not firing on #2 and #3

[toslo5o]

OK everyone I need help. if you have any ideas on this one please shoot them at me. Ok let me start with the car setup. This is a '95 Eclipse GS 420a, that is for the most part stock in form. It does have a few bolt on upgrades, and I rebuilt the engine about a year and a half ago. Bolt on items are just basics like I/H/E & UDP. About 6 months ago, the car started to stall out while driving. After a few times of this I started to trace the issue. Turned out that the coil had gone bad, so I replaced the coil and all was well again. 2 days later, the same stall out. Upon check, the coil had once again gone out. I marked this up to simply receiving a bad part from the manufacturer, so I returned the part, got a new one, and again all was well. 5 days later the car dies yet again. At this point I headed straight for the coil. This coil tested out ok. I pulled the plugs to verify spark, only to find that plugs 2 & 3 where not firing. To shorten this a bit let me get right to the meat of things. After many hours of testing and retesting, the results remain the same. Plugs 2 & 3 no spark, 1 & 4 are fine. Now before anyone tells me about the layout of the coil, and the primary and secondary circuits, these have be tested to death and are fine. As a matter of fact the issue seems to be that the BROWN wire which comes from the # 41 pin of the ECU is dead. If I switch the lead from the ECU to the 2&3 lead of the coil, those plugs fire, but 1&4 stop. I replaced the ECU, yet the issue persists. The cam sensor and crank sensor have both been replaced at this point. The cam sensor was done during the rebuild of the engine, the crank sensor during me troubleshooting. The harness has checked out ok as well at each of these locations. Long and short of it is that there seems to be no signal from pin #41 of the ECU. Any ideas here would be greatly appreciated. If anyone knows for certain what tells the ECU to fire a signal on pin #41, please chime in. I would however assume that the same command would be used to fire pin #21 (plugs 1&4) which is indeed working just fine. I really am at a loss here and need more minds with ideas I've not looked at here. As always, thanks for any input, and help on this.

 

[Stee420aT]

Did you start with the basics and replace the wires, its not uncommon for two of them to go out at once. swap wires around and see if the same two still don't spark.

 

[toslo5o]

the plug wires? because i have swapped the actual wires at the ecu, then 1 & 4 stop firing and 2 & 3 do fire.

 

[Stee420aT]

yeah, i was speaking of plug wires, obviously if you swapped the wires at the ecu, plug wires wouldn't be your issue. Sorry for the misunderstanding. Correct me if im wrong but if you swap the wires at the ecu and the opposite cylinder fire correctly wouldn't that constitute a problem with the actual ecu going bad or the harness itself?

 

[toslo5o]

yea i was thinking about the wiring harness, its the only thing i havnt tried yet. already have replaced all sensors, ecu, and motors been rebuilt.

 

[vingasoline]

Sounds like a bad Power transistor.

 

[Stee420aT]

Sounds like the harness then. My car had the harness completely redone because it used to blow engine fuses left and right.

 

[toslo5o]

question... did you actually read my post? or did you just scan over it? because if you did read it, what would switching the plug wires have to do with the issue? if i swapped the wires from the ecu and made 2 & 3 fire, then 1 & 4 stop firing, if the plugs were bad... wouldnt 2 & 3 still not fire? correct me if im wrong. sorry not trying to sound like an ass.

hmm.... really? well in that case do you by happen to know what tells the ECU to fire a signal on pin #41?

 

[Stee420aT]

I do not know what pin 41 reads off of. To take a wild guess i'd say CPS but that can't be bad or you wouldn't get spark at any of the plugs what so ever. Pardon my ignorance. I am in the newb section after all.

 

[Twinturbo120]

Sounds like a bad Power transistor.

I second this, if you have already changed the ecu and stuff. It could be the transistor.

 

[toslo5o]

420a... no transistor

pin 41 is the wire that runs to the ignition coil that fires cylinder 2 & 3