Hello forum!

I have a 96 Quest 3.0L. It recently started misfiring when driven for about 20 minuets or more on the highway. It threw a check engine light and the code was 02 sensor malfunction. I erased the code and drove it for a day or two longer. The misfiring got worse. The check engine light came back on and this time the codes were 02 sensor malfunction bank one sensor two and multiple cylinder misfires. This lead me to check the cap and rotor and ignition wires. Bingo! The cap and rotor was real bad, the rotor contact point was so loose from the plastic body it was actually wearing grooves into the contact points inside the cap. So I changed the cap and rotor and changed the ignition wires as well. The spark plugs were changed less than 10,000 miles ago.

Well, I test drove it after the fresh install and it ran great! The test drive was short though. Ooops! The check engine light came back on and the code was 02 sensor malfunction bank one sensor two again. Now it's my understanding that the O2 sensor behind the cat is just the final read for how the engine is running and most likely would not cause a misfire. So I cleard the code hoping that it was just residual rich mixture left over from the misfiring from the cap & rotor. Not the case. This morning on the way to work (1 hour 1 way) the Quest ran great for the first half of the trip, then I noticed small misfires then the check engine light came back on and the misfires kept getting worse. It got to the point that it was breaking up under any amount of load but would idle ok. I haven't checked the latest codes yet but I bet they are the same.

I'm curious about this fact as well. The Quest has 131789 miles on it and it has never a timing belt change as far as I know. I can hear an angry rattling sound coming from inside the timing case. Is it posiible for the timing belt tensioner if bad to cause this rattling and could a worn timing belt and tensioner be so worn as to not fail completely but to cause this warm running misfire? The misfire gets worse as more load is applied.

Help?

Thanks,

Questknight

 

i bet the timing belt jumped a notch and that would explain the misfire and the o2 sensor malfunction cause of the extra fuel in the exhaust is confusing the o2sensor b1 s2. i would get your timing belt changed and i bet that would fix the problem. let us know how it goes. good luck

 

Does the car eventually shut itself off and what are the codes?