Process of Elimination: P0300 P0172

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surfninjas

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Contributor
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03 mazda protege 5 automatic
Misfire and running rich.

Car was idling rough and stalled. Pulled a coil pack and it was dead.

Things Ive replaced/done:
-new NGK V Power spark plugs
-new NGK spark plug wires
-New Napa Echlin (oem replacement) coil packs

Same codes still being thrown. Car runs a little nicer.

About 15k-20k miles ago I had help installing a new EGR valve (the upgraded version I read about on here...turns out it was the cold weather/Canada version. ooh well, worked great). I installed a new radiator +cap, ect sensor, thermostat.

Head gasket repair, water pump, and timing belt around the same time (from shop).

Recently put in a catch can and new PCV. I noticed that the PCV had oil on it.

My goal today is to clean the MAF (did it 15k ago) and clean the EGR. This guy's channel, https://www.youtube.com/watch?v=Q9YPBt-EG14 seems to be helpful for that. Hopefully, I'll test the 02 sensor, but might just replace both since I dont know if thats ever been done (Im the 3rd owner).

Fwiw, my exhaust does not smell like rotten eggs and I have always passed smog, and my mpg has always been around 25-30. About a month ago, my gf put way too much oil in (she does her own oil changes, just a stupid mistake) and ended up stalling the car. Didnt drive it anywhere. Drained some and its been fine...and then she put a little too much in again the other night...I will now be the only one to do my oil.



My checklist:
A code P0300 may mean that one or more of the following has happened:
X- Faulty spark plugs or wires Faulty coil (pack)
O-Faulty oxygen sensor(s)
O-Faulty fuel injector(s)
O-Burned exhaust valve
O-Faulty catalytic converter(s)
O-Stuck/blocked/leaking EGR valve / passages
O-Faulty camshaft position sensor
O-Defective computer

Read more at: http://www.obd-codes.com/p0300
Copyright OBD-Codes.com
 
There have been at least a few cases where brand new coil packs are bad, right out of the package.

If it were me, I'd get two new coils and see what happens. It's relatively cheap and easy to do.

You can keep the others as spares. (I keep my old ones in the trunk)

badcoil_zps9ee3b5ce.jpg
 
Vacuum leak? Yeah, that should make it run lean, but with all the feedback loops in these cars who knows? The accordion part of the air intake is particularly prone to ripping, often on the underside where it isn't easily visible. This is downstream from the MAF. From personal experience, this has happened twice, once the intake rips the car runs very rough and tends to stall at low RPMs. A ripped intake can be taped up as a temporary repair until the replacement part can be obtained. The car ran just as well taped as it did with an intact intake.
 
had to pick up a wrench that would fit...dont know how it was done last time from underneath, but i remember it being a pain in the ass.
got 1 bolt off and am trying to figure out how to reach the other. i can feel it, but cant see it.

freaked out when i saw coolant dripping from different spots underneath, then i realized the upper radiator hose was loose.

anyway, ill try again tomorrow. spent about 1 hr today
 
surfninjas said:
got 1 bolt off and am trying to figure out how to reach the other. i can feel it, but cant see it.
Click to expand...

If you're talking about the EGR,... I remember one guy saying that he pushed up on the engine a little bit from underneath and it would twist a little bit giving you a little bit more room to work.
 
pcb said:
If you're talking about the EGR,... I remember one guy saying that he pushed up on the engine a little bit from underneath and it would twist a little bit giving you a little bit more room to work.
Click to expand...

ill try. just picked up a 1/4" ratchet and sockets and a thin swivel 3/8". i think these will definitely fit better...i wish i knew what i could disconnect around it to make space.
 
surfninjas said:
ill try. just picked up a 1/4" ratchet and sockets and a thin swivel 3/8". i think these will definitely fit better...i wish i knew what i could disconnect around it to make space.
Click to expand...

OK,... I remember what he said he did,.. He put it in gear and pushed the car. That made the engine twist (like when your mounts are shot) then he set the P-brake to hold the engine twisted.

