Hello forum, long time forum reader, sad that this has to be my first post.

I have a 2004 RX-8. Recent repairs include a new battery and a new catalytic converter, all dealer performed. I took the car out this morning to grab some breakfast and then drove it back home into the garage with no problems.

Fast forward two hours, time to go golfing. I fire it up, and immediately notice that it just seems very sluggish. There is an odd clunking noise under the hood. The check engine light and the battery light both illuminated. I had it in reverse and was backing out, and I had to use the emergency brake to stop the car because it seemed like the brake power went out. I turned off the vehicle and popped the hood before trying to fire it up again. I never really watched it before, but the part of the engine I can see seemed to be vibrating or moving, still making that clunking noise. I put it back into D to see if I could get it back into the garage, and the poor car sounded like it was dying. I had to put it into N and push it back into its home.

Any ideas? Would be glad to provide any more info necessary. I'm about ready to sell this car

 

Mileage? When was the last ignition change? Have you had a recent compression test?




Someone is about to suggest engine failure...and it's possible, but that's also jumping too far forward in a conclusion with the limited information you have.

The clunking has me scratching my head, since even terminal engine failure doesn't "clunk".

Can you describe the noise in more detail? Compare it to something?

 

The car is about to hit 74,000 on the nose. I bought it used over two years ago. This is not the car's first engine, the dealer told me it had already been replaced once. I don't have any information on when the ignition was last changed, nor do I have any info on the compression test. The car just had a Mazda full-circle inspection (had a coupon) about a month or two ago and everything checked out fine, but I don't know if they look at that kind of stuff at all.

It's nothing super loud, it kind of sounds like something is hitting on it with a hammer lightly, but that's probably a terrible description. I'd go out and start it again but its pouring rain right now.

 

Hammer hitting...what? A dull sullen thunk like a piece of wood? A clanging sheet of tin? a ringing tone like a steel bar?

100% understand the difficulty in trying to describe a sound with text.

Also, the frequency. Does it seem to be related to RPM? steady regardless of RPM? only exist within a certain RPM range?

When you were trying to drive it, was it trying to stall out, the RPMs dropping? Or was it just not really responding to the gas pedal? Was it trying to respond, but something felt like it was holding the car back?

 

Here we go again!

"The CEL told me there was a problem, but I didn't read the code, and now I want YOU to guess, over the internet, what is wrong....."

Actually I prolly CAN pin it down - the battery light tells us that the battery is not charging (yet the engine is running), the chugging/shaking of the idle tells us that the alternator is fully loaded and slowing down the engine, and the power steering fail tells us that the battery is not connected to the system 'reliably' which finally leads to the conclusuion that one, or both, of your battery terminals is very loose.

You're welcome, please come again.

 

Thanks Stealth.

I wasn't really including the battery light in my thought process. Barely even registered that note in the original post.

 

I hope I'm right, it's a very common problem, but precious little info to go on....

 

If that's the case, why would the car start flawlessly for weeks (up to 2 hours beforehand)? Just seems odd to me. I don't think there were any issues with the power steering at all. In any case, I'm having it towed (for the 3rd time since March) on Wednesday morning. Fun times. I'm going to have time to mess around with it some more tonight and I will update this thread at that time with any more symptoms I can diagnose.

 

OK, finally had the time after work to fire her up, things are a bit different now.

Car started just fine and was acting totally normal. Let the engine run for a good 45-60 seconds then gave it some gas, no problem. Let off a bit, gave it some more. Soon after, the CEL starting flashing on and off (no battery light this time) and every few seconds (giving it gas or not) the engine would hesitate for a second or two.

I found this topic: https://www.rx8club.com/series-i-trouble-shooting-95/blinking-check-engine-light-130155/

Is this the info I'm looking for?

 

Because when a car is running it vibrates... vibrations tend to loosen things... and it might have presented itself during start up because that's when the biggest strain on the electrical system is produced.




Did you bother checking the battery terminals like Stealth suggested? The misfires may be because of the coils being starved for power and producing an unreliable spark.

 

I went back outside to check something else.

I actually shifted into R this time, and the engine started shaking horribly. It allowed me to back up, but not without the horrible noise. I then shifted into D to inch back up, same thing. After a time or two of going back and forth, the battery light, the oil light, and another light came on (all 4 warning lights in that vertical line) and the oil temperature gauge dropped to where it would be if you turned off the car.

If you keep the car in P or N, the engine doesn't shake and the car is fine, but as soon as you shift, the car stalls out/quits soon after. I can put it in P, turn it off, and start it right back up again and repeat as necessary.

 

Did. You. Check. The. Battery. Terminals.

 

Sorry, nothing seems to be loose. Thought I included that.

 

Forget what seems to be loose.

Disconnect the negative completely.
Then Disconnect the positive completely.
Then clean the terminals and clamps.
Then reconnect the positive, wiggling it around to make sure it is seated properly.
Then reconnect the negative, wiggling it around to make sure it is seated properly.



On a prior car I had a terminal connection problem, it seemed snug, but had actually corroded away under the clamp, and it wasn't until I did the above that everything was restored because I had re-established the connection solidly.

 

No luck here, no corrosion and same issue.

 

When I first got my car the stock terminals were garbage. They were really flimsy and I didn't trust them at all.

It wouldn't hurt to try some new terminals. I got some of these marine terminals at AutoZone for like 5 bucks. It's a really simple replacement, just a couple wing nuts and a couple bolts to tighten down. I had to remove that smaller plastic cover for the positive terminal for the battery cover to fit though.


If that doesn't do anything then take it back to the dealer, you have every right to throw a bit of a fit if all this started happening right after they did the work on the car. The reason I think it has to be something with the battery is because that's one of the only major variables that's changed right before your problems started...


Oh and one last thing, don't know if it's been mentioned yet but have you done a soft ECU/PCM reset? To do this, get in the car and turn the key to the ON position but DO NOT start the car. Immediately after turning the key to ON, start tapping the brake pedal rapidly until you see the oil pressure gauge move then go back to the resting position. It should be about 20 taps. After this, turn the key back to off, take it out, then put it back in and start the car. The idle might be a little rough at first but this is because it's re-learning the fuel trims etc.

I would try the reset before the new terminals. Hope this helps...

 

I actually had the car towed this morning...dealer won't be able to look at it until Monday or so unless someone cancels, and this was the only day I was going to be able to wait for the tow guy to get there in the morning because I didn't have to be at work until 12:30.

Rest assured if the issue turns out to be battery related I will absolutely throw a fit. If it turns out to be something more complex...well we'll see. I didn't get a chance to try that reset, wish I had the opportunity. I will let you guys know what the diagnosis is, but I might not find out until next week.

 

As a final update to this thread:

The diagnosed problem was a bad engine coil (1 of 4)

 

Did you replace all four?
If not, you should really think about doing so.
I wouldn't let any of the coils go over about 25-30k miles......just my opinion.