PO104--bank two system too lean
PO401--exhaust gas recirculation insufficient detected
PO154--oxygen circuit no activity detected bank 2 sensor 1
PO174--bank 2 system too lean
PO401--exhaust gas recirculation flow insufficient detected


I also did a temperature before and aft of the catalytic converters as follows at 2000 RPM.


passengers side bank 2--front-580 rear 650
drivers side bank 1--front-400 rear 615
Rear converter 560 front rear 430
all in Fahrenheit
As usual all help is a wonderful thing.

 

Problem #1 is your P0154 code. Since you got not activity on bank 2 sensor 1, the ECU does not know how much fuel to add to run the engine efficiently. The other bank 2 codes most likely are related to that one. Figure out first what causes no activity on that O2 sensor - check to see if it got unplugged or the wire got ripped off. The P0401 can be related to a solenoid issue or a simple vacuum leak in the EGR system, thus not allowing it to engage properly. You got to do it one step at a time.

 

Hunter, Tks for the input and I will get right on it too. However the OXY sensor for bank 2 sensor 1 I would assume that it would be the passenger side and closest to the motor. Is this correct ???? My manual is pretty vague on the oxygen sensors...Tks

 

I hope someone who knows better can clarify this. But I've read different things on this. Some say Bank 1 is where #1 cylinder is, which will be left side (facing the engine) and bank 2 is right. Other places say bank 1 is right side as you are sitting in the vehicle. I honestly not sure. If i get a chance - I'll play with my scan tool tonight and unplug one side O2 to see which side will loose reading. I'll post back once I find out.

 

Ok,, Now I replaced the O2 sensor in bank 2 sensor 1 ( WHICH IS ON THE DRIVERS SIDE) I did what you were going to do Hunter..great idea you had but now I know which bank is which.
Now all I'm getting now is a code PO401--- Exhaust gas recirculation flow insufficient detected... Go figure but were gettn there.

 

Hey there 2001Mitch3.5XS, you are quick I just ran the test and you are right - Bank 2 is the driver side (US) of the engine - the right side when you are looking under the hood.

OK, now for the P0401.

Check the functionality of the EGR valve first. If your EGR is vacuum operated type then it is super easy - plug a vacuum pump to the EGR valve port and start the engine. When you apply vacuum to the valve - the engine will hesitate and stall or almost stall. When you release vacuum - the engine goes back to normal running. If you get this behavior - your EGR valve is good. If not, then you need to figure out if the valve holds vacuum or not? If "No" - the diaphragm is busted and you need new EGR valve. If "Yes" - you may have clogged EGR passages - take off plenum and check/clean air passages (don't forget to check the metal hose that connects exhaust manifold and plenum).

Also, check condition of the vacuum hoses connecting EGR solenoid, EGR valve and the intake manifold. Once i had P0401 code and it was due to a cracked vacuum hose running to the solenoid. If all these check out OK, test your EGR solenoid. From my experience - aftermarket ones do not work as well as OEM Mitsubishi. Unfortunately they are much pricier than aftermarket.

 

Tks. Hunter. Ok I took the EGR valve off and cleaned it out and the diaphragm seems to be good. I will have to do the test on it while running. That bank 2 thing was killing me..lmao. I will keep yas posted as to what happens. It is kinda nice to only have one code though and will be awesome to get rid of that one too. Tks again Hunter for all your help too.
I might add that the truck runs extremely well better than when I bought it. Power soundless and ready for anything. It's just the idol that has me stumped. It sounds almost like it has a misfire but I know it's not misfiring.... Imagine that.

 

Ok, the EGR valve did exactly what you said it would. I apply vacuum and wants to stall.
Next I applied vacuum to the EGR valve and it holds... hummmm...
OK, All ports n tubes are clear and I cleaned out the EGR valve again just to make sure it's closing all the way.
I am thinking about the solenoid now......

 

If your vacuum hoses feeding to and from the solenoid are good - than its most likely the solenoid.

 

OK, upon checking out the vacuum lines, I did check out the EGR and blew air throughout all the ports...
Checking the vacuum control valve and got no vacuum at all at idol or reving. I bypassed right to the (A) nipple on the throttle body and no vacuum there neither. I took apart the throttle body and cleaned it out and still no vacuum coming out of there still...hummmm.........??????????? a;'ldskf';lka';fldksa'f;lka'sdfkl
Ok still testing.I will check out the solenoid and will keep yas posted... What a pain in the ***...lmao.