Injector scaling help

Riles · 12-25-2007, 07:19 PM

I have an 02 wrx with a 16g/exhaust/intake. I just installed PE650 injectors and need a little help getting this to idle. I changed the latency to 3.69, 2.39, 1.88, 1.58, 0.68. The idle still sucks and the CEL is flashing. Should I now keep the latency the same and scale them back to 560 to 570 to get me in the neighborhood or what?

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DocDetroit · 12-26-2007, 10:13 AM

I had an '03 WRX with PE1818, TurboXS topmount, PE650s, Walbro, Perrin fuel rail, etc.

After I installed everything, it fired up, idled and drove in closed loop reasonably well without any tuning.

Are you sure you don't have some other mechanical problem (vacuum leak, etc)?

mickeyd2005 · 12-26-2007, 01:37 PM

Don't just guess.

Datalog and make an educated estimate.

Your car should idle fine if you wait for AFR learning to set in as long as you are within 15% of your target.

First thing is to check your CEL and log roughness.

Then log AFR, AFR learning #1, AFR correction #1, IPW, MAF, rpm, load, CL/OL status.

Riles · 12-28-2007, 01:02 AM

Thanks guys, I'll try some data logging

benw · 12-28-2007, 02:30 PM

what intake did you install? you're gonna have a beast of a time scaling the maf and the new injectors simultaneously. can you reinstall the stock intake?

Riles · 12-28-2007, 10:52 PM

its the spt intake and yeah its a toughy to scale but its doable

mickeyd2005 · 12-28-2007, 11:49 PM

If you scale the injectors and the intake simultaneously, your resultant maf and load will be slightly off. The AFR can be tuned such that it is correct. A small error is not that big a deal. My guess is anywhere between 1 and 10% depending upon how good you can guess.

It only becomes a problem when the load scale is really off like when you try to get around the 300 g/s of the 16 bit ecus by dividing everything by two.

The problem is that there are a LOT of ancillary tables that are MAF or load dependent. A lot of tuners forget to rescale the other tables.

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12-25-2007, 07:19 PM	#1
Riles Scooby Newbie Member#: 121154 Join Date: Jul 2006 Chapter/Region: South East Location: Knoxville, TN Vehicle: 2002 Impreza WRX PSM Stage 47, Romraided	Injector scaling help I have an 02 wrx with a 16g/exhaust/intake. I just installed PE650 injectors and need a little help getting this to idle. I changed the latency to 3.69, 2.39, 1.88, 1.58, 0.68. The idle still sucks and the CEL is flashing. Should I now keep the latency the same and scale them back to 560 to 570 to get me in the neighborhood or what? * Registered users of the site do not see these ads.

12-26-2007, 10:13 AM	#2
DocDetroit Scooby Newbie Member#: 24977 Join Date: Sep 2002 Location: Waterford, Mi Vehicle: 2003 WRX Blue	I had an '03 WRX with PE1818, TurboXS topmount, PE650s, Walbro, Perrin fuel rail, etc. After I installed everything, it fired up, idled and drove in closed loop reasonably well without any tuning. Are you sure you don't have some other mechanical problem (vacuum leak, etc)?

12-26-2007, 01:37 PM	#3
mickeyd2005 Scooby Newbie Member#: 122595 Join Date: Aug 2006 Chapter/Region: NWIC Vehicle: 2005 LGT Wagon ABP	Don't just guess. Datalog and make an educated estimate. Your car should idle fine if you wait for AFR learning to set in as long as you are within 15% of your target. First thing is to check your CEL and log roughness. Then log AFR, AFR learning #1, AFR correction #1, IPW, MAF, rpm, load, CL/OL status.

12-28-2007, 01:02 AM	#4
Riles Scooby Newbie Member#: 121154 Join Date: Jul 2006 Chapter/Region: South East Location: Knoxville, TN Vehicle: 2002 Impreza WRX PSM Stage 47, Romraided	Thanks guys, I'll try some data logging

12-28-2007, 02:30 PM	#5
benw Scooby Specialist Member#: 103320 Join Date: Dec 2005 Location: Oklahoma City Vehicle: 2005 wingless aspen white	what intake did you install? you're gonna have a beast of a time scaling the maf and the new injectors simultaneously. can you reinstall the stock intake?

12-28-2007, 10:52 PM	#6
Riles Scooby Newbie Member#: 121154 Join Date: Jul 2006 Chapter/Region: South East Location: Knoxville, TN Vehicle: 2002 Impreza WRX PSM Stage 47, Romraided	its the spt intake and yeah its a toughy to scale but its doable

12-28-2007, 11:49 PM	#7
mickeyd2005 Scooby Newbie Member#: 122595 Join Date: Aug 2006 Chapter/Region: NWIC Vehicle: 2005 LGT Wagon ABP	If you scale the injectors and the intake simultaneously, your resultant maf and load will be slightly off. The AFR can be tuned such that it is correct. A small error is not that big a deal. My guess is anywhere between 1 and 10% depending upon how good you can guess. It only becomes a problem when the load scale is really off like when you try to get around the 300 g/s of the 16 bit ecus by dividing everything by two. The problem is that there are a LOT of ancillary tables that are MAF or load dependent. A lot of tuners forget to rescale the other tables.