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Old 10-12-2007, 01:06 AM   #1
suby_will
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Default injector duty cycle high on stage 2?

I took some data logs of my Stage 2 WRX a few days ago and I cant figure out why my injector duty cycle is at 92%. I'm running a basic stage 2 map from OSEcu roms.

Is there a certain reason why it would be so high? I'm a newb to Subarus (only had mine for 1 year) and extremely new to tuning and data logging.

Any help/constructive comments are welcome and appreciated.
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Old 10-12-2007, 06:04 AM   #2
dynamix
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It is purely because the std injectors are too small. Either bigger or modded injectors will give you more headroom.
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Old 10-14-2007, 05:38 PM   #3
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I logged some WOT runs in my stock 2005 and saw 93% injector duty cycle briefly. I'm about to go to stage 2 and I'm interested to see what happens!

Mark
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Old 10-15-2007, 12:13 AM   #4
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I just got finished logging a few WOT runs and my max injector duty cycle only hit about 85. I have stock injectors running 16 PSI. The map is my own custom stage 2 map though. Your numbers seem high, but not that high, maybe 5-10%. Are you using the XPT Map or the one free from the forums?

/Brox
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Old 10-15-2007, 01:27 AM   #5
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keep in mind a pro-tuned or a tuned stg 2 will have lower overall IDC's because you are leaning out the Air/Fuel ratio on the top where it's overly rich from the factory.

Jeremy
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Old 10-15-2007, 03:28 PM   #6
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I agree with the above post in alot of cases, but I still think IDC over 90 is alot, even on a stock fuel map.
On my map I didn't drop the fuel all that much for safety sake. My EGT's, which is how I tune mostly, are pretty low even at WOT which means I do have alot of headroom to work with. My fuel map is not as dialed in as I would like, but it is still in its first revision and I can't complain. As I get more seat time and dyno time and with the addition of my WB02 I'll dial them in alot better.

/Brox
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Old 10-17-2007, 12:29 AM   #7
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Right now I'm on the free map. But I have the XPT stage 2 on my computer.
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Old 10-17-2007, 12:35 AM   #8
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iirc you don't want your injectors to be more then 80% duty cycle "cruising"
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Old 10-17-2007, 12:47 AM   #9
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i agree w/ the above statement but keep in mind guys when you are full throttle running a protune stage two (speaking for STi's) you will see high 90's in the duty cycle. unless of course you have larger injectors. the nice thing is adding meth to a stage 2 STi then you can run full throttle in the low 80's for your duty cycle.
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Old 10-17-2007, 02:15 AM   #10
Broxma
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Kram has it right in the high 90's for the STI for sure.

I flashed a Stage 2 map on an 04 STI the other night and the IDC maxed out at about 93. I was watching the logs but from what I saw the driver was WOT through 2nd, 3rd, and 4th, and the IDC does get pretty high. I was a bit concerned about it, so I checked the Base fuel map of the stock ROM and compared it to the Stage 2 one and the difference was pretty slight, so I figured that it was meant to be.

I know that Honda's run a very high IDC from the factory with not alot of overhead. I suppose it's possible Subaru gave at least a few models the bare minimum as far as overhead on the IDC as well.

/Brox
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Old 10-17-2007, 03:06 AM   #11
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Quote:
Originally Posted by Prevent View Post
iirc you don't want your injectors to be more then 80% duty cycle "cruising"
umm, if your IDC is running 80% at cruise you've got problems.

Normally you don't want to design a fuel system to run your injectors past 85% although it's been shown that Subaru injectors don't fail at 85% infact it's been shown that the stock ECU displays 100%+ IDC's while still being able to increase the duty cycle further
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Old 10-17-2007, 03:26 AM   #12
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Mine was getting 103% on stage 2 tune. Ideally you dont want to run over 90% so I added a fuel pressure regulator and ran increased fuel pressure.

