90 maxima maf ?

[Nahkapohjola]

Originally Posted by ivan355

...the 02 sensor ...

It may very well be O2. Do measure its voltage output.

O2 sensor measures exhaust gases. To function, it has to be hot (sensor technology in its infancy). Thereby it is not used at all when cold. Derived from this, the O2 code cannot appear on cold engine (or code is bs).

TPS -input is used by ECU as engine is cold. Then injection is ECU -table average, not based on actual feedback measurement.

I'd verify the temp sensor reading at ECU connector when the fault is on. If that is ok, replace O2. It may also be that those two ECU's are faulty this way or that way... It is very typical that problem grows nasty exponentially when multiple faulty devices mask the basic fault. Easily ruins the logic from troubleshooting. In this problem the logic might go like this: faulty MAF, bad temp sensor resistance input to ECU - error code for O2. I dont really know, but dont put your 'trust' in the code.

I find such a problem very challenging: most ppl do sell their vehicle b/c they dont want this kind brain exercise. At stealership its even not possible... they love to throw all $ensor$ out, new in. (For me its far more challenging than computer games, as problem is real. Here as 'my' problem is around the globe and one cannot hear, touch the problem, challenge is even greater. Best of all, hlp to fellow humans is real).

Check also Nissan TSB NTB94-085.pdf; idle fluctuation due to filter.
TSB's see for http://maxima.theowensfamily.com/tsb

Early 3gen maxes had software? problems with cam pos sensor (inside distr). No start with bad signal etc. Is your distributor gnd now ok, signal level good?

.

[ivan355]

Originally Posted by Nahkapohjola

It may very well be O2. Do measure its voltage output.

O2 sensor measures exhaust gases. To function, it has to be hot (sensor technology in its infancy). Thereby it is not used at all when cold. Derived from this, the O2 code cannot appear on cold engine (or code is bs).

TPS -input is used by ECU as engine is cold. Then injection is ECU -table average, not based on actual feedback measurement.

I'd verify the temp sensor reading at ECU connector when the fault is on. If that is ok, replace O2. It may also be that those two ECU's are faulty this way or that way... It is very typical that problem grows nasty exponentially when multiple faulty devices mask the basic fault. Easily ruins the logic from troubleshooting. In this problem the logic might go like this: faulty MAF, bad temp sensor resistance input to ECU - error code for O2. I dont really know, but dont put your 'trust' in the code.

I find such a problem very challenging: most ppl do sell their vehicle b/c they dont want this kind brain exercise. At stealership its even not possible... they love to throw all $ensor$ out, new in. (For me its far more challenging than computer games, as problem is real. Here as 'my' problem is around the globe and one cannot hear, touch the problem, challenge is even greater. Best of all, hlp to fellow humans is real).

Check also Nissan TSB NTB94-085.pdf; idle fluctuation due to filter.
TSB's see for http://maxima.theowensfamily.com/tsb

Early 3gen maxes had software? problems with cam pos sensor (inside distr). No start with bad signal etc. Is your distributor gnd now ok, signal level good?

.

This is a happy update.
The car is running fine now. The first thing I did was disconnect the 02 sensor and took it for a drive and no problems. Ran smooth, better than ever and no hesitation. Went home and checked the wires and connectors with the multi meter. Found the sensor was bad. Installed a new sensor and still no problems.(Day1/2 now).
As you were saying, these things are challenging and well worth the time to trouble shoot. I will probably end up with other problems but still plan on holding on to the maxima. It`s a fun car to have.
Well Thank You again, and if there is anything I can do for you just let me know.
Ivan.

[Nahkapohjola]

Originally Posted by ivan355

This is a happy update.... disconnect the 02 sensor and took it for a drive and no problems. ...anything I can do for you just let me know. Ivan.

As O2 wire is out, ECU uses TPS and a average injection table for adjusting injection; no feedback.

Pic of u max, smiling users/owners would be nice to show my wife, he thinks I am weird [true]... thats for starters