well I got my 91 4runner back from belize and I've run into issues. I've had MASSIVE power loss and recently coming from the toyota dealer for a $400 timing belt they told me that I have 50PSI in cyl 1.
Now I am going to seafoam tomorrow but in case this doesnt work i want some possible issues to look for tomorrow while I'm under the hood.
Now i should note that it has had a rough idle for well over a year now but it had great power until my grandpa had an exhaust customized to fit from a 3rd gen 4runner 5VZ-FE to my 3VZ-E and now there is massive power loss and we did just find out about the cyl compession.

 

No ideas? would adding an exhaust too big or with too much restriction kill so much power?

 

I doubt it, how could a 3VZE get more restriction anyway? Did you run the motor without the exhaust manifold on at all? If so, you probably warped a valve. If not, you may have burnt one.

 

It sounds like you need to perform a cylinder leak down test to determine what the source of the low compression is.

 

Okay sounds good, thank you guys for the great ideas to check out. I'll let everyone know what happens.

 

Okay, so here is the scoop, after failing the inspection for stupid PITA things i asked a mechanic about the low compression and he said that it's an indication that the motor is on the way out. Now I'm here to ask the Toyota experts, whats the thought on low compression on Cyl 1?

 

Well I'm not an expert but I think the things that seal the pressure in a cylinder are the valves, rings, head gasket, and I guess injector seals. That's all I can think of now after a few beers. Dang I usually try not to drink and post.

EDIT: I thought of another one, the spark plug hole, but if you do a compression test you will use that hole so maybe the tester wasn't screwed in all the way. I hope that helps, good luck.

Oh thought of another one, a crack in the head...maybe, but that is a stretch.

EDIT: Now that I have a clearer head the injector seals shouldn't hold back any cylinder pressure unless an intake valve was bad. As mentioned in post #4 do a leak down test to try and find where its leaking pressure.