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Boost spikes then falls

E

echostatic

Turbooo
I've noticed that my boost will ramp up quickly to 18lbs, then drop down to 15lbs about a second later and hold steady there. I guess that's s boost spike. Anybody else experience/stop this?
 
What boost system are you using? If you are using the stock "Y" wastegate hoses get rid of it. Buy an RJC boost controller and run a hose straight from the wastegate to the turbo.

I had this issue on the stock turbo, albeit at higher boost, but the rerouting of the boost lines fixed it.

I'm assuming this is at WOT?
 
I'm wanting to say it was a turbosmart single stage boost controller I got... It was years ago and the thing has no sticker or label on it. Still got the stock Y WG hoses, and yes it is at WOT.
 
echostatic said:
I'm wanting to say it was a turbosmart single stage boost controller I got... It was years ago and the thing has no sticker or label on it. Still got the stock Y WG hoses, and yes it is at WOT.
Click to expand...

I don't know a dang thing about that boost controller. Is it electronic? Sit in the interior? Does it work?
 
It's a manual controller mounted in the engine bay around the passenger side valve cover. It's worked well before, with the stock turbo. I would get a spike of maybe a pound when running 22lbs of boost but that was it.
 
echostatic said:
It's a manual controller mounted in the engine bay around the passenger side valve cover. It's worked well before, with the stock turbo. I would get a spike of maybe a pound when running 22lbs of boost but that was it.
Click to expand...

Take a picture please.

I think it is just a grainger valve. If that is the case route the hoses like I suggested.
 
I must have some other issue going on, I romped on it some on my lunch real after maxxing the boost controller. It got close to 20 before dropping to 18, then falling to 15 a couple seconds later.
 
I've never used header gaskets and they didn't have any cracks when we put the motor back in.

As far as the boost controller, here's the mounted unit.

029c479e.jpg


And it tees into the vacuum lines here

b49a7f10.jpg
 
Try bypassing the boost controller all together. Put a piece of hose from the turbo to the actuator....
 
Quiky One said:
First and foremost, put a ziptie on the connection to the turbo.

I see wires going to it...what are they for?
Click to expand...

The wires run inside the cabin to a switch. Flipping it will enable or disable the controller, effectively giving you two boost levels to work with.
 
I feel silly. But it's worth a simple and easy fix. I shortened the wastegate actuator rod by about 3 turns... It hits 20lbs and stays there now. I guess it was too loose. My boost controller is maxxed though, I suspect replacing it will get me more boost. I wanted the RJC boost controller anyway, so I'm gonna buy that.

It feels pretty good at 20lbs. I wasn't able to stay in it for long though because I was on city streets and it gets up to 60-70mph in no time. I noticed that turbo isn't making much power until you get north of 10lbs of boost, so any reduction of spool up time would be great. Apparently thats a benefit of the RJC unit.
 
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