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boost delayed? :(

wickedfrisone

wickedfrisone

New member
So I thought I might have had a bad boost bypass valve/solenoid because I noticed I wasn't getting more than half boost on the gauge, but turned out I was just going easy on him. But I still have delayed boost, as in when accelerating hard the engine will rev and do all the work for maybe 1-1.5 seconds as though I had the SC Belt off and then the boost will kick in and the Pumpkin rears accordingly.
Bypass valve/solenoid still a possible culprit or anything else I should look at?
 


boost is RPM reliant with a sc. so you wont see full boost till you hit the top of the rpm range, aka right before it shifts.
 
Weally...cos I swear he used to get more instant boost before...ah maybe I'm becoming an old granny too soon and I don't floor it like I used to. :D
And surprise: another irrelevant question from yours truly..
Brake pedal clicking sometimes when being depressed - can feel it and it's audible too. Cause for concern? :/
 
A roots blower will go straight to 90-95% of what it should be making straight away, there is no real delay with this style supercharger. You'll peak boost right before the shift but there should be no delay. A centrifugal supercharger will take a long time to reach boost as those are rpm dependent.

You can even data log this, if hold first gear or make sure it didn't downshift and you just stab the throttle at speed it'll come up to 6-8psi very fast.

Hard to say what you are feeling. Maybe the throttle blade is closing to help with traction control if DBW or it revs, waist a second, downshifts and moves out.
 
Hmm...I dunno. It's usually getting on the freeway that I notice it (because that's usually where it's safest to really floor it), right after clearing the ramp and finding a chance to merge, I will do it and of course engine revs by itself for the second and then the boost suddenly wakes up and car lunges forward. I know it used to be that I could floor it (but not literally /completely) and the boost was instantaneous and there was no disconnect like this between the engine and SC.
 
Are you sure it's not just a second or so until the trans is downshifting? Try it again at a merge point, but hold it in 2nd at about 40 mph and nail it. I'll bet the acceleration is instant.
 


I'm wondering if the boost bypass valve on your supercharger is heavily gunked up and sticking open temporarily. I recently pulled one off of my parts car that was so gunked up I could hardly turn it by hand, I could only imagine the impact it would've had on the responsiveness of the valve when it was being operated by the vacuum system.
 
With the vehicle off, try moving the valves handle back and forth by hand, and see if it feels very stiff or sticky.

The one in this picture:


0LUbvDHl.jpg
 
I will try both of your suggestions on my way to work later and when I get out of work for the valve (as I wouldn't have enough time now before work to check that)
Thanks
 
Okay, at work right now but I can make a quick post. Tried on the highway again but still found varying amounts of delay in the boost (half second /second) and I just checked the valve and it initially is a bit difficult to lift the handle but then the rest of the way it is easier to fully lift, did it a couple of times and was the same.
 
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