So I have just "broken in" my new re-build (22RE, block re-built by local machine shop with a new performance head from 22REperformance). over 400 miles on it now and I think I have screwed up. It's had low power the whole time, and was also runnign really rich (black soot and fuel smell in the exhaust).

Turns out my O2 sensor wire was shorted to the shielding wire, so I've been running rich for a while (chalked it up to the bad engine before, didn't fix it before the re-build)

Once I got the O2 sensor wire fixed and reset the ECU for Air:Fuel ratio, I discovered a rough idle/miss that wouldn't go away with any of the other troubleshooting steps in the FSM (distributor air gap, wires, idle adjustment, timing adjustment, valve clearance adjustment, checked for vaccuum leaks everywhere). I did find a couple of issues in that list, but fixing them didn't fix the rough/low idle. So I checked the compression and all 4 cylinders are low, between 120 and 130. FSM says they should be 170, and minimum should be 141. Pressure did go up with a squirt of oil in the cylinder, about 6-8 PSI (still lower than factory minimum) I can do a leak down test, but I think this is already pretty likely diagnosed as rings...


So my theory is that the overly rich ratio from the broken O2 sensor fuel washed my cylinders and I never got my rings to seat well. Does this make sense? If so, I think my only real option at this point is to pull the motor back out, pull the head and the oil pan, re-hone the cylinders (hope I haven't done any bore damage) and try again with new rings. I haven't done my own honing or rings before, I assume I'll need new rings but be able to re-use just about everything else, like connecting rod bushings. I will likely just take the long block (I'd like to leave the timing cover assembled) back to the machine shop and have him do everything, but if I could get away with doing it myself relatively easily, that'd be nice too. I'm hoping I could just pull the rods off the crank leaving the pistons attached, hone the cylinders using a ball/drill hone, put new rings in and re-assemble everything. Is that crazy?

Any thoughts? The other option I have is to just drive it with low compression and hope it doesn't start burning oil too quickly, but that seems like a bad option for an already weak engine.

 

I have re-ringed a couple 22r engines with the block remaining in frame.

I let a machinist overrule what I knew about cylinder honing and good ring break-in.

He said that a fine hone was sufficient. It wasn't, and my engine and I suffered for it.

Every precaution must be taken to keep any grit from cylinder honing from fouling the crankshaft and the lower portion of the block.

I pad and cover the crank throws with large cotton rags and place a plastic lid from a 1 pound coffee can at the bottom of the cylinder bore.

I like a real three, or 4 bar stone hone, rather than any ball hone. 220 grit stones are about right. They quickly make a good cross-hatch without honing too much.

I use a little kerosene while honing, and then wash each cylinder several times with hot water and dish soap on a rag rung out enough that it doesn't drip.

The rings that failed to seat with fine hone were NPR, and I have had good results with NPR products in the past. (With coarser hone)

I re-ringed with Hastings Moly rings and light 220 grit hone.

About 8 or 10 thousand miles on it now, and the oil stays honey colored after 3-4 thousand miles and oil consumption is nil. Running 10-30 Castrol GTX.

 

Do you reckon that the shops cross-hatching is still there? And if so, would you think it would need honing again?

If the fuel washed the walls so the rings never had a chance to seat, do you think they even (the walls) got run down at all?
But then if that's the case, would not have fuel possibly flowed back to the crankcase, and perhaps bearings are at risk?

Askin' for a fren.

 

New rings need a fresh hone with some 'tooth'.

When the pistons and rods come out a judgement can be made about the bearing shells.

Rod and main bearing shells are inexpensive and both can be changed with the block and crank in the frame.

 

Was the engine at operating temp when you did the compression test?

 

yeah, admittedly it was approaching the cool edge of operating temp, probably took me about 10-15 minutes to get the whole check done, but the plugs were too hot for me to grab by hand when I started it.