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Discussion Starter #1
On my recent Whipple install I've been using a tune sent to me by Livernois and overall it's worked rather well. I've only had one real item I've been trying to track down and I'm not 100% sure if it's tune or hardware based. Off boost the car drives and feels very much pre-Whipple, WOT it's well it's a supercharged LS3 nuff said there. The area where something feels off is gradual rolling into boost from vacuum. It feels like right where the car transitions from like ~1 to 2 inches of vacuum till boost there is what feels like a hesitation. It's only right there and seems to be in that window, it ends with what feels like a surge of power like something was stuck for a second. It's not a smooth transition. Under mild throttle when this happens it feels like a 50 shot of nitrous hitting, nothing earth shattering but very abrupt. Medium to heavier throttle it's felt as well but shorter duration and more ooomph. WOT doesn't feel like it's really there but then it could be but happens so fast I'm not sensing it. This all kinda makes me feel like it's tune based because the ramp in pressure or air/fuel just aren't meeting the tables expectations.

Now here's where the thought of mechanical comes to mind. During this short window (or long if the throttle is held right on the edge of switching over) there is an distinct audible shrill or whistle (no not the SC) that sounds like a lot of air being sucked through a tiny accordion straw. As soon as the boost starts the sound stops immediately and doesn't seem to do it rolling out of boost (need to test this better). My first thoughts were the bypass valve wasn't set properly or it's stuck. I've tested it with a vacuum pump and due to a different problem with it was replaced with a new one from Whipple. I've also preloaded the bypass by setting it closer per Whipples instruction to see if that did it. Nothing helped. I have checked the hoses and they seem fine and secure. I've also looked everything over for obvious leaks as well with nothing showing up. The car idles and drives fine other than this with no codes.

Whipples been very helpful but I understand they’re limited to a point because it’s not their tune. I’ve reached out to LMS today as well to see if they’ve heard of this before. I also asked them if I'm able to roll back to the stock tune with the mycalibrator and then load the stock Whipple tune via HPTuners to see if this solved it. That could at least potentially rule out the tune side of it. Has anyone experienced this previously or have some suggestions? The bulk of my online queries end up coming back to the 6G mustang guys who experienced something like this like 2 years ago with Whipple chargers but it looks like it was solved with some tuning (that problem was different here, was a cam timing issue).
 

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Steve,
I am no expert so just my thoughts here, along with phone questions and info from tuner dude down here...


The bypass valve is spring loaded, make sure there are NO kinks, pinch points on the vacuum lines feeding the bypass valve.It still could be a slight diaphragm issue only under load to unload condition.
I agree there may also be small issue in the A/F table in the phase change from non-boosted to boosted operation.
(My) tuner dude says "it don't take much in that area for it to feel if it were falling on it's face for a second or two before boost comes in and WOT happens, and all is good .


The only real way to see is Dyno time and watching what the duty cycle on the injectors is doing verses what A/F ratio is saying, verses just what boost pressure is doing. per turner dude.
Did your tune also improve the Trans pressures for shifting under load? (Not my question not smart enough to ask it) Tuner dude question.


Good luck,


Cheers,
tp
 

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Discussion Starter #3
Steve,

The bypass valve is spring loaded, make sure there are NO kinks, pinch points on the vacuum lines feeding the bypass valve.It still could be a slight diaphragm issue only under load to unload condition.
I agree there may also be small issue in the A/F table in the phase change from non-boosted to boosted operation.
(My) tuner dude says "it don't take much in that area for it to feel if it were falling on it's face for a second or two before boost comes in and WOT happens, and all is good .

The only real way to see is Dyno time and watching what the duty cycle on the injectors is doing verses what A/F ratio is saying, verses just what boost pressure is doing. per turner dude.
Did your tune also improve the Trans pressures for shifting under load? (Not my question not smart enough to ask it) Tuner dude question.
Thanks fully the vacuum line for the bypass is one of the easiest to check as it's only 3 inches long :) To be safe I even replaced the hose that came with the kit for good measure.

