Car: 1991 SI
Motor: stock d16a6
ECU: stock
No mods

I'm getting oxygen sensor code 1. It comes on about 5 minutes into driving. The oxygen sensor looks new and the wiring is connected up properly.

I'm getting driveability issues of bogging. Once warmed up if I cruise at part throttle for a minute or two and then try to accelerate I get serious bogging. The bogging will clear up if I downshift and floor it. It accelerates decently and idles perfectly normal at 600-700 in open loop.


I did a compression check and got 163, 106, 162, 170 (1,2,3,4 respectively). Surprised with the low reading on cylinder 2 I added some oil to it. It came up to 130psi. Just for comparison I added oil to cylinder number 1 and it shot up to 189.


The headgasket is brand new. Spark plugs are black around the base, clean on the pos electrode, and whitish on the negative arm. I would say they look slightly lean compared to most plugs I have seen.

I'm not burning any noticeable amount of oil and I'm not loosing any coolant.


What can cause the low reading on cylinder 2? I'm guessing something with the valves is the most likely cause but I would like some opinions.

Can one of the cylinders running low compression like that cause the oxygen sensor code? What about the bogging issues?

Any input is appreciated

 

also thought I should mention that I don't have access to a leakdown tester at the moment, but I'm trying to source one.

Still please post any ideas.

Can a really bad valve adjustment affect compression? Like so tight that it is pushing on the valve slightly?

 

anyone?