New owner, power loss and misfire concerns
 

I bought a 2008 RX8 Sport w/ manual transmission about 3 weeks ago. It has 28,855 on the odometer right now. I've through 3 full tanks of gas and I'm averaging about 18 MPG. I've used 91 octane gas since I got it. I changed the oil the second day I had the car. I used a STP filter and Castrol GTX 5w30. I'm the second owner and the looks to be in excellent physical condition. The exterior body and interior look brand new so I'm hoping the previous owner properly maintained the engine.

So here's my concerns...
Yesterday afternoon it was about 95 outside. The oil gauge is always a little past the middle marker. The temperature gauge was slightly before the middle marker (on the cool side). I was driving for about 20 mins on the highway, got off, came to a stop sign and made a complete stop. I put the car in 1st and tried to take off. I had no power to the wheels and it felt like I was in the wrong gear. I put the car in neutral, back in first, and tried again with the same results. Then I put the car in neutral and revved it a bit. At about 3k RPM it started to (what felt like) a misfire but I didnt see a CEL. I put it back in first and the car took off but with less power than usual. I made another stop and it was idling really rough, a lot of shaking, and it felt like it was going to turn off.

When I got home I checked the oil and spark plug connections and they both look good.

This morning I took off to work (68 degrees outside) and the car is driving normal. I read a few threads about ignition system maintenance so I ordered new plugs, plug wires, and coils. Hopefully this will prevent it from happening again.

Any thoughts? I just want to share my experiences and look for input from the community.

Ignore the oil gauge- it's a dummy. Temp only moves when at 130*, up to normal operating temp. If it moves higher, you engine is likely already in the danger zone.

Plugs/coils could be an issue. And, yo are around the mileage for a change.
But, there are other areas that could be an issue.
Did you fill up with gas/ change oil recently?
Any work under the hood?

I changed the oil 3 weeks ago (about 600 miles ago) and had about 1/2 tank of gas when this happened. I just filled up again this morning. The only thing I've done under the hood recently was check the oil level.

Was your AC on and working properly? Did you have any signs of overheating?

The AC was on full blast but there was no obvious signs of over heating. Now that I think about it, the AC air flow would decrease and increase significantly as the car lost and gained power.

Without much more information, you only ruled out the plugs and coils (and sounds like you got raped with dealer prices doing so).

Other possibilities are:
- Vacuum leak
- MAF sensor fouled
- E-shaft sensor fouled
And the dealer's commented compression loss.

You can check and usually fix the first 3 yourself for free. A compression test must be done at the dealer. I'm guessing that you are over 100,000 miles

Where you say: "The speed shown on the speedometer didn't feel like what I was actually driving.", this seems like either a clutch slipping (MT) or a torque converter (AT) issue?

You aren't all that clear about what your problem is other than general power loss with idle issues. You are using lots of subjective terms that could have significantly different meaning depending on who is saying them.

RIWWP,

Usually you're much more thorough than this, so I'm going to guess you either are drunk, or you're mixing up this guy with someone else's post.

I'm going to highlight the OP's post to point out the things where you didn't read his post properly:


So, he hasn't eliminated the ignition system, and I don't know where you came up with the idea that he got raped by the dealer for them.

I really, really don't understand why you thought he has over 100k miles on the car, as he clearly stated it only has 28k on it, in the second line.

Usually your spot on, so I'm going to assume you were posting while rescuing puppies from a burning building on your Android phone.

BC.

^............ha ha ha.....yeah, he was way off on that one!
Posted at ~10pm last night..................from the bar perhaps?

Hmm. I may have posted to the wrong thread? :scratchhe

I remember making that post, and reading that he had just changed plugs and coils.... :dunno:

Thanks for catching it :lol:

And no, just working as well. Been working ~10am to ~midnight for the past few days.

Hmm, I'd need a mod to verify, but I SWEAR there was another post from someone hijacking the thread that I was responding. I responded within a couple minutes of seeing the post in live, and as you can see, there was a day back to the prior post.


I'm not losing my mind!

Well, maybe, but it's OK! :) :icon_tup:

Bladecutter, I think RIWWP was replying to a post by Carr7802. Looks like Carr's post was deleted sometime after RIWWP replied. Carr7802 said his car has similar issue and the dealer changed out the plugs and coils but the problem returned shortly after.

Well back to my story :)
The plugs came in yesterday I got all 4 for $73 including shipping from Amazon, I got the coils at O'reilley's for 29.99 each plus tax with life time warranty. Now I'm just waiting for the wires to get here so I change it all out. Hopefully I can get this taken care of by next weekend.

finally got all the parts in and changed out the coils, wires, and plugs. My car is running better than I expected.. Thanks for the help and suggestions!!

That sounds similar to mine. After two years, my '07 GT started misfiring (front rotor), after sitting in a construction zone. It limped home and started run almost okay about halfway there. The construction zone is pretty rough, so I thought something might have shaken loose. One of the plug wires felt loose. I reseated it and headed out. It drove normally...for a half mile.

I ordered the BHR ignition (coils, plugs, wires) and it's fine now. After installation, I took it out and ran it pretty hard to test it, with no problems.