cpenner

I'm in the process of wading through the P0300 and P0301 threads. I'm a good troubleshooter, but have entry level mechanical inclination.

I'm hoping that the collective wisdom can help me through my troubleshooting by trying the most likely things first.

Car:

2007 GT - completely stock except for
- Mazdaspeed CAI
- BHR Coils/wires
(and winter rims, but those are hardly the culprit)

- 55,000km on the car
- less than 5000km on the BHR coils, wires, and OEM plugs
- new battery (less than 500km)

Situation

Tonight, pulling out of a parking lot, I stepped on the gas briskly. It accelerated for 1/2 second, and then started to sound like a tractor. I got a CEL. I limped to a safe spot, and pulled in (approx one mile). Using my Torque app, I checked the codes and see:
- P0300 (current fault)
- P0301 (pending fault)
- U1900 (probably related to turning the ignition off and on when logging)
- U0073 (see above)

The car had no power, and felt like it was lugging like crazy. The car also smells really bad. Like burning rubber bad. When I opened the hood, I was expecting to feel a wave of hot air, but things didn't seem any hotter than usual. I saw no signs of fluid leaks. I checked the oil, and it was pretty much right in the middle of the acceptable zone. I didn't see anything that looked like a glowing cat, but I'm not sure I got under the car fast enough and/or looked in the right place. For a while after turning the car off there was a definite "crackling" sound from underneath.

Working backwards, here is my recent maintenance:

In the last few weeks, the car had been getting harder and harder to start - hot or cold, but mostly cold. so LAST WEEK I had the battery diagnosed, and it was bad. (OEM battery with 5 years on it). Barely held adequate voltage, and dropped off fast under load. I replaced that. The starts got easier, but still a good full second or two of cranking. (from the 3-4 seconds with the bad battery)

In SEPTEMBER, I replaced the original coils, wires, and plugs with a BHR set. I saw an instant improvement in performance, and a repeated gas mileage increase of 50km per tank (from 300km to 350km).

In JULY before swapping the coils (5000km ago) I had a compression test done:

Rotor 1 8.5, 8.7 8.4 @ 318 RPM (measured in kgf/cm2)
Rotor 2 8.4, 9.0,8.7 @ 333 RPM

I also had the 48,000km service done, and the service checklist had all green checks. I had also asked about the coils, and Mazda said they were still good.

So, at the moment, my plan of attack is to:
- check the plug wires to be sure they are properly attached
- scratch my head a lot
- if absolutely necessary, put the old coils back in (hopefully within my range of abilities)
- get car towed to Mazda to look at

Does anyone have any other ideas?

Grace_Excel

iTrader: (5)

P0300 and P0301 are misfire codes, I would check how the spark plugs look but I doubt it since they are still pretty brand new. Could you check you MAF/IAT sensors, the ESS also, if they need to be cleaned. Out of curiosity, see if you have excessive white gunk in your oil dip stick; monitor your coolant fluid level, as well. Oh, check your Catalytic Converter "honey comb" too!

cpenner

OK. Finally got a chance to do some work tonight.

I finally found this thread https://www.rx8club.com/tech-garage-...t-here-222280/. Would have been nice if the p030x code was in the title.

So I started with the basics.
- checked plug wires for proper connection at all ends
- checked harness connections to coils

No problems found, no differences in running after popping each connection off and on.

So then I wondered if I got a plug that failed in my install. (mind you, I've got a few hundred miles on them, but hey. Let's eliminate variables)

So I pulled the front rotor plugs. (P0301 seems to hint that would be the problem)
- plugs looked fine to my untrained eye

So I put the old plugs back in - just to check.

Went to crank it up, and it wouldn't start. Cranked for a bit, gave it a break, cranked, break, put battery on charger. Smells like gas, possibly flooded. (first time I've flooded a car in decades).

Pulled the old plugs out again, and the car is definately flooded. Replaced with the new plugs, and followed the deflooding procedure here: https://www.rx8club.com/do-yourself-...lumber-182410/

Clouds of smoke, and "running" car. Same codes, car still misfiring. Calling it a day. I'll see what comes next in the misfire thread tomorrow.

bse50

After a misfire come a new set of coils and wires. OE or upgraded, it's your choice.
If the car ran with worn coils and possibly a failing catalytic converter for a long time then you may want to perform a compression test.

cpenner

The thing was, the coils, wires, and plugs were ALL new. Less than a couple months on them. That is what had me baffled.

So after eliminating plugs and wires as the issue by checking with the old stuff, I swapped the new BHR coils out for my old OEM coils.

Started right up, purred like a kitten.

After the weekend is done, I'll sort out the coils with BHR. A good thing about dealing with reputable people is that you don't have to sweat wondering if you are going to be treated right.

paimon.soror

iTrader: (15)

in the meantime you could go out to the local autoparts store and get yourself a coil tester (costs about $9 USD) to check to see if one or more of the coils are shot.

Grace_Excel

iTrader: (5)

Wait, I'm confused. Didn't you install the BHR kit already? Anyway, look over these links below for further guidance as paimon.soror suggested:

Suffering From a Misfire? START HERE? DIY: Testing GM LS2/Yukon coils and sparkplug wires

Addendum: That's weird, the link I posted seem to not work... Well, in the web address, just delete the characters up to the "https://www.rx8club.com/..."

cpenner

Yes, taking out the BHR coils seems to have fixed things. I'll sort out what was wrong with them (or the installation of them) and report back here for future misfire searchers.

Fazil Malik

Did you find any solution. Let me know if you remember anything about it. Really appreciate that.

Thanks,

cpenner

Whoops. Forgot to post back.

I contacted BHR, and without any fuss they had me ship the coils back. Very quick diagnosis of a bad coil, and a very quick shipment back of a brand new set of coils.

If you're getting the same codes (and searched for them) definitely swap out your plugs, wires, and coils. Most likely it's the coils, but you may as well clean up all the ignition while you're in there.

HeatherMarie1280

I recently had the same problem. Took my car to Mazda to get an oil change. A day and a half later it was stalling and smelled like burning plastic. Smoke coming out of the hood but not running hot. Mass air flow sensor was also not plugged in after they did the 99point check during oil change. Turns out that somehow my CAT converter became restricted, melted the O2 sensor, and melted the main wiring harness (that was the burning smell I'm guessing). Maybe bad ignition coil caused failure of CAT converter? Dunno. But $5,653.44 later they still couldn't get it to run. Finally, after 3 weeks, they got with a Mazda engineer and discovered that they crossed two connectors on the harness install. Fixed that and runs fine except now I'm getting over ten codes and my dash is lit up like a Christmas tree! Check engine light and airbag light have been on since the day they gave it back to me and now my power steering is gone, heater goes from hot to cold and back whenever it decides to work at all. The codes (which I had another auto shop check since Mazda was saying the CEL was not related to what was done) basically say communication failure with electrical system, with ABS system, lights, and airbag. Needless to say, I am very angry. I have had it at the Mazda dealership 3 times and they can't get it right yet I paid nearly $6k to have it fixed. It's pretty much unsafe at this point and I'm afraid to even drive it. Lesson here is be careful where you take it for repairs because even some Mazda technicians do not know how to work on these cars!