so my 2000 maxima is running really sluggish and is having problems with accelerating and power loss so ive heard that it could be one of three problems..knock sensor , MAF or o2 sensor..

i dont think it's o2 sensor cause that would cause the engine light to come on, so im leaning toward either KS or MAF..

i was wondering how to diagnose between the 2 if the car isn't throwing any engine codes..i looked though the FSM for where the KS harness is located but it only shows the KS .. which looks like it's under the intake manifold?

anyone have a picture of where the harness is?

and how can i diagnose if the MAF is bad or not.

thanks.

 

Read the FSM furter. More specifically, in the MAF area. It will tell you what specs (with respect to voltage) you should be seeing in certain situations (i.e. throttle position/RPM). Get a voltmeter and 'spec' it.

Same goes for the coil packs.

Whoever told you an O2 sensor can hurt performance does not know what they're talking bout.

My guess, leave the O2 and KS out, and start looking at the MAF and coil packs.

 

Agreed, KS is not an issue. Bad ones rarely are found unless another problem surfaces.

Maybe could be an O2 sensor, but the bad MAF & coil packs are known 5th Gen issues that will substantially decrease performance. Plus the MAF could be bad without generating a trouble code.

 

uhmm humm guess ill check that later today or tomarrow and report back, thanks guys.

edit: according to the FSM if the MAF is bad the car shouldn't go over 2500 RPM's? im getting very sluggish reactions from about 3K -> 6K in 1st gear, anything over 2.5K in 2nd gear, and all of 5th gear..the car just doesn't wanna move..

no one has anything for me :/

 

I had no top-end (hi-rpm) power in my 2000 maxima about a year ago. It ran OK at low power settings though. I fixed it by replacing all 6 ignition coils, yes all six. The coils are bad on these cars and there is a TSB that says so. A while later I had more and worse engine misfires, especially when cold after start up. I replaced the MAF (Mass airflow sensor) which fixed that as well. I only use the Nissan air filters now because other cheaper brands like Fram (budget filter) can deposit micro fibers onto the MAF causing it to go bad. The ignition coils I got at buynissanparts.com (genuine Nisaan parts) for a big discount compared to the dealer. The ignition coils were $55 ea. and the MAF sensor I got at Alleurasianautoparts.com was $105 if I remember correctly. The car runs like new now. I hope this helps.

Phil

My old post from 6/06 re: MAF, Engine misfires.

MAFs Damage Easily! Air Filters are Critical.
-------------------------------------------------------------------------
I Just got done replacing the MAF on my 2000 max. Wow, what a difference! Runs like new again. I also just got the ECM (eng. computer) re-programmed ($95 at the dealer). I recommend it because the new MAFs are slightly different than the original and this is a critical input to the ECM and I believe other updates are also included. I noticed slightly more top-end power after the program update.

Also I have been warned about using cheap and/or non Nissan air filters.
These MAF elements are easily damaged by foreign material or even dust entering the intake. If you were using a cheap filter like I was (std. Fram) then your MAF will probably fail soon. These Fram filters (as well as other brands) can emit micro fibers that can/will damage the MAF element. Other filters (also, definitely would not use an Oil soaked filter) may not fit just right and obviously can leak air around them. Any foreign material (like oil) can cause a change in the chemistry of the heated element of the MAF. I got this info not only from a Nissan tech. but also from an independent shop. I switched to a NAPA Gold filter (probably OK) after I installed the new MAF, but now I'm going to use the Nissan filter ($10 at the dealer). I don't want to re-do this job anytime soon. I found the MAF at AllEurasianAutoparts.com for $105 w/free shipping.

She hauls azz now!

 

I don't mean to be rude but I have to disagree completely. The O2 sensors are critical in engine performance. If they are dieing or gone completely, then your computer has no clue what the A/F ratio is and is going to give the engine the wrong amount of fuel.

I've also seen a few different scenarios where a bad O2 sensor didn't throw any codes (weird but true). However the car starting bucking hard and literally started guzzling fuel every now and then (how's that for hurt performance).

I don't know if you fixed the problem but I do agree that its either the MAF or possibly a coil pack.

As for Fram VS Stock VS Oiled Filters.... a NAPA Gold filter is nothing more than a fram extra guard filter. NAPA does nothing but put their name on other brands. Just stick with Nissan (though I don't feel that Fram/Purolator are that bad). I like Oiled filters as well but I would take care not to over oil it. Some people (say a dealership tech for example) can be extremely biased in their opinions.

Jay

 

so MAF can go bad w/o triggering the CEL? My light was on for bad O2, so I replaced them and still running 300mile/tank which is CRAP... Time to invest in new MAF...

 

They play no role @ WOT/full throttle performance. Mine are in my trunk and in my garage, and my car still is able to lay down 242whp, WITHOUT O2 sensors. @ WOT, the MAF&CPS are the only sensors that have any input.

MAF for airlfow
CPS for RPM.

Their (O2sensors) main role is to maintain stoich at part throttle.

 

NMEX your second statement is true; so o2 sensors work at part throttle to provide 13.7? a/f ratio so your engine runs at optimum performance and efficiency

at WOT, your A/C compressor will also stop running

 

It's 14.7:1 actually (I'm sure yours was a typo).

As far as tagging on that BS about optimum performance and efficiency, if you're referring to WOT, and even then, my idea of part throttle driving/idling etc. do not coincide with the word performance, maybe efficiency, but not performance.

No one wants that AFR@ WOT.

 

See, I'm in this section too

I'd love to see how a VQ would handle stoich WOT runs over an extended period. They're stout motors, but...

 

Now you're being a stalker. .

I've run mine @ 14.1:1 - 14.2:1. No SK, ECT's seem happy, timing still optimal. I do this for indirect timing advance, BUT, that's another subject, and is steering away from what this thread is about.

Carry on.