Can a clogged fuel injector cause P0302?

[artbuc]

On a 99 3.0L V6, engine running rough and threw P0300 & P0302. Swapped plug and coil with #6 and problem stayed with #2. Injector ohmed out ok and it clicks just like the others, BUT, when you disconnect #2 injector engine runs about the same. When you disconnect #6 or #4 injector, you see a noticeable drop-off in engine smoothness. Compression of #2 & # 6 are exactly the same. Looks like #2 injector is operating but it is clogged. Does this make sense?

Two days before this happened, I filled-up an almost empty tank with no-name supermarket gas. I wonder if I got some bad stuff?

Check engine light will sometimes flash on/off, usually on heavy acceleration so I can't really drive this thing until I get it fixed.

If the injector is just clogged, can I clean it or should I put in a new one? Thanks.

Edit: Here is a good article I just discovered. Both #2 and #6 plugs (only ones I pulled) were white hot. Maybe I have a "lean" misfire.

http://repairpal.com/OBD-II-Code-P0302

[Brian R.]

Clogged injectors are common. You should be able to clean it. Apply battery voltage across the connections and spray internally with non-residue electronic cleaner. However, Toyota recommends replacing the injector if it's clogged. Cleaning may not work if it's totally plugged or if there is a piece of some sort of residue blocking the injector passageway.

[artbuc]

Originally Posted by Brian R.

Clogged injectors are common. You should be able to clean it. Apply battery voltage across the connections and spray internally with non-residue electronic cleaner. However, Toyota recommends replacing the injector if it's clogged. Cleaning may not work if it's totally plugged or if there is a piece of some sort of residue blocking the injector passageway.

Thanks Brian. Did you see the link I added to my original post?If I have a lean misfire due to a clogged fuel filter, for example, woudn't I also get a P0171?

[Brian R.]

Fuel filter would affect all cylinders equally. No, I didn't see the article before I posted. But, I think your identification of one cylinder as the problem eliminates any of the sensors or general parts of the fuel system. Placing the injector in solvent in an ultrasonic cleaner is another method. In that case, you might as well clean them all. You can always try adding Techron fuel treatment to your gas tank and see if that helps.

[artbuc]

Originally Posted by Brian R.

Fuel filter would affect all cylinders equally. No, I didn't see the article before I posted. But, I think your identification of one cylinder as the problem eliminates any of the sensors or general parts of the fuel system. Placing the injector in solvent in an ultrasonic cleaner is another method. In that case, you might as well clean them all. You can always try adding Techron fuel treatment to your gas tank and see if that helps.

Yep, already added two bottles of Techron, as it has worked wonders for me in the past. Since I depended on someone from Autozone to read the codes for me, I was wondering if I might have some other P030X codes pending, especially since my #6 plug is white. I have since pulled #4 plug and it looks almost normal. I would guess all of my plugs are fouled to some degree. Think I will do Bank 1 first and see how it goes.

[artbuc]

Update: I used the fuel pipe to pressure clean bank 2 injectors. Two cleaned up fine producing a strong spray. The trouble maker improved somewhat but after multiple tries, I could not get a strong atomized flow.

The bad injector ohms ok and the clicks ok but for some reason it won't flow correctly. Just bought a Denso replacement from Rockauto. Will let you know what happens.

I still think bad gas may be a factor as I filled an empty tank Wed night and my engine went haywire the next morning after driving about 5 miles.

I am considering removing bank 1 injectors but I want to see if the new bank 2 injector solves the problem. The 4 air let ports which help atomize the gas were all partially clogged with a couple mostly clogged. Fuel injector additives may clean the injector internals but I don't think it will do anything to clear the air inlet ports.

[Brian R.]

I would check all the injectors and replace the ones that can't be made to work perfectly. Replace the fuel filter.

Also, drain all that gas out of the gas tank. Flush the lines when possible.

I don't understand how the crap got past your fuel filter.

[artbuc]

Thanks Brian. I think I gave you the wrong impression. The two injectors that performed well did so without much cleaning. The material in the air assist holes had been there for a while. It was hard, almost carbonized looking. Don't think it came from the gas.

Since my last post, I cut open the problem injector. It was very clean inside so the low flow wasn't from debris. When you pop off the plastic pintle, you see a stainless shroud with 4 tiny orifices where the gas leaves the body of the injector and enters the pintle. I had to use magnification to see these holes well and they were clean. The needle seat is attached to a small cylinder which strokes against the return spring. The needle is able to rock inside the cylinder to allow free movement presumably so the needle doesn't bind and/or so it can "wobble" into its seat to stop flow. Pretty clever design. On my bad injector, the needle was slightly cocked and tight in the cylinder. It was obviously able to seat ok but I don't think it was able to fully open. It did come loose fairly easily with cleaner and manipulation but I would never have been able to free it up without cutting into and destroying the injector. Perhaps ultrasonic cleaning would have worked, but it made more sense to get a new injector.

[Brian R.]

I got it. Sounds like you need to run Techron through your tank more often. Good job.

[artbuc]

Wanted all to know that cyl 2 injector was the problem. Thanks for your help.

[Brian R.]

You're welcome. It is a good idea to alternate fuel brands so that you don't get deposits from one brand's additives being deposited. Gasoline is a bad solvent for its additives and they build up when it evaporates, in the intake manifold. Different brands of gas have different additive packages so they dissolve each other's additives to some extent.

[danielsatur]

It's nothing unusual todo an ''Out of car injector service'', you can take injectors to a local diesel shop for a micro bath, blow out, and have the flow rate tested.