90 maxima maf ?

hello all,

I`m new to this forum and I hope someone can help with an ongoing problem I am having with my wifes car. When we bought the car I did the regular tune up on it. The car did not run too bad, but idled a little rough. I changed the plugs(nkg), fuel filter, wires, cap and rotor. The car got worse. ( the car would not idle properly when started up and when driving on the road at about 1500 rpm it would loss power). I would have to pull over and let the rpm`s come back up. I took it to my machanic friend and he could not find a problem with it, but he thought it could be the fuel pump. I changed the fuel pump but there was no difference. I installed a pressure guage and the pump is right on specs, but if you clamp off the return line the runs great. Up until this friday when it started doing the same things.

Well I went out and replaced eveything again this weekend. Checked the voltage at the maf sensor and it is reading the same as the battery. Cleaned up all connnectors and grounds. The car starts good, idles down to about 850, then the rpms jump a couple hundred then come back down. When you go to drive the car it sputters and spitts and the idle drops to 5-600 and wants to stall.

Is there anything else i can check before changing out the maf sensor? I have read a few other posts and this seems to be the solution that keeps coming up.

This is a great forum and Thank you in advance for any help.

ivan.

...the car it sputters and spitts and the idle drops ...

Theres no warranty u NEW cap is ok. I got frustrated swapping the maxima plastics, sprayed the cap with lacquer, both sides (not electrodes). Problems gone... See my CD web page for that. The wires u got are definitely a new problem source. Only NGK has smtg that actually works intermittently... See my CD page 12.

Seems the IACV sticks, needs to be cleaned after 60-100k.
see http://www.cardomain.com/ride/748507/4

"Is there anything else i can check before"
Yes, checkit first: http://www.cardomain.com/ride/748507/9

I dont think its MAF: thats what stealers$hip will do if u let them. The reason is price: they buy it at 50$ and force-sell it to unawares with 750$.

And btw. Pays to clic my CD site Favorite Links at left.

.

Hey Nahk, you wouldn't happened to have done a IACV write-up on the 5th gen max, would ya? :D

...write-up on the 5th gen max, would ya? :D

Donate me one 5th gen, soon you'll find one:)
Actually I need 3 of them. Two to sell, and pay the gvmt levied taxes on the donation... Socialismus WonderLand.

Try Substitute Manual at: http://www.phatg20.net/
With 94 & 02 -manuals u may find what u need...

BTW. To the MAF issue: if disconnected (3gen), causes idle roam...

.

Theres no warranty u NEW cap is ok. I got frustrated swapping the maxima plastics, sprayed the cap with lacquer, both sides (not electrodes). Problems gone... See my CD web page for that. The wires u got are definitely a new problem source. Only NGK has smtg that actually works intermittently... See my CD page 12.

Seems the IACV sticks, needs to be cleaned after 60-100k.
see http://www.cardomain.com/ride/748507/4

"Is there anything else i can check before"
Yes, checkit first: http://www.cardomain.com/ride/748507/9

I dont think its MAF: thats what stealers$hip will do if u let them. The reason is price: they buy it at 50$ and force-sell it to unawares with 750$.

And btw. Pays to clic my CD site Favorite Links at left.

.
Thank You much for the info you sent me. I dismanteled the air valve and found it was very dirty. Cleaned it up and it runs much smoother, will pick up some lacquer for the cap, and have ordered some new wires.Will let you know the results in a day or two of driving the car. My wife will be very happy.
Thanks again, Ivan.

...My wife will be very happy.
Thanks again, Ivan.

2ppl happy at once:) ...Then this was a nice day!

http://memimage.cardomain.net/member_images/4/web/748000-748999/748507_299_full.jpg

Here is an update on the car.
Did the lacquer to the cap and changed the plugs.(old plugs looked good and tested ok) Waiting for new wires.
Now this is where it gets interesting,started up the car and it ran real smooth with not a miss. Took it out for a quick ride down to the river and everything was great. Went back home, the car sat for 3 hours before I had to pick up the wife. Started the car and nothing but low rpm`s, sputtering and hesitating.
Shut it off and immediately restarted it and it ran perfect. Tried it a few more times and the same thing. One time it would run good, the next bad.

Any suggestions for this one? I might take apart the throttle body tomorrow, and clean that up. It probably is as dirty as the iacv was.

Ivan

... Shut it off and immediately restarted it and it ran perfect. Tried it a few more times and the same thing. One time it would run good, the next bad...

MAF, TPS, Cam Pos sensor (or distr gnd). If one of these fails, engine drops to safe mode 2.2k rpm limit. No way but tst, swap one after another. Intermittents are the nasty ones...

