Guys, I've been having a spark issue for way too long on my DD. According to my mechanic it loses spark while Im driving. So after sitting it'll regain spark until it cuts off again.

I have replaced both CAS, the Ignitor, all Coils, the wiring hareness has 30xxx miles on it. The only thing left is the ECU..but is this really the problem? Is there anything else that could make the car do this? I've searched and it seems that everything I've replaced (except the ECU) would cause this. Im totally lost.

While driving it'll shut down (completely) after maybe 30-45 minutes depending on how aggressive the driving is. At idle, its anywhere from 3-4 hours before it shuts down. Please ask me any more questions you have to help me figure this out. Thanks.

 

Have you changed the ignition coil harness?

Dave

 

Well the whole engine wiring harness was replaced with one that has 30,xxx miles on it.

 

those are two different harnesses.....so....

but i wouldnt rule out the ecu.

~Jonathan

 

I see..I didn't know that. But heres the thing..would a bad harness cause this though?

 

yes bad wiring is bad wiring....

also how do you know its your spark thats causing this?

~Jonathan

 

It could, and it's cheaper to replace the harness than the ecu, so start with making sure the harness is in good shape.

 

Because I had my family mechanic scan the ecu for the code it was throwing and it was spark. He also checked to see for spark himself and there was none.

Now..are the symptoms I'm having appear to possibly be anything else? I see it as I could be having spark issues..but what other possiblities are there?

 

...I'm not sure what you have actually done...but you can't just rely on someone elses word...especially someone biased like your mechanic...and solving a problem has more to do with testing for correct reading as opposed to replacing everything that you think might be causing the problem. you'll end up replacing everything then eventually find something as simple as your negative battery cable being loose.

Start first by examining you plugs...if one looks wet, switch it with one that looks to be firing. drive it around then remove the plugs again. If the one that was wet is now firing and the one that was firing is now wet, then you have narrowed down the problem to the specific coil and coil wire...go from there...

If they are as you say, you loose all spark verify it with a timing light on all spark plug wires while someone cranks over the engine... if the timing light does'nt come on...check the resistance in you coil and spark plug wire after your car has lost spark and everything is still hot...make sure you have multiple clean negative grounding, battery to body, battery to engine, body to engine, ecu to body etc..

I once replaced a bad alternator with a new one from the dealer...and my new battery still wouldn't keep a charge...after rechecking everything I finally tested my new alternator and it was faulty...as I was putting it back in the box I noticed a piece of paper on the floor...turns out someone else returned it before before the dumb *** sold it to me.

 

Well the spark plugs and wires are newer. I'll check the groundings again. Any other adivce people?

 

Did you do anything of things in your old thread?

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/still-having-spark-issues-after-doing-fixes-550799/

 

What about the body harness?

 

Everything except checking the wiring harness for it. In the process now of getting one.

 

Definitely replace the coil harness. There were problems with the earlier harnesses, and Mazda upgraded the part.

Dale

 

"I once replaced a bad alternator with a new one from the dealer...and my new battery still wouldn't keep a charge...after rechecking everything I finally tested my new alternator and it was faulty...as I was putting it back in the box I noticed a piece of paper on the floor...turns out someone else returned it before before the dumb *** sold it to me".[/QUOTE]
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yep i always say, just because its "new" dosent mean its good.
as a mechanic i see this all the damn time.

 

+1 on the harness.

so after it dies and has no spark if you just let it sit for awhile and cool off it will fire right up?

as another idea look at the main/egi relay,

 

yes but a relay is either ON or OFF and when it breaks it breaks.
~J

 

I really appreciate all the feedback guys. I will be buying an actual DD this weekend soo..it'll be down and out until I get this fixed..then it'll be a weekend beast.

 

Smart move. Using the FD as a daily is IMO a bad idea. Some people get away with it for years with no problems, but I personally will always have 2 cars.

 

dont work on many hondas or other cars do you? they can get pitted and intermitently open.

you could pull the upper when it wont start and check for power at the terminals.
put a high impedence test light on the pos terminal of the battery and probe the harness on the controll side when someone cranks the engine and see if the light flickers letting you know that the ecu is switching the ground side.

seriously replace the harness first