Help Please: P0300, P0171, P0302, P0171, P0506
 

So I finally got rid of my very small evap system leak by replacing my gas cap last week & was planning on getting the '8 smogged tomorrow. (Just my luck) Last night, I'm merging onto the highway, and suddenly I am greeted by a clunk and a huge loss of hp as I put the car into second gear. The car got me to the next exit, but now stalls out whenever under 2k rpm. I got it to a gas station, plugged into the OBDII, and was greeted by 5 codes. P0300 (random misfire) P0171 (system too lean) P0302 (misfire cyl. 2) P0171 (system too lean) P0506 (idle control sys. Idle low).

Plugs, cables and coils are only 2k miles old. The standard diagnosis seems to be these, a loose vacuum line, or the cat. Could a cat cause such an immediate loss of hp or am I looking at defective spark plugs, etc?

I leave myself in the hands of you diagnostic gurus. Thank you for any assistance which you may be able to provide.

a clogged cat CAN cause a big loss of HP but you'd probably be hearing noises as well.
Did you play with the MAF sensor? try checking those connections or even cleaning it. (be very careful when cleaning)

Normally misfires are due to bad coils or plugs but you said they're only 2,000 miles old. Check all of your spark plug wires to make sure they are on properly and that they're going to the proper spark plugs.

Thanks, Jedi.

By "noises" would you happen to be referring to a shaky, more gutterral exhaust note, accompanied by a mild burning smell? If so, I think we know our problem. I was just surprised that it would be such an abrupt loss of hp without any preliminary signs. On the bright side, that would be a great excuse to switch over to a high-flow cat.

I checked the spark plug wires last night & all seemed well. I'll head out to the car to check the MAF right now. If the issue is a clogged cat, could could I hypothetically remove it temporarily to diagnose the problem & see if she'll run, or will the lack of air flow to the MAF keep the trouble shooting from working?

I've never had a cat fail (yet) but I hear it can happen suddenly. by noise, I mean that members often describe a metal(ish) rattling sound coming from the cat. (the honeycomb material inside breaks and starts bouncing around)

If you remove the cat, it probably won't run and it'll be LOUD. Drop the cat, peak inside and see if it looks broken. IF so, reinstall and head to the dealership.
Emissions warranty is something like 80,000 miles on a cat.

Thanks again for all of the help Jedi.

Today was blatantly not my lucky day. I dropped the cat & all was well. Cleaned the MAF & O2 sensors...then my dog broke her leg so I had to rush her to the vet.

Came back & started testing the coils (yes the ones with 2k miles on them). The #2 coil wasn't firing. Located the issue in the harness & got it firing again. I went to put the spark plug back in & it started to strip the threading in the engine. Now it won't seem to go more than 1/4 of the way. Anyone have any tips or shall I call this round a wash, tow the 8, & go drop some bills on Mazda's desk?

wow,,

sucks to be you.. with the spark plug. white grease it up on the treads. make sure it is straight on. then rotate it backwards. as in loosen it. till it drops. do it a couple of times. you will feel it.. then just after it drops the last time you try. make sure it is straight and tighten it up..

that is you best chance..

beers :beer:

I got the spark plug back in but was still dealing with a major loss of hp. We brought the 8 over to the dealership & after a ridiculious diagnosis fee, they tell me that chamber 2 isn't getting compression & I am going to need a new engine. My favorite part was that they tried to convince me that they could do the work for a "discounted" $9600. Looks like I'm going reman & finding a local mechanic.

huh? you're over 100,000 miles? why would your reman not be warranty work?

ShellDude, I appreciate the warranty head's up. I brought this up to the dealership & now they have been avoiding my calls for 2 weeks. I finally wrote an email to Mazda a few days ago, but no response yet.

Others on the forum have called Mazda USA complaining about stealerships and have gotten immediate results.

Give the 800 # a call and tell them in a calm, concise, manner how you're getting the run around from the dealer and they'll not only call the dealer on your behalf, they'll make sh*t happen... or so I've read.

Good luck man.