LS1 Lean Cruise

[rrauscher at nni.com]

Ah, the 'ole EPA. By making it a separate function,
it is kept out of the IM240 loop. Clever. Makes
sense now.

BobR.

Gee, be nice to have source, wouldn't it? Anybody
here work for the EPA? <g>

>
>I'd suspect two things:
>It was again a patch job, someone had an idea way late in th program, or one

>area had no clue about what someone else was doing.
>Or, it was lets try this, and see if we can get away with it.  Figuring if

>one area didn't get approved then another might.
>gotta remember the EPA had the source code, and could look up anything they

>wanted.
>Bruce
>
>
>> I haven't quite figured out why gm kept them separate. When in
>> light cruise, closed loop, it is easy to use the main SA table
>> to give the SA required.
>>
>> When going into a lean fuel mode, additional timing will help.
>> It stabilizes the burn, along with bringing some power back.
>> Only need a couple of degrees (2-3). On my daily driver, I
>> ended up tying the hiway SA and fuel together. Secondary info
>> from the NACA site Dave posted supports this. I also had some
>> roughness when at 16.1 until I added a couple of degrees of SA.
>>
>> Then like you mentioned Mark, the hiway afr & sa change with
>> the map load.
>>
>> BobR.
>>
>> >There are two things going on here.
>> >1) Hwy Fuel
>> >2) Hwy Spark
>> >Two separate things.
>> >Hwy fuel is a light load commanded, calculated afr setting.
>> >Kind of like pe, it checks back to 14.7 to one to make sure the
>> >BL and INT are ok.
>> >Hwy spark is a light load commanded spark adder.
>> >The hwy spark is just load and rpm dependant.
>> >The hwy fuel is speed, load, coolant temp and rpm dependant.
>> >(My experience is ONLY on the 89 Vet code.
>> >86-87 code has only hwy spark (As far as I have been able to determine)

>> >Mark
>> >----- Original Message -----
>> >From: <Stephen.Kaminska at HSC.com>
>> >To: <gmecm at diy-efi.org>
>> >Sent: Wednesday, December 06, 2000 9:08 PM
>> >Subject: Re: LS1 Lean Cruise
>> >
>> >
>> >>
>> >> romans at starstream.net writes:
>> >> >
>> >> I never heard it, just picked up by the knock sensor, 1-2 deg usually.

>> >> My hwy cruise mode is in for 60 seconds then out for 5 then back in.
>> >> <
>> >>
>> >> OK, finally have to get out of lurk mode here because I am lost by this

>> >> thread.   What happens if you do not jump in and out of hwy cruise
>mode?
>>
>> >> Do you start getting lean misfire?  Or does the ECM decide you are
>running
>>
>> >> way too lean and command full rich?  Or both? Or none of the above?
>What
>>
>> >> is the engine telling you?
>> >>
>> >> Rick
>> >>
>> >>
>>
>> >
>> >
>> --------------------------------------------------------------------------

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