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Not to hijack the thread but I'm having a similar issue. Had misfire on #7, and P0430, with new COP installed, no more misses or P0430.
Now I'm having misses on #5 and P0174 (lean bank 2). Plugs change at 115k, COP were not.
Going to change out COP on #7 tonight and monitor up/down stream O2 volts on bank 2. My question, how can you diagnose a faulty O2 sensor. To my knowledge they haven't been changed and I'm at 161k. Also, how difficult is it to change out a CAT on these trucks? (newer owner here).
Not to hijack the thread but I'm having a similar issue. Had misfire on #7, and P0430, with new COP installed, no more misses or P0430.
Now I'm having misses on #5 and P0174 (lean bank 2). Plugs change at 115k, COP were not.
Going to change out COP on #7 tonight and monitor up/down stream O2 volts on bank 2. My question, how can you diagnose a faulty O2 sensor. To my knowledge they haven't been changed and I'm at 161k. Also, how difficult is it to change out a CAT on these trucks? (newer owner here).
Change the coils on either all (recommended) or on the cylinders that have a miss and reset codes. If you have a miss you're probably sending raw fuel downstream and that can heat things up downstream and throw off an O2 sensor.
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My question, how can you diagnose a faulty O2 sensor. To my knowledge they haven't been changed and I'm at 161k.
Pretty much, if an O2 Sensor or its Heater Circuit just simply isn't working - you WILL have a code & DTC. But, I know of NO WAY to truly determine if it is still in calibration. That is to say, it should do its little electrical magic of .45 volts at 14.7:1 air fuel ration. But HOW would one ever figure out if it was producing .45 volts at - say 11:1 air/fuel ration? I've read they do 'drift' and get 'tired' or slow to respond. For these reasons - I am an advocate of preventative replacement of O2's around 100k miles.
Originally Posted by rmortime
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Also, how difficult is it to change out a CAT on these trucks? (newer owner here).
After monitoring 02 sensor on bank 2 it is clear the downstream sensor is matching the upstream and not going to a steady state. Going to go find a CAT tonight and replace tomorrow. Want it done before a drive back to michigan on friday. I'll swap out the COP on #5 as well.
Going to spend a little more change and get the direct fit CAT which requires no welding. Unlike @nugget68 I don't have a welder on standby haha
After replacing the COP and CAT...do I need to worry about the injectors? Also, while monitor the STFTL and LTFTL on bank 2, i notice the min and max were both larger and the STFTL ran on average lower than on bank 1. I'll admit, i don't know much about the fuel trim levels and what they indicate. I do have saved logs from my last drive though.
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After replacing the COP and CAT...do I need to worry about the injectors? Also, while monitor the STFTL and LTFTL on bank 2, i notice the min and max were both larger and the STFTL ran on average lower than on bank 1.
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Tempered only by the pending trip to Michigan on friday --- my suggestion would be to not get too crazy with injectors or fuel trims, and take another look after relacing the COP & CAT. They BOTH can have a profound effect on fuel trims. Fuel trims are the primary control the PCM can exercise BASED on O2 sensor readings (which can be contaminated by COP misfires, and poorly functioning CATS).
Negative fuel trims could point a suspicious finger at injectors, but do a battery reset/relearn procedure after replacing that COP and CAT, and look again. More information about that can be found in this thread. https://www.f150forum.com/f4/p0172-s...9/#post4744357
BTW: May your journey be met with safety and reliability only.
Thank you Torque. Replacing CAT and COP today. Direct fit CATs are hard to find locally btw. Got 20% through advanced auto online and got a Walker. Hopefully, its not garbage.
How can I rule out a faulty MAF or vacuum leak? Mine as well make sure. I cleaned the MAF and throttle body this past weekend and they looked good and were relatively clean. I've cleaned way worse.
Oh also fysa, I researched STFTL and LTFTL. Bank 2 LTFTL is running ~.8V positive and STFTL is running ~1.5V positive wrt Bank 1. Which make sense with a lean P0174 code.
Thank you for good regards for my upcoming travel. The truck runs well with no misses under normal conditions but I do worry about hill/mnt climbs in PA and while passing...which is when the misfires become an issue. Hope your holiday travels and festivities treat you good as well.
I'm a little off balance on your fuel trim readings reported in "volts". I think you're using (or your scanner is using) KAM_BARn & LAM_BARn -- ????. Fuel trims (OBDII PIDs 06, 07, 08, and 09) - STFT1, LTFT1, STFT2 & LTFT2 respectively, are presented by the PCM in units of %, positive and negative from the base perfect fuel mixture being "1.00"
If that is the case, ~1.5 is over the 1.25 (or 25%) limit. If LFFT exceeds that for > 2 secconds it will set a lean code. ///BUT there again, you are referring to Bank1 very positive -- and P0174 is Bank2. ///??///
Nevertheless, one quick easy way to nail a vacuum leak (the primary cause of a lean code) is, WHILE engine is idling, monitor STFT1 and STFT2 readings, and blow 'unlit' propane from a propane torch all around, under the intake manifold, 4x4 vacuum lines, fuel injector bases, evap lines, oil filler cap, valve cover gaskets, PCV hoses -- EVERYWHERE -- and if there is a leak you will see the fuel trims go absolutely BERZERK when you hit it.
Replaced CAT, O2s and #7 COP last night. Took the CAT off and realized I didn't need a flange seal to manifold.
02 data looked great, truck ran well. Still getting misfires, below CEL threshold. Misfire count was 56 this morning over a 15 mile/40 min commute, no noticeable power loss. Any idea how to pin down which cylinder is misfiring. Or is best to just to change out all COPs. The COP on #7 looked pretty good when I pulled it and inspected it. No significant carbon build up on the spring.
12-20-2016, 03:03 PM
when you hit it.