(I don't know if he had an automatic or 5-speed or if that matters ?)
 
finally got the 2nd bolt. definitely a tight fit. moved some hoses/lines without have to disconnect anything.

moving the transmission fluid dipstick definitely helps with a little bit of space (put tape over).

this tool: http://www.harborfreight.com/14-in-drive-quick-release-stubby-ratchet-62191.html

that tool was awesome. if you have a 2nd person, it definitely helps. gf was able to help get it on then i pulled and tugged it until it got off ;)
 
been busy...went to put the egr back on tonight and it would have been impossible for my t-rex/bulldog-like arms to put it back on without my gf.

the spring was not sticking, but i cleaned it anyway. i also cleaned the throttle body and threw a new air filter and pcv (noticed some coolant on it). there are no holes/cracks in the intake hose.

sometime this week or weekend, i will put everything back and try it out.

i was reading this: http://www.mazdas247.com/forum/showthread.php?123732861-Canadian-EGR-valve-exposed

im a little lost on what to do with the hoses im supposed to disconnect, that the egr hoses replace. ...realistically, in a dry, warm climate does it matter? i noticed my egr hoses were not connected to anything (last time i was down there was before a headgasket replacement).
 
I had similar symptoms with my P5 and took it to themazda miata specialist here in LA and they found that the problem was with the solenoids. Also, had the motor mounts replaced since those were all broken after 150K miles. Runs like new again.
 
surfninjas said:
i was reading this: http://www.mazdas247.com/forum/showthread.php?123732861-Canadian-EGR-valve-exposed

im a little lost on what to do with the hoses im supposed to disconnect, that the egr hoses replace. ...realistically, in a dry, warm climate does it matter? i noticed my egr hoses were not connected to anything (last time i was down there was before a headgasket replacement).
Click to expand...

I'm gonna hazard a guess and say that your EGR is not a problem (but it could be if not "fully" hooked up ??)

What about cleaning your IAC valve ?? It's not that hard to do (you probably don't even need to bug your gf).
It is the valve in charge of idle (it could make your car run rich ?)
(If I recall correctly, its got tamper proof screws/bolts but they're not that hard to deal with)

I personally would look for a different cause before trying to hook up your EGR coolant lines,... save that for last.
One guy wrote that if he had to install a new Canadian EGR again, he would just get a new car,... it's a PITA.

You did check your intake snorkel right ?? (vacuum leak stuff)


If it were me, I'd get a can of Seafoam and put half in the gas (after it drops below 1/4 tank) and half through the Vac. system and clean the IAC.

It mentioned dirty/clogged injectors as a cause,.. (and Booom mentioned "solenoids",... they tend to be replaced as opposed to cleaned (the IAC fits in that category,... it's a solenoid operated valve ))


Your car may simply just have a dirty fuel system ?? (you can even use the Seafoam to clean the removed IAC)
 
My car has 150k miles. I've read seafoam may not be the best idea for first time use in high mileage cars, because it can basically turn minor wear and tear leaks and crap into big problems.

I plan on keeping this car for a long time. Its a great way for me to learn how to become a decent shade tree mechanic.
 
I have used seafoam in many cars, Ranging from my 1952 GMC truck to my 2012 maxima. Awesome stuff. Just follow the instructions. It does actually help. One of the products in its category that actually does work. Do as suggested above. I have never heard or experienced any issues with seafoam. Just look on youtube or around the internet on how to suck it in the intake. The best place is through the vacuum line that goes to the brake booster.
 
+1 on seafoam. as he stated follow instructions and it can clean the car very well. were the plugs wet or oil covered when you took the old ones out?
 
surfninjas said:
seafoam ... can basically turn minor wear and tear leaks and crap into big problems.
Click to expand...

Don't treat your oil then,... Only your gas and vac. system.

Are you leaking or burning any oil ???
 
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Could be something as simple as an 02 sensor. I don't see that anywhere in this thread and it's probably the 1st thing I'd check/replace.
 
Doing the Seafoam is a good idea either way. It's not a waste of time or money and you might get lucky and fix your car.

If Not,.. it's back to chasing Gremlins,...




I Wonder if the list of "Probable Causes" is listed in a "Most Likely" order.
 
pcb said:
There's a bunch of codes for that. Our car is supposed to "know" if it needs a new O2 sensor.
Click to expand...

It's 2nd on the list in the OP. ;)

..and cheap. and easy to replace, and is a wear item anyway. etc etc.

Also, Seafoam is a great way to loosen and flush away carbon deposits. The reason some say don't put in in a higher-mileage engine is because the carbon deposits build up over the years. They could be flushed INTO the engine and make things much worse. A tiny speck will burn away in a cloud of black smoke, but something bigger could be like a bolt in the machinery.
 
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