Misfire on 2.3

[mazda-fla]

My 99 Millenia S has been idling a little rough at start up the last couple months. Now about 3 times out of 10 on a start up it runs rough and throws a flashing code for "Misfire on Cylinder 2". Then after I get going down the road the car smooths out and runs fine.

I swapped the coil pack between Cylinders 2 and 4, then still got the "Misfire on Cylinder 2" code. So I swapped the spark plug between 2 and 4, and still got the "Misfire on Cylinder 2" code". So kind of ruled out the obvious coil pack and spark plug causing the misfire.

Then I did the ohm test on the fuel injectors. I got a good ohm reading (about 14 ohms) on cylinders 2 and 4, but I get nothing on cylinder 6 (reads as if it is an open circuit, same reading as if you held the multimeter probes apart not touching anything).

So this is kind of puzzling. Coil packs seems good, plugs seem good, OBDII reader shows "Misfire on Cylinder 2". But ohm test seems to indicate fuel injector on cylinder 2 is within specs, but 6 is bad. This doesn't make sense.

Any thoughts? I'm about to break down and buy 3 remanufactured fuel injectors and swap out the entire left bank of 2, 4, and 6 while I'm in there doing the work. Don't know what else this could be.

Also, just for kicks, I ordered a new fuel filter (haven't change it since 2004) so I figure that can't hurt to give it a try.

Any ideas?

[bigb]

before you go off an buy injectors, are you sure you are measuring them correctly. 0ohm means open circuit or short (depending on your meter) and your car would not run if that was the case. I would go back and re-check. maybe the contacts are dirty. to me 0ohm means its dead, not intermittent. plus, if it were really 0 ohm you would get a code for the injector as well.

what if the problem is not your plug or coil pack. what if the wiring harness or ground is dirty. then swapping the coil or plug would not help since it's the wiring. also, warming up the engine may help this since it will expand / contract the metal.

I'd back track the wiring from bank 2 and just make sure the pins are all ok and there are no cracks in the wire.


now... if you still want injectors, I have about 6 different sets if you're interested... but I still don't think it's the injectors.

[keninn]

you wont get a code for the injector. when i went thru this, all i got was a missfire code, and, of course, it was the friggin #5. always the most difficult for me. and, like everyone else, i first swapped the coil AND the plug. didnt even bother checking the injectors. my symptoms were the car started cold and ran fine, then after about 10 min, missing, ce lite flashing. starting hot almost immediatly, but cold it would take a while. i was lucky to find a complete set on ebay, and swapped out the right bank, rail and all, and hoped no leaks. fired up right away, and has been going since. i took a chance on the seals, i didnt have any, and them suckers is expensive. also took a chance that the used injectors werent stuck, they ohm'd ok, but one never knows. there is another poster on this forum from austin who also had a bad injector. we can no longer just change the plug and coil, now we gotta check injector resistance, too. cars are getting old. dont forget that when you change the rail, you will need new crush rings for the connector between the rails, dont reuse the old ones. someone here did, and they leaked, get to do the job all over again. i think i would not take a chance on the seals again, either. also, before removing the rail, spray in there with cleaner, and a LOT of air, because all kinds of dirt is way down there, and when you pull the rail out, some of it will fall into the seal area, and guess what that does

[mazda-fla]

The wiring harness looks visually clean, but the pins may be a little cruddy from being 13 years old and my valve cover gaskets used to leak like the Exxon Valdez before I changed them. Do you think I should get some kind of electrical contact cleaner spray and spray them down?

When you say "ground is dirty", what ground are you referring to?

The reading I get on that injector shows 1 (which may mean infinity), which would be the same reading you would get if you held the probes apart or if you cut the wire or something, basically open circuit. But that's why it doesn't make sense, because that would mean a dead injector and it would be running on 5 cylinders (not intermittent). If you've ever tried to ohm that connector on the car, you see how hard it is to get the probe tips in there, because they are deep in the connector and the air intake pipe blocks it. You need three hands, someone to hold a flashlight and then your two hands to touch the probes. I was thinking to run over to Radio Shack and get some probe wires that have small alligator clips on them, because it is really hard to check that particular connector.

