Replaced Dist ign system with SDI system, and computer running very different

Roger Heflin rah at horizon.hit.net
Sun Aug 9 18:48:17 GMT 1998


Hey,

I have a 93 Z28 LT1.  I have a custom computer reprogram.   I replaced
the stock (probably worn out) OPTIspark (basically distributor with some optical sensors
for better timing) with a SDI ignition system.  The SDI system has 1 coil per 2
cylinders.  

Before the SDI system:

Idleing out of gear:
	Learns: 113/124   Integrators: 108/114
	Injectors 2.1 +- .1 or so.  
	O2 sensors are cycling pretty regularly. 150-950 mv

Idleing in gear:
	Learns: 128/129   Integrators: 122/122
	Injectors: 2.5 +- .1 or so.
	O2 sensors are cycling pretty regularly. 150-950mv

After the SDI:

Idleing out of gear:
	Learns: 108/108   Integratros: 1/1
	Injectors 1.7 (not really changing)
	O2 sensors are mostly rich.  Some cycling.

Idleing in Gear:
	Learns:  108/108  Integrators: 110/70
	Injectors: 2.1 +- 1 
	O2 sensors less rich than above, cycling is 
	lower frequency than before the sdi, but there
	is cycling.

I do have the before and after diacom runs.

The learns seem to stop at 108, my guess is that at idle before I
was having alot of missfires from a aged ign. system, and now that
is no longer the case.  Originally the guy doing the reprogramming
adjusted the injector (I had new bigger injectors) until the block
learns looked reasonable.  Now with the new ign system, things are 
running significantly different, so it did change something.  Also before the gas mileage
was really poor, 4-5 mph off what I thought
it should have been, it will take about a week or so for me to get enough miles to
determine if the gas mileage has changed.  Is this a reasonable conclusion given the
data?   And if it is a reasonable conclusion does anyone know the address and format of
the injector size in a 93 Z28 GM prom?  I have the necessary tools if I knew where the
injector size was.

			Thanks
			Roger Heflin
			93 Z28
			rah at horizon.hit.net



More information about the Diy_efi mailing list