GEN 2 Cylinder 6 misfire

[Old-Raptor-guy]

We have one ordered. We are going to try that tomorrow.

Which injector? The truck has dual fuel injection, port AND direct injection. Port is used idle to 3000 RPM, direct is 4000 RPM up (transition between the two obviously between 3000-4000 RPM)

Despite popular belief that it was done to help with intake deposits, that is just a secondary benefit. The reason is/was that direct injection is not super efficient at lower RPM and creates lots of soot (just look at the tail pipe of a direct injection engine without port injection, like my wife's SHO) the EPA required less soot. It was that or a gas engine particulate filter (like a diesel, and yes they do exist) Trust me we should be thankful Ford did NOT go down that path!!!

 

[Old-Raptor-guy]

So an initial manufacturing issue?

Man after 95,000 miles it's hard to say manufacturing issue, not impossible of course. Normally actual manufacturer issues show up sooner. Now design/engineering issues can definitely show up later.

 

[someday]

Leak down test

 

[thatJeepguy]

Shouldn't be a problem with the port fuel injection, but worth a look. Maintenance and fuel will vary.

Agreed but consider this:

Ive been studying how often port injection is on and under what conditions via access port. You can drive a certain way for extended periods that would induce enough carbon to foul valve seats. Its a theory but there was a youtube i saw where the valves on a gen 2 eb looked pretty bad at high milage even with PFI.

 

[Zeusmotorworks]

Man after 95,000 miles it's hard to say manufacturing issue, not impossible of course. Normally actual manufacturer issues show up sooner. Now design/engineering issues can definitely show up later.

Meaning alloy/heat treat… think there is possibly thermal warping of the valves themselves over time? Seats?

 

[Zeusmotorworks]

Agreed but consider this:

Ive been studying how often port injection is on and under what conditions via access port. You can drive a certain way for extended periods that would induce enough carbon to foul valve seats. Its a theory but there was a youtube i saw where the valves on a gen 2 eb looked pretty bad at high milage even with PFI.

Interesting

 

[someday]

5.0l valves had a problem with valve hardening and would eventually "tulip" causing leaks

kinda sounds like this might be the problem and a leak down would confirm a valve leak

still think it might be electrical than mechanical. if mechanical then its prolly a "new" engine

 

[mtbdad67]

Well, thankfully it wasn’t tuliped valves. #6 direct injector was stuck open. We replaced all three on that bank. It is running much better now. Thanks for responding!!