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Old 08-10-2008, 09:11 AM   #1
mapleleaf
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Member#: 103399
Join Date: Dec 2005
Chapter/Region: E. Canada
Location: Halifax, Nova Scotia
Vehicle:
2009 Stripped STI
Dirty White

Default High RPM hesitation, missfire, studder

A couple of night ago I did a 4th gear pull and noticed a studder or hesitation.
Feels a little like a missfire, but not throwing a code.
Last week I replaced my plugs as I was getting a #1 and #3 cyl. missfire code at a track day. After I replaced the plugs all was well.
Compression is good, no smoke, no obvious signs of ringland or piston problems.
I took it out today to run a couple logs, unfortunately my cable did not want to cooperate.
This is mostly occuring in 4th or 5th at over 4500 rpm when I'm making my highest boost. At first it was just a hiccup and felt like it was pulling timing, now it is more of a buck and much more prominent as I was trouble shooting and running through the gears. At 3/4 throttle it is fine to redline.
I run 23psi in 4th and 5th, 20-21 in 3rd gear. It usually does not happen in 3rd unless I run through 4th at WOT first.
It does not seem to be an issue in 1st and 2nd at all. It is similar to when I tore an IC Y pipe years back on my 2L.
Just trying to gather the usual suspects, inlet leak, Y pipe leak, burnt valve,
clogged injector, etc.
I'll try to pressure test the system and check for leaks and torn hoses tomorrow.
It's unfortunate because the car is right about to go to make room for my new one. The car has been trouble free since I owned it up until I swapped plugs last week.
It's an 06 WRX on meth.
Any feedback would be appreciated
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Old 08-10-2008, 01:34 PM   #2
rhinotech
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Location: Cajun Country
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Rollin' hard...

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you sure it's not boost spiking?
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Old 08-10-2008, 02:02 PM   #3
mapleleaf
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Dirty White

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I've never had an issue in the past, I doubt it.
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Old 08-10-2008, 02:22 PM   #4
06redsuby
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red

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it could be your meth kit whats your water meth ratio?
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Old 08-10-2008, 11:23 PM   #5
mapleleaf
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Quote:
Originally Posted by 06redsuby View Post
it could be your meth kit whats your water meth ratio?

50/50

I'll run my pump map tomorrow.
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Old 10-25-2008, 03:04 PM   #6
kuldud
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i am having the exact same issues right now. any input from the guru's out there?
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Old 10-25-2008, 04:40 PM   #7
mapleleaf
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Quote:
Originally Posted by kuldud View Post
i am having the exact same issues right now. any input from the guru's out there?

Check for vacuum leaks. Throw it on a smoke machine and do some pulls with a data logger. I had a torn inlet.
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Old 10-25-2008, 04:50 PM   #8
silver-duck
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When you changed the plugs you may of damaged the coil pack.It will fire except under the most boost[cyclinder pressure]Check the spring in each coil pack that carries the spark to the plug.This happened to me and it is hard to locate[same symptom's as you describe].
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Old 10-26-2008, 03:40 PM   #9
kuldud
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Quote:
Originally Posted by mapleleaf View Post
Check for vacuum leaks. Throw it on a smoke machine and do some pulls with a data logger. I had a torn inlet.
smoke machine ey? how does one do that?

did some datalogging already and everything looks ok. it's holding boost at 22.05, no spikes and no -kc at WOT. slight hesitation was there at 4th around 5500+ rpm but it goes when pressing all the way to WOT.
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