He He - Thanks LEVE - seems I can never remember how to do that.
Remember - the light flashing is what the computer "thinks" is happening. Sometimes that's not "what" is happening. It's interpreted values.
Most anything that affects how much O2 gets in the exhaust affects it - timing off, initial or advance, or even just a bad plug wire or plug or any ignition problem causes less burning in the cylinder, and more O2 in the exhaust, making the computer "think" it's lean, so it adds fuel - rich.
Sometimes just changing initial advance 2 or 3 degrees can make a world of difference with them.
Howell uses several computers - they use what they can get from local wrecking yards - GM TBI's - but they will deny it.
Some are set to use different initial timing advances. Some might be set to use 0 degrees, some 4, some 8, some even 12.
Look on the ECM itself - find the numbers on it - look them up on the internet for the application it was used in. Then look up the base (initial) timing for that application. It may be different than what they told you to set it to.
Remember - the Howell people are electronics guys - harness builders, not automotive people. Every time I've tried to get help from them, they've proven they don't know about cars and how they work.
For instance when a guy called and told them the TBI didn't fit the manifold - bolts did, but it left a huge hole by the side of it - major vacuum leak. They him to fill it with silicone.
Car folks would know silicone won't stick with gasoline around.
Another time a customer of mine had been trading chips with them several times trying to solve a dead cylinder problem. They kept telling him they were re-programming the chips for him.
I replaced the bad plug, no more problem.