I have had the car at the dealer 4x in a little over a week trying to fix the p0301 and now the p0302 misfire issue. The dealer has been unable to resolve it and they are now pointing the finger at my aftermarket parts (Agency Pulley / High Flow Cat) as being the problem.

Brief Dealer History Regarding Misfire Issues:

Dealer visit #1, replaced 1st two coils. P0301 error went away. The next day I got a P0302 while driving.

Dealer visit #2, replaced 2nd set of coils. P0302 came back same day.

Dealer visit #3, replaced spark plug wires. P0302 came back in two days.

Dealer visit #4 (car in for 3 days).
a) Rechecked bottom of all coils, checked plug wires, checked for vaccum leaks - none found.
b) Checked injector pulse width - all ok.
c) Checked fuel for water ok.
d) Ran compression check 7.6 on all rotors ok
e) Put coolant testers on system 16 lbs for 8 hours no signs of coolant leaking from rotor housing, no pressure loss, all checks ok.
d) replaced all 4 spark plugs.

Damn CEL started blinking on drive home away from dealer. P0302 Misfire.:banghead:

Thoughts??

Did you/they do an ESS profile reset?

Let's be honest here - you're dumb for going in with the pulley. The cat is not the issue.

I do not have aftermarket pulley on my car.
have Mazdaspeed CAI, MSD wire, New coils, new plugs and highflow cat
but having P0302...
whenever I get on highway...
when I give quick taps more than 3 times, then CEL starts to blink.
I have SCAN and it always shows P0302...
and... also my car is kinda having hardtime with hot start.

any help?
did all the search and...
so I changed plugs and coils and also MSD wire.

MM, I was going to reply that I reset the eccentric shaft 3x. However your post got me thinking that maybe I was not clearing it correctly. I continued researching on the forum and it looks like I found the answer.

Original ECC reset method I used: Ignition to ACC and pressed brake pedal approx. 20x till hand swept midway on oil gauge. CEL always came back.

Revised ECC reset Method: Disconnected battery for approx. 5 min. Reconnected bat. turned car to ACC. Pressed brake pedal approx. 20x. Turned steering wheel left and right lock to lock. Turned ignition to off and restarted.

Viola. This time no blinking CEL after a night of some fun driving.

Credit goes to MM for pointing me in the right direction. Hope this helps anyone else whoever finds themselves in a similar situation.

I know that you mentioned that they checked the fuel for water, but did they check the fuel pump unit itself? How about the eccentric shaft position sensor?
I'm just throwing out ideas...

^^ I should have refreshed the page before my post.... glad to hear that its gone!

Glad it worked for you. You may have to do it again eventually.
I have discovered, to my dismay, that not all PCM resets are created equal.

Even if you follow the method that you used to clear this exactly every time, you may have different results from one rest to the next.

I have found that it sometimes takes a few resets before the car runs well. Sometimes I'll reset to clear the KAM and then the car runs like poop and never straightens out. I clear it again, same story. I clear it again and - MAGIC! - it runs great.

Probably some cap or something deep in the PCM that is storing some bit or byte of data just to screw things up.
The other possibility is an error in the initial calibration of the sensor package caused by noise or an unstable battery voltage.

I keep getting the OBD code p0301 even after the reset that was described on here. I've brought it to the dealer 4 times over the past 2 weeks and have had numerous things done to the engine. However, they keep replacing all the friggin electrical parts. Has anyone gotten this problem fixed by the dealer and if so what the hell did they do to get it to go away? I noticed my problem happens when I go to merge on the highway and I go to shift gears. If you step on it, the light inevitably starts blinking and stays on. Also, I had my pcm reset by the dealer but it didn't help.

the 8's have something called keep-alive-memory or KAM. while mazda doesnt brief us techs as the the exacts of KAM and what it does, suffice it to say that it will remember a driveability problem and make the car act the same way even after you fix it. well, it doesnt remember the problem, but it remembers how the car was running when you last shut it off and it retains the values of fuel trims, spark advance, shift patterns and other stuff im sure im forgetting. it is essential to clear KAM after every repair concerning a running problem or CEL or you may end up chasing a wild goose...

to clear KAM simply disconnect battery for at least 5 mins and preferably step onthe brake pedal for 30 secs. that will clear all capacitors or any latent charge they may have.

oh yea.. and do the eccentric shaft profile reset as indicated previously.. after resetting KAM

Thank you very much. I will give it a shot and report back with the results.

Let's be honest here - you're dumb for going in with the pulley. The cat is not the issue.

the pulley has nothing to do with a misfire.

the pulley has nothing to do with a misfire.

Well, a crank pulley might.
Mazda has recently redesigned the front cover of the engine to fully encase the ESS. Obviously, they feel there is an issue with interference, sensitivity or vibration.
Who knows what the effect of a different crank pulley might have.
Pulleys on the alt of water pump probably wont affect that, though.

Exactly - he has the AP pulley.

I have the AP crank pulley. First day with it on the I got the misfire. I reset the KAM and ESS and it went away and never came back again.

I have had the car at the dealer 4x in a little over a week trying to fix the p0301 and now the p0302 misfire issue. The dealer has been unable to resolve it and they are now pointing the finger at my aftermarket parts (Agency Pulley / High Flow Cat) as being the problem.

Brief Dealer History Regarding Misfire Issues:

Dealer visit #1, replaced 1st two coils. P0301 error went away. The next day I got a P0302 while driving.

Dealer visit #2, replaced 2nd set of coils. P0302 came back same day.

Dealer visit #3, replaced spark plug wires. P0302 came back in two days.

Dealer visit #4 (car in for 3 days).
a) Rechecked bottom of all coils, checked plug wires, checked for vaccum leaks - none found.
b) Checked injector pulse width - all ok.
c) Checked fuel for water ok.
d) Ran compression check 7.6 on all rotors ok
e) Put coolant testers on system 16 lbs for 8 hours no signs of coolant leaking from rotor housing, no pressure loss, all checks ok.
d) replaced all 4 spark plugs.

Damn CEL started blinking on drive home away from dealer. P0302 Misfire.:banghead:

Thoughts??

does the car run like shit or sound like shit like a sputter sound?