PO171 and PO174
07-11-2019, 12:52 PM
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PO171 and PO174
Hello everyone.
New to the forums and just bought a used truck (2000 F-150 4.6 193K) and it has these codes. It seems to be idling rough and possibly a little knocking sound from the driver side valve cover area. I have been using a OBD scanner to look at live data and have attached the recording at idle. I don't think it's a vacuum leak because the LTFT is around 3%. I have replaced the fuel filter, cleaned the MAF (with MAF cleaner
) and replaced the PCV valve. I don't want to blindly just replace some part, I really want to understand how to troubleshoot and fix what is needed. I was going to look at replacing the EGR DPFE sensor. Should I be checking overall fuel pressure (for possible bad fuel pump)? Should I be resetting the codes and let them come back?
Looking at the live data, I'm wondering why I am not seeing value for STFT B1S2 (near O2 sensor readouts). I am seeing 99.2% for STFT B2S2. What should be the voltage readings for downstream O2 sensors? Could the issue be the O2 for B1S2?
I look forward to meeting you all and appreciate the feedback.
New to the forums and just bought a used truck (2000 F-150 4.6 193K) and it has these codes. It seems to be idling rough and possibly a little knocking sound from the driver side valve cover area. I have been using a OBD scanner to look at live data and have attached the recording at idle. I don't think it's a vacuum leak because the LTFT is around 3%. I have replaced the fuel filter, cleaned the MAF (with MAF cleaner
) and replaced the PCV valve. I don't want to blindly just replace some part, I really want to understand how to troubleshoot and fix what is needed. I was going to look at replacing the EGR DPFE sensor. Should I be checking overall fuel pressure (for possible bad fuel pump)? Should I be resetting the codes and let them come back?Looking at the live data, I'm wondering why I am not seeing value for STFT B1S2 (near O2 sensor readouts). I am seeing 99.2% for STFT B2S2. What should be the voltage readings for downstream O2 sensors? Could the issue be the O2 for B1S2?
I look forward to meeting you all and appreciate the feedback.
07-11-2019, 04:05 PM
#2
1. What are you using for a scan tool?
2. Pull and post your freeze frame data. You have to know the operating conditions when teh codes were set.
3. Ignore the downstream 02 sensor stuff, it's probably an issue with the scan tool or software. In any event, they cannot cause your fault codes.
4. There's nothing that indicates any problem with the DPFE sensor. Leave it alone.
2. Pull and post your freeze frame data. You have to know the operating conditions when teh codes were set.
3. Ignore the downstream 02 sensor stuff, it's probably an issue with the scan tool or software. In any event, they cannot cause your fault codes.
4. There's nothing that indicates any problem with the DPFE sensor. Leave it alone.
07-11-2019, 06:02 PM
#4
Senior Member
Your trim numbers look good but the data in the file you supplied is all at 194 degrees, a fully warmed up engine. Codes can get set when cold, and gaskets tend to leak more when cold.
Get the same numbers on a cold engine. And, as ProjectSH says, the freeze frame data will show what was happening when the code was set.
Get the same numbers on a cold engine. And, as ProjectSH says, the freeze frame data will show what was happening when the code was set.
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F150Torqued (07-11-2019)
07-13-2019, 10:06 AM
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Here is the freeze data that was on the scan tool. I went ahead and cleared all codes to try and get it trigger again, but it has not yet. We took it for a drive yesterday and when hitting the gas it makes the truck jerky.
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07-13-2019, 02:54 PM
#10
Lots of good ones out there. HF aren’t shabby in regards to capabilities, either. My old Innova 3100 (Walmart splurge buy well over a decade ago) and a recent Craftsman scanner buy both serve me well. The Craftsman does have ABS and other trucks, though.