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2006 Forester XT 6 speed
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Discussion Starter · #1 ·
Hey everybody. I finally got my car on the road and am in the process of E-tuning. We got it running pretty good and decided to start adding ethanol into the mix, car has flexfuel. At E35 I have an aggressive hesitation in 1st and 2nd gear as boost comes on or once in boost. Tuner thinks it is spark blowout and recommended new coilpacks and to log roughness on all cylinders. The pulls showed roughness in cylinder 1. I was running NGK LFR7AIX one step colder iridium plugs gapped at .028, only 1000 miles on them. I checked them and they all looked ok, I gapped them down to .025 and moved the plug from cylinder 1 to cylinder 3 and the coilpack from 1 to 2. Logged again, roughness in cylinder 1, no change. Replaced the coilpacks anyway, since they have 243K on them, now I don't have any roughness in the logs but the problem still occurs exactly the same. I swapped out the Iridium plugs for coppers gapped to .024, tuner said gap should be .024-.028, no more, no less. No change. I've attached some logs of the issue, 2nd gear pull. Sns only R is wideband. 3rd gear pulls clean from 2500 to redline. The big thing that stands out to me is the FP Diff Comp, but I'm not sure exactly what it means. I plan to take it to a shop to get this diagnosed at some point but until I can make that happen with my work schedule, I wanted to see if anyone here had any ideas that I can try on my own. Car had a predyno inspection done, and passed with flying colors, compression and leakdown were good and no boost leaks. Car has an FP Blue, ID1050x, Cobb FlexFuel, Aeromotive 340 stealth, 38mm EWG, TGV deletes, ELH, Catless DP and 3in catback. Thanks in advance for any advice guys!
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2018 X3 M40i / 2016 X3 xDrive35i
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I cannot discern based on the logs, but the MAF reading drop while in boost doesn't seem right.
 

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Those logs aren't long enough to diagnose but your AFRs are off. You jumped to a very lean 17 w/ 50% throttle im not seeing if you're logging closed/open loop in there but if it went to 17 while still under throttle that's not good. Based on your AFR learning i'd probably look for a vacuum leak post MAF? From the very little information you're showing your AFR seem off for a WOT pull especially with a wideband.

For example WOT for me without a wideband completely maxes out the factory AFR sensor at 11 until I lift. You aren't even getting to 11 and I'd expect even lower with a wideband which seems like a lean condition. The lack of knock though is very suspicious as you would think a WOT lean condition would produce FBK at the least. Did your E tuner desensitize your knock sensor?
 

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2006 Forester XT 6 speed
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122 Posts
Discussion Starter · #5 ·
3rd gear pull sits at about 10.8 AFR. Car is at Six Star right now, they think it's a fuel pump so they are throwing one in for me. I'll let you guys know what they find once I get the car back and know the issue is gone. Thanks for all the input!
 

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2006 Forester XT 6 speed
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122 Posts
Discussion Starter · #6 ·
So Six Star got the car tuned and I am back home in NC. For the issue I was having, they replaced the AEM Stealth fuel pump I was running with a DW and hardwired it. Issue hasn't reoccurred as of now but if it doesn't I'll let you guys know.
 

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2006 Forester XT 6 speed
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Discussion Starter · #8 ·
For those curious, car made 388hp and 385ft/lbs or torque on E85 and 337/332 on E30. 19psi.
 

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2001 Forester STi 6spd with MapDCCD and 535hp
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There are a few factors that lead in to "hesitation" with these cars.

Noting your use of ID1050s, are you using larger rails, lines, regulator and pump, and if so, what is the arrangment (parallel, series fed) ?

-Mikey
 

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2006 Forester XT 6 speed
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Discussion Starter · #10 ·
There are a few factors that lead in to "hesitation" with these cars.

Noting your use of ID1050s, are you using larger rails, lines, regulator and pump, and if so, what is the arrangment (parallel, series fed) ?

-Mikey
No, everything else is stock. For now, the new fuel pump and hardwiring kit for the fuel pump, seem to be doing the trick. I'll keep this post updated if the problem returns. The issue did get much better when I replaced the fuel pressure regulator but did not go away entirely until we did the pump and hardwire kit.
 

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2001 Forester STi 6spd with MapDCCD and 535hp
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No, everything else is stock. For now, the new fuel pump and hardwiring kit for the fuel pump, seem to be doing the trick. I'll keep this post updated if the problem returns. The issue did get much better when I replaced the fuel pressure regulator but did not go away entirely until we did the pump and hardwire kit.

9 times out of 10, i have ALWAYS had hesitation issues using OE components with larger injectors slapped in there, more-so on the older models. I've seen this debated over among some of the industry's most well known tuners, and the consensus seems to be around poor dampening, which could be traced back to the OE line layout, size and even a stock regulator. Ultimately, in every single case, going to a full system (Lines, rails, Reg) gets the car to cooperate exactly how you want it to in terms of lower load behavior. Its one of those things thats close to impossible to totally "tune" around since its a mechanical phenomena.
 

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Discussion Starter · #12 ·
That's good to know. I'll keep that in mind if more issues arise.
 
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