Calling Ford Techs! 4.2 ongoing issue

[Toaster556]

I've got a 99 F150 with a 4.2 V6, a tick over 200K km on it.
Background: The truck was parked for four months while I worked close to home, then drove the wife's Hyundai to BC for work. At some point, the intake gaskets let go and puked coolant into the left bank of cylinders. I tried to start the truck, and it hydrolocked on #3 and partially on #6. I replaced the upper and lower intake manifold gaskets and had both manifolds surfaced before I reinstalled them. I also replaced the plugs and wires at the same time, as the old ones looked haggard after 60K km.

The problem: After the intake gasket replacement, the truck started running hot and rough but didn't throw any codes. I sprayed ether all over the intake and had no change in the idle RPM. I ran a compression test, and got 165 on all cylinders except #1 and #3 (180 and 145 respectively). It will start and idle a bit rougher than it used to, but under load it runs really rough and seems to have no power. Anyone able to point me towards things I should check? Thanks all

[YTZ drew]

It sounds like you lost a head gasket instead of, or in addition to, the bad intake gasket. Does the truck smoke excessively when running, and do you get never ending bubbles out of the radiator when running? Also, look at the plugs, are there one or two that are spotlessly clean unlike the others? Burning coolant will wash a cylinder down, leaving the plugs and piston crowns perfectly clean like brand new.

[briano]

Make sure the plug wires are on correctly. The right side from front to back are 1,2,3 and go on the coil in that order. The drivers side is 4,5,6, and the coil is numbered 4,6,5

[Toaster556]

Plug wires are all correct Briano. I double, tripled and quadruple checked it. Although, I threw my timing light on it and noticed that the flash was intermittent, so I'm ordering a coil pack.

Drew, the #1 plug WAS clean, while the others were white showing a lean condition. No smoke or rad bubbles tho, and the second flush of oil came out looking like oil instead of milkshake aswell. I'll check the oil again after running it for a bit

[big specht]

Those motors are know for frt cover gaskets going out too. Hope fully you didn't run it to much with antifreeze in the oil cause it will take out the rod bearings.

[Toaster556]

I flushed the motor out with cheap oil before I started it. Ran it for five minutes then flushed again, it still looked like a milkshake so it got a proper oil change with decent oil. Looked good when I changed that, so I'm hoping to have avoided that. Also hopin the front cover gasket holds for a while longer.

Found my multimeter and checked the coil pack. Primary resistance was good, but secondary was really high (15-16K ohms). Strange thing is, before the intake gasket let go the truck always ran fantastic, didn't burn or leak any oil, and I didn't notice it drinking any coolant. Limited slip was good and tight too:naughty:

[YTZ drew]

Are you positive the firing order is correct? I just remembered an issue I had with a 4.2 in an Econoline van years ago in the field- no label on the coil + flat rate tune up (rip all wires off at once no diagram) and Mitchell was WRONG! It ran like crap till I looked up the mechanical firing order and figured out the companion cylinders from there. On your coil, 1 & 5 should pair up, 2 & 6 should pair, and 3 & 4 should pair. Looking at coil- 123 front to back pass side, 564 front to back drivers side.

[Toaster556]

Just a quick and probably final update on this. I pulled the upper intake again, and was in the process of stripping the lower to remove that as well when I noticed the #4 and #2 injectors weren't quite seated right. After removing the injectors and seperating them from the fuel rail, I noticed the o-rings were split and the tips were dirty and gummy.
I had the injectors cleaned and flowtested, replaced the o-rings and reassembled the intake with another brand new gasket (Cometic this time, not F-M or Motorcraft) and it seems to have done the trick. 3 weeks and 1200km later, no burning coolant smell, no coolant loss and good temps. Its not as strong running as it was before, but its got 200k km on it and a nice 4 valve 4.6 on a stand now waiting to replace it. Just need the rest of my swap parts