JoshG

So the past 2 years owning this car with 132k miles now, I didn't drive it much, 3k miles a year and only driving around town, driving with 87 octane gas.

It drove okay, every time I stepped on the gas, It would not pass 2k RPM when driving/ at a complete stop. I even tried multiple times trying it

Now that I have a new job, I have been starting to drive on the highway and using 93 octane gas for atleast 2 months now.

after a while with the highway + 93 octane gas, I step on the gas from a complete stop.. I can Rev the car up to 4.5k RPM! It felt alot better to have atleast a 4.5k RPM limit than 2K, I have done this a multiple times revving to 4.5k RPM to see if it really was just not a one time thing.

I don't know what happened but I guess Highway + 93 octane did a positive thing to my car?

And yes I have been told my Mass air flow sensor was bad when I couldn't rev 2k RPM back then, didn't really bother with it cause the car drove fine and didn't drive much anyway.

but now that I can rev to 4.5k RPM, I guess theres no need for the air flow sensor now. The car drives great and quiet.

I find that weird, because I didn't replace any parts or anything.
but I like it!

96i30azn

Your car should've been fine on 87.... It baffles me how changing gas raised your rev limit, but it equally baffles me that an engine limited to 2000rpm was somehow "drove fine" to you and that you can drive on the highway limited to 2000rpm.

JoshG

well when i mean drove fine, It didn't drive weird or anything, I just was driving around town. But like i said I am confused as well, because I know that if an engine is limited to 2k RPM it wont fix itself magically unless I replaced that part that was causing the problem.

When im driving on the highway, it stays at 2,500 RPM going 70 MPH

I do notice differences after driving on the highway and using 93 octane gas for a while and that is being able to rev to 4.5k RPM from a complete stop. I couldn't do this before when I was using 87 octane gas... I know they say 87 octane would be fine and doesn't effect the car, but on the gas tank it says that premium fuel for maximum performance.

maximaham

iTrader: (1)

I put 87 in my max and cel came on. Put octane booster and it went right off.go figure.

kjlouis

Odd...run codes. Side question. You said 2.5k@70mph? Im not sure why but mile will run between 2.3k-3.1k at 70mph and its a stick.. Can't make sence of it. It doesn't change on the fly some trips is closer to 2.5 some closer or slightly past 3k

CMax03

iTrader: (3)

MAF maybe? Maybe TPS?

JoshG

well my cel light never came on. don't know how gas would trigger the cel light though. I do know it works cause in ignition mode it shows up.

JoshG

I have been told that a year ago when I questioned why I couldn't pass 2k rpm

But even if it was the throttle position sensor.. it has to be either one of them

when im in park, I can rev to 6.5k RPM If i wanted to.

but now after what I have done with the highway+ 93 octane, I can finally drive and rev to 4.5k RPM from a complete stop.

quite strange if u ask me.

maximaham

iTrader: (1)

I'll give 87 a try again and let you guys know if my cel comes on.

dwapenyi

iTrader: (3)

You should buy one of those OBDII pocket scanners to see if the engine computer is storing a knock sensor code. If it is, then you are not feeling the car's full potential when running 93 octane.

You could also go to autozone and have one their staff read your codes for free.

dwapenyi

iTrader: (3)

The automatic is geared better for highway cruising than the 5 speed...EPA highway numbers are 1 mpg better for the auto. The 4AT does sacrifice performance compared to the 5MT, though. Especially on the highway.

JoshG

my guess is that when I ran 93 octane for a while, my knock sensor is still good and is giving my car its full potential for maximum performance?

hence thats why I am able to rev to 4.5k RPM without me replacing any parts.

njmaxseltd

iTrader: (19)

No.

The thought of octane ratings changing the rev limit (which points to a problem in this case) or even shift points under normal acceleration is completely ridiculous.

The average driver would never feel the difference between 87 or 93 octane fuel.

Jor

Did you flip your MAF or something

JoshG

Well I don't know what happened either way, I like it regardless Being able to rev to 4.5k, I did it twice today again.

And no I did not flip my MAF, not a single thing touched under the hood.

surban1

iTrader: (17)

could this be an instance of the infamous and fabled "Italian tune-up?"

JoshG

Probably yeah lol

maximaham

iTrader: (1)

I did replace the knock sensor when I purchased the car. The knock sensor was on it's way out when I used 87 gas. It was a pita to do with my big hands.

JoshG

Well haha just great

2 days ago, my brake lights were on at all times when driving and even when the car was off. my brake switch underneath the pedal was loose/stuck but either way that was fixed.. drained my battery completely of course, took 15-20 min to charge to start the car

a day later, my ever first check engine light comes on after 2 years owning this car,
went to go check it out asap

codes 0400- EGR
0325 - Knock sensor

Gotta clean up the EGR as it probably is clogged up, and clean other stuff like MAF/throttle body/etc
Knock sensor is a ghost code I notice.. but I heard a fully working knock sensor is a good thing for a car for full response.

2 good codes I have here.. I can potentially restore the acceleration and speed, Clean up the gunk... got to give it an oil change.. I am off all week this week now that I have time. great time for check engine light to come on.

As I have may know, for knock sensors, I hear people buying them on ebay, but could I buy them off autozone?

The 4th gen maxima is sensitive to aftermarket parts, and only works with OEM parts

if anyone has the link to what OEM parts must be replaced if the part is broken, and what aftermarket parts I can use please post it. I would gradually appreciate that.

JvG

I purchased my knock sensor from amazon.com for about 30 dollars. The differnce was detectable immediatly. More power, and faster reponse. It has worked for me for two years now.