Regarding the trans pressure for shifting, I'm a lucky 6 speed manual guy so only pressure increase is on my sphincter when I floor it :grin.

LMS got back to me just a short while ago and they want me to test it on the different traction control modes. I'll give those a whirl tonight when I get out of here. Although I have been using track mode a lot more lately, oh momma THATS how the car should drive all the time. I love the steering and pedals firmed up.
 

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Mine had a similar issue and I had a kink in the vacuum line fir the bypass valve. I cut the line down shorter to eliminate the kink. But it sounds like you’ve already eliminated this from your testing.
 

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Have you checked the range of movement for the bypass valve? It can bind if installed in a certain position.
 

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Discussion Starter #6
Have you checked the range of movement for the bypass valve? It can bind if installed in a certain position.
Good call on that I'm gonna check that on lunch with the car running. I've looked at it when the car was running on the old one and the bypass was working at idle. It held the bypass plate open at roughly a 45 or like \ - against the set pin on the SC. I would have thought it was further back but honestly I can't remember if the car was warmed up or not so that could have played in to it.

So what kind of vacuum levels are others seeing on the engine after it's warmed up? I need to get a mechanical vac/boost gauge installed as I learned from many days with turbo'd cars the vacuum side of things can be a great indicator of engine / tune health. I can see what the HPTuners is showing but I still need to figure out how to convert it from the map reading of 3.6psi at idle to vacuum-->boost. I see there's a formula or calculation for it in one of the drop downs at the top. Just need some time to learn more about the app.

I tested the LMS suggestions last night with the different modes and it does it in all 4 modes. It seems more pronounced in 2nd and 3rd gear at @2500+ rpm. If I rolled in med hard at <2k it did not seem to do it that I could tell.
 

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I can tell you right now, its not mechanical. Its the tune. Have them fix it.
 

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My tune that Whipple sent me had a hesitation off idle acceleration and would set long term fuel trim codes occasionally. I spoke with Whipple and they said I probably had a vacuum leak. They supplied me new intake gaskets and I was very careful the second time and guess what? Same thing. The tunes they supply are generic and if I were you I would not mess with anything except the basic checking it over until you take it to a tuner (dyno or street tune) and have it tuned/tweaked. There are a few of us that had issues with a generic tune. Look at some of the other Whipple posts.
 

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Both tunes indicate a condition. Both tunes worked for other customers. What is different on your vehicle? Your computer will try to adjust for changes in inputs differently with each tune. After all the common sense diy tests are exhausted, find a shop that can test and tune your vehicle properly. Canned tunes work when all the variables fit in the tuners baselines. Evidently your vehicle does not fit. As evidenced by issues during transitions, you have a condition that falls outside the tunes capability to allow for the smoothing of the changes in fuel, air and spark. Keep trying to figure out what is different with your vehicle. If possible, start over with a quality custom tune and evaluation. I am not a Livernois fan (bad experience) but they should be able to help if they would take the time and have the right mechanic-tuner personally work on your car. Good luck. I have started over from square one with no locked tunes allowed. Custom or otherwise, being trapped in a tune leaves limited options. HP and N Gauge is my option of choice now. You have a great package. With proven results. Keep that in mind and enjoy the good stuff while you work out the small bugs. I salute you for doing your own work. Use outside help when you need it. Even a local garage may sniff out your condition where you can’t find it.
 

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What size restrictor is in the bypass valve? sometimes whipple includes none, sometimes they include the wrong one. Their bypass valve is VERY touchy so the transition from vacuum to boost can happen almost instantly. If the restrictor isn't present, or it's too big this makes the problem worse.

We always suggest addressing the mechanical aspect first as you don't want to tune around an issue, you want a tune to help diagnose issues. Unfortunately most places choose to tune around problems, which can lead to other issues later.
 

