I don't know what has happened to the old girl, but she is starting to realy get on my nerves. I got the car at 35k from the dealer about 4 years ago. She was a dart by comparison. When I got her, I changed the plugs (ngk plats), changed the fuel filter, Pcv valve, air filter and changed all fluids to synthetic. My car now has 80k. within those 45k I have kept the fluids fresh religiously, auto rx'd the crankcase, seafoamed 3 times, and techroned here and there. I also cleaned the MAF sensr with CRC electonic parts cleaner about 15k ago without any ill effects.Now my car is also heavier then ever with a system and 04 SL rims, but recently, my car has seemed like its sick. It drives like a bus and really is relucant to produce any real torque. I can barely chirp the tires anymore from a standstill. I remember my car used to put a smile on my face, but no more. No CEL. I bought a knock sensor with the hopes of putting it in soon, but have not had the chance. All sensors are original.

Should it be time already for a full blown tune up again?

Plugs
knock sensor
fuel filter
pcv vlave

Any help would be greatly appreciated.

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Your knock sensor is a big possibility. I'm sure someone else will chime in and tell you to test it. I think i'm one of the few that didn't notice a power gain from replacing the knock sensor but my gas milage got better. Definately check out your knock sensor. Many people report a huge loss of power with a bad knock sensor.

 

Knock sensor, o2 sensors or/and coils. But i bet your coils are going bad if you have a 99 model. Just get some used ones and swap them out. I replaced mine with ones from a 97 and the power came back. This after o2 sensors and knock sensor. I'm at 130k and the car runs awesome. Knock sensor and o2 sensors should be replaced at 100k. Coils on the 99's should be replaced.

 

are the knock sensors that you get off ebay good ones ??? Like this one : http://cgi.ebay.com/ebaymotors/NISSA...QQcmdZViewItem

Also whats a good place for getting an O2 sensor and whats the avg. price that they run ?? My car has been giving about 18 mpg in city/hwy mixed. It picks up decent but still my probs might be similar to urs . Whats your mileage Accordman ??

 

I have 4 of the 6 coils available if you need them.. 2 for 1 bank and 2 for the other. They list $118 each and are known to be problematic. I have the updated #s too. $185 shipped for all 4. PM me if interested.
DJ

 

Hey DJ,

I tested the coils last month and they each tested okay with infinate resistance. I don't know what you mean by updated #'s. I remember hearing that it was the mitsubiti ones that were the ones to get. I know I have the hanshin ones right now.

 

I bought one ks off ebay and it works just fine. Also you can get the o2 sensors off ebay . But I bought mine from http://www.automedicsupply.com/index.php?&make=Nissan
I got the walker type and they give a org discount so the sensors came out to around $100 shipped. If you have a non-ca model then you need the 2 upstream sensors to fix the mileage. The downstream sensor doesn't affect the mileage, just your check engine light.

 

ks
clean throttle body
clean Mass Air Flow Sensor
change fuel filter
air filter (if not done already)
.........
then plugs
coils
etc.

go for the cheap routine stuff first.

 

I'll add
- throw in 2 servings of RedLine Fuel Injector cleaner into a full tank of gas.

You may have been nicked by a fuel station with poor quality gas - causing your injectors to gum up a little.

 

sweet , that looks like a good price !! I am leaning towards denso though , just knowing that I have had great experiences with that company in the past. How do I go about getting an org discount ???

 

Just call them up on the phone and mention a maxima club price discount. They were really nice on the phone and they took my order right then. Had those suckers in 3 or 4 days.

 

why not go factory from pinnacle. when it comes to plugs, o2 sensors, fuel filters knock sensors and a couple of other things i wouldnt ever go anywhere besides factory.

 

Maxima fuel filter needs changing every 20k or so.

Go with the 300ZX Fuel Filter. It's fatter and might pop out of the hanger every now and then but its life span is double that of the max's fuel filter.

Like these other guys said, change the knock sensor. I wasn't getting a check engine light either when mines went bad. After the change there was quite a noticeable torque difference after a week of driving.

 

If the factory has a deal then I'll buy from the Factory! But the KS I bought from ebay was the exact one that the factory sell for $140. I got it for $64 shipped. The $76 bucks I saved paid for me to replace my coils.
If money was no object then I wouldn't be driving a Max, probably a Ferrari.

 

+1 on the KS! My check engine light never came on. I changed it anyway after 100k.

 

Testing coilpacks will yeild inconclusive results... Trust me I know. On my car, they tested fine, but when I swapped my so called "good" coils with my friends coilpacks per the advice of fellow orgers, my car became alive again. I have a 99 as well.

 

So was your car "misfiring" before with your original coil packs before you swapped them with your friends? Honestly, I don't know what a misfire feels like or sounds like. I have heard that also the knock sensor can be bad and still not trow a code. The other day, somehow my gas cap became loose and the CEL light came on. I brought it to autozone to see what the CEL light was about and was supprised that the car had no codes whatsoever other than the gas cap code (evap) Some people say that if it does not throw a code, then it does nto need to be replaced, others say different. I dont ahve another max to compare it to, let alone take coil packs from one to do an experiment with. My idle is rock solid and the car is quiet at idle, just a hint of vibration in the wheel when in park. I dunno. I wish I knew what pinging and misfiring sounded like so I could diagnose better.

 

basically yeah a knock wont always through a code i believe. if its bad, youll be getting pretty crappy gas mileage and lose lots of low end torque (0-3000rpms).

a misfire will make the car feel like its shaking a little bit, back and forth, usually while accelerating but sometimes while cruising.

its normal for a check engine light to come on when your gas cap is loose, just tighten that up and be on your way.

pull out all 6 plugs and take pictures and post them so we can look at them.

