My 5-speed rx7 was running pretty well. Daily driver with a nice idle, around 850, no hesitation, good grounds. I had just done Hailers starter circuit rewire job about four days before, and it really cured my starting "click-click-click-start!" problem when even a new ignition switch (the electrical portion) did not. Last Monday I drove it home from work and parked for the night, inside the garage.
Next morning, no start. It cranks really well; no indication of catching fire at all tho. I thought it was flooded. Wouldn't start that nite, either.
Wednesday, I cranked it over, but no start. I removed a spark plug. It was dry.
I cranked it over with the plug out, but no spark.
I am stumped. What would cause both the fuel and the spark to go out at the same time? I checked all the fuses, in the engine bay and the driver's footwell, and they look good.
Any ideas? Thanks for the help!

 

By the way, I used my nifty led-diagnostic lites; when I turn on the ignition key, both lights come on, but they do not go out! Previously when I used it, they went out after 3 sec or so, with no codes. Now, they just stay on....?

 

I am just throwing a guess out there, but maybe a bad ecu ? Make sure to check all your wiring under the dash and make sure none of your wires have grounded into each other(melted).

I had a similiar problem with my rx7 when i bought it, it had no spark at all and I ended up replacing the entire main harness to the car to fix it along with all the relays, coils, and ecu.

 

I have had many customers bring me their RX7's in similar situations.
4 out of 5 times it was a broken harness somewhere grounding out.
I have rarely ever seen an ECU go out without some cut wires as the cause.
I more often see a bad CAS over an ECU.
Bring it to my shop, the tow bill shouldn't be to bad.....LOL. J/k
Update us when you discover the problem.

Good luck.

 

Ditto on the bad CAS. I had the same problem, swapped it out and it worked first crank. My friend had the pin break/fall out on his CAS's gear and the gear fell off inside the front cover. did the same thing. Sucked, had to pull the front cover and fix it. Too bad we can't just turn our cars upside down and shake.

What does the ECU do when you unplug the AFM? Does it default to a rich condition? Or does it turn everything off.. could it be that too? Just trying to give you things to check.

 

If the two diag lights are not going out, then there is a MAJOR problem with the ECU. The lights coming on, then extinguishing is sort of a "Diagnostic" routine that lets you know the ECU is alive and healthy.

Since you are getting both no fuel AND no spark, its safe to say you can rule out the CAS as the possible culprit, since the CAS in no way controls fuel.

Check your fuses, pure and simple. No need to overcomplicate this on "CAS" problems. Also, check your wiring that you did previously, you may have disturbed something else.

 

Thank you all for your responses!
Is there a ground wire ("initial set coupler") that I need to use when plugging in the diagnostic leds to the 4-hole green female plug? I know there is a two-hole connector next to it...and I don't remember whether I used a jumper wire when I used the diagnostic leds a while ago. But I do recall that it worked normally, lights on for 3-sec, then both out (no codes came up), about two months ago.
I will check the wiring, especially in the area behind the driver's shock tower, where the relay went in. Main harness below that; I have had a brake fluid leak in that area (o-rings at fluid tank), just recently fixed with two large steel clamps.
I will try unplugging the AFM tonite and see what it does. And I'll watch the tach needle upon cranking.
I had thought that by adding the starter circuit relay, I backfed the starter circuit and fried my aftermarket alarm, but it is acting normally and wouldn't cut fuel in any case, just prevent cranking and kill spark. The car still cranks very well.
I am hoping that the ecu is okay. I could remove it and check inside for burned components...and check the connectors down there while I'm at it.
A CAS would be an easy fix, when I source one. I will look in the manual to find out how to check mine.

 

Let me clarify some things:

The ECU can control fuel, as in the event that causes it to inject. I was incorrect in my last statememt. This could possibly mean the CAS is bad, but if it was, I doubt it would be causing the ECU to malfunction, which is what it is happening.


No, all the ISC does is disable the BAC valve for setting idle. Nothing more..

 

i know you probably have done this but did you check the "engine" fuse in the fuse box by your feet. my car didnt start one time and i did all the same stuff. checked for flooding, checked and found no spark, tested the coils for resistance and power, then got pissed and finally checked the what i thought where only acc. fuses and found that my engine fuse was toast. what a stupid broad name for a 15A fuse, thats like having a fuse called interior or car

 

The engine fuse in the footwell looks good to me. I may try replacing it anyway. I can always hope! I took a good look at all the fuses, first.
I'm inclined to think the wiring near the brake master cylinder is the culprit here.

 

The diagnostic leds staying on is what scares me! ecu....

 

Hey guys thanks for all your help. J-Rat was right; when I did the starter relay, right next to the main relay, I must have loosened the connector to the main relay just enough to where it was intermittent. When I removed the coils and cleaned all the connections down there, the relay connector came right apart.

Well, in the meantime, I had checked both coils, the CAS, the TPS, and the AFM per the FSM, and they all checked out. The diagnostic leds are back to normal with no codes...looks like all is well! Glad to be driving my RX again!

By the way, the TPS is marginal, which is not unusual I think. What's the best source you've found for a new one?

 

Dont let that get around, it will ruin my reputation.