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Exhaust cutout causing KR and misfiring

Wsmccoy

Wsmccoy

New member
So I have a 07 GP turbo. I just installed an exhaust cutout and went for a drive with it open. When I get into the throttle, just like half throttle, I get a ridicules amount of KR and get misfires on pretty much all cylinders. On the last run I even tried I was at 56% throttle and I got a spike of 14.9 KR. Of course it was followed by lots of misfires, I would assume cuz I went to 0 degrees timing, sounded like I had an anti lag switch. Anyone have any idea what it could be? Oh and I do have hpt to tune with.
 




Anybody have any idea what it could be or what I can do? I know I can just leave it closed but I want to be able to run it at the track in the spring
 
you can still make full boost on half throttle... And when the cutout is open you will make more boost faster.

What is your AFR before it starts missing? Commanded and actual please.
 
I was making full boost a lot quicker, I could really feel the difference even at half throttle. Commanded for closed loop is 14.7 and for open loop it stays between 11.7 and 12.1. When i drove it with the cutout open my AFR was all over the place and really lean. When I did get into the throttle I just noticed my injector duty was at 110% where on all my previous scans it would be around 70 and 80 at the same throttle and gear. My LTFT's and STFT's were also jumping around really bad which it never does. just before I started seeing KR my AFR was at 13.2 and i was at 56% throttle. I'm still kinda new to tuning thats why I want to get opintions before I start doing anything but I was hoping to get things worked out this weekend. I just don't understand how the cutout is effecting everything so much.
 
I thought this was rather odd myself as it wouldn't seem it would ping just by having a cutout. Sal actually had a similar problem I believe he actually ended up running faster IIRC by closing the cutout. Unfortunately, he doesn't get on here often but does frequent clubgp. I would recommend sending him a pm. His name is Silver2K1 or something similar, he has a silver GP in his sig doing a burnout. Makes me want to close my cutout and scan to see if i notice a difference. Weather permitting ill do that this weekend.
 
Well I could feel it was a lot quicker before I saw KR. I'm wondering if the cutout is coming in contact with something maybe the swaybar and creating false knock because its not steady knock. It will go from nothing and spike up to crazy KR. So I'm going to crawl under the car and see today
 


Wsmccoy said:
I was making full boost a lot quicker, I could really feel the difference even at half throttle. Commanded for closed loop is 14.7 and for open loop it stays between 11.7 and 12.1. When i drove it with the cutout open my AFR was all over the place and really lean. When I did get into the throttle I just noticed my injector duty was at 110% where on all my previous scans it would be around 70 and 80 at the same throttle and gear. My LTFT's and STFT's were also jumping around really bad which it never does. just before I started seeing KR my AFR was at 13.2 and i was at 56% throttle. I'm still kinda new to tuning thats why I want to get opintions before I start doing anything but I was hoping to get things worked out this weekend. I just don't understand how the cutout is effecting everything so much.
Click to expand...

this entire post is exactly what's happening.
 


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