That's a good range.....I'm at a loss. I really don't know. It's getting air and spark, and you swapped injectors to determine it's getting fuel.

The only think I can conjure up, is that the injector port on the fuel rail is clogged?

 

After new lifters, the sound is more like clatter now, so im thinking the exhaust valve for #4 is burnt...


Because think of what i did....

I ran the engine hot, NO WATER, now if i melted 3 pistons, #4 is farthest away from the front, AAND the exhaust valve is the farthest away from the front of the truck, so in the event of overheating, wouldnt it be possible that the #4 exhaust valve is burnt due to lack of all possible cooling, #3 is firing, and #1 had readings of 140psi all 3x i ran the tests

^ Thats my guess now, as we determined shes got Fuel and spark, but 125psi compression readings with a burnt valve?

And i sprayed the intake/exhaust gasket to hell with carb cleaner, not a change in rpms

Im going to go pull the head from the 2.5 in the yard tomorrow.......

 

I'm confused what do you mean you ran it Hot?


I'm missing something what happened?

 

did you not pull the head when you changed lifters? If you overheated it, that'sth first thing I would have done, to change the head gasket.

 

also, if the valve was burned, it would show in the compression/leakdown test. Burning the valve doesn't affect how much air flow into/out of the combustion chamber, it affects how much stays in the combustion chamber. Burning a valve or valve seat just causes it not to seal. We've killed a couple of them on our motor. We burned and replaced an exhaust that caused a 12% leakdown last year, and we have a burned intake on #3 that we are not servicing over winter because it was only a 5% leakdown. The burns are caused from the fuel igniting with the valve open, malforming the valve edge and valve seat.

 

I initially rebuilt the motor with Stock pistons, that first rebuild went perfect, no problems

One day my power steering pump blew up, causing the serpentine to come off, which made it overheat an the radiator plug came out, then i drove it without water until it came to a hault because i couldnt stay in the middle of nowhere

So i pulled the engine AGAIN to bore it .060 over, because 3 pistons were melted into the cylinders, Now i had to rush and rebuild it because my father kept pushing me to get it done ASAP, i overlooked the bottom end so much, that i totally forgot to check the valves (Big DOHHHHH!!!) on the top end, new head gasket and all.....

Me and my father almost got into a fight over my rebuild because i got lucky the first time i rebuilt the engine, and this second time, the fuel sync was off... its been misifiring since i rebuilt it this second time, and ive been called a billion names and cussed out because i initially got lucky the first time and this second time had me asking for assistance because i didnt understand Fuel sync

dont have to pull the head to change lifters on the 2.5, just need a magnet and patience

Well, like my brother said, if it was ring related, id be seeing Some kinda sign of oil SOMEWHERE, which i am NOT AT ALL... theres not many possibilities left on the table...

Confirmed #4 is sparking
Confirmed #4 has fuel

Last but not least, Compression!!!!.... which my Regular compression test brought readings of 125psi, doesnt mean something isnt wrong in the cylinder, it just has the capability to produce compression readings

 

You can light a combustion with as little as 60psi and a spark. Really, the combustion pressure is a bonus, spark will ignite fuel on it's own. And no, you wouldn't necessarily see oil. We didn't and we had 34% blow-by in the rings. We never did a compression check, didn't see a need to because the EGT's were never off.

The fact that you originally said that the miss is intermittent makes things more difficult.

 

Well i know i aint that crazy/stupid, im noticing the problem is more during the day time, when the cool air comes through, the problem does get better....

Went out last night about midnight, it was Very cool out, i can Always tell by the shifter jumping around

Aaand this thought doesnt make sense, but if i changed the Throttle body on the 2.5 to a 4.0 throttle body, i wouldnt think the throttle body could do this...



I will pull the fuel rail and see if possibly something is obstructing the #4 injector, but i saw gas pour out of it when i pulled the injector...

 

When you changed to the 4.0 throttle body did you swap over the TPS, MAP, IAC and the IAC body?

You must do this or it will idle weird on you

You must move the 2.5 TB parts from it to the 4.0 TB and to do this you must cut off the 2.5 IAC body manifold key if you look at both you can see what I'm talking about

One thing I noticed in one of your Pic's is you inserted the air temp sensor in the wrong hole now I don't think it should make a difference but at this time the little things may be killing you and that is the #4 intake port it normally is in the # 3 port.