2006 LR3 HSE Rear Locker
Had bad misfiring cylinder 1. Ran several cans of injector cleaner, a much better. Swapped coil pack cyl1 with cyl3... few miss in #1, more in #3. Put in new plugs, a bit better. Cleaned MF, no change. Cleaned throttle body, run perfect for a week. Now upon starting cold, many misfire cyl3. Let it get to temp and gave it full throttle, cyl3 miss 99+, all other cyl started missing a bit, approx. 5k RPM truck slowed and dash said ENGINE FAULT. Repeated. Turned off truck and set scanner to read but could not repeat. GAP tool says either 0 miss fires or maybe 1 cyl 3 currently

Reading some other post.. I too have a mystery coolant leak.
Advise...
Coil pac(s)?
vacuum leak?
low compression?
pcv valve?

 

There's always throwing new coils at it.

How's the injectors looking? A dirty/clogged one vould cause it too.

Can also run a compression test to rule out a blown gasket/bigger issue

 

Whats the best way to check injectors? Also forgot to point out I'm getting a lean bank 1 and lean back 2 about once a week.... how is this corrected and how may it relate to a misfire?

Reading many post, mystery antifreeze leak van case misfire... not sure how but will run some live data on Gap tool

 

Most foolproof way is on a flow tester, but assuming you don't that available you can swap two injectors to see if the misfire follows like you do for coil packs.

Also check the live values using the gap tool to see if any are electrically out of whack

It's actually pretty easy to pull injectors on these. There's 4 torx bolts (2 per side) that hold the rail down. Remove those and you can simply pull the rail and injectors out as 1 piece. Then pop off the little metal clip and the plug to remove an individual injector. Putting it back together is just the reverse. Gently put weight on the rail to help the gaskets seat then tighten the torx bolts down to fully seat them.

All in all you can have it off and back on in 30 minutes.

 

The positive for you is that It is an intermittent misfire. Constant misfires can be anything, including bad compression. Intermittent is most likely an issue with fuel or ignition.

I’ve had an intermittent misfire that was only present on cold start. Turns out it was a fuel injector. I hypothesize that it was dirty or worn, and would lose pressure. Not an issue at idle or driving, but if left for a few hours that injector would be starved of fuel and misfire would occur during startup. You could have a similar issue.

Another possibility is your ignition coil failing or the wiring for the ignition coil having a short or chafe that stops the electrical pulse from making it to the spark plug.

If you want to narrow it further, switch the #3 injector to cylinder #1, and #3 coil to something other than #1. Whichever cylinder misfires, replace that part. If #3 still misfires, look at the coil wiring.

 

As I sort this issue, what is a good brand for injectors and coil packs?
Was looking at
Looking at NKG coils and Denso Fuel Injectors... I see a lot of rebuilt injectors... is that worth saving a few bucks?

 

I'm running a set of rebuilt Denso injectors off ebay with no issues.

Make sure they are '4280'. I ran into an issue as some of the ones listed as for our trucks don't flow right. Those are '4260'

The Denso part number you want is 195500-4280. You can search ebay for that to find them. 2W93-AA and 4280 and the other key identifiers to look for