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Discussion Starter · #1 ·
Hey all, so I just installed a Cobb SF Intake and flashed the car to 91-ACN Stage-1+ with the Cobb AP in my 2011 WRX. No other mods aside from the intake.

On the AP’s boost gauge it’s displaying -10 to -10.75 at idle, at normal operating temperature. I also live in Southern California area. Is this normal vacuum readings?

Also, does the ECU have to learn/adjust to the new Cobb map? I did a few a runs, and the AP recorded peak boost of 14.75-psi. While Cobb Support shows peak boost should be 16-psi.

How long should I drive till the ecu “learns” if it does do that. And if it’s not reaching peak boost, should I reflash with the HWG version?

I appreciate everyone’s input!

Thanks,
Ralf
 

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Check for boost and vacuum leaks. If I'm not mistaken the 91acn has way lower boost targets than the 93 or normal 91
 

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Discussion Starter · #3 ·
Check for boost and vacuum leaks. If I'm not mistaken the 91acn has way lower boost targets than the 93 or normal 91
So far I’ve read that -10 is about normal vacuum reading. But would like confirmation by others with the same year engine.

Is it safe to run the normal 91? Or are people specifically using the 91ACN in California.

Thanks!
 

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You have to use the acn in California because of the fuel.

The vacuum will vary depending on each individual vehicle and elevation. My 2011 saw about the same
 

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Discussion Starter · #5 ·
You have to use the acn in California because of the fuel.

The vacuum will vary depending on each individual vehicle and elevation. My 2011 saw about the same
Correct the vac reading also depends on sea level too. I just wanted to get an idea.

I can’t seem to find info on the peak boost for the 91ACN.
 

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BooSTIng
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Your vacuum is perfect and right where it should be. Remember, the accesport only reads in PSI, when most of the time vacuum is measured in inches of mercury. Inches in mercury is almost exactly 2 times as much psi. So -10psi equals about -20inches of mercury.

Every time you reflash your car, regardless of what tune it is, there is a brief learning period for your ECU. In my experience my cars would act like they wanted to stall out upon coming to stop, and have pretty crappy throttle response. This is normal as your ecu learns the new map. Mine usually felt much better after a few hours of driving. Your experience may be slightly different.

And per Cobb for the Stage 1 +SF intake for the ACN91 fuel your target peak boost is 16psi, tapering down to 11psi at 6700rpms/redline. +/- 1 psi.
 

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BooSTIng
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I would not load the HWG map yet. Drive your car for a week or so on the current map. Do a few 3rd gear pulls at WOT and monitor your boost gauge. If you are still not reaching your target boost (remember +/- 1 psi is still normal for the map, so if you are hitting 15.XXPSI of boost your tune is fine and I would not load the HWG map), then change to the HWG map.
 

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Discussion Starter · #8 ·
Your vacuum is perfect and right where it should be. Remember, the accesport only reads in PSI, when most of the time vacuum is measured in inches of mercury. Inches in mercury is almost exactly 2 times as much psi. So -10psi equals about -20inches of mercury.

Every time you reflash your car, regardless of what tune it is, there is a brief learning period for your ECU. In my experience my cars would act like they wanted to stall out upon coming to stop, and have pretty crappy throttle response. This is normal as your ecu learns the new map. Mine usually felt much better after a few hours of driving. Your experience may be slightly different.

And per Cobb for the Stage 1 +SF intake for the ACN91 fuel your target peak boost is 16psi, tapering down to 11psi at 6700rpms/redline. +/- 1 psi.
I appreciate the confirmation! Also being that my target boost reached 14.75psi. Outside air temp was pretty warm, can't remember the temperature exactly. I assume this can also affect hitting target boost? I also read about monitoring the TD Boost Error to see any discrepancies. Thanks for the input!
 

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BooSTIng
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You are very close to the target boost. Almost right at -1PSI. I would say this is safe for your car and would leave it alone. I do not have any experience dealing with 91ACN that you guys have in California. I do know that you should expect less boost on ACN fuel when compared to lets say 93oct/ron. Monitor your feedback knock and fine knock learning tables on your accessport. Under WOT if you are not experiencing any knock events over -1.40 (per cobb, -1.40 knock events are considered normal), then I would leave it be and run it.
 

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Discussion Starter · #10 ·
You are very close to the target boost. Almost right at -1PSI. I would say this is safe for your car and would leave it alone. I do not have any experience dealing with 91ACN that you guys have in California. I do know that you should expect less boost on ACN fuel when compared to lets say 93oct/ron. Monitor your feedback knock and fine knock learning tables on your accessport. Under WOT if you are not experiencing any knock events over -1.40 (per cobb, -1.40 knock events are considered normal), then I would leave it be and run it.
Thanks! Also is there a specific gear I should test in WOT for knock events? I assume datalog this portion of the WOT test. Much appreciated!
 

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Discussion Starter · #13 ·
Yesterday afternoon, and this morning on the way to work I was monitoring my gauges. The DAM, Fine Knock, Feedback Knock were well within the normal/acceptable range. I did notice that the A/F Learning-1 did reach to -6.75% at one point, and returned back to zero. But majority of the time it would fluctuate near zero. Which I've read is still within normal range, as long as it does not go past +/- 8% range.

So based on these readings so far, everything seems to be good. I'll continue to use this map for the next few days to see if I can reach target boost. I was able to reach about ~14.25psi yesterday.
 

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Discussion Starter · #14 ·
Last night I added the HWG map into the AP. And did one last WOT pull this morning on the way to work. The AP gauges looked good, but still only able to hit a target boost of 14-14.5psi. So I'm going to switch to the HWG map today, and see if that makes a difference.
 

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Don't do that until you verify that is the map target for your octane.
 

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Discussion Starter · #16 · (Edited)
Don't do that until you verify that is the map target for your octane.
I'm running the Stage-1+ SF 91ACN, since I live in Southern California. Cobb states I should be hitting target boost of 16psi; +/-1psi, so like 15-17psi. And all the parameters for knock have been looking good during WOT. There doesn't seem to be any boost leaks either, based on my AP's boost gauge reading. And it's already been about 3 or 4 days on the current normal wastegate map as well.
 

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Ok, just wanted to make sure, you can get down a bad path really fast with the wastegate stuff.
 

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Discussion Starter · #18 ·
Ok, just wanted to make sure, you can get down a bad path really fast with the wastegate stuff.
I appreciate the heads up! I'm definitely making sure I triple and quadruple check everything. Especially since it is my daily driver.
 

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Discussion Starter · #19 ·
I just changed maps, and now it’s hitting 15.38psi. So it’s within the target boost range, and knock levels were good too.
 
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