Will an adjustable map sensor help a lean running 95 4.0 in closed loop at loads required during a smog test? Or does it only richen only at wot? I've tried everything to richen it up and the ecu always leans it out making it fail the nox part of the test.

 

Reset the ecu. Take the battery cables off the battery and hold them together for a minute. It will reset the adaptive memory and put it in relearn.
There is a reason it's running lean. Throwing a map sensor at it isn't a fix.

 

I've replaced the cat all sensors,fuel pump,regulator,pickup,lines,injectors,sea foamed the motor,checked for vac and exhaust leaks,tried different t stats,99 octane fuel,cap,plugs rotor,and I'm sure I've forgotten a few things.It is a 4.2 with the hesco mpi on it.Runs good.It just won't pass smog.emissions are super low except for the nox.They are around 1300.Nothing has made even the slightest change.

 

Have you reset the ecu?

 

Not lately.This has been going on for about 4 years.no codes.i guess it would not hurt to reset it.I've tested it at least 20 times.1 thing at a time and nothing has made any change.

 

Any other suggestions?

 

Yes I have a good one.........MOVE where they don't have that crap testing to where all they check is the brake's and lights and your done, but that is even too much for what they really do

 

I might try resetting the eCU for giggles.

 

Try this....


This may help with your NOx emissions, and also make your engine run better. Free and easy to do...

Drive your Jeep around until it is at full operating temp. Take the intake tube off of the throttle bottle. Hold the throttle linkage at the throttle body down to rev the engine to about 2000 - 2500 rpm. and pour water into the throttle body a little bit at a time. A little dribble in at a time until you put in about 8 to 12 fl oz. I used a spray bottle and just sprayed it in there as fast as I could squeeze the trigger...

Bolt the intake hose back on and enjoy your freshly decarbonized motor! +100 hp! (ok, maybe not the much gain...)

 

I love doing that!!

Have my own special cup also:

This:

 

You and that cup....I'm putting a pic of it in the book btw...

 

It is real and gets used. The text on there is also accurate and I put it on there just to irritate someone on this forum. Sycoglitch maybe?

 

I used a spray bottle to pour it in..what's that mean?

 

Dew it to it!

I used the spray bottle because my hands were too shaky from drinking the mountain dew. Didn't want to pour the whole thing in at once accidentally...

 

No it will not richen it up, the O2 sensors and ecu will bring it back to 14.7.
Do all the above, maybe disconnect the water temp sensor, but that might cause a CEL.