missing out above 5k rpms.. maybe a fouled plug?? - RX8Club.com



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Old 10-11-2012, 03:06 AM   #1
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missing out above 5k rpms.. maybe a fouled plug??

I have owned this car for over a year now and kept up with regular maintenance. car runs excellent in lower rpms, and idles great.. but when I accelerate, the car has a dead miss when i get around 5000 rpms or more. I think it is a weak plug that is possibly getting more fuel to it than it can burn off, possibly flooding the plug. Just looking for any other ideas on what else it could possibly be. I am driving my 300zx right now just to keep it from getting worse.

I don't have catalytic on it either so I know it isn't a clogged cat issue or anything like that. And it also pulls good and doesn't have the miss in first gear, it only starts to miss out in second gear or higher, this is why i think it could be getting too much fuel on the plug and causing it to miss due to weak spark

Last edited by 37_wonka; 10-11-2012 at 03:08 AM.
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Old 10-11-2012, 04:42 AM   #2
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When you say you have kept up on maintenance, can you be more specific? What exactly have you done and how recently did you do it.
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Old 10-11-2012, 08:16 AM   #3
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Quote:
Originally Posted by xexok View Post
When you say you have kept up on maintenance, can you be more specific? What exactly have you done and how recently did you do it.
+1

A misfire is almost always bad coils or plugs.

When is the last time you changed those items?

A dirty ESS can cause a misfire. Easy and free to clean.

I've never had the Maf cause a misfire but it's easy to clean.

BTW part of the reason you don't experience the misfire (or notice it .. as it's likely still there) in 1st gear, where you do in 2nd gear is do to engine load.

Around 5500-6500 rpm the Renesis engine is its power band (if you will) where it will produce the most torque and you'll see it's maximum Calculated Load here.

For boosted folks it's this zone that is most dangerous for misfires and knock.

While the NA engines will mostly experience a misfire in this area if the ignition is weak.
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Old 10-11-2012, 12:37 PM   #4
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+1



BTW part of the reason you don't experience the misfire (or notice it .. as it's likely still there) in 1st gear, where you do in 2nd gear is do to engine load.

.
this is what i thought, thats why i think i have a weak spark on one of the plugs. i am going to change them and see if that fixes the problem. i changed coils and plugs when i got the car. I have put around 5000 miles on them
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Old 10-11-2012, 05:34 PM   #5
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You know, you can test your spark plugs and coils.
Also, as wcs said, your ESS could also be causing you to misfire. Search for thread "misfire issue START HERE!"
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Old 10-11-2012, 05:57 PM   #6
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Inspect your coils, and plugs. Make sure you pull all your plugs out, I was misfiring about a week ago and when I pulled out my plugs my Trailing plug on the rear rotor was cracked. Also make sure your spark plug wires click when you put them onto your plugs, a loose wire also causes misfires.
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Old 10-11-2012, 05:57 PM   #7
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check your AFR if possible, if you are running lean, might be fuel injectors or fuel pump

check out plugs, its easy to do
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Old 10-12-2012, 01:29 PM   #8
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check your AFR if possible, if you are running lean, might be fuel injectors or fuel pump

check out plugs, its easy to do
im running rich if anything.. it puffs a hint of black smoke out when you rev it hard and shoots flame when you let off. I seafoamed the car last night and it seems to be a lot better, but still noticable. I am almost 100% sure its a plug
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Old 10-12-2012, 02:05 PM   #9
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Okay you're sure it's a plug, but have you visually inspected them??
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Old 10-16-2012, 02:36 AM   #10
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problem solved, one of the trailing plugs was bad
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Old 10-16-2012, 06:43 AM   #11
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Thanks for the update
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Old 10-16-2012, 11:06 PM   #12
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they all looked rough really but the rear rotor trailing plug was the worst. it also seemed as if that plug wire had a weaker connection on the plug than all the rest. i changed those as well.
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Old 10-17-2012, 01:34 AM   #13
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accelerating at 5k rpm the trailing plugs have very little impact on engine performance..

trailing coils/plugs/wires - idle, start, cruising

leading coils/plugs/wires - accelerating/WOT
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Old 12-06-2017, 11:53 PM   #14
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I know this is an old thread

I have an 04 Mt with 126k on the car. Just put an engine in on 12/2/17 and I am having a few problems. Most of them I have gotten fixed but I have 2 left. The first is p0661 which I have ordered the solenoid after switching it to another and it solved it. The second and the one I am worried about and stumped is a misfire on rotor 1. I have brand new coils, wires and plugs installed on 12/4/17 and also new intake gaskets. Have checked for intake leaks and haven't found any more after installing the intake gaskets. Cat has been gutted don't know when it was like this when I got the car. Bought the car at an auction with a motor with bad Apex seals. Filled the car up with 93 gas and premix. Car idles perfect and runs great loads of fun unless I stomp it and then at 6500rpm it hiccups and cel starts flashing. Pull code and have rotor 1 misfire. Been dealing with this since Monday. Can't figure it out. This is the first rotary engine I have messed with. Until this I have only dealt with 4-8 cylinder engines. I have tried the brake stomp to reset everything and nothing changes. If Im easy on it I can redline with no problem. No cell flash or anything. Only when I stomp it. I have swapped the coils and plugs to see if it would move to rotor 2 but it hasn't. It's killing me not being able to figure this out. And no I have not had a compression test done. This is a used motor with about 20k miles and I have a video of it running in the car it was pulled from with no problems so I'm thinking it is not the motor. Please any suggestions would help and I would appreciate it. Sorry about the long post.
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Old 12-07-2017, 08:20 AM   #15
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Where did you get the new coils? If it's amazon or ebay random imitation brand, there's a chance you got a dud.

Move the coils around and see if the misfire moves to rotor 2. As for vacuum leaks, I would still hook up an OBD reader and check your fuel trims.

Also also, how is your fuel pressure? It's possible the pump is dying, so when you stomp on it, the fuel requirement exceeds what it can provide, but when you nurse it , it's fine. Following that logic, potentially a dirty injector as well. Did you use the new motors injectors or the old ones?

Anyway, get that OBD fuel trim data and we can go from there.
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Old 12-07-2017, 10:38 AM   #16
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Haven't checked fuel pressure. Car is at the dealer as of 8 am this morning. Getting all the recalls taken car of( ball joints, airbags and fuel pump replacement). I have already tried to swap the coils and plugs around and it didn't move rotors still staying on rotor 1. And the injectors are the one that came on the "new" motor. Coils and plugs were purchased from AutoZone and wires were purchased from O'Reilly's.
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Old 12-07-2017, 02:43 PM   #17
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You said it has bad apex seals?

Get a rotary-specific compression test at a Mazda dealer or rotary specialist.
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Old 12-07-2017, 02:44 PM   #18
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The old motor I pulled out has bad Apex seals.
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Old 12-07-2017, 02:49 PM   #19
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So did you get a reman engine? Where did you get it?
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Old 12-07-2017, 04:28 PM   #20
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Just talked to my Mazda dealer and found out I had a aftermarket fuel pump and it was kinda rigged in with silicone for the top seal. And found out they don't have the parts for the recalls I took it in for so I'm not getting my car back til next week
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Old 12-08-2017, 01:44 AM   #21
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Edited: I was being too critical and not considering the full issue. For safety issues it’s better to have the car not operating until it’s safe to do so. Hopefully they gave you a loaner car to drive.

Last edited by TeamRX8; 12-08-2017 at 12:35 PM.
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