I have a Texas Speed 570 horse LS3 with Speartech GM ECU and harness in my 69 Firebird street/track car. I switched from a RacePak IQ3 set up to more traditional Speedhut guages. The install was pretty straight forward. Everything works as it should (still need to calibrate the speedo). Anyway, I also installed a Moroso kill switch in the dash that will completely kill the motor when switched off as well. I took the car out for a quick spin around the block and noticed it seemed to be down on power and running a little weird. I rechecked all of the connections in the harness that had been removed during the project. Everything was fine in that regard. I have my coil pack mounted on my valve covers and had to remove a few spark plug wires to gain access to the temp sender in the passenger head. Last night I pulled the plug wires to test them. I noticed that the coil end of #8 was corroded. Pilled it apart and cleaned it up and it tested fine. I looked at a few plugs and noticed that all looked good except for #8 looking a little washed off/clean (probably from unburnt fuel. I grabbed a spark plug and did some testing of #8:
1. no spark when the motor was running
2. no change in sound when #8 plug wire on or off its plug
3. swapped out to the wire from #1 (after verifying that it had spark at that cylinder before pulling): no spark still
4. installed plug wire from #8 to # 1 and had spark (verifying that the plug wire was good.
5. No check engine light on (red light by the OBD2 port)
I have square coils that Texas Speed sent with the motor 10 years ago. Am I right in thinking I have a bad coil?

 

It sure sounds to me like your not hitting on all cylinders. I purchased one of these last week to check for ignition spark on my 03 Silverado that's throwing a P0300 code.



Duralast In-Line Ignition spark tester that's about $9