Rough Running P5

[FujiToast]

Hey guys, I've got a sick p5 and I can't quite find the cure for him and I'm hoping you guys might know something. First a little background and what's been tried and replaced.

A couple of months ago after about a 1.5 hour drive. I pulled into the driveway with no troubles. I pulled out 15 minutes later to run an errand and it started bucking and popping and puffing white smoke all over the place. (My girlfriend though it was going to explode and walked home (lol2) ) I pulled the codes and saw a Cyl 3 Misfire code. So bought a reconditioned injector and drove it up to my mechanic and he replaced it for me. He said that old injector was absolutely spewing fuel out of it. Fixed.

But nope, On the way back it starts stuttering here and there and it seems like the engine is losing power a little but I don't get a code thrown until I get to my parents place. That code is P0131 (o2 Sensor Circuit Low Voltage Bank 1 Sensor 1). Ok, I give my mechanic a call and he assumes the flood of fuel from the bad injector ruined my topside O2 Sensor so I order another. I drive home and get a better sense of what's going on. It seems most prevalent when I start from a stop. I press on the gas, it goes for a split second and then it cuts out for a second like the engine isn't getting any power, sometimes it'll do it twice and then it'll rev up as normal.

I get the new O2 Sensor delivered but before I install it, I run the codes again and find that there is now an additional code. P0304 (Cylinder 4 Misfire). I clear the codes and hope that the O2 sensor will fix the issue. But nope, I install the new O2 Sensor and it's still doing the exact same thing, but now it's not giving me any check engine codes. I check with my mechanic again and he recommends I start simple and and try some new plugs figuring the old ones may have gotten gummed up with all the spewed fuel.

Last night I installed the new plugs and still exact same thing stuttering and hesitating. I drove it more today and now I've got a NEW code. P0171 (System Too Lean Bank 1). I checked all the hoses, well the ones that I can see. I have a K&N Cold air intake installed so I checked all of the hoses on it. I kind of don't know where to go next. MAF sensor?

Any ideas?

Oh and a little more info. The car is an auto P5 with the 2.0 with 66,660 miles on it. Had a new coil installed at 60k and I THINK new wires installed a little before that. (When the coil went bad my mechanic first thought it was the wires and plugs so he replaced those first. I'm not POSITIVE if he put the old wires back on after he found out it wasn't them or not. I kinda doubt it, so I'd assume Ive got new wires as well.)

Any help or ideas would be MUCH appreciated!

 

[Installshield 2]

Ok, from what it looks like i'm guessing you have some multiple little issues that are all sort of working on the same thing...which is a misfiring condition that seems to be migrating haha.

Coils are generally sort of easy to spot when they go bad. Each coil controls two cylinders, so they'll rarely create a specific cylinder misfire, instead giving the infamous p0300 which illustrates multiple cylinder missing. This would more than likely, if its ignition related, be a plug or wire...although, as mentioned, you're now getting it in a different cylinder too, right? Coils die in very strange ways, and i don't know the firing order off hand...is the 'other' cylinder controlled by the same coil?

but coils aren't going to give you that lean mixture code. That is usually caused by a vacuum leak behind the MAF...could be a cracked hose, broken fitting, etc. Lean would be caused by extra air, not extra fuel, so look at the purge system closely. This could also be a hiccup with the EGR system getting stuck open, which will recirculate some exhaust gasses in non-ideal operation ranges. But the go to sign for the EGR system is a poor idle often resulting on throttle off stalling...a lot of time never tripping any code of any kind.

the mechanic is right about your plugs. missing and hesitation could quickly gunk them up. What is very strange though is that you went from a dead injector dumping fuel (very rich condition) to now having something lean in nature. Lean will quickly eat up a plug by melting it, and usually completely closing the gap on the next compression stroke.

