Gutless after rebuild

[Nalanthi]

So much as I hate to start a thread... I figure that it's time to reach out to the community to help me scrape the bottom of the barrel.

The backstory: Successful 2.9 to 4.0 swap happened about a month ago and ran just fine until an underlying issue with the HG/heads garaged me until I could assess the situation. Machine shop took forever (friend of a friend), but came back to me with one supposedly cracked head and the other with supposed valve problems (not sure I believe that second one). Not wanting to take any risks, I located a pair of heads verified 12k miles and tested fine - $50 a pop. Dude had them and never used them - obviously wanted them gone.

The heads arrived and were simply immaculate... no carbon anywhere and the valves were still for the most part shiny. I proceeded to rebuild the 4.0, new gaskets, head bolts, etc. all torqued to spec as outlined in the Chilton manual.
I fired 'er up - no smoke and no pressure in the coolant. I glove tested it JUST to be safe and everything seems to check out ok, but... For some reason it's dogging badly - almost feels like I'm behind the wheel of the 2.9 all over again.

What I know:
Not really sure if this is compression-related, as the block/rings/pistons were fine post-teardown and nothing leaks. I had to bastardize the vacuum system after a cluster I forgot fell across the exhaust manifold and fried off, but believe all major components necessary for a non-dogging engine are hooked up - a4ld, throttle body, etc. #3 is potentially suspect, as yanking fire doesn't affect idle. Fire and fuel verified in cylinder... so this probably isn't looking too good for me.
...hoping to high hell I don't have to yank a head (again) - not that it's a difficult job. The 4.0 is easy to work on.

 

[RonD]

I would check the firing order...........and then check it again, after 30+ years of wrenching I still get it wrong and swear it's right, I have come to the conclusion I am firing order dyslexic, lol.

Was the timing chain touched in this rebuild?
Compression test should show average 170 psi, lower would mean valve timing is off, engine still runs just sluggish.

Test coil pack with OHM meter, there is spark and then there is SPARK
Google: How to Check an Ignition Coil Pack the easy way
Video is worth a thousand words

 

[Nalanthi]

I would check the firing order...........and then check it again, after 30+ years of wrenching I still get it wrong and swear it's right, I have come to the conclusion I am firing order dyslexic, lol.

Was the timing chain touched in this rebuild?
Compression test should show average 170 psi, lower would mean valve timing is off, engine still runs just sluggish.

Test coil pack with OHM meter, there is spark and then there is SPARK
Google: How to Check an Ignition Coil Pack the easy way
Video is worth a thousand words

I'll def. check the coil pack - gives me something to go by, although it was cranking as it should have before the rebuild and stored in a safe place during the rebuild.
I have the firing order right, as it will FOREVER be burned into my brain after the first time around. Clockwise 1-2-3-4-6-5 (who thought that shit up?).

 

[jhammel85]

I may have missed it but check the timing too. Doesn't take much to upset the way the truck runs!

 

[Nalanthi]

I may have missed it but check the timing too. Doesn't take much to upset the way the truck runs!

Please correct me if I'm wrong, but... since I didn't touch anything below the heads and since it's distributorless, then should timing really be an issue?

 

[RonD]

Also don't forget this:
http://www.therangerstation.com/tech_library/CleanMAF.html

And it is important to disconnect negative battery terminal when working on newer engines, while this is for your safety it will also reset the computer so it will learn any changes you may have made during the work, 5 minutes is long enough so .......most work will cause the reset

 

[Nalanthi]

Also don't forget this:
http://www.therangerstation.com/tech_library/CleanMAF.html

And it is important to disconnect negative battery terminal when working on newer engines, while this is for your safety it will also reset the computer so it will learn any changes you may have made during the work, 5 minutes is long enough so .......most work will cause the reset

I might as well swab it out again.
The MAF is actually from the 2.9 - cleaned this past summer. After driving the 4.0 donor home, I found that the previous owner disconnected the dead MAF - the only thing tossing a CEL on that engine. Plugging it back in told me everything I needed to know about it.
Oh, and... the dumbass put a cone on the end which gave the intake enough weight to drop down into the alt's pulley - something I had to redneck up with duct tape 'til I get a chance to drive ALL the way across town to the JY again. lol.

 

[Nalanthi]

Well... I borrowed a compression tester from my friend/neighbor and didn't have to go further than the dry test. Compression in every cylinder was uniform exception of suspected#3 which showed a big fat zero.

Looks like I'm going to be removing the valve cover this weekend to see what's going on there. I can confirm that the rings aren't the issue since I replaced both heads as a matching set and that side of the engine (passenger) was perfectly fine prior to replacement. That having been said, the obvious culprit is not the rings and shouldn't be the new HG, as I'm not blowing or burning anything.

Here's to hoping that it's just a stuck valve, as the head was supposedly tested - or or OR... I may have accidentally installed a pushrod upside down, causing the valve to not close all the way?

 

[BabyBronco89]

Double check spark plugs, make sure you have the ohv style not sohc, also check to make sure there not cracked, happened to me once and it was shorting out on the head causing it to run like crap, just an ideeR


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[Nalanthi]

Got it.
I took the valve cover off and found that one of the rods somehow popped out of place. God knows how the hell that happened - I probably installed it like a dumbass in my eagerness to finish the rebuild.
Feels like a 4.0 again.

Thanks for the pointers/support.