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08-18-2017, 12:09 AM | #551 |
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Join Date: Apr 2004
Location: soon to be somewhere else
Vehicle:1998 RS |
unfortunately i didn't get a fuel pressure reading from when the stock FPR was in there. base pressure should be around 42-45 though... i'm running 52 psi base now and my idcs are still higher. and my Fuel pressure maxes out at 60 WOT. at 18#s of boost with 52 base should be more like 70. and it begins to fall while i'm still WOT. kind of sounds like FP not feeding enough, weird part is, i'm running RICHER than when i was running the OEM FPR. hitting low 10's AFR wise WOT. richer and higher IDCs make sense, but why it's reporting a such low fuel pressure is puzzling.
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08-18-2017, 07:17 AM | #552 |
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Location: Pittsburgh PA
Vehicle:2018 Exotruck |
im confused on how the IDC changed. Those are set off airflow unless you have open loop fuel correction enabled. Without OLFC, the only way you should get more IDC is either more air or cooler air, or a fuel change. Also a changed in fuel pressure will need a retune. Can you share more info, like fuel pump used, fuel type, how its tuned etc..
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08-22-2017, 02:25 AM | #553 |
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Vehicle:1998 RS |
i've been messing with different fuel pressures is how the IDCs are changing. problem is, they're going the wrong way. with higher base pressure they should be falling to give me headroom for E85, but they're going up.
mods: 06sti engine, 20g turbo, stock side feed tgvs and oem fuel lines, 1000cc dw side feeds, 300dw FP. during one install, installed both aeromotive FPR and cobb flex fuel unit with fuel pressure sensor. the idea was to go to E85 and bump base pressure a bit so that i can use these injectors and not max them out. after the install, i was instructed by my tuner to set base FP to 52 psi. the plan was to increase fuel pressure, run the base map, then he will revise and send back etc. but i ran into fuel pressure problems, indicated pressure was only going up to 60 or so under 18# of boost at 52 psi base (42 under full vacuum). my first thought was that i'm running out of pump, that doesn't really make sense considering people are making 500HP with the dw300FP. with 52 psi base pressure only going up to 60psi under full boost, my IDCs were higher than with the OEM REG. OEM i never saw 70% IDC. i can get into the 80's now easy, and if i turn the base pressure back down to OEM levels my IDCS go up into the 90"s, with ONLY changing that. this is where it gets weird: my afr's are richer with less indicated fuel pressure. i'm seeing low 10's, and a lot of popping and backfiring under WOT. IDCs going up when it's running richer makes sense, but how it's running richer if i'm running out of FP/pressure doesn't make sense. maybe i just got a bum regulator.. however, i put the OEM reg back on in the strut tower position (where the aeromotive unit is installed now), and the car breaks up under any positive pressure. this leads me to believe the problem lies outside the regualtor, since neither are working as they should. i've wanted to go top feed conversion anyway, and have a line on some top feed TGVs, ID1000's and fuel rails. i'm going to go this route and bring it to a tuner/shop. i'm tired of fugging with it. |
08-22-2017, 07:36 AM | #554 | |
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Quote:
The pulse width is controll by the tune. For example if MAF is reading 3.0 volts at 4,000 rpm (plus compensator, temps etc) it will inject say 15ms of fuel (depending on injector sclae,latency etc). The only impact fuel presure will have is have much fuel gets past the injector in the 15ms. But thd Duty cycle stays per the tune. Now in closed loop, the o2 sensor will pick up the extra fuel from the extra pressure and reduce IDC to get back to target. This will show up in the AF learning values as a negative number. I'd be wary going to high on base pressure with sidefeeds. They are already pretty slow, too much base presure may cut you idle and cruise IDC's to the point of misfires. I use to run DW850's sidefeeds and went to top feeds. no regerts |
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08-22-2017, 11:41 AM | #555 | |
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Quote:
interesting i didn't realize that regarding IDC's. i assumed when i bumped pressure the IDC's would fall since the ecu now now needs to allow the injector open time less to hit xyz fuel target. i'm assuming the ecu doesn't know or care or what the fuel pressure is, it's just trying to a hit final fueling number. just got a revised map with less fuel in it, and my afr's came back to normal in the low 11's. idcs were less at 60%, less than what the OEM reg was showing. this is good news. AFRs are the same as they were before but IDC's have dropped, which was my intention all along. problem is my indicated pressure is still way way off. at 18#'s it maxed out at 63 and was falling during the pull into the 50's. i'm beginning to think the fuel pressure reading is simply not correct. at this point everything seems fine with AFR and IDC is acting the way it should, but reported fuel pressure is low. i just don't know why. i orignially had the FP sensor in the aermotive bung. thought maybe that was the issue, so i put it in the feed line on the cobb ethanol sensor unit. however it still reads the same low bunk readings. maybe it's not calibrated properly but i asked the tuner and he assures me it is. |
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08-22-2017, 12:23 PM | #556 | |
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Quote:
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08-22-2017, 12:42 PM | #557 | |
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Vehicle:1998 RS |
Quote:
i get that. just trying to understand from a diag perspective, if my changing the base fuel pressure should be affecting IDC's. you're saying, all else equal, changing the base fuel pressure should have no affect on IDC's... right? |
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08-22-2017, 01:02 PM | #558 | |
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Quote:
and by IDC, i mean injector pulse width. IDC is just the percent of time the injector is open during each 2 strokes. So yes, all being equal, changing the pressure should not effect IDC. The computer is unawre of any pressure chnage and thus makes no corrections on its own (only in closed loop). I assume the computer is basing everything of 3bar fuel pressure, and uses the MAP sensor as part of its fuel correction. There may even very well be a table inside the ECU for changing the factory fuel pressure calculation, i just dont think anyones ever defined it, if it exists. Last edited by no694terry; 08-22-2017 at 01:11 PM. |
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08-22-2017, 01:31 PM | #559 |
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ok thanks for explaining that.
