maunmaun

Hello I am in need of some help to diagnose a problem I am having. I will try to keep this post short but I also believe that it's better to provide too much info than too little, so I will start with some background.
I bought my rx8 2 weeks ago, 2009 R3, manual, 40000 miles, fully stock - except wheels. It seemed very well looked after (service history, knowledgeable looking private seller, lost of what had been changed with receipt, etc...).
2 days later after a 100 miles highway trip, hot then, it had a little trouble re starting (as in I had to crank for 5-7seconds). I did not experience this again since, warm or cold.
Spark plugs are about 4000 miles old. Coils are original.
Spark plugs were changed after the previous owner had problem starting and car was running poorly (which leads me to believe quite a but if misfire happened then).
Now my problem:
Car runs and starts fine, idles fine,wngine runs smoothly.
While under hard acceleration though it seems that rpm rise slows down around 7500rpm, then continue climbing again but not very fast, until red line (and into it).
I also sometimes have some weird vibrating noise (like sand in a can) coming from just under the center console - just forward of the stick. Only sometimes though.
My first thought was a partially clogged cat - and that is still a possibility in my books - because of the loss of power and weird noise at times, and also because the car is known to have had misfire which might have damaged it.
I also thought maybe previous owner didn't redline it often and my redlining it may have pushed some carbon in the cat and clogged it a bit.
I do realize there is a valve opening at 7500rpm and it could explain the slight hesitation then, but not the seemingly slow rise to red line. Then again this is my first rx8 so it might be normal, but from others YouTube videos it looks slow.
I received my odb2 dongle in yesterday. No CEL, no codes present.
Still, on a 0-60 run it seems my max hp (113hp lol) is reached at 7800 rpm, which again sounds low to me and I don't think matches the power curve of this engine.
Now my other potential idea was maybe Coils. They have never been changed and it seems they would cause a loss of power if old (I haven't checked them yet, too busy at work and evening weather abysmal lately). But wouldn't misfire then cause a code to appear in the ECU?

Please any idea or area of search welcome. I understand I haven't looked under the hood yet to find out the issue, but ideas about what it could be could help me pinpoint what to check first.
Thanks guys - and gals!

masonflint44

A sticking valve would do it. Bad coils could cause loss of power. The sand in a can sound could be a rattling heatshield on your exhaust manifold. OBD-II dongles are never accurate in measuring horsepower. There should be no hesitation at any RPM, though. When everything is working properly, the entire RPM band is very smooth. I would definitely check the cat first. That sounds like a very likely culprit.

Colon Terminus

What Mason said plus I'd check the intake system. Replace the intake air filter if necessary and clean the IAT/MAF while you're in there. If they're particularly dirty you might also wanna clean the Throttle body.

maunmaun

All great suggestions thanks guys. I will start with what I can do with the tools I have: intake - I have no axle stands, it's on the list of stuff to get.
I'll let you know the results when done

Mysterion

In all honesty, were it my car I would do the following. Sit down with all the history you have on the car and evaluate each and every regular wear item using the following criteria: has it ever been changed? If so, when? If not, put it on a list of things to do ASAP. Examples of this are coils which need replacing, for the most part, every 25 to 30 thousand miles. Plugs AT LEAST every 40,000 but better if done with the coils. Wires, every coil change.

Continue through the list, using the reading material in the2 links below as a guideline. Then, once you have evaluated everything listed and created a to-do list, gird your loins, break out the credit/debit card and start shopping. It probably won't be cheap, but your car and the grin on your face while driving will thank you for it.


https://www.rx8club.com/new-member-f...ot-8-a-202548/

https://www.rx8club.com/new-member-f...t-here-202454/


BTW: Yes, I realise I will get raked over the coals for failing to mention the BHR ignition upgrade, but if this is a first time full service, the added cost might overwhelm and push other, needed items to the background. My thinking is get it running 100% correctly, THEN upgrade if desired. (Butt now covered )

Steve Dallas

After reading the OP, I am very suspicious of the coils. They tend to last 20K miles, and I see no indication they have been changed at 40K. I would start there.

maunmaun

MAF and IAT have been clean, I guess it maybe made a slight difference but it might just be psychological.
Anyways, I ordered OEM 4 coils (the C version) and leads from mazparts and am now waiting for teh post office to deliver them to me!
I will report on improvements as soon as changed.

Thanks for all your comments and help

fireishot34

iTrader: (1)

I think its coils also. I had similar problems as you, i changed my ignition wires and plugs, it fixed all my issues.

maunmaun

So I changed the coil packs and wires about 4 weeks ago and things improved quiote a bit/a lot. I have definitely more power across the entire RPM range and the acceleration is much smoother. Now however I DEFINITELY feel/see (on the tachometer) an hesitation around 8000, and then it continues climbing. I can't think of anything else than some port/valve opening and sticking a bit - will have to look into that.
Thanks every one for all the replies - I will keep updating until I get to the bottom of this

Steve Dallas

Now it is time to inspect your cat. Failing coils lead to misfires and dumping fuel and oil into the exhaust, which leads to a clogged cat, which leads to engine trouble.

