O2 Sensor problem
I'm hoping someone can really help me with this problem, because I'm running out of time (and money!) trying to solve it.
I recently bought a used 2002 Kia Rio Cinco with 137,000 miles on it. I was having a problem with the car. The only way I can describe it is the sensation of driving through water. The car can drive just fine with no problems when suddenly the power just goes out of it. RPMs of 3000 drop to 2000 and hitting the accelerator won't do anything unless you floor it. When it's acting up and you're at a stoplight the RPMs are around 500 and it acts like it wants to stall.
With the check engine light on I made a trip to Autozone showed a P0130 02 Sensor Circuit Malfunction error Sensor 1 Bank 1. So I took it to a mechanic to have the sensor replaced with a OEM Bosch sensor. The mechanic spent an hour trying to get the sensor off and when he finally did it broke the threads, prompting the need to replace the manifold, which worked out for the best because there was a crack in the manifold.
(Now this may be important, I do not know -- the mechanic said when the sensor did finally come off some coolant liquid came out with it.)
Anyway, he replaced the sensor and the manifold and drove it around, only to have the check engine light come on again. P0130.
So I took it to another mechanic, because the dealership is asking WAY too much money, and he did a check on it. The scanner showed that while the downstream O2 sensor was fluctuating normally, the upstream sensor - which is what I'm having the problem with - was staying at around 420-425, with no fluctuation. He look around and found that the spark plugs were the original factory installed, as was the fuel filter. So we replaced all those and the car ran just fine... for about twenty miles and the problem happened again, this time without the check engine light coming on. But it did eventually kick back on.
I really do like the car; other than this problem it's not a bad car at all. It's just that I'm planning on taking my family on a trip at the end of the month, and this car right now is in no shape to take such a long trip the way it's acting.
Does anyone have any ideas as to what I need to get fixed on this? THANKS!