Hey guys,

I've suspected my 06 (V6, 230k miles) of having a bad head gasket for ~6 months now. It would randomly misfire on startup and sometimes show a P0302 (Cylinder 2 Misfire). I made that assumption, and started ordering parts to replace the gaskets.

I finally started to work on the truck today and decided that I needed to confirm the head gasket before I tore into it. I performed a leak down test on all 6 cylinders. No cylinder had more than 7% leakage and the Cylinder 2 plug was soaked in fuel, the other 5 were dry. It looks like I'm returning some parts and buying an injector!

I've found a few threads that have had the same issue. I feel like an idiot jumping right to the head gasket failure.

-Rob

I know that's a relief. Hope I never have to deal with headgaskets either.

Leaking Injector seal? I've seen couple of thread where the leaking injector seal caused the same symptoms as the leaking headgasket.

Seems to be a leaking injector. I have a new set of six on order, should be back up and running next weekend!

-Rob

Had the same issue with mine! Apparently the injectors on 1GR-FEs (especially injector 4 and 6) like to stick open as they get older/go through lots of heat cycles. Fuel then dumps into the cylinder when the vehicle is turned off for a few hours and causes a misfire on startup.

Make sure you get a quality set of injectors. The first set I got were eBay specials and didn't work out of the box. The next set were OEM remans from Rockauto and are perfect.

I'd also recommend changing your oil, as it's likely pretty contaminated/thinned by gas.

Did you get the BeckArnley or GB Remanufacturing injectors from RockAuto? They both say Denso, but the BeckArnley injector is almost twice as much and looks like crap in the picture lol.

I went with GB. They came super well packaged and work perfectly.

I ended up ordering some cheap eBay ones. We'll see how they do, the seller has been around forever and seems to have legit feedback.

6x OEM Denso Fuel Injectors 03-15 Toyota Tacoma 4Runner Tundra FJ Cruiser 4.0L | eBay

-Rob

Those are about twice as much as I paid for my eBay ones, so hopefully you have better luck than I did!

did you notice a drop in your coolant level?
i think 100 percent of all hg issues, exhibit a drop in coolant levels.

i went with ebay remanns, and they are doing great, 7 months down the line

When I first checked the coolant level after owning the truck for a year or so, it was a little low. It doesn't seem to have dropped at all since then.

I'm still waiting for my injectors to show up, they seem to be in USPS limbo.

-Rob

the odds of having a head gasket leak, without drop in coolant level is ultra slim. its a surefire way to rule out HG issues, if/when you have a misfire.

park on the same spot and observe your coolant level frequently