 

my knock sensor was bad, changed it out a couple of months ago. it took about 3 days for the ecu to get used to it, but when it did, it was like night and day on the power and gas for me!im now gettin about 390-410 miles on my tank. That is compared to the 320 i was getting before the change

 

what i do at least 3 times a year is:

clean the tb
remove and clean intake manifold
fuel filter
pcv valve
engine flush (every 6 months)
oil change at around 3500 miles
always 92 octane
spark plugs twice a year
clean the maf twice a year

But your main problem is the KS. replace the harness also it will make a huge difference.

 

But your main problem is the KS. replace the harness also it will make a huge difference

The wiring??I didn't know that needed to be changed also. I have a similar problem, but it's at 4000rpm and over...i loose all my power...kinda like choking...i did the fuel filter, complete exhaust, spark plugs(ngk plats), air filter, iacv/tb cleaning and i have a KS waiting to be installed. I thought it was the KS, but everyone is saying they lose low end power...al i have is my torque and no horse power...How do i check if my fuel pump is bad?? Or how do i know if an injector is bad?? Last but not least, would a failing differential carrier bearing to this?? I wouldn't think so, but it was once suggested to me. Sorry to be jacking the threat, but i guess it's helpfull for others...

 

all of this stuff is not only overkill its plain old stupid. and changing the KS harness makes no difference unless it is bad. it wont perform better, it either works or it doesnt.

 

Honestly, I haven't been on this board for this long, but I hear so many similar threads. I've experienced these things my self and wasted big $$ trying to diagnose and correct. Seems like we bought a car that has many variables to its proper running. I dunno, maybe its an obdII thing.

 

Crikey! If you do all of that 3 times a year, that's way overboard IMO.

 

Crikey is no longer an acceptable response due to sensetivity for Steve Irwin fans.

 

"Crikey is no longer an acceptable response due to sensetivity for Steve Irwin fans."

 

what is overkill? if you change the ks and it still bogs then change the harness too.

 

the diff? i would not think that would be it. but changing the ks harness does not hut. i went through 2 ks's and still had a car that felt like i was driving a Sherman tank. i changed the harness and it got 100x's better.

how many miles are on your car?

 

Spark Plugs twice a year!!! Insanity for sure. Spark plugs are rated to last 30K or 60K, depending if you use Copper or Platinum. "The average American drivers 12-13K," I think was last the figure I saw. Some/Most people are way to lazy to remove the intake manifold and deal with getting a new gasket. Seafoam will take care of that for me.

 

LOL you need a life. Of the stuff you listed, the ones I actually do I might get around to about once every 3 years.

But I do change the oil on schedule.

Dave

 

How do you change the KS harness? Is there an OEM part number for it?

 

Wow I would have never figured the wiring would really change all that much...and do i have to perform a surgury to the harness itself?? It sounds really weird to me, but i'm willing to give it a shot if it's plug and play...I have about 125k(miles) on it, actually i have 200500kms on it...i'll give it a look when the tranny is out

 

http://www.courtesyparts.com/Merchan...Code=22060-A32

but again there is no point in doing it unless you have changed the knock sensor and it still isnt working (after resetting the ECU). it is nothing more than a wire, so either it works or it doesnt.

 

Thanks for the link. I probably don't need to replace my harness, but I might try anyway. I replaced my knock sensor because I got a ghost code and thought maybe I was missing some power. Did not notice a difference, and the old knock sensor was not cracked so I probably wasted $80. Still, my car feels kind of sluggish to me, but that's really pretty subjective so I don't know for sure. I probably should replace my PCV valve and maybe check my coils.

Can someone describe what misfiring sounds like? At idle, my car will do this thing where once every 5 seconds or so it will make a little skipping noise like the RPM is blipping, but it's very minor. It's done this for as long as I can remember and it doesn't seem to be getting worse. I suspect that major misfiring would sound a lot worse and I would know it when I hear it.

 

clean the Throttle body. fuel filter. IAC Valve. How long ago did you change your plugs? Air filter? Clean the MAF sensor. reset the ECU is the light is on. a bad coil will usually result in a rough idle. if you have the check engine light on get the codes before doing anything to give you an idea where to begin. do them all at the same time and then see if you feel any difference.

 

another way to go about this is to repair in stages, if you plan on doing things soon take your time and replace each thing seperatly, that way you'll know for the future what causes certain things to happen with your performance. thats just an idea. cause if you replace everything at once you'll never really know what the main problem was.

 

its actually very easy to change. if you need to get one on discount shoot me a pm and i can do it for ya. but yes it made a large amount of difference. i had changed the KS first drove for 2 weeks then i changed the harness, and it drove like the day i got it.

 

i got my car in 02 with 36k on the odo. its now 06 with 170k on the odo. I DRIVE A LOT.

 

Part number for the knock sensor sub-harness is 24079-31U01. It'll run you around $20 to $30 at the dealership. Fits 95-99.

 

Today I unplugged my knock sensor harness and went off to do some errands. The car feels no different! So I'm 90% sure that the harness is bad. I replaced the knock sensor not long ago but not the harness. The old knock sensor was probably fine since it wasn't cracked. Neither of the Nissan dealers near me have the harness in stock, so I will have to wait until next week to replace it and see if it finally works.

If I'm right, this means that probably as long as I've owned the car, 2.5 years, I've had a non-functional knock sensor.... As much as that sucks I hope I'm right because then I will get a bunch of "free" horsepower....