A/T uses TPS: typically A/T is also problematic when TPS is faulty. (you have not complained that - or maybe M/T?)

My bet is faulty MAF. They say its 50$ from junkyard...

.

Thanks for the quick reply Nahkapohjola, will start at it again. Will let you know.

Ivan

Thanks for the quick reply ...

I am (am I?) lucky to be free to answer.

If the current problem is only cold, points to MAF, TPS.
If the current problem is only warm, points to MAF, O2.
If the current problem is warm&cold, that seems to drop out O2&TPS.
Which (O2-or-TPS) ECU uses, depends on cue from temp sensor - which may also drop out intermittently; p.8. What is Temp gauge showing??

http://memimage.cardomain.net/member_images/4/web/748000-748999/748507_230.jpg

(Cam pos sensor seldom depends on temp.)

Have u got A/T Automatic tranny or Manual M/T???

.

Hello again, just got in from the car and found your new post. The car is an a/t. I just finished replacing the fluid and adjusting the shift linkage. The max starts to act up when hot and cold, more so when you take it for a drive. Run real good then the rpm`s drop off and there is no power at the pedal. The rpm`s drop to about 500 and then slowly come back up, even then it`s hit or miss if it will move.
I have found that there is a wire problem on the left side wires running to the iacv, if you give them a pull the engine surges. I have just removed the wrap to trouble shot any loose or broken wires.
I off to pick up the wife.

Thanks again Ivan.

... hot and cold,...

Its not then the TPS. Driving shakes the wirings etc more, take also MAF conn out, inspect conn pins & wiring...

Long shot is alt charge voltage generated spikes: easy tst is to disconnect alt by taking connector off, see page 5.

.

Hello again, it`s been a long week and weekend.
This is what has been done to the maxima since last post.
1- maf sensor changed.
2- changed wires.
3- repaired break in wiring harness.
4- cleaned and regreased all connectors.
5- traced all grounds, cleaned and regreased, added extra grounds to alternator and distributor, missing o2 ground at exhaust. (added).
6- tested and reset TPS.
7- melted hole and cleaned out TPS, added missing o-ring.(reset)
8- added boost to gas just incase.
Took car for drive after each repair, and it seems car ran a little better each time but the adle problem is still there.
When car is warmed up in park it idles at approx. 850. When in drive and reverse 700. When you go from reverse to neutral 850, when you shift from drive to neutral it will rev at a 1000 or better. ( would this be a bad TPS?) or has this anthing to do with the fuel system. the car has tons of power and not stopping at 2200.

Any suggestions would be a great help. I will admit its been fun working on it, but a little aggrivating to.
Ivan.

...I will admit its been fun working on it, but a little aggrivating....

I also like it / hate it...

Originally no o-ring; if TPS box is sealed, then this closes one possible water route.
1. Did you tst TPS resistance, if its ok?
2. TPS zero pos sw needs adjustment... is it switching at 1k rpm?
3. Idle is adjusted warm, ECU sw turned in the process. Does the process hlp, work?
4. Small airleak causes hi idle as ECU increases injection to match airflow. Likewise Sticking IACV.
5. As MAF measures airflow, injection is controlled by its signal. Another MAF may be also faulty... (How does old MAF work, any difference?)
6. TB butterfly adjustment is ok, should be minimum clearance?

...so many changes have now happened, needs problem refocusing. Sit down and write down all things; is the problem now original, or self inflicted (very typical).

I also like it / hate it...

Originally no o-ring; if TPS box is sealed, then this closes one possible water route.
1. Did you tst TPS resistance, if its ok?
2. TPS zero pos sw needs adjustment... is it switching at 1k rpm?
3. Idle is adjusted warm, ECU sw turned in the process. Does the process hlp, work?
4. Small airleak causes hi idle as ECU increases injection to match airflow. Likewise Sticking IACV.
5. As MAF measures airflow, injection is controlled by its signal. Another MAF may be also faulty... (How does old MAF work, any difference?)
6. TB butterfly adjustment is ok, should be minimum clearance?

...so many changes have now happened, needs problem refocusing. Sit down and write down all things; is the problem now original, or self inflicted (very typical).

Well I did what you said and wrote everything down, and since doing all the changes the car does run better. It use to just die at about 1500 rpm with no pedal response. Now there is some response. Tonight I borrowed another ECU and tried it and came up with a 33 code, which if I think is the 02 sensor or the MAF sensor or the connections. Do you think this sounds about right and would this give the car this kind of problems.
Thanks again for any advise.
Ivan

...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?

.

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.

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:)