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Old 01-11-2003, 07:51 PM   #1
RS_NW
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Default Fuel correction for 440 Injectors and Link

The stock injectors are 280cc and the RC's that work with the link are 440cc. Under the same inector pulswidth I would be flowing 60% more fuel? Anyone have any suggestions on how I should adjust my master fuel?
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Old 01-11-2003, 07:57 PM   #2
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Theoretically, you should lower master fuel and row fuel that 60% if you are going from 280 to 440. Graham and I just did the exact opposite today and it seemed to work pretty well. He used my map on his stock injectors.
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Old 01-11-2003, 11:25 PM   #3
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Yup, lower your master fuel by 60%. Double check your crank and fuel enrich values to make sure they still work properly (they should).

-Chav
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Old 01-12-2003, 01:19 AM   #4
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Yes, after some bogging and bucking, wcbjr and I figured out that it was best to raise the fuel. It seems to be running alright now, though I am still getting some bucking on throttle tip in and let off. Just gotta mess with it....


Graham
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Old 01-12-2003, 11:42 PM   #5
RS_NW
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Quote:
Originally posted by Graham
Yes, after some bogging and bucking, wcbjr and I figured out that it was best to raise the fuel. It seems to be running alright now, though I am still getting some bucking on throttle tip in and let off. Just gotta mess with it....


Graham
I don't get it... why would it be doing that? There is no reason why you should have to raise the fuel as opposed to lowering it... Did you monitor fuel pressure? Any difference after the new injectors?
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Old 01-13-2003, 12:53 AM   #6
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The response time of the stock injector solenoids seem to be slightly different then the response time of the RC's. I did the same with mine when I went from stock to RC 440's and cut (IIRC 63%) and then I had to tweak a bit (more fuel, I think) to get it closer to perfect. Granted, I'm running really rich, but until I get my J&S in, I'm more confortable paying a bit more for gas then for motor repairs (even though now the damn thing has natural disasters ).
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Old 01-13-2003, 01:14 AM   #7
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8Complex has a good point, in that not all injectors are created equal. Most injectors vary wildly in response time in their own sets...............let alone a totally different injectors.

Not all ecu's are very adept at recognizing this and don't have internal software functions to deal with this.

That's part of the reason why in theory you would just increase or decrease the master fuel numbers, but in reality it doesn't always work that way.
-B
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Old 01-13-2003, 10:16 AM   #8
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I guess I'll just play with the master fuel until it feels right. I appreciate all the responses.
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Old 01-13-2003, 10:59 AM   #9
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BTW, if I were to pick a number, I'd say start at 50% and work your way leaner.

Safety... it's not just for the people that can't afford to buy new motors anymore.
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Old 01-13-2003, 01:37 PM   #10
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Quote:
Originally posted by EFI-GUY
Most injectors vary wildly in response time in their own sets...............let alone a totally different injectors.

Not all ecu's are very adept at recognizing this and don't have internal software functions to deal with this.
This has piqued my curiosity. Are you suggesting there is an aftermarket ECU which can:
  • recognize that one of my injectors is flowing either too much or too little fuel, relative to the other injectors,
  • deal with this variation (i.e. set a different fuel trim for each cylinder) on the fly?
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Old 01-13-2003, 01:43 PM   #11
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Hmmmm... I know for a fact that some can trim each cylinder individually (my Haltech can), but I hadn't thought that any could do it automatically. Perhaps with a good WB setup...?
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Old 01-13-2003, 01:56 PM   #12
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Quote:
Originally posted by 8Complex
Hmmmm... I know for a fact that some can trim each cylinder individually (my Haltech can), but I hadn't thought that any could do it automatically. Perhaps with a good WB setup...?
It's the recognition part of the problem that most interests me and it boils down to being able to recognize each cylinder's A/F ratio. There are three possible ways to do this:
  • [a]brute force: a separate A/F ratio sensor for each cylinder.
    [b]finesse: using equal length headers, a very fast responding A/F ratio sensor, and knowledge of how long an exhaust pulse from any cylinder takes to arrive at the A/F ratio sensor.
    [c]ultimate: using ionic current detection at the spark plug gap to sense each cylinder's A/F ratio (as well has whether it misfired or pinged) during the last power stroke.

