At 05:04 PM 2/2/99 -0500, you wrote:
>I have a question: Is the computer in control of the motor at Wide Open
>Throttle in the 318's and 360's? Doesnt the oxygen sensor have a "window" in
>which it works.(also the speed density system?) This is why cars like the
>buick Grand National can run 9's with the stock computer. (I also relize that
>the GN's use chips that vary the timing, boost, and fuel tables). Doesnt it
>become just a matter of keeping the motor within the correct air/fuel ratio
>increasing each for more HP.
The computer controls the engine at all throttle positions, but the
area where it has the "least control" is at WOT and open loop. In
normal closed loop conditions, the computer reads the O2 sensor and uses
it to vary the amount of fuel it spits out the injectors to try to keep
the A/F ratio at 14.7:1. But, during open loop and WOT, the computer
just spits out a fixed amount of fuel, and the list of stuff that it keeps
tabs on is significantly less. (You could sort've think of it as only
monitoring the "bare essentials".)
> All this talk about new computers confuses me. If
>the nitrous guys are using the stock computer why cant everyone else? I was
>just wondering.
The biggest reason is that nitrous is a WOT condition only. The computer
isn't monitoring the A/F ratio, and you know how much extra fuel you have
to add to keep the ratio from going too rich or lean. With a supercharger
or a turbo, boost comes on before WOT, when the computer is still "in control".
The computer will see the extra air and add fuel to adjust the A/F ratio,
but if the amount of fuel it has to add goes outside of some predetermined
range, the computer will think there is some sort of problem. I think that's
the main reason why the supercharger folks would like new computers; so normal
supercharged conditions won't get flagged as malfunctions. Basically, the
stock computer doesn't "know" there is a supercharger on the engine, it
just sees "weird" readings. For a computer that has been set up for a blower,
these "weird" readings are considered "normal".
-Jon-
.--- stei0302@cs.fredonia.edu ------------------------------------.
| Affiliations: DoD, EAA, MP Race Team, NMA, SPA, USUA. RP-SEL |
| '96 Dodge Dakota v8 SLT CC (14.58@93.55), '96 Kolb FireFly 447 |
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