Pettit Racing’s Forced Induction System
01-25-2008, 10:53 AM
#1152
Power!!
A longer distance would help with more accurate MAF readings and potentially allow you to take out the screen. I don't know if, in the end, it means more power or not.
01-25-2008, 11:18 AM
#1153
That won't work. Part of the accuracy issue is the heater control. That is where a WB does its magic. You have to have the sensor under complete control of one or the other controller.
Best test is to install both in one pipe, calibrate them at the same time and then run tests for a week or so.
Or, you can just read the article I posted above.
I had the Autometer EGT gauge - it was useless, especially in a rotary since it only read to 1600°F. I also had the Autometer narrow band (equally useless) and the Autometer wideband (worse than useless because it was misleading in a really dangerous way).
01-25-2008, 11:37 AM
#1155
That makes me sad. Tell her "Jeg er ked af det" for me. (Pronounce it "Yie err kay ah day" or she will laugh at both of us.)
http://www.fordmuscle.com/archives/2...tout/index.php
Several years back (before Autometer started manufacturing in China), except the wideband, which I used for about two days on the '8 before I sold it in '06.
http://www.fordmuscle.com/archives/2...tout/index.php
Several years back (before Autometer started manufacturing in China), except the wideband, which I used for about two days on the '8 before I sold it in '06.
01-25-2008, 01:47 PM
#1159
Administrator
yes
Trims can be (and are) both positive and negative. Their purpose is to account for environmental factors (humidity, etc.) that are not otherwise accounted for plus variations in the individual cars and their parts. Yes, the LTFT will be built - but it is the same with or without our flash, since the oxygen sensor never sees our street flash changes (open loop) and it is simply correcting for things that should be corrected.
Jim Mederer
Jim Mederer
01-25-2008, 02:09 PM
#1160
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thats the reply i was expecting...
trims still build like they should. They probably never touched the target lamda tables because they have an NA flash and there is no reason to change the closed-loop target values since they are all stoich -shrug-
trims still build like they should. They probably never touched the target lamda tables because they have an NA flash and there is no reason to change the closed-loop target values since they are all stoich -shrug-
01-25-2008, 02:42 PM
#1163
Power!!
According to RB website they mention that the target is richer than stoich at high RPM so I suspect that's where pulling the room fuse comes in to play. I thought their NA street flash gains were based on changing that target to make it leaner and closer to stoich.
Edit: I just caught in Zoom's quote from Jim that he said he only adjusts the open loop values so he's only leaning out open loop. Hence the fuel trims don't come in to play with the RB flash correct?
Edit: I just caught in Zoom's quote from Jim that he said he only adjusts the open loop values so he's only leaning out open loop. Hence the fuel trims don't come in to play with the RB flash correct?
Last edited by shaunv74; 01-25-2008 at 02:45 PM.
01-25-2008, 02:59 PM
#1165
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Their flashes change the open-loop fuel tables to acheive leaner then stock afr's. They want afr's around 13-13.5 for their NA application in open loop (aka when you are pushing the engine).
In closed-loop conditions (cruising), the PCM looks at the MAF and rpms, calculates an engine load, looks at a table for that load/rpm for how much gas to squirt, then uses the WBO2 sensor as feedback and compares the actual afr it acheived to a table of "targeted" values. If its off it creates a short term fuel trim which eventually carries over into a long term fuel trim to modify the fuel table... and the long term fuel trim carries into open and closed loop conditions since its thinking if i'm off on the fuel in closed loop i'll probably be off in open loop.
multiply that a table grouping for differnt gears and different engine temps and you have the modern day convoluted engine management system.
Racing Beat probably did not have to change the closed-loop target table because of their NA application where everything is pretty much stoich. This is not the case with fored induction applications where you can not be in boost and at stoich at the same time and you will reach boost at throttle positions the OEM tune is trying to be in closed loop mode. So for this reason the closed loop "target" tables have to be modified.
If the target tables are properly modified, the fuel trims build to keep it into the tune you want. So fuel trims should be helping you and not being reset.
01-25-2008, 03:55 PM
#1166
Power!!
Agreed. I think you hit it on the head with "if the target tables are properly modified." My understanding is the OEM targets are detuned to help save cat. life instead of best power.
02-03-2008, 03:24 PM
#1169
Who put it after the CAT? I missed that.
The OE wide-band is a bit non-linear at the rich end. It tends to read progressively less rich than reality below 11.5:1 or so.
Plus, you can't datalog it without dealing with the CAN bus stuff.
A nice voltage output is an excellent thing to throw at your engine management.
If and when your flash programmer becomes viable, then it will be a whole different can of worms.
Until then, the OE sensor is just a curiosity.
The OE wide-band is a bit non-linear at the rich end. It tends to read progressively less rich than reality below 11.5:1 or so.
Plus, you can't datalog it without dealing with the CAN bus stuff.
A nice voltage output is an excellent thing to throw at your engine management.
If and when your flash programmer becomes viable, then it will be a whole different can of worms.
Until then, the OE sensor is just a curiosity.
As did I miss this resonse from you. There was at least one mention of it a few pages back in this post.
Does "less rich" mean lean? Is that like in air traffic control speak they use the term "negative" as a short word meaning "no"? LOL! (OK - I understand it is that way so not to be confused with "go". But it is still a funny anecdote.)
Excuse me for forgetting how easy it is for me to read WB02 since I have already done the hard work on the CAN bus stuff! To some extent it is already viable because sCANalyser logs it anyway - I just don't provide a really cool graphing tool -yet. Excel seems to work OK for now, but that is something I want to improve after I get the pro tuner done.
The other thing is the "than reality" bit. It all depends on which reality is considered to be really the real reality
Cheers,
Hymee.
02-03-2008, 04:32 PM
#1172
Having actually compared the OE sensor on several cars via Scanalyzer to a variety of third-party systems (including a Horriba), the OE starts to show progressively less lean than the numbers from the external systems as the values go below RBT.
