Misfiring troubleshooting
 

So my '06 xA has had a misfiring issue for a couple weeks. At first it was just a skip here and there that I noticed and I knew something was wrong but I couldn't chase it down because it had not set a code. Then the CEL began flashing.


I got a code reader and the ECU is reporting a P0303, So I changed all the spark plugs and swapped the #1 and the #3 coils, I wasn't about to buy a new coil until I was sure that was the issue. hoping that the misfire would follow the coil about a week and a half later the issue popped up again.


Same cylinder P0303 so not the coil. I figure it has to be fuel so I check the injectors the #3 injector is reporting 300kΩ, O.K. now we're getting somewhere.


I'm 95% sure that it's the injector the problem is when I listen to the injectors #3 still sounds like its pulsing but the resistance is way out of tolerance, the problem also seems to be based on how long the car runs. the injectors all test fine when the car is cold (about 14Ω). Another funny thing is when driving if I am at neutral throttle and on a flat road the check engine light goes off but as soon as I throttle it starts flashing again. (don't yell at me for driving it I know if its flashing im not supposed to.)


So my main questions are
Have any of you ever experienced an injector going bad?
What kind of failures have you had due to a misfire?


I'm also looking for some sort of confirmation on my part, from what I have described how many of you think I have found the issue or is this just one of a number of problems that are causing the misfire?


I plan on changing the injector this weekend and I will post pictures and results.


Any input would greatly be appreciated.


~Thanks~

Injector changed
 

So I changed the #3 injector and so far everything seems to be O.K.
The CEL is off the engine idles properly and I went for about a 15 min drive and I didn't detect any skipping or missing.

As far as the replacement goes it was actually a lot easier than I expected and it took me about an hour and a half while taking my time.

First I removed the relay that turns on the fuel pump.
Attachment 121653
It's the blank spot next to the big grey relay.

I started the car and it ran for about 3 seconds and then died, I attempted to restart the car and it wouldn't run so the fuel system is depressurized. I also took off the gas cap per the service manual.

Attachment 121654
Took out the coils and plug and did a compression check I got 180 across the board I then put the plugs back in to prevent anything from falling in the cylinder. I also disconnected the battery at this point.

Attachment 121655
I disconnected all the wires from the injectors and I pulled off the 2 vent hoses and took out 9 bolts and 2 nuts. the bracket on the left side of the valve cover also had to be removed to allow access to bolt #10.

Attachment 121656
I pulled the valve cover off it took a couple hits with a mallet but it came easy enough. the next step is to remove the fuel rail. it says to disconnect the hard line from the fuel supply. Don't bother doing that just remove the 10mm bolt from the bracket on the side holding the hard fuel line in and the 2 12mm bolts in front and lay the fuel rail over.

Attachment 121657
it was easy enough to get out just have to maneuver it so it doesn't hit anything especially sense I'm reusing the other 3 injectors that aren't bad.

Attachment 121658
New injector vs old injector.

Attachment 121659
The ports were full of crapola so I used a vacuum to clear out all the material that were there and used a rag to wipe off the old injector seals.

I dipped the end of the new injector that goes into the rail in a cup of gas and installed it into the rail. It didn't take much to go in and it should spin around freely.


Installation is the reverse of removal. The two bolts holding the fuel rail on were torqued to 14lb-ft and the valve cover gets torqued to 7lb-ft in 3 steps. I did have to "peel" the valve cover gasket off of the head and put it back into the valve cover groves. but it wasn't that much of an issue. I followed the diagram in the service manual for torquing the valve cover.

The car started right up after I put everything back together and I let it idle while i checked for fuel leaks and there weren't any. (thank goodness)

Overall not to hard of a job it seemed a lot more difficult on paper than it really was. A good learning experience.

My xB 2005 had the same issue since the repair manual for an xB costs an arm and a leg. I found out that the 2004 Toyota Corolla share the same motor except the Corolla engine is a bit larger, however still the same engine. So I use that repair manual on my car. My issue was that at a stop light or just a stop the car began to stumble and sputter. I changed all the spark plugs and Ignition coils (amazon sale them by the 4 pack). I put a better quality spark plug. Also near the air filter intake is the Mass Air Flow sensor. Remove that and clean it with MAF spray DO NOT use a carburetor cleaner and DO NOT touch the sensors with your fingers.
That cleared things up for me.

Did you find and fix the issue... pretty much having the same thing with my 06 xA!

_______

Misfire
 

Yes, I found that the 2004 Toyota Corolla uses the same motor but slightly large. Using the Chilton manual I used the troubleshooting section and it listed the sputtering or misfiring. Replace the spark plugs. But use a good quality brand like TGK. And also a good gas treatment.

I have a 2009 Scion TC.with an After Market Turbo.
I have been chasing my Misfire Codes for Three and a Half Years!
Mechanics out here see a woman and are not as honest as they should be.

I have learned by fire and a process of elimination.

Check your Fuel Regulator and Fuel Pump too.
Good luck.