rough idling
 

Chevrolet cavalier 2000 2.2lt.

got a OBD2 and torque lite.

got a P0420 code.

set 02 1x1 and voltage variate good, the 02 1x2 voltage variate a little on idle but good amount when on the road. Are the 02 sensors OK ?

also how to see if injectors are Ok or need a good cleanup? I set F/T 1x1 signal greend and variate a little (idle), the 1x2, 1x3, 1x4 no signal and no green light. set STFT1 and get a signal but not variate much (on idle).

thank you

Mickal

Off the cuff I think you have a bad rear O2 sensor for the P0420, but it still could be the CAT. Since 2005 was the last year it was built, and yours is a 2000 Cavalier, I'd do a cylinder leak-down pressure test. If the valves or rings are gone, well you probably know what that means. How much oil is it using? How many miles on the odo?

it have 115 K miles and it don't take oil or much.

it is a few days i take out the P0420 code and it is not back yet, and the rough idling is a little bit less.

it is 16 years i have that car and clean the injectors only 1 long time ago (garage), how many miles before a good injectors cleanup?

thank's again,

mickal

Well the injectors can get so dirty, if you have purchased the low-price fuels that dont contain a deposit control addtive or a "DCA", to the piont that a gasoline additive that you pour down the fuel tank, such as Seafoam or Techron, cannot clean them up back to specification, and it also can involve the intake valves as well, but not as often.

One of the issues with Direct Gasoline Injection systems is that the fuel injectors are located IN the cylinders, bypassing the intake valves, but the DCA's will still keep the injectors clean. Your motor does not have that system/problem, but your intake valves can still become carbonized with the cheaper gasolines, and oil that runs down past the intake valve seals over a long period of time.

At 19 years of age, your Cavalier has done well, but it sounds like you may need some work on it, or at least some testing done to see if your combustion cylinders are operating at normal pressures and are within 15 percent or less, then one to another cylinder pressure reading.

I honestly dont know if it will help, but I suppose you could try a large can of Seafoam or Techron down the gas tank at about one-quarter full, so you have lots of cleaning,
and then get it hot and rev it out good. That has worked for some few people, but I have never tried it, only heard of it working, but the odds dont sound that all good to me.