2001 Corolla misfiring w/low compression- is it the chain?

#1
Hello, first post here. I'm big into Hondas, but the Corolla is my mom's car. It has 270k miles on it with the original 1.8L (1zz-FE?) engine. Recently cylinders 1 and 2 have been getting misfire codes. New sparkplugs didn't solve it, so I did a compression test:
1 - 85 psi
2 - 60 psi
3 - 100 psi
4 - 105 psi

This led me to believe the cylinder 1 and 2 rings were on their way out or the valves and seals were bent, since the car burns a little oil too. I pulled the valve cover off, head and cams don't show the wear I was expecting in a 270k engine. Borescope'd the piston walls for signs of failed rings, they look amazingly in perfect condition. The piston tops look a little weird, but it's a high mileage engine and all I know are the symetrical honda pistons, so who am I to judge. I know I can't truly test valves with the head on the block, but shining a light into the spark plug hole and borescope through the intake I could see no light. Since it's VVT, I'd assuming the intake would be damaged valve-wise before the exhaust. That lead me to the timing chain. The cams are still in time and line up at #1 TDC, but with excessive slop.

Again, coming from the Honda D, B, and K series engines: The K20 has a recommended chain, tensioner, and guide life of 100-120k miles. D and B series engines use belts, but they recommend similar replacement schedules.

This timing chain (1ZZ-FE? Please correct me if I'm wrong on that engine code) has about 1/8-3/16" of play up and down at #1 TDC. In a K20, that would probably ruin the engine. So, is my bad compression likely due to a failed timing chain and tensioner/guides, or are there other issues present? Car has never had a timing chain service done to it as far as the family know. I've been snooping here on the forums, some users say that the chain is indestructible. The K20 chain is 3 ply (4 links wide) and it definitely is NOT good for the life of the car.

Videos and pictures from the borescope to follow when I can upload them at home.

Please advise.
 
#3
Did you check your wires to see if they were bad also? The Corolla in these model years 98 to 02 are notorious for having problems with the Rings. They are poorly designed and susceptible to sludge in the oil holes so that one or all of them can give out from lack of lubrication.
I highly recommend you check to see that your wires are okay I seriously doubt it is the timing chain but you can have the tensioner checked as the previous poster has stated. If the timing chain is fine I suggest you get the biggest bottle of Restore that you can find and start using 20w 50 motor oil. I had the same problem on my 98 Corolla with all of the Rings and this was what helped a great deal. I still drive the vehicle period after you use the restore along with the thicker oil redo a compression test I think you will be genuinely surprised at the results. Just make sure you don't overfill restore is another half a quart so only add three and a half quarts plus the bottle. If you can give an update I'd like to see how it turned out! I hope I helped you.
 
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