HELP: Missing power under 5k rpm!?!?!?
 

I've had this problem for about three weeks now. Under 5k rpm my car is lacking about half its normal power. After 5k rpm it still feels strong. When taking off from a stop, or accelerating under 5k, the engine sounds like it's being flooded; however, it starts and idles perfectly fine.

Here is the interesting part: when the car is cold. It feels very strong from idle all the way to redline. After the car warms up I loose most of my down low power.

The only engine mods I have are RB intake+duct and RB exhaust. Both mods have been installed for over 2 years without any issues. The car has 57k miles on it.

I tried the normal fixes. I installed new plugs. Checked all the fluids. Cleaned the air filter. I even completely reset the computer.

Help?

loss of power when warm seems to usually be bad cat, or bad engine. Hopefully it's not the engine.

Did you replace the coils? That'd be my first thing to replace.

The coils and cat are original.

My first guess was the coils as well. I looked at the bottom of them about a year ago and they didn't look that bad. Only a little white. I took it to the dealer the next day and they said it wasn't enough to warrant a replacement.

If it was the cat, shouldn't I have power down low and none at the top?

you can't tell if the coils are good by looking on the bottom. Replace the coils as your first step. They tend to last 12-40k miles usually, so you're overdue IMO. I usually change them once a year just to avoid having issues.

When the BHR coils come out, I can stop that cycle.

the items listed will actually be worse at high rpm than low, and then this doesn't explain why they're fine when the car is cold

I love this forum ...

How about MAF sensor cleaning? Maybe debris on the E-shaft sensor? SSV stuck open? Bad fuel pump resistor?

When I cleaned the air filter I noticed that my intake screen was badly ripped. After replacing it with a new one, the car did seem to run a little better. It could have just been my imagination though.

The new screen probably DID help as the MAF sensor is notoriously sensitive to turbulence.

Do you think my MAF sensor is dirty? What could I clean it with if it is?

Maybe it got air filter oil on it?

Some people like to use MAF cleaner from a spray can. I just use a little rubbing alcohol on a Q-Tip. Try checking each individual wire as it runs into the connector and take a look at the connector interface on the sensor, too.

Find a mountain road go up hill in a high gear, see what happens.

Stalls or no power = CAT

It hasn't stalled once but i'll try that.

I just got some rubbing alcohol and i'm going to clean it. What exactly am I cleaning?

wait wait wait. What !

STOP. Dont FREAKING touch anything on the MAF !

Go buy a can of MAF cleaner, its in a spray can and it cost like 4 bucks, spray clean it, dont touch anything on it. remember to clean the inside too. Search for DIY

dont cry if u mess it up by touching them, that thing is like a 100 something bux item.

Does this help?

https://www.rx8club.com/series-i-tech-garage-22/define-dirty-149934/

Well, I took it out and cleaned it with rubbing alcohol and they blew it with the air compressor. After reinstalling it the car idled rough for about 30 seconds and them evened out. It now runs like before.

The problem still exist.

Jackson, relax. I have cleaned my MAF sensor countless times and it works fine. The part that shouldn't be "touched" is shrouded. If one doesn't handle the sensor like a gorilla it'll be fine. Blowing air on it, however, probably isn't good. Then again, he didn't touch it did he?

Any other ideas?

Yeah, I'm missing power under 5k too...I think it might be this weird engine I see under my hood.

Couldn't resist:lol:

In my first 8 when this type thing happened to me, when I stopped and shut off the car it sound like a small pump was running, and ended up I had the compression loss issue, and that car had 17K on it, but I hope that this isn't the case for you. Have you tried what Razz1 suggested?

I did try it. It didn't stall; however, variables such as speed, incline, and gear all affect it. So his method, while a good preliminary test, doesn't definitively tell me anything.

I'm working on attaining a compression tester from a friend. I need to do some searching to see what the compression should be and how to test it. That is unless anyone knows off hand.

A normal compression gauge will not work; there are three areas for compression on each rotor...
You need a compression gauge without a "stop" so the needle can move back down after the compression stroke, watch and compare the high points on each rotor as the engine is turned over.
You may want to get a Mazda dealer to test the compression, but that is like pulling teeth, they don't want you to possibly prove you need a motor.

crap... I didn't know that.

I wonder if I can rent one.

I've seen a few people on these forums talk about running perfect when the engine is cold but lack of power due to bad compression when warm - that was how it was diagnosed by the dealer multiple times.

Happens because when the engine is cold you have a good seal, but when it gets warm the metals expand (like any engine) but a failing seal will not adjust to the expansion to create a good seal.. leading to this.

I didn't think it would stall but I thought that you would have to start revving really high to get any power. That's how I really knew mine went bad. I had nothing until I started to go into higher RPMs.

Yup, exactly how my first one was. I really hope that this isn't the case for you. I would def get a compression test done. At least that would rule out the main engine parts, and if it has lost compression, warranty? Isn't there a local RX shop near you? I'm sure one of them would have a tester suitable for rotaries. I know Mazdatrix sells two testers, one from Mazda, expensive, and the other from some other company, less expensive but still not cheap. Just a thought.