pintobronco

OK I am new to this rotary program but with 2005 RX8 m6 the engine light shows missfire. However not showing any code. In 6th gear and wot at 4300 rpms engine light goes out and stays out as it goes from open loop to closed loop. Back off and engine light comes on and blinks. Wot again and as it crosses 4300 rpms light goes out. Open loop light blinks. closed loop light out. Also at idle light goes out. Car runs great and very strong. No start issues either hot or cold.
Btw, new BHR coils, wires and plugs. Decat pipe and new 02 sensors. 40,000 miles.
al

Red line envy

Maf or crank sensor maybe. Try and cleaning them.

pintobronco

Thanks will do.
al

mazdaverx7

iTrader: (6)

Have you run a health check to see what the ecu is picking up? A flashing check engine light is a result of a catalist destroying misfire. Even though you don't have a cat, misfires are not good in a rotary. I would start with a health check to see what the ECU is picking up and go from there.

CaymanRotary

You sure these are installed correctly? You should run a scan tool and see what codes pop up. New ignition system the engine should be running just fine. Leads me to believe it’s either a fueling issue or an intake issue so long as everything is properly installed. Do you have fuel trim data?

pintobronco

Well first I said it wrong. At wot above 4300 rpms it switches to open loop. Back off and below about 50 mph it goes back to closed loop and engine light comes back on. So under heavy wot load and open loop no CEL or misfire. I cleaned MAF and crank sensor. Two different diagnostic tools show no codes. However CLE blinks showing missfire in closed loop. Wed morning I have appt with Mazda dealer to do compression test and see what they can find out. Thanks to all for advice. More later.
al

mazdaverx7

iTrader: (6)

Keep us posted on the compression numbers and what Mazda shows in the live data during the test drive. Live data will show the misfire count and show you which rotor is misfiring.

pintobronco

Thanks, will do.
al

CaymanRotary

Always good to know if its compression but that may end up not being your issue. Good luck! Post the readout when you get it.

pintobronco

Whopppie!! Compression is great Rotor #1 78, 76, 75 Rotor #2 79, 77, 77 @ 250rpms. certified by Mazda of Elk Grove. Now I will have to toss good parts until I find the bad one.....hahaha Am I happy, yes.

CaymanRotary

hope you mean 7.7 bar and not 77 psi. If so, good that compression isn’t an issue. Need to further diagnose other issues.

vvette

Clogged cat will also cause mis-fire..I had that issue...

pintobronco

Thanks for your reply but this car has a decat. No cat...But you are right of course. Since I live in Nevada in a county that doesn't require smog the decat is just fine. Very noisy though.

mazdaverx7

iTrader: (6)

Did they say whether that was 77 psi or 7.7 bar?

pintobronco

Engine is good shape. Lowest 7.5 bar and highest 7.9. New BHR coils, wires, and plugs, Decat pipe, new 02 sensors, cleaned MAF and crank sensor. Starts immediately hot or cold, runs strong but CEL on and off. CLE flashing showing miss fire when in closed loop. WOT above 4300 rpms CEL goes out and stays out until it goes back into closed loop. Doesn't show any codes. Could I have bent the crank sensor plate when I dropped the engine on the cross member? Could the K&N snorkel cause the MAF to run too lean? The dealer wanted the car overnight and $1000. to run diagnostics . So I'll just replace good parts until I find the problem.....any thoughts will be appreciated. Have a great 4th.
al

Red line envy

I'm just making suggestions here. Could it be a ground not making good contact. Or fuel injector. I'm just trying to help. Maybe get someones brain turning lol.

Loki

iTrader: (1)

Changing parts blindly is goingto be expensive. Do you have an OBD reader that can show engine data? Try reading airflow, AFR, fuel trims and rpm on a warm idle and again when the misfire happens. The clues will be in there.


What was that about a K&N snorkle? K&N intakes on these cars cause exactly this kind of problem.

pintobronco

The comment about changing parts is a joke. I have a quality OBD reader and have checked the AFR. It appears to be OK. The cold air system I called K&N snorkle could be bringing in too much cold dense air. I wonder if anyone else has had this issue. I see lots of cars with this system installed so there must be a lot of experience with them.
al

CaymanRotary

The stock intake is always best. It could be worth your while to switch the intake back to stock as well if you still have it. Is the air filter clean on the K&N?

Loki

iTrader: (1)

The K&N Typhoon intake for the RX8 specifically causes a ton of problems. It's not a question of air quantity, the MAF should be able to measure how much air is entering, the problem is the K&N intake and some other cheaper ones don't provide stable airflow over the MAF, meaning it can't read properly. Search this forum for threads that start with "weird misfires, can't figure it out" and end with "so I replaced the K&N garbage and everything is fine now". I'm sure on other cars they do fine, on this one they pooched it.

Stock, Racing Beat or AEM/Mazdaspeed can be trusted. The other intakes didn't do their homework.

UnknownJinX

K&N sucks in hot engine bay air. Even if it doesn't cause any problems, you are losing air. OEM takes cooler air from outside the engine bay.

pintobronco

Ok thanks to all. New MAF solved all issues.

pintobronco

OK, guys the MAF solved the problem partly but CEL came back on and code showing CAT failure 420. I had replaced the up stream 02 sensor as the old one seemed to be dead. After discussing the issue with my mechanic buddy he suggested we replace the downstream 02 sensor with the failed sensor. Guess what. CEL out now......does the dead sensor fool the computer??

pintobronco

btw I installed a decat pipe some time ago.