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Old 08-01-2006, 02:06 AM   #1
austintheen
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Member#: 68861
Join Date: Aug 2004
Chapter/Region: South East
Location: Venice, FL
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2002 Impreza WRX
Silver

Default OTS Stg2 with only DP?

I'm still a noob, so if this is the wrong forum, please move it. Other than that, here it goes. I just finished installing a Stromung downpipe onto my 02 WRX. After that I (upon reading here that it would be *ok*) upgraded my ECU to Cobb Stage 2, 93 Octane 1.30 with my Access Port.

I drove around town and it felt like a dog, AP Live boost said I wasn't getting over 8psi.. Drove back to the house, did a ECU reset and that seemed to go away, atleast it got 13psi the next trip out.

So I started searching on here and found the wastegate actuator rod mod, and tightened that up 2 full turns after running datalogs of the car with ECUEdit. After I was satisfied the car was getting target boost 15.8psi (+/- .5) I started looking at the datalogs. My concern is the knock correction values under boost.

Here's is the engine mod list
  • APS catless UP
  • Stromung Ceramic coated DP
  • underdriven lightweight pulley
  • Cobb AP Stage 2 93oct 1.30
  • snorkel removal

Everything else looks decent to me. It's no protune, but once I get more $$$ I'll get the rest of the toys (TMIC, CBE, pnp Headers, pnp Monster TD05)

Here is a before and after according to my GTech Pro. Runs were done before and after, about the same fuel level and same temp on the same road. I didn't launch hard either time (I like my clutch!).


I'm not sure why the graph is so spiky, it doesn't feel like it surges or anything, I think it might be the pitch factor setting is to low.

So what's everybody think? Is it normal to get 30 HP from a downpipe and reflash?
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Old 08-01-2006, 08:44 AM   #2
Unabomber
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You got a LOT to learn son. If you are only running a downpipe and not a full 3" turbo back exhaust, messing with the wastegate to get the target boost is BAD JU-JU. You probably won't get the true full boost until you get a full 3" TBE. Quit trying to reinvent the wheel before you blow something up! Cobb sets forth a mod path.....STICK TO IT!!! Realize that without a 3" TBE you won't see the full potential and trying to force it will only make things worse. Get some knowledge and start modding smartly.
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Old 08-01-2006, 10:04 AM   #3
future_GDB
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cobb does say you can run a downpipe only for stage 2, but I wouldn't go any further with wastegate adjustments until you go full TBE.
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Old 08-01-2006, 03:16 PM   #4
austintheen
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Default better datalog

So should I switch back to the stage 1 map and wait till I get a complete exhaust before switching the AP map?

looking around at other datalogs, and seeing most are only showing a 3rd gear pull (Mine shows a full .25mi run, 1st, 2nd, 3rd and 4th) might make the graph look more spiky than usual. So I made another 3rd gear pull and looked at the KC which looks alot better. I still got something wierd at 4900rpm.
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Old 08-02-2006, 02:56 AM   #5
MISTSHIFT
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Your fine with just a dp and stage 2, practical experience and cobbs own literature suggests that the primary components are the DP and for safety sake the UP that need attention. lots of people ( see cobb's own forum) run stage 2 with stock exhaust components myself included. There is some speculation that increasing the exhaust tube diameter reduces flow rate and as a result the gasses become denser as they cool, etc,etc,etc.... But im not a god like authority on the physical universe. What I can say is that my car hits the "target boost" with stock exhaust components from the DP back without any coaxing or tensioning the wastegate. Somthing to consider which appears to be widely overlooked is that when you shorten the arm and preload the wastegate that initself does not allow it to hold anymore boost there is a point of diminshing returns once the assembly is preloaded. The amount energy the spring can supply does not change because it is preloaded. Its like changing ride height on a bike or car preloading the spring does not increase its rate. I like the quiet stock exhaust and from what I can tell Im not giving up a whole lot with this setup. I believe someone did a back to back test to determine back pressures from various setups, it was a really good post. That would shed some light on how "necessary a full 3in TBE is.
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Old 08-02-2006, 02:59 PM   #6
austintheen
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From Cobb's website:
Quote:
The Stage 2 was tuned on a car with a full turbo-back system. If you have pieced together a less than optimal combo of parts or those that were not designed to work together you may not get the full benefits of the Stage 2 AccessECU. Boost may not come on as quickly and the peak power may be down from those that have a well designed full turbo-back system. If you have replaced the first section (second cat or downpipe section) and nothing else, then the Stage 2 map is what we would recommend. Again the results will be far less than optimal, but it will control the boost better than the Stage 1. If you have replaced sections 2-4 (third cat, mid-pipe, and muffler section then you are still Stage 1. You managed to get all except the part that makes the most difference. Again, we want to reiterate that Stage 2 will only get the intended results with a well designed complete turbo-back.
Since I have replaced my DP and Cobb says Stage 2 handles the boost better with that mod than Stage 1, I went with that. I realize I won't be getting the full potential of what a full TBE would offer, but I do like the fact that it's *quite*, stealthy and cheap.

Also, after looking at the full datalogs I think I found that the 4900rpm blip in KC values are from a rise in timing at the particular point, so the ignition timing stays the same through the rpm range. So I'm not as worried as before. It looks fine to me.
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