Cylinder 3 Misfire

[chimmike]

Leftover from the carb days when the heat kept fuel from the carb from puddling in the intake.

V8s used to route exhaust through the intake to heat it.

yeah, there wasn't an extensive amount of re-engineering done on the 4.0 to convert it to FI. Which is fine, it's a stout motor with excellent simplicity!

 

[Jerry Bransford]

Eh, it may have been on designs 40+ years ago. Most slightly modern straight 6's aren't. BMW, Nissan, Toyota at least.

This is a Wrangler forum.

 

[chimmike]

This is a Wrangler forum.

indeed it is.
I was just responding to your generalization about usual configuration for a straight six, that's all!

 

[Jerry Bransford]

indeed it is.
I was just responding to your generalization about usual configuration for a straight six, that's all!

My "generalization" was correct for all of the straight sixes in our Jeeps which is solely what this forum is about. We are not concerned about BMWs or any other non-Jeep brands here.

 

[Rdeitz]

Sometimes a cracked 0331 cylinder head can present with a #3 misfire. You aren't losing coolant, right?

Nope. No leaks, no loss of fluids. And I keep all fluids changed and clean. Probably change the oil every 500 miles just because that is a year.

 

[pagrey]

Probably change the oil every 500 miles just because that is a year.

A trusted engine re-builder I've used, H&H Flatheads, told me you don't need to worry about that, just go by mileage. Obviously do what you feel is okay but I took their word on a few vehicles that I don't drive much and the oil tests fine after years. Just warm it up fully every few months and it'll be fine.

 

[Rdeitz]

So after replacing coil, injector, valve springs, adding heat shield - the check engine light had not gone off. Tried resetting it with the Fixd sensor - which had worked in the past. So I disconnected the battery cable overnight. Hooked it back up - no check engine light! And drove it and the light has not come back on.