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Re: RePOST:Intake,Software, does it really matter? (archive)

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Posted by Bob ///M3 on April 28, 2000 at 09:43:26:

In Reply to: RePOST:Intake,Software, does it really matter? posted by ///M3 on April 28, 2000 at 00:25:39:

My understanding is that if you have a significant modification other than just a pulley, an aftermarket intake, etc. you might need "special" performance software that Jim C. (or others) can configure for you.

"If" changing to a HFM unit produces a different signal voltage to the DME (as Shawn Fogg said it would), that would be considered a significant change. Re-calibration (by way of the software) would be needed for the DME to "understand" (and read) the newly referenced airflow voltage signal. On the other hand, just a simple change to a CAI which doesn't change the way the airflow is measured (and the reference voltage signal to the DME) would not require "specially" configured performance software. As Shawn Fogg described, a change would have to be made in the software for the DME for work properly if using a HFM.

The very best way to tweak or fine tune an individual car is to have the performance software specialist (engineer) with the car along with a dyno. Since each car is a little different, the performance software engineer can determine the best set-up for your particular car. This, of course, is the ultimate in fine tuning but is really not needed for most street driven cars unless you have a multitude of major modifications i.e. bored-over/stroked bottom end, headwork, intake work, headers, larger capacity fuel injectors, open exhaust, turbo or supercharger, etc. In other words, by changing a lot of major things (major modifications) you will need custom modifications to the software!

Bob ///M3

: Posted by BOB M3
: "Jim C. can "configure" the performance software for various modifications IF is familar with it (the modification) and has run the necessary tests.
: I would think the modification/s that would require a different performance configuration would be considered a "major" modification i.e. headers, cam, headwork, larger throttle body, individual throttle bodies, (maybe a HFM), etc.

: Bob ///M3"

: Well, if we purchase one of the euro kits;ie JC or ECIS, and later add lets say a underdrive pulley or headers... will this effect the ecu? How are we suppose to fully maximize our performance when the chips were pre-mapped for a specif setup?


: Posted by Shawn Fogg:

: "Yes. You gotta understand how the HFM works. It basically measures the air mass passing through it. It does this by measuring the resistance of a heated film near the center of the meter. It 'tells' the DME what the air mass is basically by using a 0-5v signal to the DME.

: Using totally fabricated numbers as an example...

: say the HFM internally measures 10 lbs/minute of airflow. It tells the DME this by sending a 2v signal which the DME knows means this equals 10 lbs/minute. Now the airflow is 20 lbs/minute so it sends a 2 v signal which the DME understands what the airflow is. The HFM and DME have the same voltage to air mass 'table' so everthing works.

: Now you put on a bigger HFM that has the capacity to measure (and flow) more air. But it still needs to work with the 0-5v spec. Now when the DME is seeing a 1v signal you may actually be flowing 12 lbs/minute of air but the DME is basing its injector opening time thinking that the airflow is 10 lbs/minute and it injects the wrong amount of fuel that in this case would make you run lean.

: Sooo.... what the HFM 'chip' does is recalibrate the voltage to air mass 'table' inside the DME. With it in place the DME knows a 1v signal = 12 lbs/minute of air.

: Hope this helps,"

: So I would guess that both kits have the chipped tuned for everything? I ask this because on JC's kit, they have a re-tuned chip to work with the just the intake. So what about the rest of the stuff in the package?

: Thanks all

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