O2 sensor/test pipe rough idle?
#1
10-11-2018, 08:14 PM
O2 sensor/test pipe rough idle?
So I’ve installed 50mm Manzo test pipes to replace the stock rear cats and installed a full HKS high power dual exhaust kit obviously popped the cel light right away bought new O2 sensors and Megan racing spacers for the test pipe O2 sensor ports, ran beautifully for about 3 weeks then popped another O2 sensor related cel. Now I’m noticing a rougher idle when I’m parked or stationary. Obviously the car is running super lean and the ECU can’t get the F/A ratio right. My question is is that normal? My RPMs aren’t jumping or fluctuating. It just feels like maybe there is no backpressure? Am I stuck getting an Osiris tune to fix this issue or are there any other options for all the test pipe/O2 sensor related headaches besides going back to stock cats.
#2
10-11-2018, 08:20 PM
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What code are you throwing, there are 4 total O2 sensors.
Back pressure, or lack thereof, is not a problem. There is plenty of flow across the upstream sensors and those are the ones that determine your actual fuel ratio, the downstream sensors measure catalytic efficiency and can be tricked into not throwing a code usually with a set of non-foulers, sometimes two sets (screw them together) is needed. A downstream O2 sensor code will not affect idle, an upstream sensor can potentially blow up your motor but you typically hear the pinging unless your stereo is cranked up or something.
Back pressure, or lack thereof, is not a problem. There is plenty of flow across the upstream sensors and those are the ones that determine your actual fuel ratio, the downstream sensors measure catalytic efficiency and can be tricked into not throwing a code usually with a set of non-foulers, sometimes two sets (screw them together) is needed. A downstream O2 sensor code will not affect idle, an upstream sensor can potentially blow up your motor but you typically hear the pinging unless your stereo is cranked up or something.
#3
10-11-2018, 08:21 PM
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#4
10-11-2018, 08:35 PM
What code are you throwing, there are 4 total O2 sensors.
Back pressure, or lack thereof, is not a problem. There is plenty of flow across the upstream sensors and those are the ones that determine your actual fuel ratio, the downstream sensors measure catalytic efficiency and can be tricked into not throwing a code usually with a set of non-foulers, sometimes two sets (screw them together) is needed. A downstream O2 sensor code will not affect idle, an upstream sensor can potentially blow up your motor but you typically hear the pinging unless your stereo is cranked up or something.
Back pressure, or lack thereof, is not a problem. There is plenty of flow across the upstream sensors and those are the ones that determine your actual fuel ratio, the downstream sensors measure catalytic efficiency and can be tricked into not throwing a code usually with a set of non-foulers, sometimes two sets (screw them together) is needed. A downstream O2 sensor code will not affect idle, an upstream sensor can potentially blow up your motor but you typically hear the pinging unless your stereo is cranked up or something.
#5
10-11-2018, 08:37 PM
Not sure what the average short term fuel trim is or how to check that. It’s leaned out because I can smell the excess fuel not getting burned every time I start the car. Which makes sense considering the specific mods I have on it. I haven’t pulled plugs or the MAF yet.
#6
10-12-2018, 09:05 AM
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I would start by getting an OBD2 scanner plugged in to check both upstream sensors for any cycling problems, make sure it's a nice transition from high to low, chances are you just have an O2 sensor failing but you should also check for any intake or exhaust leaks (anything past the cats won't throw a code). A good OBD2 sensor will also have the capability to test bank1 and 2 short term fuel trim and long term fuel trim.
If you have an Android based phone you can use a Bluetooth OBD2 adapter (I use one by BafX) and the app Torque Pro, I know that combo works great on the G and has logging functions so you can also go for a drive and log data which can be helpful for some troubleshooting issues.
If you have an Android based phone you can use a Bluetooth OBD2 adapter (I use one by BafX) and the app Torque Pro, I know that combo works great on the G and has logging functions so you can also go for a drive and log data which can be helpful for some troubleshooting issues.
#7
10-12-2018, 12:13 PM
I would start by getting an OBD2 scanner plugged in to check both upstream sensors for any cycling problems, make sure it's a nice transition from high to low, chances are you just have an O2 sensor failing but you should also check for any intake or exhaust leaks (anything past the cats won't throw a code). A good OBD2 sensor will also have the capability to test bank1 and 2 short term fuel trim and long term fuel trim.
If you have an Android based phone you can use a Bluetooth OBD2 adapter (I use one by BafX) and the app Torque Pro, I know that combo works great on the G and has logging functions so you can also go for a drive and log data which can be helpful for some troubleshooting issues.
