'94 Mighty Max 8V SOHC 4G64 About at my wits end!!!

[kylekoch]

Hello all!

It has been a while since I could work on my truck. I am still battling 2 dead cylinders. Some back story leading up to today:

When I bought the truck, it ran on all 4. I drove it 2 miles to my workplace and parked it. I wanted to do a full tuneup on it before taking it home. Before I changed anything I first wanted to address the ticking noise coming from the valve train. At the time I was naive as to the inner workings of the truck and the 4G64 engine. So I disconnected all of the sensors, put the harnesses to one side or the other, removed the intake and proceeded to remove the valve cover. After removal I learned that the lifters were hydraulic and I could not adjust them. So I put everything back together. Spark plug wires were not removed from the plugs or the distributor cap. I simply pulled the cap and laid it off to the passenger side. So after I put everything back together, and double checking everything, I tried to start it. This is when it started with 2 dead cylinders and I have been fighting it ever since.

Over the past year I have done the following to it:
-Replaced timing and balancer belts. Checked timing (the hard way) and made sure I had it right.
-New distributor, cap, rotor, plugs and wires
-Injectors
-Tried ECU repair then bought a refurbished one
-New master relay (the one mounted to the kick panel under the ECU)
-New fuel pump and filter
-Pulled the head, took it to machine shop, had it cleaned, valve seats cut, valve stem seals, surface decked and new lifters installed
-Checked all fuses and grounds

So for this past weekend (9/21/19 - 9/22/19 I have been troubleshooting it more. First we, my father and I, checked and verified the timing again. Looks to be spot on. Next we noid light tested the injector harness to verify pulse at injector end. Then we checked all spark plugs and thats when we noticed something strange. The two cylinders that are firing (1 & 3) both looked to be running rich. The other two (4 & 2) still looked brand new like there has been no combustion at all. Since we verified that all 4 spark plugs are firing in order, verified all of the injectors are firing in order and metered out the injector harness, that leaves us with not a dadgum clue as to what is going on.

I am completely out of ideas. Whatever issue I caused, the first time I ever took it apart, is above my head to fix. If there is ANYONE on here that has ANY idea of what the issue could be the I beg of you to please impart your wisdom upon me!

Thanks for reading and hope you will respond,

Kyle

P.S. A motor swap is out of the question for now. I do not have the money to do what I want and I already have far too much invested in trying to fix what I already have.

[claych]

I remember this, good to hear ya'll survived mother natures wrath---

So, to help may I impose for the following ?
Humor Me, I understand You have done huge time & $ work on this! thx.

Post 'running compression test' readings ,cold readings are fine.

[Chargerx3]

This sounds electrical. I wouldnt rule out a bad ecu or PTU.

[claych]

^^^
Maybe, I remember his post from 04/19 & yes the board did show damage from C109,
However sooo many parts have been changed I just wanted to establish a solid mechanical
baseline.

[kylekoch]

Good to see ya claych! Somehow I knew someone would want me to run a compression test. It will have to wait till this weekend, after payday. I can promise you it wont be too stellar. When I had the head off the block, I checked all four cylinders. All were clean except for a carbon ring at the top; that was an easy clean. While there was no scoring I also could not see the crosshatching in the bores/ Taking the piston to the bottom and giving it the wiggle test showed all 4 to have signs of wear, though it was only a millimeter or two.

I'll pickup the compression tester this weekend. I am also going to replace all three temp sensors and the oil pressure sensor.

[geezer101]

A mm or 2 is excessive. You should only get a little lateral play (enough to be able to feel it). If you only had minimal play but the bores looked glazed, you could run a scourer ball through it, clean and polish up the pistons and install standard rings and that would be enough to get it running well without going through a machine shop and new pistons etc. It is a grubby sort of shortcut but when you are lacking resources it will do the job.

[claych]

Kyle, good to see Your back!!!
We will get it sorted out.