Cylinder 4 Misfire or Fuel Injector Help?
03-15-2009, 01:53 PM
#1
Cylinder 4 Misfire or Fuel Injector Help?
I did a search and read multiple threads. Not sure what to do next. First, let me tell you what I've done so far.
95 Maxima started to idle very rough, worse at lower speeds this weekend. RPM's stay the same and putting car in neutral makes it a little better but the shaking is still there. Took the car to Advance Auto and they ran the car diagnostic tool which stated I have a cylinder 4 misfire, so I bought replacement spark plugs. I replaced the 3 front spark plugs and swapped coils 4 and 6. Issue was still there and disconnecting coil 4 (which was 6) did not cause the idle to change. Disconnecting coil 6 (which was 4) did cause the idle to change. This leads me to believe it is not the spark plugs or the coils. I used the screwdriver trick and could hear clicking on the front 3 injectors and the upper left and upper right injector since you can reach them with a screw driver without removing the manifold. Unfortunately, there is the top middle injector that you cannot reach, but I wanted to check and see if I was completely on the wrong track before removing the manifold and checking the one injector that I cannot reach from the outside.
95 Maxima started to idle very rough, worse at lower speeds this weekend. RPM's stay the same and putting car in neutral makes it a little better but the shaking is still there. Took the car to Advance Auto and they ran the car diagnostic tool which stated I have a cylinder 4 misfire, so I bought replacement spark plugs. I replaced the 3 front spark plugs and swapped coils 4 and 6. Issue was still there and disconnecting coil 4 (which was 6) did not cause the idle to change. Disconnecting coil 6 (which was 4) did cause the idle to change. This leads me to believe it is not the spark plugs or the coils. I used the screwdriver trick and could hear clicking on the front 3 injectors and the upper left and upper right injector since you can reach them with a screw driver without removing the manifold. Unfortunately, there is the top middle injector that you cannot reach, but I wanted to check and see if I was completely on the wrong track before removing the manifold and checking the one injector that I cannot reach from the outside.
03-15-2009, 02:57 PM
#2
Why would you check number 3 if cylinder 4 is the one misfiring?
Ohm out the injector, if that looks good then pull the front rail and see if it's actually spraying fuel.
Short of that, you've got a wiring problem (or a few others, but they're outliers; ECU, internal, etc).
...why did you replace the front plugs and not the rears? To save 10 minutes?
Ohm out the injector, if that looks good then pull the front rail and see if it's actually spraying fuel.
Short of that, you've got a wiring problem (or a few others, but they're outliers; ECU, internal, etc).
...why did you replace the front plugs and not the rears? To save 10 minutes?
03-15-2009, 03:12 PM
#3
I replaced the front 3 plugs while I had the cover off, swapped the coils and checked to see if the problem was fixed. I am changing the back 3 spark plugs also, but my most pressing concern is getting the problem fixed.
What is the process for ohming the injector?
What is the process for ohming the injector?
03-15-2009, 03:15 PM
#4
Touch the two leads of an ohmmeter or multimeter to the two pins on the injector, read the resistance. Looking for ~10-14 ohms.
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