Is this something I can fix with basic tools in my driveway? Fairly savvy but never gone this deep.

Engine has 275k and is very dirty. (Friends truck) shows codes p0300, p0302, p0304.

Compression in 1,3,5,6 at 150, 4 is 110 dry, 125 wet.

Should this truck be driven much?

Thank you

 

What do the codes mean? You probably shouldn't drive the truck at this point. Does the oil look ok? Does it looses coolant? Is there any oil leaking from the head near the bad cylinder? Just basic questions that will help us help you. Hope this helps

 

Codes are for random misfires and misfire on cyl's 2 & 4. Oil is a bit dirty but clear, no oil or coolant leaks, no oil in coolant or vise versa. I cranked it with the radiator cap off and no coolant came out.

However there is now oil on electrodes of plugs and it won't stay running for more than a few seconds. Fires up fine but chugs out and dies. (Was running before compression test)

 

You broke the seal the spark plug boots had on the spark plugs so they flood now. More than likely the rings are toast. I picked up a 97 4runner that had 1 cylinder at 170 2 at 120 1 at 80 and 2 at 40. It took a quart of oil between the 3 low cylinders to get it to even fire up and run for a couple minutes.

I'd pull the timing cover and verify the cams line up and haven't jumped a tooth or two

 

Oy, thanks. How does the plug boot seal get broken? Only the bottom of the plugs are oily and not an incredible amount. I'll pull the timing cover in a bit and check the cams. It was 'drivable' until I ran the compression test.

 

(Should this be a new thread?)

Examined plugs again, on the engine side it seems to be fuel not oil. Boots are clean.
Timing is good.

Before the compression test I cleaned the IAC, TB, MAF sensor, PCV valve, tested the TBS, swapped coils, ran fuel injection cleaner and replaced a few vacuum lines. Plugs, wires and air filters are fairly new. It was running after these things.

Disclosure; I did unhook the positive battery terminal while doing the compression test. Also pulled the EFI fuse. Could I have triggered a kill mode in the ECU (or ECM)?

Have been over everything I can think of multiple times. It is definitely getting air, fuel and spark at start up. Dieseling after ignition. Seems like the engine is shutting itself off, then it chugs a bit before dying. No smoke when it starts. Not throwing codes.

At this point I'd just like to be able to drive it to the shop!

Thank you in advance

 

You may have swapped the firing order... YES its only 3 wires, but i've seen it done before.

 

Thank you for that suggestion. I have two manuals and have re-checked the firing order several times. 1-4, 3-6, 5-2.

Could I have caused a problem by disconnecting the positive battery terminal?