Normal STFT conditions?
12-26-2015, 01:54 PM
#1
Normal STFT conditions? I just had an exhaust shop weld in some new v band clamps, since the slip fit crap was leaking. I also had them install a bung for a wideband. As soon as I drove away from the exhaust shop I could feel something wasn't right. My new wideband showed I was running really rich. I figured he may have screwed up my narrowband o2 sensors by welding so closely to them.
I setup a scanner and see that my STFT's reach as high as 51%. I assume that is not normal.
My truck was tuned well, and running great. I just installed a set of long tube headers, ORY and a 3 inch super turbo muffler. I was prepared to tweak the tune after the header install (already removed the DTCs for no rear 02s), but this seems abnormal. Should I buy some new 02 sensors before I attempt to retune?
I setup a scanner and see that my STFT's reach as high as 51%. I assume that is not normal.
My truck was tuned well, and running great. I just installed a set of long tube headers, ORY and a 3 inch super turbo muffler. I was prepared to tweak the tune after the header install (already removed the DTCs for no rear 02s), but this seems abnormal. Should I buy some new 02 sensors before I attempt to retune?
12-27-2015, 07:15 AM
#5
Yea, i checked to make sure none of the welds touched the sensors. Since i previously eliminated my cats and rear o2s, i had two spare sensors. I tried using those sensors instead, but it actually got worse. All 4 of my 02 sensors, besides the aem wideband, have 155 k miles on them. Is it time for a new set?
Ill scan the voltage.
Ill scan the voltage.
12-27-2015, 08:39 AM
#6
From your description, I should be seeing it bounce from 100mv to 900mv constantly. Like non stop peaks and valleys.
I'd be glad to post the log if you'd like to see it.
12-27-2015, 09:44 AM
#7
I just swapped in a spare set of 02 sensors I had laying around. Now I see the MV signals bouncing like they should. Anywhere from 3mv to 856mv. Truck runs much better. No more stalling, and no more stft of 50%.
However, I am still running a bit rich since I installed the new headers/exhaust. I thought I would be leaner, but I'm not. The commanded AFR is 12.39, but my wideband reads in the 11 range at wot.
Since my truck was already tuned by a good shop. I assume the MAF/VE/PE has all been tuned. It runs pretty decent. Would it be ok to ONLY adjust the PE EQ Ratio table, to try to hit my desired WOT AFR?
Or is it necessary to retune everything?
However, I am still running a bit rich since I installed the new headers/exhaust. I thought I would be leaner, but I'm not. The commanded AFR is 12.39, but my wideband reads in the 11 range at wot.
Since my truck was already tuned by a good shop. I assume the MAF/VE/PE has all been tuned. It runs pretty decent. Would it be ok to ONLY adjust the PE EQ Ratio table, to try to hit my desired WOT AFR?
Or is it necessary to retune everything?
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12-27-2015, 01:56 PM
#8
I just swapped in a spare set of 02 sensors I had laying around. Now I see the MV signals bouncing like they should. Anywhere from 3mv to 856mv. Truck runs much better. No more stalling, and no more stft of 50%.
However, I am still running a bit rich since I installed the new headers/exhaust. I thought I would be leaner, but I'm not. The commanded AFR is 12.39, but my wideband reads in the 11 range at wot.
Since my truck was already tuned by a good shop. I assume the MAF/VE/PE has all been tuned. It runs pretty decent. Would it be ok to ONLY adjust the PE EQ Ratio table, to try to hit my desired WOT AFR?
Or is it necessary to retune everything?
However, I am still running a bit rich since I installed the new headers/exhaust. I thought I would be leaner, but I'm not. The commanded AFR is 12.39, but my wideband reads in the 11 range at wot.
Since my truck was already tuned by a good shop. I assume the MAF/VE/PE has all been tuned. It runs pretty decent. Would it be ok to ONLY adjust the PE EQ Ratio table, to try to hit my desired WOT AFR?
Or is it necessary to retune everything?
You need to retune VE tables. Changing PE tables is a hack fix.
O2 Sensors are meant to read stoimetric AFR only. If you are running a closed loop tune you should be commanded to 14.68 and the O2's should be switching back and forth and keep your afr bouncing on either side of 14.68
12-27-2015, 04:11 PM
#9
Why is your AFR being commanded to 12.39? Should be 14.68.
You need to retune VE tables. Changing PE tables is a hack fix.
O2 Sensors are meant to read stoimetric AFR only. If you are running a closed loop tune you should be commanded to 14.68 and the O2's should be switching back and forth and keep your afr bouncing on either side of 14.68
You need to retune VE tables. Changing PE tables is a hack fix.
O2 Sensors are meant to read stoimetric AFR only. If you are running a closed loop tune you should be commanded to 14.68 and the O2's should be switching back and forth and keep your afr bouncing on either side of 14.68
The truck has already had a good tune. Only change is the LT, ORY, and exhaust.
Can I adjust the PE to achieve the desired afR at WOT, or should I start over with the VE tuning? Retune the maf and VE, everything?
12-27-2015, 04:47 PM
#11
First thing I would do is do a free air calibration on your W/B and see if your readings change any. If the PCM was adding that much fuel there's a good chance it knocked out the WBO2 sensor.
Were you seeing 12.39 on the WB before the exhaust swap?
IF the WBO2 is accurate the MAF table will need to be adjusted.
As mentioned you don't change your PE to match your WB. You would adjusted the VE table or in this case the MAF table for WOT.
Also things like COT, if it's not disabled will richen up the AFR at WOT
Were you seeing 12.39 on the WB before the exhaust swap?
IF the WBO2 is accurate the MAF table will need to be adjusted.
As mentioned you don't change your PE to match your WB. You would adjusted the VE table or in this case the MAF table for WOT.
Also things like COT, if it's not disabled will richen up the AFR at WOT
12-27-2015, 05:11 PM
#12
In the PE table I have 1.190 across the board. 14.7/12.35=1.190 At WOT, I am commanding 12.35, not at part throttle.
The truck has already had a good tune. Only change is the LT, ORY, and exhaust.
Can I adjust the PE to achieve the desired afR at WOT, or should I start over with the VE tuning? Retune the maf and VE, everything?
The truck has already had a good tune. Only change is the LT, ORY, and exhaust.
Can I adjust the PE to achieve the desired afR at WOT, or should I start over with the VE tuning? Retune the maf and VE, everything?
12-27-2015, 06:23 PM
#13
First thing I would do is do a free air calibration on your W/B and see if your readings change any. If the PCM was adding that much fuel there's a good chance it knocked out the WBO2 sensor.
Were you seeing 12.39 on the WB before the exhaust swap?
IF the WBO2 is accurate the MAF table will need to be adjusted.
As mentioned you don't change your PE to match your WB. You would adjusted the VE table or in this case the MAF table for WOT.
Also things like COT, if it's not disabled will richen up the AFR at WOT
Were you seeing 12.39 on the WB before the exhaust swap?
IF the WBO2 is accurate the MAF table will need to be adjusted.
As mentioned you don't change your PE to match your WB. You would adjusted the VE table or in this case the MAF table for WOT.
Also things like COT, if it's not disabled will richen up the AFR at WOT
I just did a couple more runs, and i saw 11.3-12.3 at wot. Noticed a good bit of new power.
I think I may have either an exhaust leak near a sensor, or false knock reading from the header barely touching the frame. The knock would pull timing and that could cause it to go richer.
I'll log KR tomorrow, and check for leaks again.
