Fixing the GR 2400-3000rpm stumble with Accessport - Page 2

Airboy · 02-23-2013, 11:51 AM

Quote:

Originally Posted by lancelucas

According to theory, yes, the damper serves a well-intended purpose (absorbing fuel line pulsation). This isn't from the pump being run at partial speed, but rather, from injectors opening and closing and such.

http://www.injector.com/cart/pc/Puls...Dampers-c4.htm
http://injector-rehab.com/shop/fpd.html

Here in the real world, our 4 cylinders do perfectly fine with no ill effects without a damper. The OEM dampers don't do a whole lot and are prone to getting noisy anyways, unfortunately.

I would think the pump being pulsed on/off at 33/66% duty cycle will create pulses in the fuel line as well, at whatever frequency that it is toggling at.

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cummins990 · 02-23-2013, 12:05 PM

yes i could see that being an issue also which is why i might try to bypass that. But if the stumbling is due to pulsation or noise and in my case see more noise with dampers. There are others that have seen success with no dampers so I cant see it being an issue.

Airboy · 02-23-2013, 01:04 PM

Quote:

Originally Posted by cummins990

yes i could see that being an issue also which is why i might try to bypass that. But if the stumbling is due to pulsation or noise and in my case see more noise with dampers. There are others that have seen success with no dampers so I cant see it being an issue.

I am sure it works, as far as the issue at 25-3000RPM goes. I am just not sure what potential side effects it would have.

cummins990 · 02-23-2013, 01:17 PM

Yes but wouldn't you see any side affects in the learning view

lancelucas · 02-23-2013, 01:43 PM

Oops.

lancelucas · 02-23-2013, 01:45 PM

Quote:

Originally Posted by Airboy

I would think the pump being pulsed on/off at 33/66% duty cycle will create pulses in the fuel line as well, at whatever frequency that it is toggling at.

The PWM output from the fuel pump controller is ~18000 hz. Not a concern.

cummins990 · 02-23-2013, 01:47 PM

Quote:

Originally Posted by lancelucas

The PWM output from the fuel pump controller is ~18000 hz. Not a concern.

So you don't think the duty cycle fluctuation will make any difference with or without dampers? So no need to bypass?

lancelucas · 02-23-2013, 01:49 PM

Quote:

Originally Posted by cummins990

So you don't think the duty cycle fluctuation will make any difference with or without dampers? Do no need to bypass?

Correct.

Airboy · 02-23-2013, 02:16 PM

Quote:

Originally Posted by lancelucas

The PWM output from the fuel pump controller is ~18000 hz. Not a concern.

That fast eh? Good to know.

lancelucas · 02-23-2013, 09:41 PM

Quote:

Originally Posted by Airboy

That fast eh? Good to know.

Fast lil bugger. My rudimentary understanding of the situation thinks that any lower would cause issues with the "audible" range (at least from an OEM designer's perspective).

cummins990 · 03-08-2013, 06:09 PM

I ended up totally fixing the problem. My comps are all zeroed out and no stumble.

No dampers with an after market FPR. Runs better than ever.

kapp_badbloodz · 03-08-2013, 07:12 PM

The rails with larger injectors + tuning gave me ZERO stumble. Its phenomenal to drive a car that feels normal again

cummins990 · 03-08-2013, 07:14 PM

Quote:

Originally Posted by kapp_badbloodz

The rails with larger injectors + tuning gave me ZERO stumble. Its phenomenal to drive a car that feels normal again

Did your tuner zero out your comp tables? If not then it is likely to come back.

kapp_badbloodz · 03-08-2013, 07:24 PM

Quote:

Originally Posted by cummins990

Did your tuner zero out your comp tables? If not then it is likely to come back.

