H_M

iTrader: (7)

I've already changed the primary injectors & rail for another pair. The problem did not go away

Tom93R1

iTrader: (2)

The lower injector o-ring
If it leaks you will flood a rotor despite the injector working just fine and not dumping fuel all over the outside of the engine. All your symptoms point to an injector dumping fuel, so if the injector itself is ok it pretty much has to be the o-ring.

H_M

iTrader: (7)

Thanks for the input but I've been through all that already.

I replaced both lower o-rings on the primary injectors with Mazda OEM o-rings about 4-5 weeks ago. I have double and triple checked them to make sure that they are seated correctly. I checked them again when I pulled the primary rail and switched the primary rail & injectors with another set. All o-rings on my 2200cc injectors were perfect when I pulled them and I switched all o-rings when installing my old 1600cc injectors.

I also pulled the primary injectors and rail while still being hooked to the fuel lines to check them. They do not leak when the system is primed to 40psi and fire normally during cranking.

H_M

iTrader: (7)

Ran to the garage really quickly after getting home from work to check spark. Both leading plugs are firing a bright white spark. Neither trailing plug has any spark.

I have never had a coil fail and, up until now, I was only looking for spark at the leading plugs. I've heard a lot of people say that the engine will run on only leading/trailing plugs so I never gave it much thought. After reading today, I learned that the leading coil fires both plugs simultaneously, which could mean that one rotor is in sync with the firing while the other is not. Normally this would not make much of a difference but it's probably wreakjng havoc with my heavilg ported engine.

I'll pull the coils and check them. I will also test the signal. I believe that it's a wiring issue because I had already switched coils a few weeks ago but still had the same results.

scotty305

iTrader: (2)

Very interesting. Due to the way the OEM primary dual-post coil works, I would be surprised if the front leading spark is much stronger or weaker than the rear leading spark. As a test, you should be able to swap the front & rear leading spark plug wires without affecting how the engine runs. Don't ever swap the trailing spark plug wires, that could be dangerous.

It will be tricky to test the signal that triggers the coils without an oscilloscope. The trigger pulse is around 0.003 seconds duration, far too short to catch when using a multimeter in DC Volts mode.

Some info about the wiring and control in this thread, although I'm not really sure how the HKS box affects the OEM setup.
https://www.rx7club.com/3rd-generati...iagram-964089/

H_M

iTrader: (7)

Another update. I decided to put the original 550/2200 injectors since they were not the issue and focused my attentin to the spark/coils not firing.

The trailing coils were not firing so I swapped in a diferent set = still no spark on trailing coils.

Got a multimeter from work and went to work checking for continuity. This is what I discovered:

All three coils get 12v when ignition is turned on. So the trailing coils might not be getting a trigger signal.
ECU --> igniter = all good wires & continuity.
Igniter --> gray plug = leading coil wire is good. Front trailing shows continuity on both F and R wires. Rear trailing coil shows continuity on both F and R wires (hmm).
Gray plug --> coil plug = leading wire has good continuity. Front trailing wire has good continuity. Rear trailing has no continuity (hmm).
Coil plug --> coils = all good wires & continuity.

My thoughts are that the trailing trigger wires are shorted and possibly touching each other inside the main hassis wiring loom. Which is causing all sorts of mess. Hopefully this did not short out the ECU. I started peeling away some of the wiring loom to see if I could see any issues. I'll report back if/when I find something new.

I also realize that I could bypass this whole wiring mess by going with an AEM coil setup. I plan on eventualy doing this but I want to get to the bottom of this mess first so that there aren't any more surprises.

DaleClark

iTrader: (55)

Good call on finding the issue. I've seen MANY people with some odd problem just say "well, I'll just replace the whole thing with (aftermarket part)" - that usually has the end result of a car that never runs again and gets parted out.

Wire harnesses left on their own don't short out. It's either a place where something aftermarket was tapped in or a place where the harness could rub against something - don't know if any of the wires go through the fender well, having wiring damaged from hitting the front tires is common.

I want to say that harness from the igniter to the coils is pretty nuts - like it goes all around the car or something weird. Seem to remember Chuck Westbrook building a straight harness from the coils to the coil packs to decrease resistance.

Dale

H_M

iTrader: (7)

I may depin the connectors and make a new harness to cut down the confusion. You're right that the harness runs through half the engine bay and is a jumbled mess.

I unwrapped some more of the loom as well. Just a few short minutes but I quickly found a major issue. The wire that supplies the trigger signal to the rear trailing coil was completely split jn half insie the harness leading to the coil plug. This explains why there was zero continuity on that wire. I have no idea how this could have happened because the harness looked untouched...

DaleClark

iTrader: (55)

Wow! Well, there's a good place to start on the problem!

Dale

H_M

iTrader: (7)

I want to update this because I hate reading old threads in which the OP never says if they resolved the issue or not.

The wiring was to blame for my troubles. I went through the harnesses with a multimeter and something was going inside of the main loom that is tucked up inside the fender. I didn't want to tear half the car apart and decided to bypass the whole thing and replace everything with an AEM coil kit. AEM coils were already on my "to do" list so this was an easy decision for me. I did the normal deflooding proceedure, charged the battery, and checked plugs/ fluids as a precaution because it was cold and the car had been sitting for six months. The car sputtered a bit and then fired up. The engine ran as it should after a minute and I let the car get up to temperature while I checked everything. This took about 30 minutes as it was -15C. Everything ran great the whole time. Problem solved.
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Johnny Kommavongsa

iTrader: (13)

Nice. Thxs for the update.