Hey guys, I needed some advice on how to fix a high rpm sputter. Starts to cut off around 7k while driving and will rev up to red line with no problems while revving. The first time this sputter happened the check engine light started flashing. Prior to this I had changed to new spark plugs (NGK laser iridiums) and added new MSD 8mm spark plug wires and a AEM cold air intake all on the same day. Then once the sputter happened I spoke with friends about it and they said to also change my coils so I added new coils afterward as well and the sputter still remains. I have a check engine light on that reads "faulty catalytic converter" due do a hollow cat I used to have but took it off and put the factory cat back on along with a new o2 sensor and the engine light didn't go away as well as the code continues to read the same error code. ANY help on this will be appreciated! Thanks!

 

Check your wires I had the sputter and figured out one of the wires was not clamping on the plug. This was after I changed plugs and coils.

 

Thanks! I'll do that. Is there a way of knowing if a wire is bad besides an obvious tear or visual problem?

 

double post: https://www.rx8club.com/series-ii-technical-trouble-shooting-160/high-rpm-sputter-help-213110/

 

Too late already got him lol

 

Maybe some useful information on the topic WCS an invasion08..?

 

Ok what is the code now? Is the AEM intake installed correctly? Are the Leading and Trailing spark plugs in the right spot?

 

AEM intake is installed correctly. Only think that might be wrong is would be a small vacuum line had to be capped off from the intake manifold that hooked up to the factory intake box. Thought that might be a possible reason and yes the T and L spark plugs are placed correctly as well as the wires. Although the wires are all the same length and didn't have a T or L type of notification so I figured there wasnt a special wire for either the T or L plugs as long as they were wired correctly, note (two of the wires have grey ends and two have black ends) if someone knows what the grey and black ends mean that would be really helpful. And the plugs and wires and coils all have around 10k on them so far and the problem arose when they had around 6k of use. A friend also thinks maybe a spark plug is already fouled or cracked or damaged etc

 

clogged up cat could affect highrpm

 

Vacuum leak is not good, they casue problems. So cap it.

 

Code was P0410 and yeah it might be a clogged cat since it's the original cat which has around 50k on it. Note I had a single exhaust put on shortly before the sputtering started to occur an the single exhaust has a higher air flow which might be messing with something as well

 

The vacuum line was capped the day I installed the intake and is still currently capped.

 

When you put in the AEM intake, how many MAF screens you still have in place?

 

MMMmmmm Actually I think I do .....
Darkbrew had a simular problem and it ended being a leak in the SSV diaphragm

We were able to diagnose the problem using the Cobb AP ....
In the end what was happening was that the diaphragm would slowly leak ability the ability to draw air would go to ****.

Aaaah **** I dunno exactly what we did ... Darkbrew did everything ... I was only there..... drop him a pm I know he will help you out

 

There are 2 screens in the intake and I had cleaned off the maf sensor after installing the AEM intake. Filter is also in tip top shape.

 

Okay, had to check.........and was going to suggest MAF, but...........does sound like a vacuum leak somewhere.
How bad is the sputter, or is it more just like a hesitation?

 

Vac leak is unlikely, high rpm has more total airflow and less vacuum to draw leak air in.

I'm thinking clogged/fouled injector/s..... ECU thinks it's sending X amount of fuel, but injector max's out at Y = a lean misfire at high rpm.

I'd add a full bottle of injector cleaner to the last 1/4 tank of top tier gas, then 'go for a ride' if you get my dorifto......

 

The sputter is really bad and really loud so I no longer take the rpms past 6k until it's resolved
Idk if this is normal but after installing the intake and all the other things there is a very noticeable increase of power after 6k similar to vtec and will put push you into your seat. It never used to do this prior. The rpms used to smoothly increase with out any type of bursts of power.

 

The injecters have never been changed and have 50+k on them I am prolly due for some in the near future good call! I took it to Mazda once to have them fix it and they said my fuel pump was bad so they replaced it with a new one and said my battery was beyond dead?? But had no problems with anything electrical and my volts were at 14.4 prior so i think they were lying to me but whatever and they cleared the engine light and it ran beautiful until about week later when the engine light reappeared and so did the sputter so I gave up on bringing it to them rip offs.

 

Is the injector cleaner on a 1/4 tank of gas a good idea? I heard from someone that it is not good to use on rotaries? I seafoam it every year or so and it usually runs a bit smoother afterward (maybe it's all in my head) but I think it works a little. And I have tried an octane booster since our premium gas here in NM is only 91 an I hear it's higher in other states but anyway I added a full bottle of octane booster to a full tank of gas and it was running great until I got to around 1/8 of tank an then suddenly when I'd let it idle it would go into this revving mode where it would constantly rev up to 3k and then to 600 and then back to 3k similar to what a Honda does when the idle air control valve is messed up. It only did it until that gas was gone but never used any type of booster ever again and it's been fine until the sputter came along.

 

What's the procedure for resetting with the brake 20 times? I want to try it. Checked on the screens today's and they are all in there properly.

 

Turn key to on, but do not start.
Pump the brake pedal with your foot pretty fast(not hard) until the oil gauge sweeps to the right and back to the left.
Turn key to off.

Wait a few seconds and then start as normal.

If it doesn't sweep, they start over again from the top.

 

I did the brake thing, is there something supposed to be noticed? I do not know of anything that was changed after the procedure. Is there any other secret reset procedures?

 

i'm kinda having that problem. although it will kinda cut out if the water temp is still a little low, if it's warm tho it will get there just fine, but seems like it hesitates as soon as i shift up to the next gear if i shift around 8k. Any ideas?

 

At 6800 to 7200 RPM the ports open up