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Discussion Starter · #1 · (Edited)
Disclaimer: I thought about just hijacking someone else's 4k rpm thread, but changed my mind. I've read several places that the normal 4k hesitation is due to fuel mapping changes, but this is different.

Preface: I posted yesterday in the "what did you do to your car today thread" about cleaning my throttle body because the throttle felt sticky at times. And while that was an issue, it wasn't THE issue. It took me a little while to figure out exactly when it was happening until I checked my logs.

Issue: When I hit 4k rpm at partial throttle, my throttle plate closes a good bit. Even with pedal pressure exactly the same, the throttle plate closes. Which in turn causes my AV6 BOV to open and dump boost which causes the acceleration to slow rapidly, but just for a half second. This only happens at partial throttle though. At full throttle/WOT everything is fine. THIS ONLY STARTED ABOUT 2 DAYS AGO. I looked back through my logs over the past few months, and they all look good.

Question: Anyone else ever experience anything like this? Any insight is appreciated.

Examples: Notice the pedal pressure is consistent and flat.
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And here is a WOT pull with no issue.
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Can you run the log in a zero map, as in off? What mode are you in as well?

The ECU has an issue keeping the butterfly open as it needs to be. This has to do with the throttle-by-wire system mapping. Even at WOT, the butterfly isn’t 100% open. This is something we found out tuning on the dynamometer and it needed to be adjusted in the throttle map.

Initially, it will open as per throttle pedal input. However, when it hits a target rpm it then backs off around 5%, No matter the pedal position. Not really sure why. Originally, we found the same thing in several new 1 liter plus Super-bikes.

I imagine this is what your seeing an feeling in the seat of your pants.👍🇺🇸
 

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Discussion Starter · #3 ·
Can you run the log in a zero map, as in off? What mode are you in as well?

The ECU has an issue keeping the butterfly open as it needs to be. This has to do with the throttle-by-wire system mapping. Even at WOT, the butterfly isn’t 100% open. This is something we found out tuning on the dynamometer and it needed to be adjusted in the throttle map.

Initially, it will open as per throttle pedal input. However, when it hits a target rpm it then backs off around 5%, No matter the pedal position. Not really sure why. Originally, we found the same thing in several new 1 liter plus Super-bikes.

I imagine this is what your seeing an feeling in the seat of your pants.👍🇺🇸
I'm almost always in map2. I've dabbled in map6, and used to run map1, but 99% of the time now, I'm in map2. Because of this, all of my logs in the past 2 days since this has started, have been map2. I've never felt this before, and none of my previous logs (map0,1,2 or 6) over the past few months show this dip happening. I'll try map0 over the next day or 2 to test. I HAVE noticed that even at 100% pedal, throttle never goes above 96% for Veloster Ns, as you said.
If it keeps up after another day or 2, even in map0, I'm going to pull the battery terminal and see if it resets anything.
 

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Discussion Starter · #5 ·
Did my pre-cleaning inspection and confirmed how bad the valves are. At ~15k miles, there is as much buildup as the other valves I've cleaned that were 50k+ miles. Just fishing the scope in through the manifold caked it in carbon. So much that I had to clean the camera off to see again.

This is from 1 swipe through the valve/intake runner. As in, this is just what I wiped off the camera lens.
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Discussion Starter · #6 ·
Well, after about 30 miles since the throttle body cleaning, I double checked it. It's running out of the manifold already. I check the piping from the turbo to the throttle body and it's bone dry. So this is coming from pcv side.
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I decided to pull the manifold and check the valves. They are all uniformly covered, but not as badly as I thought. The runner inserts were about the same. I cleaned them too. Before (right) and after.
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Valves before cleaning
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Check the PCV for proper operation.

Also remember, your putting out more boost with the JB4. So, you’re going to get more blow by at the rings. This creates more Fuel/oil/water vapor that circulated thru the PCV.👍🇺🇸
 

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Discussion Starter · #8 ·
Check the PCV for proper operation.

Also remember, your putting out more boost with the JB4. So, you’re going to get more blow by at the rings. This creates more Fuel/oil/water vapor that circulated thru the PCV.👍🇺🇸
I had that thought too, so I checked the pcv. It is operating properly.

One thing I noticed while testing map0 is that logs show the same throttle closing while at the same pedal input. However, boost doesn't drop off and I don't feel the slow-down in the seat. It seems smooth. Maybe the JB4 just exaggerates the condition.

Also, I noticed I get ton more crackling and popping (and louder) in map0 than map2. I'm not sure why that would make any difference, but it's substantial.

And I cleaned out the valves the best I could with cleaner spray.
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