HELP - Urgent! O2 sensors/running rich/ cat problem

[Dantheman123]

PLEASE HELP!!!

I am at my wits end...I have a 99 Sportage car...6 months after buying in Aug 2003 the engine emissions light came on..garage did diagnostics and replaced O2 sensor, MAF sensor and coils..... 3 months later light on again, car shuddering, misfiring, nearly stalling at lights/parking etc...back to garage and hooked up to diagnostics for 2 days!! One code after another kept being thrown up and counteracting eachother...said to replace O2...when that done said replace MAF..then O2 again...then nothing...mechanic eventually replaced the O2 sensor for good and air filter and the car light went off and car ran properly...for 4 weeks!!! 2 weeks ago he replaced the O2 sensor again as comp diagnostics told him too and it was thick with black carbon deposits after 4 weeks but bad smell of eggs straight after I got it back....back into garage again after 2 weeks and mechanic took out Cat converter for good (no emission tests here in malaysia so dont need it).... 1 week later again and warning light on again and car is shuddering, nearly stalling, etc etc. Mechanic reckons car is 'running rich' which is destroying my O2 sensors but he is clueless about what to do next?? he is having the car in again on monday 12th Feb 2006... PLEASE PLEASE PLEASE does anyone on this forum know a) what the problem could be and b) how to fix it...I have spent hundreds on $ on this car in 2 years and it is still BAD... HELP!

Thanks

[LMP]

With an open coolant (engine) temperature sensor, the engine would run rich all the time. You did not mention this sensor in your tests. A flat out failure should throw a P1115 code but some intermediate failure condition can avoid the code.
http://www.geocities.com/lmp4203/kia...empsenders.jpg
www.geocities.com/lmp4203/kiasport/sensors.jpg
THe sensor is a thermistor and at very low temp it has a very high resistance. AN open circuit (corrosion at connector, broken wire) mimicks very cold temp...which translates in apparent higher air density, which asks for more fuel...and since real temperature is high, this causes too rich a mixture.
One easy test is to SHORT the wires that terminate to the sensor: there is no risk but it might be more appropriate to terminate with a 47 ohms resistor that would send an near 100°C equivalent. (shorting could throw a P1115 code). THis mimicks a high temperature and starting the engine could be difficult (too lean for starting)...in which case connect the resistor or short the wires only after it is started. THIs test would lean the mixture and clear out the rich burn smell, ( if it was the primary cause.THis issue at least must be cleared for sure before looking for something else.)

Once engine is warmed up, measure the actual sensor resistance with an ohmmeter: should be around 50 ohms. If resistance is very high, the sensor itself it open. At normal air temperature (engine cold) in Malaysia...I guess temps are around 20-30°C, sensor resistance should read around 2000-3000 ohms. Also check resistance to ground on the green/yellow sensor wire: that should be a solid ground - near 0 ohms.
Notice that there are 2 sensors: one for the gauge, and one for the computer. So gauge can read OK even if the computer temp sensor is awry.

[MeettheCreeper]

Originally Posted by Dantheman123

PLEASE HELP!!!

I am at my wits end...I have a 99 Sportage car...6 months after buying in Aug 2003 the engine emissions light came on..garage did diagnostics and replaced O2 sensor, MAF sensor and coils..... 3 months later light on again, car shuddering, misfiring, nearly stalling at lights/parking etc...back to garage and hooked up to diagnostics for 2 days!! One code after another kept being thrown up and counteracting eachother...said to replace O2...when that done said replace MAF..then O2 again...then nothing...mechanic eventually replaced the O2 sensor for good and air filter and the car light went off and car ran properly...for 4 weeks!!! 2 weeks ago he replaced the O2 sensor again as comp diagnostics told him too and it was thick with black carbon deposits after 4 weeks but bad smell of eggs straight after I got it back....back into garage again after 2 weeks and mechanic took out Cat converter for good (no emission tests here in malaysia so dont need it).... 1 week later again and warning light on again and car is shuddering, nearly stalling, etc etc. Mechanic reckons car is 'running rich' which is destroying my O2 sensors but he is clueless about what to do next?? he is having the car in again on monday 12th Feb 2006... PLEASE PLEASE PLEASE does anyone on this forum know a) what the problem could be and b) how to fix it...I have spent hundreds on $ on this car in 2 years and it is still BAD... HELP!

Thanks

Have never seen a MAF sensor go bad.

I have seen P0101 for MAF circuit problems. The wiring in the fuel injection harness is faulty. Usually the wiring to the TPS at the TPS is at fault or one of the two main junctions for this harness.

Start the car, let it idle and perform a "wiggle test" on that harness. If the vehicle starts to stumble and act up there is your problem.

I would replace the fule injection harness instead of trying to repair it. Generally it is damaged in several places.

I have also noted pins backing out of connectors on O2 sensors on the harness. ALso something to look at.