3rd cylinder misfire

Hi, i have a cylinder misfire problem. I plugged my scanner in and checked the DTC, twice came up as the third cylinder kept misfiring. I have a spark plug checker that lights up when current runs through it. I have spark from the coil pack to the wire boot, but from there i cant check if i have spark from the wire, to the plug. How do I know if i have a spark issue? Or a injectore issue? At about 3000 rpm the cars rpm gauge dips down a little, like it has trouble accelerating at that point.

Sounds like you hav spark.
What engine size and year?

Most misfires are caused by injectors, but not all.
They do need cleaning from time to time,
if you dont use injector cleaners regularly.

The V6s an known to hav trouble with the injector wires on and around the intake, possible form heat. The cover on the wires cracks and shorts out..
The 4cyl could very well hav the same troubles.

Two things, get a noid light and see if the injector is firing at the proper time. If it is the light will light each time. If not you should see a pause or no light. This will tell you if you have a wiring issue. Secondly, you can pull the injector from another cylinder and place it in one of the non-misfiring cylinders. If the misfire changes the injector is the issue.

A noid light is a good investment!
It works easily on the 4cyl's .

Though on the v6 you cant get to all the injectors without removing the upper intake. Best to do it at the injector harness on these(v6s).

3.1L
im going to take out the plug firt, then try the noid light, and possibly a pressure tester to see if its firing at 60psi, maybe just the one is clogged. All the injectors were just cleaned though, and my plugs were all just changed less than 20,000 miles, which is why im annoyed with this

But did you change the wires too? Wires are one of the most common causes of misfires and one of the most overlooked maintenance items!

But did you change the wires too? Wires are one of the most common causes of misfires and one of the most overlooked maintenance items!

:iagree:

My SE has had the wires changed twice because of faulty wiring.

And a bad wire could idle fine, but once cylinder pressures raise, the spark may be going somewhere else besides the plug..

how do you use a noid light on a 6cyl without removing the plenum and does anyone sell just a plenum gasket without getting the whole upper gasket set thanks

mrelmo,
please look at the dates before posting.
We dont like to bring up threads older then 2-3 months.
AS out-lined in the Community Participation Guidelines, which is at the bottom of every page.

But to answer your questions,
follow the injector wires over to the harness connector and test from there.

I dont know for sure If they sell just the UI gasket,
but I'm sure they do at some part stores.

If you need any more assistance please post your own thread.

this is closed......