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What size restrictor is in the bypass valve? sometimes whipple includes none, sometimes they include the wrong one. Their bypass valve is VERY touchy so the transition from vacuum to boost can happen almost instantly. If the restrictor isn't present, or it's too big this makes the problem worse.

We always suggest addressing the mechanical aspect first as you don't want to tune around an issue, you want a tune to help diagnose issues. Unfortunately most places choose to tune around problems, which can lead to other issues later.
With others having no issue with the exact same setup/tune it is reasonable to gravitate towards a mechanical issue. Especially if a DIY install.
 

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Discussion Starter #12
What size restrictor is in the bypass valve? sometimes whipple includes none, sometimes they include the wrong one. Their bypass valve is VERY touchy so the transition from vacuum to boost can happen almost instantly. If the restrictor isn't present, or it's too big this makes the problem worse.



We always suggest addressing the mechanical aspect first as you don't want to tune around an issue, you want a tune to help diagnose issues. Unfortunately most places choose to tune around problems, which can lead to other issues later.
I just checked and there is/was no restrictor in the line or the bypass balve itself. I've also replaced it as well with a new unit. In still seeing the same issue now and have find some more testing as well. So when I move the bypass back as far as it can go with still touching the set screw the problem seems to be me pronounced. It takes longer to get it to boost ie more peddle needed then when it's more heavily preloaded.

So I'm getting more familiar with HPTuner and getting it setup working for my needs. Today I tested moving the valve back as far as it'll go and still work. What I noticed is that when I'm idling in only seeing about 14 in mmHg vacuum on the absolute intake manifold pressure sensor. It's reading about 36-37 kpa. I would have expected closer to 18 or 19 mmHg. That makes me wonder if something else is amuck. Yesterday I did a diy leak test around the intake hoses and throttle body with no leaks detected. In planning on trying a diy smoke test as well under pressure tomorrow.

What vacuum levels are others seeing warmed up with a Whipple?

Sent from my SM-G965U1 using Tapatalk
 

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What vacuum levels are others seeing warmed up with a Whipple?
Cant tell you what a Whipple pulls until I get mine later this year … but any normal healthy engine should pull about 18-19 like you said. My supercharged Ford pulls over 21 at idle and runs like a beast over 15 PSI. Loss of vacuum indicates an external leak - I wouldn't rule out a faulty MAP sensor if you don't have a mechanical gauge.
 

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Discussion Starter #16
Cant tell you what a Whipple pulls until I get mine later this year … but any normal healthy engine should pull about 18-19 like you said. My supercharged Ford pulls over 21 at idle and runs like a beast over 15 PSI. Loss of vacuum indicates an external leak - I wouldn't rule out a faulty MAP sensor if you don't have a mechanical gauge.
I'm thinking about that as an option as well. When I DIY smoke test today I'm planning on using a mechanical vacuum gauge off the port the bypass hooks to and hold the valve open to get a reading. I wanted to A check the vacuum reading is the same and B see if manually opening or closing the valve more/less changes the vacuum in reading. I'm interested to see if maybe the valve isn't opening far enough and that's why the vacuum isn't low enough. When idling this is where it goes to even though it can go a fair way more.


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OK so I removed the bypass valve and hooked a mechanical vacuum gauge up to the port where the bypass normally does. My mechanical gauge read a solid 18 inches. Moving the bypass arm varying degrees of open made no difference in the vacuum at all. When I hook up HPTuner and log the car without it on the intake manifold absolute pressure matches the barometric pressure exactly, which is 104kpa. So my next step was I wanted to run to the local pep boys and pick up an auto meter vacuum boost gauge to monitor while driving. Then I saw where Whipple recommended to hook it up.

There's a port with a plug in it on the driver side lower intake manifold. Ummm yeah that would require taking the top of the blower off and the fuel rail as well. It's anyone else tapped in for a mechanical vacuum boost gauge and if so where?

Any other suggestions to try? So far all the mechanical things I'm looking at check out fine.