If you have an Android based phone you can use a Bluetooth OBD2 adapter (I use one by BafX) and the app Torque Pro, I know that combo works great on the G and has logging functions so you can also go for a drive and log data which can be helpful for some troubleshooting issues.
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#8
10-12-2018, 02:59 PM
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#9
10-12-2018, 03:32 PM
#10
10-13-2018, 10:02 AM
Im getting a p0420 and a p1273 with test pipes also.
I've spaced my o2s, fresh oil, new oem plugs have you seen this before?
#11
10-13-2018, 10:14 AM
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P0420 is just the catalyst efficiency code you can try using a set of non-foulers (or two sets screwed together if that doesn't work) and usually get rid of that code. P1273 is the lean code for the upstream O2 sensor so what's LIKELY happening is the ECM recognizes a lean problem then goes back into failsafe mode (rich mode, hence the negative fuel trim) to prevent engine damage. I would monitor O2 sensor data while the engine is warming up to see if the O2 sensors are actually fluctuating properly, if they're not cycling then you might just have a bad O2 sensor or you may simply need an uprev tune. How many miles are on your upstream O2 sensors? They only last about 80-100k before they start failing and sending bad data or delayed data back to the ECM.
Also, just to verify you are NOT installing those non-fouler spacers on the upstream O2 sensors correct? Those are designed ONLY to be used on the downstream O2 sensors.
Also, just to verify you are NOT installing those non-fouler spacers on the upstream O2 sensors correct? Those are designed ONLY to be used on the downstream O2 sensors.
#12
10-13-2018, 10:32 AM
P0420 is just the catalyst efficiency code you can try using a set of non-foulers (or two sets screwed together if that doesn't work) and usually get rid of that code. P1273 is the lean code for the upstream O2 sensor so what's LIKELY happening is the ECM recognizes a lean problem then goes back into failsafe mode (rich mode, hence the negative fuel trim) to prevent engine damage. I would monitor O2 sensor data while the engine is warming up to see if the O2 sensors are actually fluctuating properly, if they're not cycling then you might just have a bad O2 sensor or you may simply need an uprev tune. How many miles are on your upstream O2 sensors? They only last about 80-100k before they start failing and sending bad data or delayed data back to the ECM.
Also, just to verify you are NOT installing those non-fouler spacers on the upstream O2 sensors correct? Those are designed ONLY to be used on the downstream O2 sensors.
Also, just to verify you are NOT installing those non-fouler spacers on the upstream O2 sensors correct? Those are designed ONLY to be used on the downstream O2 sensors.
They seem to fluctuate however they appear to be the original ones. According to the TSB, it calls for new sensor and re calibration at the dealer.
#13
10-13-2018, 08:06 PM
#14
10-13-2018, 08:48 PM
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Do the pedal dance method to reset the idle air, make sure the engine and transmission are up to temp, ALL power consumers are turned OFF including heated seats, air conditioning (turn the entire panel off), stereo, wipers, headlights, window defrosters, etc. Optionally if you have a bluetooth OBD2 adapter you can use the Android app Nissan Datascan 2 to simply push a button to reset the idle air calibration.
If it doesn't work exactly as shown then the reset didn't work, there is a power sensing algorithm in the ECU and if it detects anything is turned on (or if the transmission isn't up to temp) it won't work, if the engine is not up to temp you will end up with a REALLY screwed up idle.
http://nicoclub.com/archives/g35-350...procedure.html
If it doesn't work exactly as shown then the reset didn't work, there is a power sensing algorithm in the ECU and if it detects anything is turned on (or if the transmission isn't up to temp) it won't work, if the engine is not up to temp you will end up with a REALLY screwed up idle.
http://nicoclub.com/archives/g35-350...procedure.html
#15
10-13-2018, 09:09 PM
Do the pedal dance method to reset the idle air, make sure the engine and transmission are up to temp, ALL power consumers are turned OFF including heated seats, air conditioning (turn the entire panel off), stereo, wipers, headlights, window defrosters, etc. Optionally if you have a bluetooth OBD2 adapter you can use the Android app Nissan Datascan 2 to simply push a button to reset the idle air calibration.
If it doesn't work exactly as shown then the reset didn't work, there is a power sensing algorithm in the ECU and if it detects anything is turned on (or if the transmission isn't up to temp) it won't work, if the engine is not up to temp you will end up with a REALLY screwed up idle.
http://nicoclub.com/archives/g35-350...procedure.html
If it doesn't work exactly as shown then the reset didn't work, there is a power sensing algorithm in the ECU and if it detects anything is turned on (or if the transmission isn't up to temp) it won't work, if the engine is not up to temp you will end up with a REALLY screwed up idle.
http://nicoclub.com/archives/g35-350...procedure.html