03 running rich, even at idle
06-20-2014, 09:04 PM
#1
03 running rich, even at idle
Over the last few months, my Maxima has been running rich. It has progressively gotten worse. The average AFR at idle is now ~13.4. It also runs rich in open loop. I did a 3rd gear pull today, and the AFR was in the low 11s throughout most of the rpm range. The car also seems to be experiencing some loss of power, but the idle is smooth.
The last time I checked codes, I didn't have any (other than the EVAP code I had for years and codes for rear 02 sensors that are not currently plugged in).
My first guess was that it must have been the MAF. I first cleaned it, but that did not make a difference. Then I bought a used MAF at the junk yard, but that did not improve the situation either. I made sure it was not the air filter.
I don't think it's the front o2 sensors as the issue occurs in both open and closed loop.
I will be trying a friend's MAF soon (in case the one I got from the junk yard was bad). I have an Emanage Blue... I may try unplugging that (I guess I could check the map too, although nothing should have changed there).
Anyone have any suggestions of what else it could be? A vacuum leak? exhaust leak?
Thanks
The last time I checked codes, I didn't have any (other than the EVAP code I had for years and codes for rear 02 sensors that are not currently plugged in).
My first guess was that it must have been the MAF. I first cleaned it, but that did not make a difference. Then I bought a used MAF at the junk yard, but that did not improve the situation either. I made sure it was not the air filter.
I don't think it's the front o2 sensors as the issue occurs in both open and closed loop.
I will be trying a friend's MAF soon (in case the one I got from the junk yard was bad). I have an Emanage Blue... I may try unplugging that (I guess I could check the map too, although nothing should have changed there).
Anyone have any suggestions of what else it could be? A vacuum leak? exhaust leak?
Thanks
06-21-2014, 07:53 AM
#2
Running rich
[I]First thing to do is to hook up the engine to OBD II scan tool fo error code , with live feed : for impending error code.
There's a lot of causes: Throttle valve assembly
MAF Sensor
PCV valve
Clogged precats, (two secondary 02 sensor monitor the condition of the two precat)
You said: it was unplugged for years, Its better to gut your two precat and install 02 nonfouler to the two secondary 02 sensor instead of unplugging it. If the precat is clogged ,this will cause the deterioration of the engine.
Read this:http://www.energeticforum.com/renewa...n-foulers.html
Clogged injector
sparkplugs
Ignition coil
If the scan tool pinpoint the error buy a brand new sensor (OEM Genuine Nissan Parts) or the OEM Genuine aftermarket parts (Rockauto. Do not buy the parts in junkyard,(you wasted your money for a non working sensor unless you can return it to them) specially sensor or to those autoparts or internet parts because it will clear out the error code but the problem will persist. Its better not to use the MAF sensor of your friend because you might end up with two engine with maf sensor problem.
There's a lot of causes: Throttle valve assembly
MAF Sensor
PCV valve
Clogged precats, (two secondary 02 sensor monitor the condition of the two precat)
You said: it was unplugged for years, Its better to gut your two precat and install 02 nonfouler to the two secondary 02 sensor instead of unplugging it. If the precat is clogged ,this will cause the deterioration of the engine.
Read this:http://www.energeticforum.com/renewa...n-foulers.html
Clogged injector
sparkplugs
Ignition coil
If the scan tool pinpoint the error buy a brand new sensor (OEM Genuine Nissan Parts) or the OEM Genuine aftermarket parts (Rockauto. Do not buy the parts in junkyard,(you wasted your money for a non working sensor unless you can return it to them) specially sensor or to those autoparts or internet parts because it will clear out the error code but the problem will persist. Its better not to use the MAF sensor of your friend because you might end up with two engine with maf sensor problem.
Last edited by colt149; 06-21-2014 at 08:12 AM.
06-25-2014, 08:54 AM
#3
I pulled the codes again and it was nothing new (just the EVAP and unplogged rear o2s). I have the sim that I need to install.
I replaced the PCV valve not too long ago, as I did spark plugs. Don't think it's spark plugs and not likely a clogged injector as there is no misfiring.
The last time I checked the AM600 MAF was over 500 CAD... which is a lot to spend on high mileage 03 car that has endured many harsh Canadian winters. I guess I could get a 2000-2001 MAF for cheaper, just move over the temperature wire...
Pre cats are not the cause as I have headers... but now you got me thinking that maybe my main cat that has gotten clogged up (although not sure if that would make it run rich or lean).
I replaced the PCV valve not too long ago, as I did spark plugs. Don't think it's spark plugs and not likely a clogged injector as there is no misfiring.
The last time I checked the AM600 MAF was over 500 CAD... which is a lot to spend on high mileage 03 car that has endured many harsh Canadian winters. I guess I could get a 2000-2001 MAF for cheaper, just move over the temperature wire...
Pre cats are not the cause as I have headers... but now you got me thinking that maybe my main cat that has gotten clogged up (although not sure if that would make it run rich or lean).
06-28-2014, 07:22 AM
#5
Yeah, you're right... it's definitely a possibility. I don't think it's the map as it's also bad in closed loop, but the EB could definitely be acting up. I wish I had made a harness for it for an easy unplug... but I will likely have to try disconnecting it as it's definitely a suspect.
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