Hello all,

Recently i diagnosed my car as i begin to notice a huge loss in power and i got the following Engine Codes (P0410 & P0301). The car barely moves on 1st and 2nd gear, it feels like if i was driving a standard car and trying to launch from 3rd-4th gear (No Power at all).

I ran through some forums and noticed that i may have to replace the Air pump or hopefully just the fuse. However, i do not believe that the reason for the Snapping noise coming from the Engine Bay is due to the engine codes.

• On a cold start (4-5 Min warm up) - car runs very poorly, no power or acceleration at all.
• Engine light begins to flash and then it remains turned on.
• a snap/rattle noise as the car picks up power and it comes close to shifting gears comes from the engine bay.
• Once completely warm (180-200F oil temp) the car runs better. No Power loss and no snap/rattle noises.

i will diagnose this noise today. i was wondering if anybody had the same problem and if you could kindly point me into the right direction if you had this experience before.

Car has 98K miles and its a 2005 base model. i have not had any engine or transmission issues since i purchased it as i am friendly with the rotors and have followed the SOP in keeping them well maintained.

 

You should stop driving it until disconnecting the front cat pipe exhaust connection and checking the cat converter for possible clogging/failure.

 

P0301 means front rotor misfire
when was the last time you have your ignition system inspected?
how was your cat
You said that your car runs poorly at cold but gets better when warm. Do you see your coolant level go down? It can be you have a blown coolant seal.

 

Which would lead to cat failure and needs to be checked first before it ruins the engine if it is failed.

 

thank you all.

i have no coolant leaks. I changed the ignition coils, spark plugs and ignition wires last year.

i will check the cat today soon as i get home.

 

So i checked the Cat and i did not see any issues with it at all. Below you can see the procedures i took to get the codes erased and get the car working properly again.

• disconnected and removed each ignition coil / sprayed them with contact cleaner / tested each one with a multimeter (All passed).
• Disconnected the air pump / sprayed them with contact cleaner
• Replaced the Spark plugs (A bit of carbon residue but not an excessive amount).

i assume that the motor is going bad since the last time i replaced my plugs was 14 months ago. I erased the engine light and codes and the car ran great over this weekend. You can feel the power again with no lag.

I still have not figured out what the cracking rattling noise can be. i made sure that the heat shield on the CAT was not loose. Could possible be something in the radiator / Cooling fan?

To be on the safe side, i will purchase a new catted mid pipe. Any recommendations?

 

You don't have to purchase a catted midpipe, aftermarket cat can fail within a very short period given the high EGT our cars can produce.
You can simply put your stock midpipe on when the inspection is due.

 

After Looking more into this noise, if finally replaced my mid pipe with a new catted and resonator pipe. Yes, the old cat was somewhat broken inside but that was not the issue with the rattle noise. The noise remains there after a major tune up and it usually happens right before the car shifts. The lag of the engine remains there, it takes me roughly 12-13 seconds to go from 0-60 mph.

The only code now is the P0410 which is the secondary air system which to my understanding does not affect the engine whatsoever. The Air pump kicks on as soon as i start the car and turns off about 30 seconds after start. I ended up purchasing the 3 solenoids for the valves and hope this can correct the lag issue and if it does not fix it i assume the SSV will need to be replaced?

 

I don't think it's your SSV, that issue would present all the time, not only when cold. It'd certainly not recommend troubleshooting by replacing parts, we need to narrow this down. It could be as simple as a loose heat shield, and another unrelated issue for the power loss.

Poor running when cold *can* be coolant in the combustion chambers due to a perforated water seal. It seeps in while the car sits and burns off while the car warms up. If this is the case, you'll find the car losing coolant, which I know you said isn't the case. All the same, were there coolant-coloured deposits on the spark plugs?

When you say the noise presents near the car shifting, is that always at the same rpm or different rpm but always before a shift?

How's your trans fluid level and quality?

The best way to confirm the engine's health is a compression test. That will confirm/rule out major wear and we can troubleshoot from there.

Is it possible to record the noise and share it here?

 

There was no coolant deposits/residue on the plugs. mainly just carbon residue. I will replace the Trans Fluid this weekend and hope it can help fixing the rattle. The noise is not very consistent, it varies at times (4-5k RMPs or at times above 5k) and sometimes it does not rattle. Here is a video of the noise.

Rattle Noise:
http://youtu.be/IQ-wU56346k

i am amazed at times when i start the car and let it warm up for 7 minutes It performs just fine but when i have to use it more than twice a day and the engine is warm it goes to crap. Do you know the spec for the compression test? i will also get this tested on Saturday.

 

Would you say it sounds like this? https://www.rx8club.com/rx-8-discuss...n-miac-181950/

Compression spec is 6.9 kg/cm2 at 250rpm or higher and no more than 1kg/cm2 difference between any 2 faces. I assume you're getting this done at Mazda where they have the proper equipment?