[Diy_efi] Re: idle control strategy for SD systems w/o bypass air control?

Jerry Wills jswills at attbi.com
Tue Sep 3 15:28:29 GMT 2002


After further investigation, The butterfly stop is adjusted a small
amount as part of the warmup strategy, It cracks them open when cold,
and there is a small bypass passage in each throttle body. A needle
valve set at the factory. I have no wish to try and implement a 
seperate controlled air bypass on four throttle bodies. The motorcycle
head has maybe six inches of intake port, and that includes the mani-
fold, and then another inch to the individual butterflies. I'm
going to need some Data Acquisition hardware to datalog the timing
advance and injector pulsewidth. I can load the motor in gear with
some clutch slip and see the compensation for the lower RPMs. It 
is possible that a replacement for the fast idle unit, to something
like an IAC, is in the cards, but I would like to change less hardware
and see what can be done on the software side, as this is how the
original was done.
Something I didn't mention in my first msg, and seems to have been
lost later, The system has a NB O2 sensor in the collector, before
the Cat.

Jerry

>>>>> "Kent" == Kent Martin <kentmartin at froggy.com.au> writes:

> Yep just as good, 
> Kent.  

>>----- Original Message ----- From: "Mike"
>> <erazmus at iinet.net.au> To: <diy_efi at diy-efi.org> Sent: Wednesday,
>> August 28, 2002 10:48 PM Subject: Re: [Diy_efi] idle control
>> strategy for SD systems w/o bypass air control?
>>
>> Why not just adjust the deadstop on the butterfly instead of the
>> extra plumbing for a bypass ?
>> 
>> rgds
>> 
>> Mike
>> 
>>> 
>>> At 07:13 PM 26/8/2002 +1000, you wrote:
>>> >Well since this is a DIY EFI site might I suggest you use >an air
>>> bypass valve and control it. I have written some code >to control a
>>> stepper motor to do just that.  >Using a PID loop, you can easily
>>> control a stepper motor >of an air bypass valve to get a nice
>>> stable RPM and easy >starting. 
>>> Kent.




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