I'm looking for some opinions on my situation, any help would be much appreciated.

I have a 2004 Rx-8 with 70,000 miles on it. I am not the first owner, I've had it for about 16000 miles. Back in February, I was on about a 4 hour drive, and I noticed about half way through that the car had lost a lot of the power I'm used to. It was unable to make it up even small hills at the speed I had the cruise control set to (around 72) without slowing down considerably. It was very frustrating, but the check engine light never came on

It was a critical trip, and I decided to drive through it and take it to the dealer when I got back home, so I parked it for the weekend and used a different car. However, when I got back in it to go home, the problem seemed to be gone. The power was back, and everything seemed normal.

Yesterday, however, I got volunteered to drive a friend about an hour and a half away to pick up his car at a shop, and the loss of power returned. I first noticed the car idling rough at a stoplight before getting back on the highway to come home. On the on-ramp, I felt like I was in my girlfriend's Elantra, and the entire ride back home felt the same as before...severe loss of power. I drove straight to the dealer, and got there about 10 minutes before they closed. They said they'd look at it in the morning.

The guy just called me back, and told me the tech took it for a test drive and also experienced the loss in power, and also noticed that there was a lot of resistance in the ignition system. He suggested that I replace the wires, plugs, and the coils.

Anyway, the point:
Is it possible that too much resistance in the ignition system is causing such a severe loss in power? It seems to me that it wouldn't affect the power the engine was developing, as long as the plugs were still sparking...however I don't know a whole lot about the engine...

Also, what sort of symptoms usually lead up to requiring a new engine?

 

sounds like a bad cat.
loosen the 3 bolts holding it, take a peak inside.

if you still think you need a new engine, the only definitive way is to have the compression tested. You'll need a rotary engine compression tester or a shop that has one.

coils can and do go bad, when the do common symptoms are loss of power and engine misfires. These will typically trigger a blinking CEL or a solid light.
Why is the dealership not testing the ignition coils? They have a TSB that shows them how to test the resistance on them.

 

Replace your ignition coils. Might as well do plugs and wires too. I had a similar problem, when cool I had no problems, but after hard driving or longer rides (when it really starts to cook undr the hood and the coils) I would experience that loss of power and sluggishness.

Edit: I would also add that it didn't throw a CEL unless I really hammered at the throttle, and when I finally could get a CEL (Was surisingly difficult) is was always a misfire code.

 

Too much resistance in the ignition system? I don't know what he would be refering to, unless there is a miscommunication between you two.
With 70K miles on the car, it could easily need a tune up. There have been people on this site that needed coils replaced at about 25K miles. Plugs average 25K miles for everyone.
Signs of a failing engine is loss of power or a warm engine restart problem. However, loss of power can be attributed to many issues including a clogged catalytic converter. If it was this, you would feel the floor of the passenger side get hot or looking under the car the converter would be glowing red after the car had been driven for a while.
I'll bet if the tuneup doesn't fix it, the problem is the cat converter.

 

My car was super sluggish last Aug. Replaced the coils and the problem was solved. You should also replaces the plugs and wires. You will notitice yourself replacing plugs in an 8 alot. I beleive Mazda recommends replacing them every 13,000 if I recall. Could be a number of things though. Bad cat, carbon build up, etc...

 

I believe Ash8 mentioned the plugs are good for about 36 k.
I swap them out once a year anyways.

 

Thats weird cause i noticed a loss of power today. it 63 out today and i didnt drive a lot but i did notice that the car was weaker(didnt pull the way it always does). what site has good deals and a good product for coils, ignition, and wires?

 

Bhr