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Old 10-27-2000, 08:18 AM   #1
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1995 Impreza w/EJ255
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Post SAFC or a RRFPR ? with a turbo

Which one am I better off getting for the tuning of my turbo. My understanding of them is that the both do basicly the same thing but I could be wrong. Some help would be appreciated.
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Old 10-27-2000, 09:58 AM   #2
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Join Date: Jun 1999
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2007 BMW Z4 M Coupe
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After installing a RRFPR, I was able to change all my S-AFC settings to 0% correction! The AFC works, but only up to a point because the injectors will go static quickly. With the RRFPR, the increased fuel pressure will increase the "flow" of fuel through the injector without requiring the injector to be open longer.

If anything, with the RRFPR, you might want the AFC to correct down instead of up.
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Old 10-27-2000, 10:19 AM   #3
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same here....I only put minimal changes into my AFC, and even then, only above 4400 rpm. It is nice to have though for the O2 voltage, which was a main reason why I got it.
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Old 10-28-2000, 01:32 AM   #4
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This will sound stoopid, but how do I use my AFC to get O2 sensor voltage? I have a MY00 and it may be wired differently than the older ones, since the front O2 sensor is a 5V one. I'll also as JC Sports while I'm there tomorrow.

I am looking forward to my RRFPR, and feel that it will be much more help than my AFC. I am using a plain fuel pressure regulator, and can see the changes it makes if I jack up pressure or lower it.

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Old 10-28-2000, 05:58 AM   #5
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Larry ~~ FWIW, I'm not using the S-AFC to monitor O<sub>2</sub> readings, I'm using a Jumptronix A/F meter. It's basically a self-contained voltmeter. I'm not positive, but I would think it would work with the wide band sensors on the MY00. If you go to http://www.jumptronix.com I'm sure you'll find the Alex's email address to ask him.

Anyhow, Adam is referring to the "blue wire mod" for monitoring the O<sub>2</sub> readings on the AFC. There is a blue wire which can be hooked up so that you can see the sensor readings while in sensor check mode on the AFC. It works, but it's not very convenient, IMO. (Of course, I now have my AFC in the glove box, so that makes it even worse.)

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Old 10-28-2000, 12:58 PM   #6
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I would suggest not giving too much credence to o2 sensor voltage (even from a wide-band unit) when tuning a high output turbo car. It's not a very good indicator of air/fuel ratio. It's very dependant on EGT, rpm, ignition advance, etc,. More often than not, it can lead you away from where you want to be. Without the use of a dyno, I would suggest relying on a good set of ears and EGT. The o2 sensor will tell you if you are waaay off in fueling. But so will your butt. YMMV, of course.

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Old 10-28-2000, 06:06 PM   #7
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What does RRFPR stand for?

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Old 10-28-2000, 08:28 PM   #8
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Old 10-29-2000, 01:31 AM   #9
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Location: Montreal, QC, Canada

hmm, interesting topic guys.
I have a rrfpr w. the Rimmer setup, & I'm not too crazy about it : it seems to be too 'gross' (sp?) of a tuning solution ... It's either: run too rich most of the time or too lean w. detonation at partial boost at higher rpms.
To avoid detonation it's currently set up to run rich. (I also use 94 octane fuel)
I'm still considering a TecII .. but all the 'leaves' (;-) fell off of my money tree (it's automn after all) & I'm a bit worried about the tuning part.
I'm not conviced that the std ITC / AFC combo could fix my problems, any ideas on that ?
(again, the prob is high rpms, w. partial boost : lower boost = lower fuel pressure = higher EGTs ... "popety pop")

Have a nice week-end
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