[mazda-fla]

Originally Posted by keninn

you wont get a code for the injector. when i went thru this, all i got was a missfire code, and, of course, it was the friggin #5. always the most difficult for me. and, like everyone else, i first swapped the coil AND the plug. didnt even bother checking the injectors. my symptoms were the car started cold and ran fine, then after about 10 min, missing, ce lite flashing. starting hot almost immediatly, but cold it would take a while. i was lucky to find a complete set on ebay, and swapped out the right bank, rail and all, and hoped no leaks. fired up right away, and has been going since. i took a chance on the seals, i didnt have any, and them suckers is expensive. also took a chance that the used injectors werent stuck, they ohm'd ok, but one never knows. there is another poster on this forum from austin who also had a bad injector. we can no longer just change the plug and coil, now we gotta check injector resistance, too. cars are getting old. dont forget that when you change the rail, you will need new crush rings for the connector between the rails, dont reuse the old ones. someone here did, and they leaked, get to do the job all over again. i think i would not take a chance on the seals again, either. also, before removing the rail, spray in there with cleaner, and a LOT of air, because all kinds of dirt is way down there, and when you pull the rail out, some of it will fall into the seal area, and guess what that does

When you say "seals", what are you talking about? Do you mean the 2 o-rings on the injectors?

I also lived through trying to reuse the crush rings when I changed my valve cover gaskets (leaked fuel all over the place). I'm definately going to have new rings on-hold before I start the job.

I did see a full set on ebay; complete unit (rails and injectors) that ohm correctly, but like you said who knows. I would suspect the places that have remanufactured fuel injectors are just ohm'd, ultrasonic cleaned, and new o-rings. That's it.

[bigb]

sometimes with the point style multimeter leads, it's hard to get a good contact, which is why i think you are getting open circuit. you had a good idea to get aligator clips. that way they are a bit sharper and would penetrate any film that may be on the metal contact for that last injector.

as for seals, for each individual injector there are 2 o-rings. if you take the fuel rail apart, the o-ring needs to be replaced, but so long as you get a complete fuel rail that has never been opened, the o-rings should be good. a new o-ring set is like $75 from mazda. I've seen them on ebay for about $35 but rarely. that is why ken suggested getting a fuel rail that has not been opened. to save the cost of replacing the o-rings

For each injector there are also crush washers that fit inside the intake manafold and act as a "seat" when you install the rails. they look like round flat wahers with a little lip and a hole in the center. this is where the injector presses up against. if there is a bad seal here or the seal is damaged, then air gets passed the seal and you get a vacuum leak. again, these are about $12 each from mazda.

now. if you are dead set on replacing the injectors you can go online but I have a few options for you.

1) 6 injectors only - if you want to dismantle and rebuild your own rails. as mentioned above, you will need to replace the o-rings

2) disassembled and cleaned fuel rails - I have a complete set taken apart piece by piece and cleaned, but as mentioned above, you will need to replace the o-rings. this just gives you the added flexibility of doing all the rebuild off the car and then just swapping in when you are ready.

3) complete fuel rails never opened - I have another complete set that I've never opened. I cleaned the outside as best I could without opening them. this way hopefully the o-rings are still good and you save the cost. basically you just bolt these in and hope for no leaks. Now these came off my car 2 years ago. as of then there were no leaks. I'm not sure what 2 years of storage has done to the o-rings, but I know the injectors themselves are good and the rails were fully functional when removed.

All the injectors I have OHM good and have been bench tested and verified to open / close properly. The only thing I have not done is check the spray pattern because I do not have the equipment to test that.

as for the crush washers in the intake manifold, I have a used set in extremely good shape (set of 6). I can throw those into whichever set if you want them. that way between my 6 and the 3 you pull from bank 1, you should be able to make a good set.

oh, and dont forget you will need copper crush washers when you remove the banjo bolts that connect the rail to the fuel lines.

[bigb]

so after looking at ebay, I found a few o-ring options for you:

complete set of 6 o-rings for $12. This is **** good but never tried this brand

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

individual injector seal kit, also includes the top end electrical seal, but you can easily reuse the old ones. they are made from solicone and do not go bad. $3.25 ea. I have used beck arnley before.

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices


so it looks like you are not too limited by the o-rings anymore. **** i wish these were that cheap when I played with my fuel system 2 years ago hehe

[bigb]

ok so this pic will help you if you are taking them apart. I think you need to log in to see it


Goliat, if you would be so kind as to put this on your photobucket account since it might be helpful for people rebuilding their injectors in future.

everything is laid out in mostly the right location. you can see the crush washers or "seals" mentioned above are those round black discs below the injectors.

this would be an example of one of my "disassembled" sets.

[Goliat6288]

done . btw if you do this again and i dont do it with in a day or two shoot me a pm with the link. i dont check every thread on here and i might miss it. lol

[bigb]

thank-you sir.

after looking at that pic... I think I have spare part OCD lol