When a cat is clogged, its symptoms (mainly loss of power) tend to show up above 7K RPM.

.

gwilliams6

https://www.rx8club.com/new-member-f...t-here-202454/

RX8 Club’s recommended maintenance schedule, more comprehensive and proactive than Mazda’s schedule.
30,000 miles:
- Replace Ignition coils
- Replace Plug wires
- Replace Spark plugs
- Clean MAF (mass air flow sensor)
- Clean ESS (e-shaft sensor)
- Reset ESS profile
- Clean power steering connections
- Clean battery terminals and clamps
- Replace transmission fluid
- Replace coolant (Mazda FL-22 is highly recommended)
- Replace air filter
- Replace brake fluid (fluid in the brake lines AND the clutch line)
~$300 USD in parts if you shop smartly.


every 60,000:
...all 30,000, plus...
- Clean all chassis electrical grounding points
- Replace accessory belts
- Clean OMP lines
- Replace rear differential fluid
- Replace thermostat
- Clean / Straighten AC condenser fins
- Clean / Straighten oil cooler fins
- Inspect catalytic converter
- Clean / Inspect intake valving
- Consider / inspect all points in 90,000+ as well, many items fail early
~$130 USD in parts if you shop smartly.

90,000:
...all 30,000, plus any 60,000 not yet done, plus...
- Replace coolant bottle
- Replace radiator hoses
- Replace radiator
- Replace front O2 sensor
- Replace motor mounts
- Inspect clutch pedal assembly for flex / weld breaks
~$900 USD in parts if you shop smartly.

nowakm99

I'm having similar issues that I'm working through on my 2010 R3. The car runs fine for the first hour or so and then starts hesitating at higher RPM. First I have a hard time getting to redline in 4th gear, then, 3rd, etc. The key here is that when I put the car in neutral, it has no problem reving to redline. Based on input from other members, it looks like this may is likely a fuel/air issue. I had the throttle body cleaned and cleaned the MAF sensor, replaced the air filter etc. I'm now suspecting that the fuel pump or fuel filter is the issue. I've run a bottle of Techron through the motor, but haven't been on an 1+ hour drive in a while, so will see if that made a difference.

I usually pre-mix on track and am wondering whether this has gummed up the fuel pump and/or injectors. Just a thought.

gwilliams6

Starting the Engine
• Starter
• Battery
• Engine Compression
• Grounding Wires
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Fuel Pump
• Fuel Injectors

Generating Power at Full Throttle
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Air Filter
• Intake Valving
• Throttle Body
• Mass Air Flow Sensor (MAF)
• Fuel Pump
• Fuel Injectors
• Catalytic Converter (Cat)

Keeping the Engine at a Cruise
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Intake Valving
• Throttle Body
• Mass Air Flow Sensor (MAF)
• Fuel Pump
• Fuel Injectors
• Front O2 sensor
• Catalytic Converter (Cat)

Keeping the Engine at an Idle
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Mass Air Flow Sensor (MAF)
• Front O2 sensor
• Catalytic Converter (Cat)
• Intake Vaccum

Mane

Honestly, keep a close eye on your gas gauge. You will experience a "power loss" below half a tank.

maunmaun

Small update.
I haven't removed my cat to check if it is clogged as I haven't found the time yet (bought a 100 years old house and it is keeping me VERY busy).
This being said the abrupt loss of power always at 8000rpm has disappeared, mysteriously after last oil change I did (I did screw that up somehow though and did a 10W30 instead of my usual 5W30, but it's crazy hot at the moment and I always let the car warm up before driving so no biggie...).
The only thing I did though was make sure the wires on the spark plugs were snug while I was under the car. so maybe it was a bit loose (wires are new).
Now today I experience some fluttering/loss of power, irregular, but nothing crazy, around 8000 in 4th. I am thinking my plugs might not be great as I did not change them (only because the previous owner told me he just changed them).
Still, it is running much better - somehow. I will definitely have a deeper look into this when time allows....

Oh and I will check about that half a tank of gas loss of power thing although that sounds weird.

Steve Dallas

The thinking on the gas level is that, since the fuel pump is cooled by gasoline, letting it get below half a tank means it starts to overheat. I can't comment on that, as it has never happened to me. Of course, my car is newer than most. The only fuel level-related power loss I have ever experienced was when I had just less than 1/4 tank and made a hard right uphill turn on the track. That caused momentary fuel starvation that had me heading to the gas pump ASAP.

Definitely check that cat. If it is starting to clog, it will start a cascade of problems.