Hesitation at all speeds

[soloecho2]

Good day all.
Todays challange is my 2004 ECHO with 300,000 km developed a hesitation today.
This morning it was raining like hell on the drive in to work. No issues this morning on the drive in. On the way home leaving the parking lot I did not notice anything out of the ordanary. Untill I tried to make a left at a busy intersection. I had no power untill 4000 rpm then it came on like a switch.
While on the hiway if the car was loaded up in 3rd or 4th there was nothing there until about 3200 rpm again like a switch on and off. When I got home I checked the air filter, connections on the Mass air sensor, Cam control valve, Fuel injectors, Spark plug coil packs and all four spark plugs. All looked OK nothing out of the ordanary. Retested it again and the same issue slow acceleration until 4000 in first then like a swith power on.

If anyone has any suggestions please let me know ?? :iono:

And no check engine light so far.

[soloecho2]

I have never been happy to see a CEL. On the way home the CEL came on and the problem went away. No issues from work to home. I won't clear the code until I get to work to confirm it's gone. The codes set were P0031 and P0133. Both related to the O2 sensor but they say it should not be felt just post the CEL. I will reset the code at work and check again to see if the issue comes back on the way home. If it comes back on the way home should I blame the O2 sensor.

[Vinceb]

I just did some hunting around on the web for your codes. From what i've read, both codes indicate a problem with the 1st oxygen sensor (just off the headers) in front of the catalytic converter. you can try replacing it, but it's not a guarentee that it will fix the problem. sugestions are to check wiring and the resistance of the sensor along with the resistance of the wires.

The first O2 sensor gives a readout and the computer compares this to the seocond O2 sensor it then takes this information and bases your fuel to air mixture on this. if the first sensor is malfunctioning then the computer wouldn't be getting the right info and that could cause a hesitation in acceleration. if both sensors display the exact same info then the computer knows they're not working properly (or the catalytic converter isn't working properly) and usually decreases engine performance.

it could be a dead CAT or a dead sensor, I had a similar problem with an old protoge, replaced the sensor and it was actually the CAT that was dead, not the sensor. hope you can figure it out.

I've attached a graph of what the O2 sensors read out looks like, as well as the sensor and heated sensor (sorry for the porr quality) I don't know what vehicle the graph is off of, but it gives a general idea.

[menz]

I do not know if this will help, but my 00 echo had a problem like this one. On hard acceleration it chokes then hit off. On a long drive on a highway, I was pressing on the acceleration very hard but the mileage was superb which meant that the fuel was not delivered to the motor. A friend of mine told me he suspects the MAF so we took the one in my 07 yaris and the car ran great so we bought a new one for the echo and no problems since,