2002 qx 4 fould plugs on one side of engine
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osageorange4
- Posts: 27
- Joined: Sun Apr 12, 2015 7:11 pm
- Car: infiniti qx 4 2002
2002 qx 4 fould plugs on one side of engine
I have a 2002 qx4 that is fouling plugs but only on one side of the engine. I have pulled the plugs and cleaned only to have them foul out again. What would cause this.
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barnaclebob
- Posts: 249
- Joined: Tue Feb 10, 2015 2:55 pm
- Car: 2001 Pathfinder LE
2011 Altima SR
Re: 2002 qx 4 fould plugs on one side of engine
Can you describe how they are fouled? Any other symptoms or codes?
Re: 2002 qx 4 fould plugs on one side of engine
Well, thats a new piece of info that is probably pretty helpful. Probably should continue this in the old thread, but here goes:
You have not set the code, but you you need to look at p0172 or p0175 here:
http://engine-codes.com/p0172_nissan.html
http://engine-codes.com/p0175_nissan.html
These codes are for running rich, so I am assuming you mean your plugs are gas fouled. Bank 1 is passenger, bank 2 is driver side.
The most likely cause here I think is your front oxygen sensor is failing, altho it has not set a code yet. You have already checked your fuel pressure - thats ok. You said in the other thread the engine revved ok cold, so ignition is pretty unlikely. Its also very unlikely you have bad fuel injectors on just one side of the engine. You should check for exhaust gas leaks up by the front O2 sensor on the side giving you problems. The MAF is probably not the cause - it would affect both sides.
At this point, if you disconnect the MAF sensor, it will take the truck out of closed loop so it is not using the O2 sensors - it will use data tables in the ECM to run the engine. That sets a MAF code, but the engine should run almost normally. So try that.
Post back if disconnecting the MAF helps!
You have not set the code, but you you need to look at p0172 or p0175 here:
http://engine-codes.com/p0172_nissan.html
http://engine-codes.com/p0175_nissan.html
These codes are for running rich, so I am assuming you mean your plugs are gas fouled. Bank 1 is passenger, bank 2 is driver side.
The most likely cause here I think is your front oxygen sensor is failing, altho it has not set a code yet. You have already checked your fuel pressure - thats ok. You said in the other thread the engine revved ok cold, so ignition is pretty unlikely. Its also very unlikely you have bad fuel injectors on just one side of the engine. You should check for exhaust gas leaks up by the front O2 sensor on the side giving you problems. The MAF is probably not the cause - it would affect both sides.
At this point, if you disconnect the MAF sensor, it will take the truck out of closed loop so it is not using the O2 sensors - it will use data tables in the ECM to run the engine. That sets a MAF code, but the engine should run almost normally. So try that.
Post back if disconnecting the MAF helps!