2007 base, 125k, MT, no cel

for about 6 months I have a misfire half the time at around 2000-2200rpm when the is engine cold, seems like mostly on hot days but does it on cold ones too, if I hold at that rpm it acts like a rev limiter. After several minutes it goes away.

spark plugs were changed about a year ago
cleaned intake temperature sensors
was told to look for any bubbles on coils, didn't see any. will take a multimeter to them this weekend.

Figured Id ask for ideas for other things I should check out? are there any common issues with this car that would do this? Thanks

 

I just dealt with the problem you describe. I have a 2003 350z with 106K miles.

The problem in my case was the coils.

 

If you have access to an automotive scope and an amp probe clamp, you can do a relative compression test to find out which cylinder you're getting the misfire on. From there, you can test the coil pack by swapping it out with another one and checking to see if the problem follows the bad coil with a swap. You can also check the injector pulse with a probe to see if the waveform on the misfiring cylinder is where it should be. That way you can determine if it's a fuel issue or a spark issue and go from there. If you suspect it's a mechanical issue, you can perform a compression and a leak-down test (assuming you have a compressor.)

If you want to do a proper diagnosis, you need access to the proper tools to perform the diagnosis with. Ideally, you can take the car to a dealership, where they can hook it up to a CONSULT computer so that bi-directional tests can be performed on the engine to narrow down where the misfire is coming from.

If you're going to use a multimeter, you're going to need one with a relatively fast refresh and a min/max feature to get anything useful out of it. I use a Fluke 88, and it usually does the trick.

Finally, a simple test of the coil packs and injectors can be done with a probe made specifically for those tests. Waekon makes some decent tools that have been a useful part of my kit for quick diagnosis on misfire issues:




Finally, if you are getting a misfire, any decent scan tool (particularly one with live function) will record them. For around $100, you can get a OBD-II link that will turn your laptop, tablet or smartphone into a fairly powerful diagnostic tool.

 

The misfire on my 2003 350z was at cylinder 3. Swapping out the coil pack was the fix. I also replaced the spark plugs. Car is running great now. --Spike