How can I tell if my coils are bad?
 

I’ve searched but haven’t found the exact symptoms of bad coils. I have seen the TSB on coils and resistance but if they may be bad I’d rather just drop it off at the shop and let them deal with it. Are they covered under warranty?

My car has run worse since the engine recall. The gas mileage dropped about 3MPG on that very day and has never recovered. Power seems to be lower at the lower RPMS but normal(ish) above 6K. Overall the power seems to be lower than it has been but I haven’t had the ass cheek dyno calibrated lately.

Most of the issues I've heard dealt with the upper-RPM range and not the lower, although I'd imagine it could hurt the lower RPM range as well.

The most common signs are blinking CEL's in the higher RPM range or misfiring (which is what the CEL is for).

Even with that said, though, it could be other things. How old are the plugs and plug wires? The general order of replacement is plugs, coils, wires when it comes to those types of issues.

I'd do a slight change to your order.

1.) Plugs
2.) Wires
3.) Coils

IMHO


But....to answer the original question.................go here!

http://foxed.ca/rx7manual/2003mazdarx8/

The car has 37K on it. The wires and coils are original. The plugs have been replaced about 3 times for recall - flooding - recall. They probalby have 10K on them now. I don't get high RPM CELs. (Thanks for the quick replys)

Probably should do wires and coils, but see the link I provided above.

I would get new cooils and a set of mazsports spark plug wires. OEM does not even compare to mazsport wires

^ what about Amemiya spark plug wires ?

I would do a compression check before you do anything mentioned above. (take it from me)

then go from there if compression checks out.

check all four coils on there proper resistance and see if they fall in spec.

spark plug wires are definately a must.

while your at it, a fresh set of plugs wouldn't hurt.

follow this route and you will save $$$$$$ f the stealership!!!!!

My car had been feeling low on power and didn't rev smoothly in the upper RPM's. I suspected the coils were bad, even though I had no misfire CEL's. I assume the car has the original coils and plug wires, I currently have 35,000 miles of which I've only added about 300 or 400 miles of. I pulled one of the coils off to test the resistance, it is really easy to do, unplug the wire harness and plug wire then remove a single nut. The coil tested bad, I had the msp16 recall done the other day and while I was there I told them I tested the coils and they tested bad. I asked if they were covered under the power train warranty, that is all I have left, they said no. So I ordered new coils and a new set of wires from mazda motorsports. They showed up today, I swapped them out, really easy to do. Took me about 30 minutes. Now the car runs great, idles a lot better, rev's smoother, pulls all the way to read line, and I was surprised at how much better the low end and mid range felt.

You need coils. For Plug wires, you might be able to hold on to the one u have, as long as there are no corrode on both ends.

I just changed my Coils 2 days ago, I changed my coils like about 15 or 17 K miles ago. So this is my 3rd set. Car feels great again, no misfires in the upper RPM range.

Thanks. I guess it is worth pulling out the ohm meter and checking them out.


3rd set of coils:eek: They wear out faster than tires!