An aftermarket ECU that could do any of those would be of interest to me.
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Old 01-13-2003, 03:34 PM   #13
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Me too.

-Chav
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Old 01-13-2003, 03:46 PM   #14
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Ok, I just want to get this right.

Graham- You are saying that you increased fuel right off of the bat? In other words you raised the master fuel because you were running leaner when you installed the new injectors.
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Old 01-13-2003, 04:04 PM   #15
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Graham didn't have new injectors, he still has the stockers. However, he used my map set for 440's. He needed to up all the fuel to compensate.
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Old 01-13-2003, 04:18 PM   #16
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Thanks again.
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Old 01-13-2003, 04:34 PM   #17
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Quote:
Originally posted by Jon [in CT]
[c]ultimate: using ionic current detection at the spark plug gap to sense each cylinder's A/F ratio (as well has whether it misfired or pinged) during the last power stroke.
Jon - You scare me.

It could also possibly just cycle through each cylinder for a minute richening it up for a few revolutions and getting a feel for the frequency of the header, doing this for each cylinder, then adjusting during idle to even it all out. Probably be more of an auto-learn that is activated by the user rather then something automatically done while running.
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Old 01-13-2003, 07:46 PM   #18
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Old 01-13-2003, 07:54 PM   #19
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Quote:
Originally posted by John at J&S
Ionic detection here:

http://www.adrenalineresearch.com/smart.htm


Know anybody that uses that right now?
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Old 01-13-2003, 09:40 PM   #20
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Quote:
Originally posted by John at J&S
Ionic detection here:

http://www.adrenalineresearch.com/smart.htm
Yes, I had in mind when I wrote my last post a patent by Edward VanDyne assigned to Adrenaline Research, US 6,029,627, for the use of ionic current sensing to control A/F. In its description of "prior art," the patent says:
Quote:
Most air/fuel ratio control methods use oxygen sensors in the exhaust system of the engine to measure the presence of oxygen which is indicative of whether the engine is running at stoichiometric mixtures. The O2 sensor measures the O2 in the exhaust of the engine in either the exhaust manifold or the exhaust pipe. One drawback to using an O2 sensor in the exhaust manifold or pipe is that the sensor reads a global air/fuel ratio for all engine cylinders. If one cylinder runs lean because, for example, a fuel injector is clogged, an air/fuel ratio controller that is based upon the O2 sensor will cause the other cylinders to run more richly thereby maintaining the desired global air/fuel ratio. Such a system achieves an average stoichiometric air/fuel ratio for all the cylinders, even though individual cylinders may be running at undesirably rich or lean mixtures.

There have been a number of attempts using O2 sensors to replace the above-described global emissions control with control of the air/fuel ratios in individual cylinders. The most common method of individually controlling the air/fuel ratio is to utilize fast acting O2 sensors to discern the exhaust O2 from each of the cylinders individually. The primary drawback with this implementation is that the O2 sensors are down-stream from the cylinders. The physical separation between the cylinder where combustion takes place and the sensor which measures the combustion characteristics introduces time delays, error and control difficulties. It is exceedingly difficult to calibrate this type of air/fuel ratio control system to account for the time delay and error at all engine speeds. Additionally, in some current production engines, four or more O2 sensors are required for this type of control thereby increasing the cost of implementation.
There are some OEM ECUs that use ionic current sensing, but only for knock detection. The Saab Trionic engine mangement system is an example. (Does anyone know how to reprogram Trionic ECUs, la the ECUTEK solution for the New Age WRX?)

The Adreanline system is really only an ignition management system at this point in time, not a full-blown engine management system. And it's ridiculously expensive.

So I'm still looking for one of those aftermarket ECUs that EFI-GUY was talking about.
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Old 01-14-2003, 01:39 AM   #21
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Quote:
Originally posted by Jon [in CT]
So I'm still looking for one of those aftermarket ECUs that EFI-GUY was talking about. [/b]
I have an Autronic PnP board available now for the '02 WRX and I'm currently near the end of development on a PnP for the 2.5 RS cars.

PM or email me at ben@dynospeed.com for more info........
-Ben
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