LS1 Lean Cruise

[rrauscher at nni.com]

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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