need clarification of crank fuel compensation ms vs %

s300 and SManager software questions & answers
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Joined: Thu Nov 20, 2003 12:35 am
Location: Visalia, CA

need clarification of crank fuel compensation ms vs %

Post by RMS »

from the s300 help:
Changing the injector size will automatically compensate the fuel tables for the rating of the injector (but not for the specific characteristics of the injector). Also the cranking fuel and throttle tip in fuel are compensated based on the injector size.

my question:
cranking fuel is defined as a ms value in its table. so does doubling injector size decrease the actual/internal ms value by half?

this very confusing since it appears from the description that until the cranking/starting rpm exceeds the crank exit rpm that all injection time is based of the simple crank fuel table (odd too that no "pump shot" parameters exist... maybe high crank fuel with extremely fast first step decrease to 50%?).

e85 cold start can be troublesome and knowing exactly WHAT i am adjusting would make things far faster and easier. Thank you :)

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Re: need clarification of crank fuel compensation ms vs %

Post by Hondata »

Yes, the cranking fuel tables values are altered by the injector size, so that doubling the injector size will more or less halve the injector pulse (injector opening time is in there too).

This does make it easier to change injector size as you don't then need to change the cranking, tip in, closed loop etc tables.

E85 is very difficult to start with when cold (below about 60 degrees). Basically the ~15% gasoline is what starts the engine. The ethanol doesn't vaporize.

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