VATS Bypass

[Bruce Plecan]

-----Original Message-----
From: Mike Pilkenton <mpilkent at ptw.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Monday, December 21, 1998 8:30 PM
Subject: Re: VATS Bypass


>Actually this is not the problem Bruce.

In your opinion.

  The ECM doesn't care if the >EGR is there or not , it's the fuel/air ratio
of mofdern day engines (I >believe about 14 to 1 vs 12 to 1 with older non
EGR engines) that >poses the problem.

Well on a late gm ecm can set a code, if the EGR diagnostics fail.
So the ecm does care, in this application.  In cruise the newer engines run
richer than the old.  The Cat Conv equipped engines
need to run at 14.7, and the pre converter engines can run leaner than that
in cruise.

>With this leaner mixture, the engines can run much hotter and rely on >the
EGR system to reduce this heat.  Without going into the >chemistry, the
exhaust gas recirculated into the intake not only >reduces emissions but
reduces cumbustion temperatures as well.

Yes, EGR reduces peak cruise combustion temps..
Nowadays they are also worried about pumping loses etc, so the
corrections on a late gm are to add, timing, and fuel, when the EGR is
applied..
>
>    So without the EGR, I must richen up the mixture (theoritically) to
>keep from burning up pistons.  I'm not an expert but this is what I've
>been told by several professional mechanics.

Talking generally about carbed cars that is correct.
Bruce

>
>Mike
>-----Original Message-----
>From: Bruce Plecan <nacelp at bright.net>
>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>Date: Sunday, December 20, 1998 10:14 PM
>Subject: Re: VATS Bypass
>
>
>>
>>-----Original Message-----
>>From: Mike Pilkenton <mpilkent at ptw.com>
>>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>>Subject: Re: VATS Bypass
>>
>>
>>>That was me!  I have a 92 3.1L v6 Camaro motor that I want to eliminate
>the
>>>VATS as well as the EGR system due to a custom exhaust I have to
>fabricate.
>>>I was told that I must richen up the A/F mixture if I run without the EGR
>>or
>>>I will burn up the pistons/rings eventually.  Anyone heard of this?
>>
>>If there is no way to keep the egr intact, then you'll have to turn off
>>it's diagnostics, or trick the ecm into thinking it's there.  Might need
to
>>use like a 4066 running off the egr apply solenoid signal to trigger
>>a voltage divider on the MAP signal.  Assuming this is a MAP system.
>>Bruce
>>>
>>>Mike Pilkenton
>>>
>>>-----Original Message-----
>>>From: Bruce Plecan <nacelp at bright.net>
>>>To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
>>>Date: Sunday, December 20, 1998 3:00 PM
>>>Subject: VATS Bypass
>>>
>>>
>>>>Someone needed a 55 circuit for a VATS bypass, please e-mail
>>>>me,
>>>>Bruce     nacelp at bright.net
>
>