Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

O2 Sensor, Leaking Head, Sparks, or Bad Gas?

My '92 Toyota is idling happily as well as appearing to do find when rev’ed while sitting still. However sometimes it is having trouble as if there is water in the gas. It is not always true, but generally more common when accelerating or coming around a corner. Normally I would guess the O2 sensor, but it happened the afternoon of extreme condensation (we’re talking store window inside dripping). So I am wondering if I just have water in my gas and thus am getting it only when moving the gas around?

Any ideas? Of course the worse prognosis is a leaking head, which is possible, but appears unlikely as it is fine when sitting still.

Thanks for your ideas,


If you think there’s water in the gas, add a bottle of dri-gas or equivalent.

It’s unlikely, however, that water is the problem. How old is the fuel filter? An old, clogged filter can cause fuel feed problems.

You might also test the fuel pressure to see if the pump is failing.

“it happened the afternoon of extreme condensation”

That sounds like weak ignition parts.
How long since plugs, wires, distributor cap and rotor were changed?
The O2 sensor will never cause drivability problems.

I have no idea. Only got the car about 3 weeks ago. It is just a cheap to work and back car. I’ll pull the plugs and take a look at them when I get a chance.

Well I managed to get it to fault while idling, and figured out that the #4 cylinder was not firing (although it was getting good power to the spark.)

So I pulled the plug and it was in bad shape, so I am going to replace plugs, wires, and since there was one other plug that was rather oily (and most had some oil on the top, and some oil leaking around the valve cover) I am replacing the valve cover gasket as well since I am in there.

I will report back when I get that done. Hopefully it will be enough to keep it rolling down the road.

Thanks for the help!

P.S. Yes I should likely replace the distributor cap as well, but all the wires were getting strong sparks, so I am leaving that until after this if it is needed.