Power loss through rev range in 1st
 

I just drove home my RX8 yesterday afternoon! :djcelebra

I had test-driven it 2 weeks prior, drove fine, and took it in to the Mazda dealership (D Dahle Mazda here in Utah) to have compression and other tests done on it. It needed a new engine.

So they finish the engine rebuild Tuesday night and I pick it up for one last test-drive Wednesday night. The check engine light comes on and I noticed the power in 1st is a little spotty...

It seems to hiccup a couple times, at around 5000rpm and again at 7000rpm. From what i can find on this forum, maybe it's the cat? When i first took the car in for inspection 2 weeks ago, they said all they could do is a visual inspection, but if there's something wrong with it, there's a catalytic converter light that comes on...? I took it in for inspection this morning at a random Tunex place and they said "Random/Multiple Cylinder Misfire Detected" and the guy added there's carbon buildup... He also said it's often because the car is revved up TOO often (separate thread about that here), so i don't think he knew wtf he was talking about, but the code must at least be accurate, right?

Ideas?

misfires can be caused by bad coils
did the dealership reuse your old coils?
carbon build is is NORMAL and most believe that revv'ing the motor helps to keep the carbon away.

take it back to the dealership that did the motor swap.

thanks Jedi, i've just setup an appointment for Monday morning. I just wanted to go in there having educated myself a little.

I don't know if they reused the same coils... But if the car drove fine 2 weeks ago before the rebuild, even if they'd reused the same coils, wouldn't it drive the same after a rebuild?

one would think but a coil could have gone bad.
maybe the spark plug wires aren't attached properly: that's something you could easily check. Some times they are not properly secured at the plug

the coil wires could be attached in reverse order (Leading on trailing, vice versa)
If you feel like double checking here is how they should be attached

Attachment 241084



Odds are if the tech was able to swap out your motor he's at least competent but you never know, maybe he was rushing to finish the job and made a simple mistake.

wow thanks Jedi, very helpful and will check it out soon while i wait for Monday

any time, glad I could help.
Keep us posted

My 06 rx does the same, at about the same RPM, but only after I drive my car in a boring fashion for an extended period of time.

When I decide to run a hard acceleration, it'll cut at the 2 points. At the next light, I'll do the same acceleration and it'll be completely smooth. So, carbon's probably the culprit.

I'm one of the believers that doing a nice hard full RPM acceleration will clear out the carbon. So far it's proved true. I run my car at least once every quarter tank. So far, no engine problems in 33k miles.

Mods to my car: Only KYB Gas-a-just shocks. Rest of car is stock.

they told me it was something with the cam shaft... Something needed to be reset electronically, so they did that, took it for a drive and said it drove fine now... Seems a little off to me. Nobody I've mentioned this to has said anything about electronics. There were 3 suggestions: carbon (can't be that, i do redline it and try again - same results: noticeable power loss at 7000rpm), plugs or coils...

I'll find out soon enough if all is well. They said it drove fine, but this is a Utah dealership and they're notorious for being shit.

:lol: :uhh: :rofl: :rollingla

yeah this is gonna be a really long fucking process.... :(

oh man...:rofl:

so when i do go drive the thing, i should expect to drive just as badly, yes? :)

It might be something along the lines of your ECU adjusting to the new engine. Just for kicks, drop in a bottle of injector cleaner next fillup, and run the engine fairly hard fairly often during that tank, just to see if you're having carbon issues. Plus it'll help your ECU adjust to the full range. You might also find a 30 or 35 mph street (with light traffic) and just stay in first, keeping the tach at 7000 in first gear for a half mile or so. Might help as well.

I also suggest you ditch dahle and hop up to Bountiful Mazda. They've taken better care of my 8 than any of the other dealerships in SLC. Though, since I only service my car every 5k miles, and that takes half a year to rack up, I really don't know about any personnel changes that may lower their standing.

So ok... the dude at D Dahle (Dylan) never knows wtf he's talking about... He said "cam" on the phone so i thought he meant camshaft. I asked if it was the camshaft, he said yes. The camshaft...

I get there, they cleared the KAM (Keep Alive Memory)! Big difference lol... How he read the K in KAM and said yes to camshaft is beyond me... Maybe he can't read... But whatever. So is the KAM the same as clearing the ECU?

Meantime, the engine light was off again, but the car drove exactly the same, giving me a noticeable power hiccup at 5000rpm and 7000rpm in 1st (i do notice it in second and third, but bringing it up to 3rd at 9000rpm = REALLY breaking the freeway speed limit haha)... I left it with them overnight to deal with in the morning...

My guess is that in the morning they'll find nothing and tell me the power seems fine, they'll ask me to come down and drive it for them, i'll notice it and they won't and say it's fine. After that, i'll just take it to Bountiful Mazda and hope they can find something D Dahle couldn't.

After that, thanks AngelKiha, i'll try some injector cleaner as well.

And then after THAT?.... I have no clue :/

oh and according to D Dahle Mazda, there were no misfires and they re-did a compression test (forgot to ask for numbers). So it's not the plugs? Maybe the coils?

there is no cam shaft, its an eccentric shaft and can be reset with the 20 brake pedal stomp(search). what i want to know is if you just got a fresh reman, why the hell are you redlining/beating on it allready? did you break it in?

:pat: 200.mph... I actually forgot completely about that... Isn't the break-in period 2000 miles? Or 3000?

So uh... I break it in THEN see if it's doing the same thing? I remember test-driving fresh RX8s back in the day and still not experiencing power loss at any RPM.

hey 9k was that at me?

i think it was at me, but either way i'd like to respond with the following:

"fuck you very much 9krpmrx8, you unhelpful waste of air"

Seriously. People make mistakes, forget things, break stuff, even wreck their RX8s. Not one other person before 200.mph thought to mention the break-in period. Does that mean everyone else deserves your insults?

The goal, at least in this specific area of the forum, is to help out. If you can't, please just stfu

if you need to know the recomended break in after you get your issue sorted out check out racing beat. no, fix problem then break in

Well, here's what they told me:

Cleared the KAM again and they said they can feel the secondary injectors kicking in at 5000rpm and 7000rpm but according to them, they're seeing a BOOST in power at those rpm figures... sigh... this despite the fact that they can feel a drop in power at those same rpm figures.

They still can't find any misfires and they're telling me that according to the figures they got (which they also showed to Mazda HQ or whatever), everything looks normal.

So do i take it to another dealership now?... Or is there some validity to what they're saying?

No man, not at all.

:lol: Thanks. It's common sense, no one should have to mention it.


That all makes no sense what so ever and is complete BS. Educate yourself about your vehicle.

i have, and your input is completely useless. Don't waste any more of your time, or mine

Oh don't worry about it man, I'm glad to help :suspect: