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

 

get the o2 sensor checked, i dont know how but there must be a way. that will get rid of the code your throwing. if that dosent clear it up then its something else. codes are generally a good indicator of what is wrong.

 

change the 02 sensor and go from there

When a car tells you what is wrong, always good to start fixing it from that point.

 

Low c/r reading in the one cylinder is probably due to a bent or tweaked valve, especially if it's not burning oil. Best bet's to do a leakdown and see what you get on that cylinder. More than likely a valve or 2 got tweaked during a missed shift/over rev.