Hmmm... I didn't. But that's a question I'll ask when I go back. I believe it was but not 100% sure

badkulo · 03-16-2013, 03:30 PM

Guys, when you zero the comp tables? Does your ecu still able to make fuel correction? I'm on Cobb race tuner and both my correction and learning wont budge from zero after zeroing out the load comp tables. Any ideas?

eminehart · 03-16-2013, 03:41 PM

Zeroing out that table does not effect fuel correction. Sometimes randomly after a reflash the o2 sensor takes a while to warm up. Restart the car and it should come back.

badkulo · 03-16-2013, 03:56 PM

Thanks for the quick response. I might have zeroed out the wrong tables since I'm using race tuner. Its under the close loop target load compensation a&b tables. Is it the right one?

eminehart · 03-16-2013, 04:02 PM

Wrong table.
No its in the sensor calibrations tab.
Load Compensation (Manifold Pressure)(Accel)
Load Compensation (Manifold Pressure)(Cruise)

badkulo · 03-16-2013, 04:12 PM

Thank you!

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02-23-2013, 12:05 PM	#27
cummins990 Scooby Specialist Member#: 245156 Join Date: Apr 2010 Location: Howell MI Vehicle: 2005 STI Silver	yes i could see that being an issue also which is why i might try to bypass that. But if the stumbling is due to pulsation or noise and in my case see more noise with dampers. There are others that have seen success with no dampers so I cant see it being an issue.

02-23-2013, 01:17 PM	#29
cummins990 Scooby Specialist Member#: 245156 Join Date: Apr 2010 Location: Howell MI Vehicle: 2005 STI Silver	Yes but wouldn't you see any side affects in the learning view

02-23-2013, 01:43 PM	#30
lancelucas Scooby Specialist Member#: 124282 Join Date: Aug 2006 Chapter/Region: NWIC Location: 30000 ft Vehicle: 04 WRX Wagon PSM 13 STI Sedan SWP	Oops.

03-08-2013, 06:09 PM	#36
cummins990 Scooby Specialist Member#: 245156 Join Date: Apr 2010 Location: Howell MI Vehicle: 2005 STI Silver	I ended up totally fixing the problem. My comps are all zeroed out and no stumble. No dampers with an after market FPR. Runs better than ever.

03-08-2013, 07:12 PM	#37
kapp_badbloodz Scooby Newbie Member#: 203327 Join Date: Feb 2009 Location: Mount Holly, NJ Vehicle: 2002 WRX Silver	The rails with larger injectors + tuning gave me ZERO stumble. Its phenomenal to drive a car that feels normal again

03-16-2013, 03:30 PM	#40
badkulo Scooby Newbie Member#: 53565 Join Date: Jan 2004 Chapter/Region: Tri-State Location: Flushing, NY Vehicle: 2008 OBP STi SQC 278	Guys, when you zero the comp tables? Does your ecu still able to make fuel correction? I'm on Cobb race tuner and both my correction and learning wont budge from zero after zeroing out the load comp tables. Any ideas?

03-16-2013, 03:41 PM	#41
eminehart Scooby Newbie Member#: 11205 Join Date: Oct 2001 Chapter/Region: RMIC Location: Tweakin your ECU-Northglenn CO Vehicle: 2009 WRX Dom3-e85-ewg	Zeroing out that table does not effect fuel correction. Sometimes randomly after a reflash the o2 sensor takes a while to warm up. Restart the car and it should come back.

03-16-2013, 03:56 PM	#42
badkulo Scooby Newbie Member#: 53565 Join Date: Jan 2004 Chapter/Region: Tri-State Location: Flushing, NY Vehicle: 2008 OBP STi SQC 278	Thanks for the quick response. I might have zeroed out the wrong tables since I'm using race tuner. Its under the close loop target load compensation a&b tables. Is it the right one?

03-16-2013, 04:02 PM	#43
eminehart Scooby Newbie Member#: 11205 Join Date: Oct 2001 Chapter/Region: RMIC Location: Tweakin your ECU-Northglenn CO Vehicle: 2009 WRX Dom3-e85-ewg	Wrong table. No its in the sensor calibrations tab. Load Compensation (Manifold Pressure)(Accel) Load Compensation (Manifold Pressure)(Cruise)

03-16-2013, 04:12 PM	#44
badkulo Scooby Newbie Member#: 53565 Join Date: Jan 2004 Chapter/Region: Tri-State Location: Flushing, NY Vehicle: 2008 OBP STi SQC 278	Thank you!