woohoo, no boost

Yes, it is already on the inlet side. To boil down my post up above, with the bypass closed there is enough vacuum on the inlet side to allow the bypass to open back up. At least partway. I am going back over now to play with it. Somehow, some scalars in my tune got themselves set to values that don't make any sense, so I corrected them.
 
Doesn't the inlet plenum and everything before it stay at vacuum even under boost so wouldn't it make sence that even under boost the bypass would stay open because the pressence of vacuum? I really think he should connect the bypass to the return plenum, fix his tune, take care of his belt slip then see how the car runs. Though jonathan I would take care of the belt slip before 100 percent tuning it because its not going to make full boost.

Shane
Glynn Motorsports
 
Can't get there from here...

with the bypass closed there is enough vacuum on the inlet side to allow the bypass to open back up.

A closed bypass indicates vacuum not happening...

If the engine is capable of generating 'enough' vacuum to operate the bypass properly, there is no chance of a simultaneously occurring overriding condition. You can't have both (when the controller is ok and properly connected), sorry.
 
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I think Jonathan might not be explaining this correctly so I will explain what I saw. Like normal when he starts his car vacuum plus his bypass valve closed, but when jonathan stabs the gas to make boost the bypass valve does not close or it moves just slightly but no where near what it should. At idle he is getting 16 inches of vacuum.

Shane
Glynn Motorsports
 
>when jonathan stabs the gas to make boost the bypass valve does not close or it moves just slightly

Does that really make sense (meaning you really think it's hooked up properly) to both of you guys?

Forget engine operating the bypass controller and check how much vacuum it takes to work the bypass controller via a test (vacuum/pressure) hand pump.

Compare his to another car.

Then correct the vacuum supply issue and be done :)
 
No I am not saying it is hooked up right at all right now. I am only saying what it is currently doing. To hold the valve open using a hand pump it takes around 15 inches to hold open and it will not leak. The problem, as I saw it, is that under load vacuum is not being taken away from the bypass valve.

Shane
Glynn Motorsports
 
I should jump in. Would have sooner, but I played with the car long enough to almost be late for work. So I said it was on the inlet side. Well, it WAS. It was on the vacuum distribution block per the vacuum diagram posted in here somewhere. Anyway it was hooked up to the inlet side. Well somewhere along the way when I put it together a year ago that block ended up on the return side. So I have to redo my vacuum again. Anyway, I moved it to the inlet side, and all good now. Dave, I don't like it on the return side :). Anyway I have to redo my vacuum. Anybody know what thread Charles uses on the fitting ports on the MPX inlet plenum? I measured one at 3/8-27. The fittings with barb ends or vacuum ends at Advance all have pipe thread. And I have never seen anything with 27 thread count. That is acurate, btw, I checked it with a thread gauge. There is a plug there that I want a fitting for for the bypass tube.
 
>Well somewhere along the way when I put it together a year ago that block ended up on the return side. Anyway, I moved it to the inlet side, and all good now.

Hey, that's good news...thanks for the report and good luck w/the rest of your fun :)
 
>Well somewhere along the way when I put it together a year ago that block ended up on the return side. Anyway, I moved it to the inlet side, and all good now.

Hey, that's good news...thanks for the report and good luck w/the rest of your fun :)

Thanks man. I've gotten so frustrate with it I've been eyeing that quarry not far from me. Wouldn't start, turned out I made a bracket for the crank pickup out of steel. The crank pickup is Hall-effect, so magnetic. Got it running, and my new used "worked fine" trans gave out. Rebuild the trans (that was actually fun), then ran into this. But now I am down to normal problems at least .

Speaking of, I got the belt slippage toned down. Used a powerstroke steel pulley. I had to kiss the tensioner with a die grinder to make it fit, but its on there now. Now the boost just hangs at 15 psi, or goes back down, but no more fluttering.

I know there were posts about this before, but I searched belt slip and got a bunch of results. Haven't been able to get through all of them. I will try smaller belts, but I don't know how the sizing affects the fit on this belt system. I might even need to mess with the jackshaft system, but I don't know if I can stuff the powerstroke pulley into there. Anyone remember where that thread is, or have experience on where to go next?
 
Ever thought just trying a different vacuum bypass diapham just to eliminate a source? I know you said it seemed to work and closed with 15 psi of vacuum but I would still change it and hook it to the inlet plenum side.
 
Glad you found your problem, now get that damn thing tuned in properly :rolleyes:.

I was wrong which is nothing new, but I would focus on getting the tune setup close to reality before running the car so it would eliminate it being the problem... different school, different thoughts I guess.

Have fun.
Fraser
 
I understand how the tune affecting it could make sense. Either way, you're right, I need to get it tuned. I just got my wideband put together, so I can start from there.
 
Well good news, I got it on the dyno. Got absolutely nothing accomplished, though. We commanded 11:1 AFR, for %70 absolute load on up, but the PCM absolutely refused to go below 11.6-ish. And I couldn't get the rev limiter to go away. And it poured about a gallon of coolant out the back at the end of the very last pull. The good news is it made 22 psi, 300hp and 350lb/ft on mostly 12.8 AFR from the wideband without a hint of knock. If I can find these lambse and rev limit problems those number should go up significantly I would think.
 
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