Dear 4th gen v6 wizards....

2004 SR5 4X4 v6 160k miles
Bone stock.

P0306 stutter at cold start.

Ive read all the dreaded HG posts.

Pulled plugs and borescoped. Noticed some buildup on #6 where the misfire was. No pooled coolant or anything but there was some crud in there. Other cylinders looked normal.

Attaching photo of #6 cylinder. Does this build up look like HG or just crappy plugs/coils buildup?

*clean spot in center is where I bonked the borescope seeing if it was tough or sludge.

 

Welcome aboard

Start out by swapping the coils and plugs from cylinder 6 with another cylinder and see if the misfires follow to the other hole. This will help you narrow down if its plugs/coils or something else

 

By the looks of that photo, do you think that could just be a coil issue?

 

The plug always burns out on #6
If you dont replace the plugs pretty often, the plug burning out eventually eats the coil up.
Normally neglected vehicles come in with a misfire on #6
Pull the plug and the electrode is practically gone and you have 0.110" gap and the coil is trash
Replace all 6 plugs, put a new coil on #6 and it usually goes back to normal.

If its still got the original plugs it should have a different set in the drivers side vs the passengers side.

 

When ive seen head gaskets leaking badly the top of the piston is typically clean from the coolant getting in there. Id try swapping the cylinder 6 coil and plug into another one and see what happens. It very well might be one of those two. Ive seen both fail and cause misfires