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OK so I removed the bypass valve and hooked a mechanical vacuum gauge up to the port where the bypass normally does. My mechanical gauge read a solid 18 inches. Moving the bypass arm varying degrees of open made no difference in the vacuum at all. When I hook up HPTuner and log the car without it on the intake manifold absolute pressure matches the barometric pressure exactly, which is 104kpa. So my next step was I wanted to run to the local pep boys and pick up an auto meter vacuum boost gauge to monitor while driving. Then I saw where Whipple recommended to hook it up.

There's a port with a plug in it on the driver side lower intake manifold. Ummm yeah that would require taking the top of the blower off and the fuel rail as well. It's anyone else tapped in for a mechanical vacuum boost gauge and if so where?

Any other suggestions to try? So far all the mechanical things I'm looking at check out fine.

Sent from my SM-G965U1 using Tapatalk
Yes the bypass valve position shouldn't have anything to do with your vacuum at idle. On my SC the bypass is vacuum actuated open and when the throttle is opened the vacuum decreases which causes the bypass to move to the closed position - so a faulty bypass valve or restrictor plate inline would have a detrimental effect on the transition from vacuum to boost if your engine is mechanically solid and the MAP sensor is reading correctly ( along with the tune ).

Just trying to sort things out here … so mechanically, your engine sounds fine if you have 18 inches at idle on a mechanical gauge ( with the bypass actuator removed ) - and your PCM is displaying the same readings which is a good sign that the MAP sensor is reading correctly. If you have a mechanical gauge hooked up and it reads 14 inches with the bypass installed, I would say its possible that you have a faulty bypass valve actuator. You should be able to bench test the actuator with your vacuum pump also - it should hold under vacuum but if it bleeds down, your actuator is no good.
 

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Discussion Starter #19
Thanks for the follow up, I have tested the valve with a handheld vacuum pump and it held open. I can also see it staying open while the car is idling too. I don't know if this related or normal with a SC SS but my bad mileage and to have taken a big ol steamy turd. I mean if was never fabulous before as I averaged @17 but I drove it somewhat hard mixed in there. I'm driving less on it now and I struggle to get above 13's I might touch 14.1 on the dash for a short bit but it always drops back into the 13s. If that's the price for the SC so be it, I thought if I stayed out of it I might only see small drops.

I need to learn to read and understand the short and long-term fuel trims.

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Ive averaged 13.5 MPG overall on my SS since I bought it ( 15k miles ) completely stock .. which didn't seem out of the ordinary for my driving habits.


Your short term fuel trim will contribute to the long term - the PCM will constantly adjust the amount of fuel based on operating conditions. So I wouldn't pay as much attention to the short term as the long term - a high long term fuel trim would indicate a vacuum leak of some type where the PCM has to compensate for the additional amount of unmetered air entering the engine ie. the leak is after the MAF sensor which is supposed to read the amount of air entering the engine. If your trim is going the opposite direction it would be something more along the lines of a faulty fuel system or weak spark. But like mentioned above, if you can pull the datalog for the injector Duty cycle versus A/F, and MAP readings ( Im assuming you are using the correct 3 BAR map sensor recommended by LMS ? )


I was formerly an ASE certified Master auto technician / Advanced level performance specialist with two college degrees in Advanced engine performance, Advanced Powertrain and contributor to OBDcodes website if my credentials ever come into question … Ive just been following a few threads related to Whipple superchargers since I am trying to determine if I should go with the Magnusson or Whipple ( need to be CARB approved for California smog ) .. I don't want issues like you are experiencing to come up when I am doing my own install.


Edit: also I have seen soft vacuum lines pinch under vacuum and expand in boost - we used to zip tie all of the vacuum lines on the supercharged Fords I was working on. I have also seen incorrectly routed vacuum lines - from what Ive read the Whipple kit uses a Boost a pump to increase the voltage on the fuel pump, whereas other systems used a vacuum/boost line off the supercharger to increase fuel pressure under boost.
 
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