RPM bounce when going in N

Quadrider10 · 2019-10-09 23:19:50

SEARCH IN THE CURRENT AND SHOW ME Index Evo X Evo X General Quadrider10 online MemberJoin: Jun 2019Posts: 30 about 12 hours ago ? #1 RPM bounce When going Into N I'm getting hella weird idle issues where after driving, if I push the clutch and go to N, the RPMs drop to 900, bounce up to 2k-1.5k then settle at 1500 until I stop physically moving. Also when I kick the AC on, RPMs go crazy for a few seconds then settle at 900. This has been a constant issue where it does this same thing every time. Sometimes bouncing 2-3 times before settling at 1500 until stopped. So far I've checked for vacuum leaks. Sprayed the whole engine down and found nothing. My AP is reading -9.7PSI along with my vacuum guage reading 20.5InMg. So that's perfect. I ran a compression test and all cylinders were at 180PSI give or take 5 from each other. The car is bone stock except K&N drop in filter and an AP. The issue started when I installed the AP and the ECU got reset. I have tried all the Cobb OTS tunes, my speed circuit OTS tune, and factory tune with the AP uninstalled. All do the same exact thing. I've seen post and videos online of this exact issue, but no solutions. What I'm going to try next is: Change spark plugs Though I have some serious doubts this will actually fix anything. So does anyone know what's up with this car? It's running perfect otherwise. No loss of power and I'm hitting target boost. Here's a vid of the exact issue except not my car: https://youtu.be/gKhi_RTCnq8 I swapped the fuel pump relay, cleaned the MAF, cleaned the TB, and disconnected the batter for am hour. Issue got worse. However, yesterday when I was driving around hard, I noticed that at about 6-7k RPMs, I heard a rattling sound. Sounded like a heat shield vibration. I took the intake off and looked at the compressor wheel and saw scoring around the body. I moved the shaft and it has some up and down play, maybe 2-3mm of movement. From the looks of it, it's touching the housing and causing the scoring and noise.

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Oct 9, 2019 | 04:19 PM

Quadrider10

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RPM bounce when going in N

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Quadrider10

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MemberJoin: Jun 2019Posts: 30

about 12 hours ago · #1

RPM bounce When going Into N

I'm getting hella weird idle issues where after driving, if I push the clutch and go to N, the RPMs drop to 900, bounce up to 2k-1.5k then settle at 1500 until I stop physically moving. Also when I kick the AC on, RPMs go crazy for a few seconds then settle at 900.
This has been a constant issue where it does this same thing every time. Sometimes bouncing 2-3 times before settling at 1500 until stopped.
So far I've checked for vacuum leaks. Sprayed the whole engine down and found nothing. My AP is reading -9.7PSI along with my vacuum guage reading 20.5InMg. So that's perfect. I ran a compression test and all cylinders were at 180PSI give or take 5 from each other.
The car is bone stock except K&N drop in filter and an AP. The issue started when I installed the AP and the ECU got reset. I have tried all the Cobb OTS tunes, my speed circuit OTS tune, and factory tune with the AP uninstalled. All do the same exact thing. I've seen post and videos online of this exact issue, but no solutions.
What I'm going to try next is:

Change spark plugs

Though I have some serious doubts this will actually fix anything. So does anyone know what's up with this car? It's running perfect otherwise. No loss of power and I'm hitting target boost.

Here's a vid of the exact issue except not my car:

https://youtu.be/gKhi_RTCnq8

I swapped the fuel pump relay, cleaned the MAF, cleaned the TB, and disconnected the batter for am hour. Issue got worse.
However, yesterday when I was driving around hard, I noticed that at about 6-7k RPMs, I heard a rattling sound. Sounded like a heat shield vibration. I took the intake off and looked at the compressor wheel and saw scoring around the body. I moved the shaft and it has some up and down play, maybe 2-3mm of movement. From the looks of it, it's touching the housing and causing the scoring and noise.

Dec 8, 2019 | 04:49 AM

gomcar25

Evolving Member

Joined: Aug 2011

Posts: 116

Likes: 0

From: Northeast PA

So back in September I had some stuff done at a shop, and AP tuned, and I too have this RPM issue. I assumed this is an AP standard tune... that in my case the tuner isnt actively getting rid of.

Not sure what the official answer is, but I'm currently pointed right at the AP tune as the issue.