Annoying glitches, what say yee..

[mike2004tct]

I had an iginiton module fail on my '97 2 Dr/4WD Blazer today. Could hear the pump prime, put a timing light on #1 wire, no spark. Took the cap off (why aren't those tiny screws captive?), distributor shaft/rotor turns when cranked. 12V at coil input, coil wire out the top arced real good to the block, so module unit defective I hoped. It was. No big problem, as it was the OEM unit, but the truck does only have 66K miles on it, so not overly driven, or for long periods of time per trip. (regardless).

Here's some weird observations, and a question at the end.

I had the ignition switch fail on it 5 years ago.
3 years ago, a large connector up on the fire wall loosened enough, that the 2 halfs arced, and it killed the EEM. Same symptoms of the switch failure, but I replaced the switch first, with no luck, then took it to my local mechanic for 2 days worth of diagnostics. Had to get a rebuilt/reflashed unit from Napa.
I replaced the fuel pump 3 years ago with a Carter unit. That crapped out 14 months later. Have an Adelphi unit in there now, but I'm getting suspicious of it.
Truck starts hard when cold, so I've resorted to turning the ignition on for 10 seconds before cranking the engine, so it'll start easier.

Here's the question;
Has anyone ever seen an instance where ther ignition module makes the engine hard to start?
I don't have a pressure gauge, so testing the fuel pressure is not available right now.

BTW, except for the EEM failure, all the other breakdowns happened when the wife or daughter were driving the truck, and of course I'm always at work. (I'll have to take their keys away)

[mike2004tct]

Well, after replacing the module. the truck started right up.
Ran fine, sitting in the driveway.
Took it to work, and it starts missing horribly at moderate accelleration, and at steady driving/cruising speed.
Under hard accelleration, truck performs great, no missing.
Back off the gas, and it bucks.
After 8 miles (6 mile trip each way), service engine soon light came on. P0300.

I'm hoping I got a bad module.
Truck ran fine up to the point it quit on the wife. No missing/codes at all.

[Chris Stewart]

What do the spark plugs look like?
WOT runs are open loop so no O2 sensor action.
Good idle reported.
Part throttle is closed loop, O2 sensors feeding info (millivolts) to the ECM then the ECM controls fuel.
Is there an O2 sensor downstream of the catalytic converter?

[mike2004tct]

Had taken the Echlin unit to Napa for testing this morning, and after explaining the symptoms I was having, the guy ordered me an ACDelco unit instead, but it won't be in until tomorrow.

When I got back home (I walked to the Napa store), I re-installed the Napa unit, no start.
No spark to plug #1, but plenty of spark from coil lead to distributor.
I remember checking the wiring 2.5 hours after driving 6 miles yesterday ,
and the module/heatsink was still very hot.
I guess the 6 mile return trip killed it good.

Why I do a lot of parts shopping at Napa, and also why my vehicles don't have a lot of miles
on them.

[mike2004tct]

I Put a Delphi unit in yesterday. Drove it today to work. Truck runs good again.

If I blow the Delphi unit up, I guess I'll have to replace the coil next time.
From what I've read/researched, a blown coil is about the only thing that over taxes the module.