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11-27-2017, 08:57 PM | #560 |
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Member#: 34361
Join Date: Mar 2003
Chapter/Region:
MWSOC
Location: MI
Vehicle:04.7 STI WRB IG @got2boostit2 |
So for those running Cobb Flex Fuel what are the issues if any? Looking for GD 2004-2007 results/issues. Searched and no thread(s).
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11-27-2017, 11:01 PM | #561 |
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12-07-2017, 06:52 PM | #562 |
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Location: Seattle, WA
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Hey can any of you GD guys help me out please. I’m trying to install the Cobb flex fuel. I have aftermarket fuel lines and aeromotive FPR so I’m not actually sure how I need to connect the fuel lines. Thanks!
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12-08-2017, 09:43 AM | #563 |
Scooby Specialist
Member#: 73932
Join Date: Nov 2004
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RMIC
Location: Denver
Vehicle:2005 STi EFR 6758 04 S2000 EFR 7064 |
You'll need to plumb in aftermarket fittings. The Cobb kit isn't designed for anything but stock nor do they sell you want you need and leave out the crap you don't need if you have an upgraded fuel system. It gets expensive for the little converter box you need...
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12-08-2017, 10:10 AM | #564 |
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Location: Pittsburgh PA
Vehicle:2018 Exotruck |
id just buy the innvate kit. comes with a eca, sensor, gauge, wideband and fuel pressure sensor which im almost certain is completely compatible with the accessport. its just not "plug n play" youll actually have to wire it
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12-25-2017, 11:23 PM | #565 |
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Tri-State
Location: West Chester, PA
Vehicle:2007 WRX Black |
Easiest placement would be to put it on the return after the AFPR. I asked this question a page or 2 back...but yea I bought all types of fittings to fit the COBB kit to turn everything into -AN.
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04-01-2018, 10:29 AM | #566 |
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MWSOC
Location: Champaign, IL
Vehicle:2017 WRX STI WHITE |
Is it worth it to buy the whole kit from cobb or just buy bits and pieces from them and source the rest yourself?
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04-04-2018, 10:15 AM | #567 | |
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Join Date: Jan 2018
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NWIC
Location: Port Orchard, WA
Vehicle:2017 WRX Sti Limited Dark Gray Metallic |
Quote:
I would recommend getting Cobb kit's for peace of mind and customer support...Granted my STi has less than 2K miles on it, but I'd rather keep everything within the same manufacturer for ease of troubleshooting (should there be any) and tried and true combo's... But I'm sure there are other options out there that will save a few pennies !! |
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04-06-2018, 02:31 PM | #568 |
Scooby Specialist
Member#: 218971
Join Date: Jul 2009
Chapter/Region:
Tri-State
Location: West Chester, PA
Vehicle:2007 WRX Black |
x2 their FF + FP kits are literally plug and play and worth it - quality is top notch. I pieced together the fuel lines and fueling (I went with the DW300 FP and ID1300X injectors). The rest is worked out by the Pro-Tune.
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04-13-2018, 11:19 AM | #569 | |
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Member#: 79339
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Chapter/Region:
RMIC
Location: Westminster, CO
Vehicle:2002 EJ257 6spd WRX Midnight Black |
Quote:
However, the Cobb flex fuel ecu allows a compensation for this, freezing the ethanol content above certain levels (boost, maybe RPM, can't remember all the possible choices), so even if you are getting low amounts of fuel through the sensor, it will use the ethanol content it measured before you went over those levels. |
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08-17-2018, 02:46 PM | #570 |
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This is a great thread, so much info
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06-05-2019, 11:30 AM | #571 |
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Join Date: Dec 2016
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Anybody running flex fuel on the CVT?
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11-21-2022, 01:47 AM | #572 |
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Member#: 532211
Join Date: Nov 2022
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I need a logger definition for my TGV left thats wired to my Ethanol sensor. I can’t figure it out for the life of me
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05-28-2023, 04:50 PM | #573 |
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Member#: 492368
Join Date: Oct 2018
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Is anyone still tuning for the flex fuel 2015+ cobb kit? I have one I never installed for a '19 WRX, but I don't want to sell this thing if it's useless.
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05-28-2023, 04:51 PM | #574 |
Scooby Newbie
Member#: 492368
Join Date: Oct 2018
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05-28-2023, 05:05 PM | #575 |
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Join Date: Jun 2017
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it depends
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