GM EGR

[Jennifer Rose]

George

EGR valve in this system is a negative back pressure valve. Believe EGR
depends on back pressure from exhuast system to work correctly. Since my pu
is dual exhuast with out cats, back pressure probaly nil. Just need to
increase back pressure :( or fiqure how to change valve. So don't throw your
valve away yet.

At hot temp(at or above 100 deg F outside air temp) starts in my pu are very
long and have to press on throttle alittle. So I'm more than likely lean.
The cold start injector sprays during start for 8sec at 35 deg F to nothig
at about 100 deg F . Hope my info is correct.

Also my info indicates the same ECM was used from 86-89, 1227165. The cold
Start injector was deleted in 89 and replace with wider inj pulse width at
start up. In 87 VATS was added to some systems. I have purchased a 89 calpak
from GM, just need to bypass VATS. Prefer to do in software instead of using
hardware.
My pu is a 4x4 at 4300 lbs, 3.73 gears, turbo 400, 205 transfer case.


Vance