Sadly...assuming your exhaust system is still stock...the primary catalyst does not hold up very well to overly rich conditions. If you did destroy an O2 sensor, there is a strong chance you flooded fuel into the primary catalyst...which will cause a quick 'flue fire' that will weld it nearly closed. how does the exhaust system seem? Any weird engine note or tone that seems completely off? Can you feel exhaust pulsing properly out the back with your hand under idle? in certain operation ranges the ecu uses a 'closed loop' mode where it takes readings from teh primary O2 sensor to adjust fuel requirements. A back up of exhaust gas right around that sensor will create an environment of it getting 'too rich' of a reading...resulting in the ECU pulling fuel and leaning it out...but that wouldn't throw a lean code, i'd assume anyway...as the ECU would be purposely leaning it out...not confused as to why its leaned out, if that makes sense...this would very much create hesitation though, so its something to have checked out.

Sorry, i know this has more questions than answers...but check out the things mentioned and see if you come up with anything.

 

[FujiToast]

Thanks so much for your reply. I'll have to ask you to bear with me as I'm very novice mechanic. I know just enough to get my hands dirty.

Regarding the coils. Unfortunaly I'm not sure which coil was the one that was replaced a few months ago. But from the codes it was cyl 3 which had the bad injector and then I later got the cyl 4 misfire code after the cyl 3 injector was replaced. Do you have any idea if those two are on the same coil? Does that answer the question you were asking about the "other" cylinder?

As far as the idle, it's completely normal sometimes and other times hicuping a bit. Only once since I got it back did it feel like it was going to die.

My exhaust is still stock and I did hear some popping the very first time the injector started acting up. (Possible indication of a 'flue fire'?) But with that being said, the exhaust seems and sounds normal. No noticable odd notes or tones. I'll have to go feel the exhaust for the proper pulsing but it only seems off when it's specifically acting up which is usually and most notable right after take-off (but again, not everytime) where it hesitates for a second with no engine power.

Another thing that seems to have come up over the weekend is a slightly more harsh version of the hesitating where it almost feels like your in a manual transmission car with a first time stick driver having a hard time finding the sweet spot. You know, the jerking back and forth?

I hope some of that helps you help me. I really do appreciate the reply. Please let me know if there is anything I can test or check without a full mechanics garage. I can do those tests much easier.

 

[FujiToast]

Another piece of the puzzle. It seems to do it more when it's warm than cold and also if I feather the gas really carefully it seems I can avoid the hesitation as well.

 

[Installshield 2]

well thats good news about the cat then. If it was destroyed and nearly plugged shut, you'd probably be able to tell by a very strange, almost 'muted' like engine tone, as well as little power all the time...not just occasionally. So hopefully that thing is fine, as its by far the most expensive piece of this puzzle.

Protege 5's ignition coils, according to the manual, have a life expectancy of around 100,000 miles. Not sure on your mileage, but its strange that only one was replaced...rather than both. After some more digging around yesterday i did see a few threads from people getting specific cylinder misfiring, yet still being related to the coil...as the coil died, it was internally 'dragging' on one lead...so therefor only missing on one cylinder, not both that it controls...in either case, figure out which coil is older...and replace it as well...they're pretty cheap, and even if it isn't the direct cause of everything right now...it soon could be.

Again though, this won't effect that lean code...did you get a chance to go over the vacuum lines as best as possible?

 

[FujiToast]

Good, Good.

Yeah, I looked over the lines as best I could and didn't see anything. I think I'll give my mechanic a call today and ask if he remembers if he replaced both coils or just one. I'll let you know if I discover any more pieces to this frustrating puzzle.

Again, thanks so much!

 

[FujiToast]

So in parking the car waiting for the mechanic, the problem just went away. It was parked for about a week, and then I drove it the 30ish mile to the mechanic and it didn't do it once. It also didn't do it for the mechanic. And it hasn't done it since. Weird. BUT I had the mechanic change the oil while he had the car and now I'm getting a smell of gas. I just made a new post for this issue if you have a chance to look at it. Thanks so much!

http://www.mazdas247.com/forum/showthread.php?123823347-Smelling-Gas&p=6072029#post6072029