m_dogg Posted August 8, 2016 Share Posted August 8, 2016 Hi guys Are both upstream o2 sensors the same? If I remember correctly one had a gray plug, other black gray/orange wiring. I believe both were Denso sensors. I've cut out rusted heat shields on wife's '09 2.5i so I had to take out both sensors. Since then, car has a weird acceleration delay from a dead stop, about .5 second. I can also feel slight hesitation under light throttle conditions, wot is all good. I didn't drop either sensor but I'm starting to think it might be o2 related. Car just turned 100k miles. Thanks! Link to comment Share on other sites More sharing options...
GEE-OTTO Posted August 8, 2016 Share Posted August 8, 2016 Hi guys Are both upstream o2 sensors the same? If I remember correctly one had a gray plug, other black gray/orange wiring. I believe both were Denso sensors. I've cut out rusted heat shields on wife's '09 2.5i so I had to take out both sensors. Since then, car has a weird acceleration delay from a dead stop, about .5 second. I can also feel slight hesitation under light throttle conditions, wot is all good. I didn't drop either sensor but I'm starting to think it might be o2 related. Car just turned 100k miles. Thanks! The orange or upstream of the Catalytic converter is the Air Fuel Ratio sensor the downstream one is your basic O2 sensor. Both the auto and manual 2.5i have that useless zone upon initial acceleration is this something new after you cut the heat shields off? The sensors are fairly basic they are calibrated to read a narrow band of voltages that relate to acceptable or not by the ECU as a result of sniffing the exhaust gases. Did you reset the ECU recently? Has she noticed any change in MPG? When was the last time you changed the plugs, air filter and wires? Link to comment Share on other sites More sharing options...
m_dogg Posted August 8, 2016 Author Share Posted August 8, 2016 So that little "can" in the exhaust manifold is the catalytic converter? That would make sense as far as sensor configuration. And yes, the acceleration delay from dead stop started day after I took the heat shields off. Although I did feel power loss before the job so could be just a coincidence. I did not disconnect the battery or reset ECU. As far as plugs, they are 10k miles overdue might as well get new wires. Air filter is recently cleaned, will clean MAF when she comes back. I forgot to mention that it threw check engine light AND traction control light, plus cruise control light is blinking but it did that before few times (comes and goes)...another coincidence? I'll see what codes are stored in the ECU. Thanks for chiming in! Link to comment Share on other sites More sharing options...
m_dogg Posted August 9, 2016 Author Share Posted August 9, 2016 Ok, so I pulled the code - P0172, system too rich bank 1. When I cleared it, the car got upset and after couple cranks it finally "started". Very rough idle, stumbling, barely pulled into the garage. List of things I need to check I can think of - -Check the exhaust manifold for leaks since I did take it off -Clean MAF -Spark plugs and wires (since overdue anyways) -Replace oxygen sensor if above doesn't help Anything else I would have to look into? Link to comment Share on other sites More sharing options...
m_dogg Posted August 9, 2016 Author Share Posted August 9, 2016 Hehe, tough crowd in here Header bolts were loose, I'm guessing enough to cause my problem - 28ft/lbs are torque specs for the manifolds, correct? It's got that weird surge after battery disconnect, few more cycles will tell if that truly was the problem. Car drives smooth though, no more accel delay from the stop. Happy wife happy life Link to comment Share on other sites More sharing options...
GEE-OTTO Posted August 10, 2016 Share Posted August 10, 2016 Hehe, tough crowd in here Header bolts were loose, I'm guessing enough to cause my problem - 28ft/lbs are torque specs for the manifolds, correct? It's got that weird surge after battery disconnect, few more cycles will tell if that truly was the problem. Car drives smooth though, no more accel delay from the stop. Happy wife happy life I missed your earlier post but those item I too would have tackled to resolve the issue. Running rich could be a faulty AFR sensor or a dirty MAF or both if you clean the MAF and throw 0172 replace the AFR the sensor upstream of the cat. I replaced both mine at 100K with DENSO OEM sensors. I only use DENSO skip the Bosch Link to comment Share on other sites More sharing options...
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