This worked for a while (until the turbo boost was upped)

Now I have larger injectors and loads fo headroom.
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Old 10-29-2007, 06:26 PM   #13
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I got it right up to 99% IDC @ 16 psi, but I prefer leaving the fueling stock, which is pretty rich... It gets hot here, so leaving it a little richer than the normal staged tune gives me some knock safety when it's 110 degrees out in the summer. But yeah, IDCs in the high 90s on the '02 stock injectors with added boost is not at all unusual. Now with 625cc injectors I set a high of 62%.
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Old 11-07-2007, 10:42 PM   #14
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Quote:
Originally Posted by dynamix View Post
Mine was getting 103% on stage 2 tune. Ideally you dont want to run over 90% so I added a fuel pressure regulator and ran increased fuel pressure.

This worked for a while (until the turbo boost was upped)

Now I have larger injectors and loads fo headroom.
What FPR did you use? How hard to install and was it worthwild over injectors or a fuel pump?

I just hit 101% tonight on my 03 wrx, stage 2. With just 16.5 psi and ~48 degrees F. I am not confident I will go past stage 2 with this car, so which would be more cost-effective for getting ~15% more headroom - injectors, FPR or fuel pump?

Also, I am on the OSECUROMs stage 2 R10 fueling, with a little more advanced timing and boost.
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Old 11-07-2007, 10:53 PM   #15
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I am running the same map, with an ebay topmount, up-pipe, and highflow catted DP, and my IDC are at 91% in a 3rd gear pull.
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Old 11-08-2007, 03:56 PM   #16
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LOL! The stock 07 STI injectors run in the 90's on a good day on the stock map. Low altitude, low temps they go into the 105+ range and start to lean out on the stock mapping (boom!). 100% is ok, above that you are in dangerzone.
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Old 11-08-2007, 10:57 PM   #17
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That makes me feel a bit better Gabe - Still loving the tune, but I have been logging mine alot lately - and have seen up to 96.5x IDC ! I am going to proabably go to a bit bigger injector after christmas...
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Old 11-09-2007, 05:29 AM   #18
dynamix
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Quote:
Originally Posted by controler View Post
What FPR did you use? How hard to install and was it worthwild over injectors or a fuel pump?

I just hit 101% tonight on my 03 wrx, stage 2. With just 16.5 psi and ~48 degrees F. I am not confident I will go past stage 2 with this car, so which would be more cost-effective for getting ~15% more headroom - injectors, FPR or fuel pump?

Also, I am on the OSECUROMs stage 2 R10 fueling, with a little more advanced timing and boost.
I fitted a FuelLabs FPR running at 3.8 bar static pressure (with vacuum hose disconnected and Walbro 255 pump). It gave an extra 15% IDC and helps atomisation of the fuel for a better burn.
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Old 11-15-2007, 12:08 AM   #19
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Like Gabe said, I saw IDC% of 105+ on the stock tune, and Gabe's Stage 0 during the summer here. Scary stuff... With a catted DP and stage 2, I dropped into the 90's WOT. If I were running stock on any 07 STI, I'd take it easy in the hot and swampy weather. When summer comes around again (like in mid-April here) I'll start logging regularly in the heat to keep an eye on things.

To the OP, IMHO 92% isn't too much to fuss about. Keep an eye on it, your a ways away from running unintentionally lean.
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Old 11-15-2007, 08:50 AM   #20
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Whats your AFR? If you are running really rich, your IDC will be higher than if you were running a better AFR. IF you are in the 11.2-11.8 range, and your IDCs are in the high 90's then you should prob look into getting injectors. If your AFRs are in the low 10's, and IDC is in the high 90's, then get a better tune and they will drop.
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Old 11-15-2007, 11:07 AM   #21
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Yeah I'm thinking about pulling back my mixture to 10-10.5's from 9.5. I notice the JDM WRX ECU's are all leaner for the same cell's in the fueling table.
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Old 11-18-2007, 05:11 PM   #22
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check the injector size in the rom file..
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Old 11-19-2007, 09:33 AM   #23
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Quote:
Originally Posted by reddoak View Post
Like Gabe said, I saw IDC% of 105+ on the stock tune, and Gabe's Stage 0 during the summer here. Scary stuff... With a catted DP and stage 2, I dropped into the 90's WOT. If I were running stock on any 07 STI, I'd take it easy in the hot and swampy weather. When summer comes around again (like in mid-April here) I'll start logging regularly in the heat to keep an eye on things.

To the OP, IMHO 92% isn't too much to fuss about. Keep an eye on it, your a ways away from running unintentionally lean.
You have to watch it when it is cold out as well.
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