Direct Fuel injectors - How to check?

[vipercwf]

I am getting a misfire in cylinder 1. How do you determine if your fuel injector is bad since they are direct injection?

 

[oaklandopen]

Take them out and put them in a fuel injector cleaner machine.....thats the best and probably least practical way (since not everyone has one of those laying around). You can also take the injector out and switch it with another. If the cyl misfire happens in the one you put the alleged bad one is then you need a new one. If not, you have another problem

If youre trying to determine if its an injector causing the misfire you can hook up a sniffer and see what type of misfire it is, then troubleshoot from there

i think you need to try other things instead of going right after an injector

 

[vipercwf]

Replaced the coil in cylinder one, replaced all spark plugs. As for the injectors I wouldn't even know how to remove them as they are direct injection? What is a sniffer?

Also, does anyone know how to test the wires to make sure they are good. I've really only done this on old school distributor type, with one wire to each cylinder, but on this fuel injection its just one big harness and don't know how to check that. Sorry for the naivety I just don't have the money to take it to the shop and need a little insight as i'm willing to try what I can myself.

 

[vipercwf]

Well i took it to the shop, they are telling me it is a clogged injector. Said its 725 bucks to replace it, so the tech recommended I run a couple tanks with techron fuel injector cleaner and see if it works. I thought I read somewhere on here that the owners manual warns not to use these chemicals. I can understand why the manufactuer would say that, but given my options of 725 buck to fix or try this, shouldn't I give it a try w/ the cleaner?

 

[oaklandopen]

If its fuel injector safe just use it, or put a pint of seafoam in your gas tank

 

[bova80]

i find it hard that an injector that sprays over 1500psi could get clogged.

 

[vipercwf]

I did get bad gas awhile back and thats when the CEL, symptoms started after they "Fixed" it. It just got worse recently though, it seemed to do it before only in the morning for a minute until warm up (maybe once the engine got warm it free'd up enough of the varnish for fuel to pass more freely?) I was thinking it's gotten worse as the varnish has built up upon itself or forced itself more into the injector? I dunno

 

[oaklandopen]

Things build up over time. If they didnt, no one would have clogged arteries

 

[zinger002]

Are your arteries getting 1500psi of pressure along with their flow? I would think not...

 

[oaklandopen]

I believe that even though the injectors are high pressure they have a better chance at clogging. I think it has mostly to do with the volume of fluid than its pressure...like plumbing

ive gotten plenty of issues with toilet parts when the most minute particles get stuck in hih pressure areas like the flusher assembly. A little piece of dirt in there will ruin the whole thing and it will eithr not flush or not stop flowing water

we have never had a clog in the main line....its very low flow but the volume is so high nothing has a chance to stick

 

[bova80]

yeah well your toilet doesn't have filters on it. but if you want to believe the mechanic and spend the money on a new injector then by all means.

 

[oaklandopen]

And filters never fail?

 

[bova80]

never once in the 4 years of being apart of the mazdaspeed community have I read about a clogged injector. if you are getting a misfire its from a bad coil, bad spark plug, bad injector seal, a bad connection somewhere, or some kind of air leak.

now i'm not saying that it isn't a clogged injector, i'm saying the likely hood of it being that is pretty slim.

 

[vipercwf]

I get what you are all saying. I know its rare for injectors to clogg. But on the other hand, the fact that I did get bad gas and they took it to a shop to 'fix' it as it completely shut the car down (i really don't know what they did but I know they didn't do it right. Sounds like all they did was blow out the line) Anyways, one of the reasons I tend to think it could be a clogged injector is because of this. I never had any problems but from the moment I left the shop I got a CEL, which is the misfire Cylinder 1. Its been very awkard in its sympotms, for a while it only seemed to misfire in the morning during startup until it was warm then didn't misfire. I was kinda gettin on it the other day when it started misfiring worse. Couldn't it be possible that the bad gas caused varnish build up, and the other day perhaps the varish just got more clogged in the injector and thats why its misfiring more now? I'm not saying this is the case im just wondering. I would just find it hard to believe that I had no problems, got bad gas and then instantly had bad wires, bad connection or electrical (although i know weird coincidences can happen with cars). BTW, I did replace the coil on cylinder 1, along with plugs to all cylinders. Didn't fix anything.

 

[oaklandopen]

It would be a lot easier if your misfires would stay constant because then you can start unplugging either plugs or injector wires one at a time. With the random misfiring times the best thing to do on your own is to switch them and test it out. If you change the injector from cyl 1 to cyl 2 and cyl 2 starts getting the misfire, then you can safely say it has something to do with the injector

if the misfiring cylinder stays the same after switching, its something else

i can theorize all day about whats going on, but i diagnose much better when the problem is in front of me and i have my tools

and as far as probability is concerned i do agree that its rather unlikely that the injector is clogged, but i dont leave anything out of the picture when it comes to diagnostics. But thats just me

and i dont think the type of misfire was actually explained. You need a scantool or a sniffr (exhaust tool that measures O2, CO2, NOX, HC)

 

[vipercwf]

I'm going to run a tank with injector cleaner and see if it works, though i know even if it is clogged its unlikely it would. My problem is I am not overly mechanical and never have messed w/ direct injectors. Has anyone been down in there for that, I wouldn't even know how to get to them. I would guess you'd have to take manifold, valve covers off?

 

[bova80]

you just have to take the intake manifold off. the fuel rail is right behind there.

 

[vipercwf]

Oh ok cool. Thanks for the info guys I appreciate it. I let you know how things go.

 

[zinger002]

Filters don't often fail, and if a fuel filter was to fail it would be catistrophic, not occasional.

 

[vipercwf]

Just got to the last qtr tank of gas of first tank w cleaner. Its starting to idle a little worse w steady light popping noticeable. I noticed some built up carbon on my exhaust outlet ends. Is it possible to get worse as it cleans it, like passing of a kidney stone?