouldn't you feel the slip?

 

[203Cree]

One easy way to find out. Which is cheaper? Idler setup or boost guage? Personally, if it's pulling hard all the way thru, I'd blame the guage. And when it jumps, is it a quick jump, or a smooth steady one?

 

[SVT99RED]

It would slip way more in high rpm... when it jumps from 2 to 10 #'s do you feel a huge power increase???

 

[CHUXSVT]

if it slipps the blower whine goes high then low. the boost gauge should shoot right up once you mash the throttle. mine does at least.

 

[darkagentL]

ok just went to the store. 2-4lbs til midway 2nd gear then climbs hard and fast and yes i can feel it pulling harder as the gauge jumps. The needle seems erratic not really a smooth climb, a jump is the only way i can describe it like it snags then lets go. the blower pitch climbs with the boost gauge. Not high then low. I really hope it's the belt. both idlers are shiny where the belt runs. I'm gathering mods now so if it's something else i'll know in a couple of weeks with new lower, belt and auxiliay idler. I just thought maybe there was another quirk i hadn't stumbled on like the boost actuator. Thanks to everyone for the help and suggestions. I thought it might be something I could get under warranty before modding the truck. lol

 

[CHUXSVT]

if i had a warranty, i would take it in.

 

[darkagentL]

how about i loosen the boost actuator and force it all the way down. that keeps it closed right? will it hurt anything to try and see what happens?

oh and I live in bum phuck Tennessee so I really don't want to take it to the dealer unless i have to.

 

[HalfTime]

Just a thought, but what if your boost bypass is being retarded? Or whould that not affect your boost lv? I don't know, just tossing ideas out thier. But to me it really sounds like your S/C bearing are not wanting to spin up, so it is causing extra resistance on your belt, causing it to slip until they catch up.?.? I dunno, ignor me. Good luck.

 

[LightningMAS]

where in TN u live in man???? i am in Franklin..

how much is the black lil tab that flips up and down on the s/c.. mine got bent .. plus im gonna need a new boost actuator to.. how much is both of those?

 

[darkagentL]

i'm up above Knoxville. I pulled the belt and everything spins freely. The belt doesn't look glazed or sparkled. I haven't messed with the actuator anymore yet.

 

[darkagentL]

help!

Now I've installed a CAI, 4lb lower, belt and predator tune. Still the exact same thing 2-4 lbs until midway through 2nd and then it climbs to.... well i don't know exactly it pegs the boost gauge now. Somebody help me here I've read that the boost actuator should be down against the stop with the truck off, and all the way up when started, then when you hit the throttle it should move down towards the stop...is this correct? Mine doesn't move when you hit the throttle, stays all the way up. Is this theory valid... My boost actuator is either mechanically or electrically being delayed after WOT until mid 2nd gear. What do you guys think? Is there a way other than getting a new boost actuator to tell if this is the problem. Can you gag the thing? Will unplugging it disable it? :shrug:

 

[SVT99RED]

where in TN u live in man???? i am in Franklin..

how much is the black lil tab that flips up and down on the s/c.. mine got bent .. plus im gonna need a new boost actuator to.. how much is both of those?

I have a boost actuator i just bought off of fade2black and it wasnt the problem... I paid 50 shipped and will offer it to you for the same price if you want it... :burnout:

 

[TriPodRacing]

If you think you boost by pass is staying open. You should loosen the 2 20mm bolt holding it to the blower and push it all the way down. Then tighten the 2 10mm bolts back up. You will get instant boost response. It won't hurt anything but your MPG. I have run my truck like this for over 20,000 miles with no problems.



If you still don't see the boost on your gauge. Try an aftermarket gauge. If that gauge does the same thing then look elsewhere.

I might have an old Autometer boost gauge laying around that you can try if you want. Let me know. :thumbsup:

 

[darkagentL]

Thanks for the tip Joe...and the offer. I'll try that tomorrow. I'm confused on the postioning of the actuator though. I though that under normal driving it was open(in the lever up positon) and then when you go WOT it travels closed(in the lever down position. But what your saying is to force it into a constant lever up postion so that would mean that up is actually the closed position and lever down is open? Somebody clear me up here please? I really think the gauge is working right because as it climbs through second you can really feel it seat of pants. Once it gets to max boost (pegged) it stays there til you let out. :shrug:

 

[TriPodRacing]

When the actuator is adjust right it should work as followed. With the engine off the shaft on the actuator should be out (fully extended) which would close the by pass butter fly valve. When the engine is running at idle and under vacuum the actuator will pull up on the arm and open the by pass valve. Under boost it will close the actuator.

So if you loosen the bolts and push down on the actuator,so to bottom out the arm. The valve will stay closed all the time.

With my truck running and the actuator adjust correctly it will pull up the by pass valve. When I blip the throttle from under the hood I can watch the actuator move down and up.

 

[darkagentL]

Thanks for clearing me up on the actuator. I adjusted it all the way down and it seems a little better but I'm still not seeing full boost until the top of 2nd. Just normal boost lag while the s/c comes up? Maybe a little belt slip under the low end torque? I did notice that now when I hit the throttle under the hood I see the arm moving down where as before it wasn't. The truck feels really strong so I'm happy and I'll see what kind of 1/4 mile increase when the local track opens this Spring. In the meantime I've got a few more goodies to install before I get the custom tune and dyno done. BTW that's one hell of a picture in your signature there! :beer: