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Discussion Starter · #1 · (Edited)
OK, so my car has always ran great.......until recently. Now I have a misfire........I think. It just doesn't feel like it's running on all 6 cylinders. The reason I say this is because it's definitely down on power and it vibrates like it is misfiring. Although I suppose it could possibly be a fuel issue........I don't know for sure.

I don't know if this has anything to do with my prob or not, but I'll start at the beginning in case the information may be of use. I got a new truck and while I was enjoying the novelty of it, I garaged the MX6 over at my mom's for..........maybe a month or so without driving or starting it up even once. After I charged the battery back up, I started driving it again. A day or two after that is when the misfire started. I didn't notice it running bad the first day or two, although it is possible that I just made a couple of short trips to the store and didn't notice it then too, so it is possible that it hasn't been running right since it sat in the garage.

While it had been sitting, the battery went bad (it was an old battery from 2001 to begin with) and now it wouldn't hold a charge, so I bought a new one hoping maybe that the ignition system wasn't getting proper voltage or something, but no.......it didn't make any difference.

I pulled all the plugs which have less than 5k miles on 'em. The insulators were all darker than they should've been, but not completely black or anything. The gaps were all about .005" too big, so I reset the gaps. No help there either though.

For quite a while now (since way back before my misfire issue even came along), I've been getting an occasional CEL coming on. I checked the code, and it turned out to be the code for the rear oxygen sensor. I just finally got around to changing that out last night, and it didn't make the problem go away either. I didn't really hold out much hope in that being the problem anyway since the CEL had been coming on for at least 6 months before my running issue even popped up.

I have yet to check the plug wires or distributor cap. What should I look for when checking the cap? I have a Haynes manual (piece of crap) and it gives specs on the plug wire resistances, so should I check them with my multimeter, or should I not even waste my time on that?

If some of you could point me in the right direction of some things I could check next, I would be most grateful. I just received a brand spanking new set of 17" wheels and tires for my birthday, and I need to get her running right so I can put 'em on and enjoy them! Help!
 

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I would check the resistance of the wires. When I changed out my old wires, some of them had twice the resistance of the new wires, so look out for a huge change between wires of the similar length.

Beyond that, might be an injector issue.
 

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Discussion Starter · #4 ·
i would not write in blue. doesn't that hurt your eyes?
While that was a completely asinine remark that was of no help to my car, I changed it to normal text..............just for you.:rocket:
 

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While that was a completely asinine remark that was of no help to my car, I changed it to normal text..............just for you.:rocket:
That was a valid suggestion, no need to make a rude remark about it. I had to highlight your post just so I could read it when it was in blue.
 

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Discussion Starter · #6 · (Edited)
That was a valid suggestion, no need to make a rude remark about it. I had to highlight your post just so I could read it when it was in blue.

OK, while that may be a valid suggestion or not, let's get past the previous color of my text. It's been a while since I have posted on the forums, but I always use that color of blue when I do. What can I say,..............I like it, but to each his own, so I'm sorry if I offended.

Now, the wires that are on my car are the ones that were on it when I got it about 15,000 miles ago. They are blue NGKs (they say "R-8 NGK Spark Plug Cable" on each one).........OEM? Yesterday, I checked the plug wire resistances, and they were all approximately half the resistance of Haynes' specification of 5k Ohms/foot. The shortest wire was approx. 5.5k Ohms at 2 feet in length, and the longest at approx. 5 feet long came in at 12.5k Ohms. So I guess having less resistance than specified would be a good thing.

What's the next best thing to inspect?
 

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Discussion Starter · #8 ·
It could be your egr is stuck open. After long periods the carbon cakes up, so see if you can push it open with your fingers and if it springs back smoothly. Here's a thread with a description of where to push: http://www.mx6.com/forums/2g-mx6-general/223350-egr-question.html

Ok, I'll try that out, but he (Midnightmekanik) was getting a CEL 16 (EGR) code. I was only getting a code from the 02 sensor (23) before I replaced it; no other codes at all.......ever. I will try and check it though. Also, I didn't mention in my first post that my "misfire" and power loss is throughout the entire RPM range, from idle on up..........if that helps any.
 

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Yeah, the open egr would probably throw a code and misfire would mostly be felt at idle. If it's throughout the rpm range then it's either your disty cap, plug, wire, or injector I would say.

If the misfire happens all the time, then you could take off one plug at a time and connect the plug wire back on it and touch the plug to the engine block to ground it, then run the car to see which spark isn't consistent with the rest. It's important to ground the plug to the motor because if you don't, I don't think it sparks at all, but I've heard of people blowing their disty because of it.

If the spark is consistent across all 6 cylinders, then I would turn my focus on the injectors, but it's not common for injectors to be problematic on our cars.
 

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Discussion Starter · #10 ·
Well, it's been a while, but I'm back. Since last time I posted, I swapped in new plugs and then drove the car around for a couple of days. Took out the plugs and found that they all looked perfect except for the #1 plug. The ceramic and electrodes on it appear somewhat black with a small bit of oily residue.

Removed the distributor cap and rotor button. There were no carbon tracks or cracks in either, but the contacts on the inside of the cap were somewhat corroded, so I cleaned up the cap and button contacts with some sandpaper and then checked the resistance between each contact through to the wire socket. It was all good.

Even though I had previously checked the resistance of the plug wires and they were in spec, I decided I still wanted to double check the #1 wire by switching it around with the #3 wire right beside it because since the #3 plug was doing its job, I knew the #3 plug wire was also of course fine. I switched the wires around at the plugs and dist cap and then started the car and unplugged the wire from the #1 plug.......made no difference in running quality. Plugged it back on and then uplugged the wire from the #3 plug.......made it run worse. This eliminated any doubt I had about it possibly still being the #1 spark plug wire. If it had been a bad #1 wire, the running issue would have switched to the #3 plug when I switched the wires around. So I put the wires back in their proper places.

As PaulG suggested possibly, I am now thinking it is an injector issue. I took out the #1 plug again and had someone hold a cloth over the hole while I briefly started and stopped the motor. Then I sniffed of the cloth, but smelled no gas on it at all. As a test, I repeated this at an alternate plug, and this time I smelled a slight gas smell on the cloth. Not as much as I might have expected, but it smelled nonetheless. Once again, to double-check myself, I repeated this with a clean cloth at the #1 cylinder, but still no gas smell what-so-ever. This leads me to believe that #1 is not getting any fuel.

Now, I haven't actually removed the injector rails yet, but in the Haynes Repair Manual, when removing the rails and injectors, it recommends replacing the injector o-rings.....and........what the manual calls "cushion rings". They go around the rail bolts in between the rails and the intake mani itself. Advance, Autozone, Oreilly's, etc. has the injector o-ring kits, but they don't seem to even list these "cushion rings", and for some reason I couldn't get through to my local Mazda dealership today. Anybody ever removed the injector rails and not replaced these "cushion rings"?

Now with all that said, anyone else have any further insight into what appears to be a dropped cylinder? Am I on the right track?
 

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I didn't read your whole thread but I am having a similar "cold cylinder" problem. I have been told to replace the valve cover gasket since my plug is being fouled by oil somehow.

I might be way off base on your problem though because I can definitely smell fuel on my dead cylinder's spark plug.
 

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Discussion Starter · #12 ·
I didn't read your whole thread but I am having a similar "cold cylinder" problem. I have been told to replace the valve cover gasket since my plug is being fouled by oil somehow.

I might be way off base on your problem though because I can definitely smell fuel on my dead cylinder's spark plug.
I did briefly consider a fouling issue, but the plug still fires fine when I pull it out and test it against the side of the motor. At 130,000 miles, my motor burns a little oil anyway, so I figure the slight oil residue I am getting on that plug and/or the other plugs is what would normally be burning off. Which I assume is probably coming from worn valve seals. My car doesn't puff out smoke or anything, but I can definitely smell a little oil burning at certain times. I probably burn about 1/2 to 1 quart of oil between changes.

Anyway, thanks for the input. After checking a little more, it seems what Haynes calls "cushion rings", AllData calls "injector insulators".
 

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Discussion Starter · #13 ·
Thought I would come back and say my dead cylinder was due to a bad solenoid on the #1 injector. It wasn't opening, so no fuel to the #1 cylinder = dead cylinder.

Thanks to all who participated & to Paul G especially.
 

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so you said it was a solonoid problem? so what all did you replace? i have the same type of misfire issue with no resolution so far! injectors were my next thing to check.

also did you find out where to get the cushions from? mazda wants $13ea for them.

thanks!

JACK.
 

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Discussion Starter · #16 ·
so you said it was a solonoid problem? so what all did you replace? i have the same type of misfire issue with no resolution so far! injectors were my next thing to check.

also did you find out where to get the cushions from? mazda wants $13ea for them.

thanks!

JACK.
Actually, mine turned out to be a dead cylinder rather than a "misfire" as I originally described. #1 cylinder was never getting any power because it was getting no fuel.

After I checked the injector resistances as it said to in the Haynes Manual, I found the #1 injector had an open circuit, so then I just had to remove the fuel rail and replace the #1 injector. I referred to it as an injector solenoid, but the solenoids are built-in to the injectors, so it's all one piece.

No, I never could even find anyone that had the cushion seals, but I just reused my old ones. I just tightened down the fuel rail good and tight, and hoped for the best! I did however buy a new set of injector o-rings at the local AutoZone. They were only about $8.
 
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