JoshG

Which one did u buy? does it matter what brand it is? aftermarket or oem?

njmaxseltd

iTrader: (19)

It's physically impossible for a ks to detect the fuel grade you use.
It detects pre-ignition, which causes engine knock and ping.
Using 87 in a VQ does not automatically cause knock and ping. The average driver is using regular when they fill up., especially when fuel prices are high.

Pre-ignition happens when the fuel mixture in the cylinder ignites before the spark plug fires. This does not automatically happen when you use a lower grade of fuel. Conditions in the cylinder such as high heat and/or excessive carbon build up need to be in place to ignite the fuel on the compression stroke before the spark plug fires.

JoshG

Just ordered a knock sensor from ebay, that had so many great views, over 450 sold

HQRP Knock Sensor fits Nissan Maxima 1995 1996 1997 1998 1999

only 11$ and free shipping, i even looked it up on amazon as well, nearly same price and item.

once I get that, I'm heading to the mechanic to get that sensor replaced, and EGR cleaned up/clean up maf..thorttle body etc. as that is what triggering my Check engine light. might as well get the ghost code in the way.

I'll keep yall updated to prices and take before videos/after videos of how the car runs.

96i30azn

Maybe he does have carbon buildup causing a high propensity for premature ignition which is partially alleviated by 93 octane?

JoshG

indeed ^ weird after some-time after using 93 octane, It did run better I will say that.

but after what has happened and check engine light turning on, I think replacing knock sensor and cleaning up EGR will give me its true power that it is looking for in 93 octane I have been using since.

Car does run sluggish at times such as when i push the pedal, it wont pass 1.5k rpm(and this is when I feel something is being clogged up and air is trying to pass through it but cannot) unless i step on the breaks then the gas it will proceed to 2.5k-3k+ depending how much i push the pedal

I usually go to a place where they are mechanics that are over 30 and been working there for years, going to ask them for the old knock sensor part and putting in the new one, so I know for sure they put it in... then EGR I'm going to ask them to show me the EGR valve and show the carbon build up, to make sure they are doing the job...

I have receipts for the codes.. so that should take care of it either way.

JoshG

this is my idle/revving in park, it does rev up there pretty quickly being that its stock. Need to do one when im driving(quite dangerous but will find a time to do it as i hate texting/recording while driving). but that'll be up after I fix the EGR and replace the knock sensor this week.

https://www.youtube.com/watch?v=oCjY...rIrvCQ&index=1

dwapenyi

iTrader: (3)

You really want to clean your internals, try tcw3. There's a thread on org here.

jholley

iTrader: (13)

^
Along with adding in TCW3 give it a Seafoam treatment.

1) 1/3 can in full gas tank
2) 1/3 can added to engine oil
3) 1/3 can sucked into air intake using the brake booster vacuum hose

Do some searching and you'll find the guidelines for a seafoam treatment. Also change the oil ~150 miles after adding seafoam to the oil.

Give it an Italian tune-up by driving 45mph in 2nd gear for several minutes.

My rpm needle used to bounce like crazy during idling. The rpm use to reach 3000 while driving 70mph. Performing those treatments (seafoam, Italian tune-up, TCW3) it now idles smooth as silk and only needs 2500 rpm to drive 70mph. It no doubt removed that carbon build up.

EDIT: Using 87 octane for nearly a decade is how my carbon formed. Since those treatments I've used only 91 or 93 octane for the past 5 years. The manual suggests 91 octane because they didn't offer 93 octane when these A32s were built.

96i30azn

From the video, looks like you fixed whatever the problem was... mine doesn't do any better than that. I would just leave it alone... unless you want to play around.

Edit: here's what mine looks like.

JoshG

well when i recorded that, it was the day before i got the check engine light

However with the 2 codes, i can still do that in park and it idles very quiet in idle/park. my car in drive is starting to run rough a bit( Able to rev to 3k-3.5k rpm but not smoothly), just waiting for my knock sensor to come in and then the mechanic will be able to do the 2 jobs.

I don't see any difference when you did yours? it looks like once u hit the pedal, the RPM delays and does its action 2 seconds later? am i right?

96i30azn

There's no 2 second delay dude - that's a long time. Delay maybe 0.2s - about as much as you'd get in any other car, video was meant as a control.

Last time my car threw a KS code was like 4 years ago, didn't notice anything driveability-wise. Probably should've saved my money as the KS is known to be a ghost code on the 4th gen.

JoshG

knock sensors are cheap now, so it doesn't hurt to get rid of the ks code, as every sensor is important for the car to operate properly.

JoshG

I went to the mechanic I always go to for repairs and there was alot of people today, So i dont know if they were doing their "business money chunk where they charge a ton" but...

I was quoted 3.15 hrs for knock sensor replacement for 280$ ( i already have the part in hand) 13$ part from ebay HQRQ
1.2 hrs for EGR cleaning, 80$ I was like ... Lol I've seen people replace knock sensors in 20 mins, he told me then "i mean u can do it yourself if u want"

money isn't an issue but I believe that they're charging me 85$ an hour for labor.. which is crazy, but does this sound right to yall? They are street mechanics age of 20-35. a small shop that does all kinds of work/sells mufflers/sell rims/does suspension work/lowering cars/mechanic work under the hood/mostly a tire shop to replace tires. they are not those professional business such as midas...etc I would of done it today but didn't have time for 5hr wait cause of an event to go to today.

also revved to 4k rpm, heard knocking and retarded the timing, hence bringing my RPM down.

The Wizard

iTrader: (43)

What year is your Max? If you have a 99 Cali spec Max, then $280 is fair. Any other year you're getting ripped off.

Please update your user cp profile information to include the year of your Maxima.

JoshG

96 maxima, as u can see in the pictures above. whats so different about the 99 cali spec max?

The Wizard

iTrader: (43)

swirl valves get in the way of changing the knock sensor. On your Max, changing the KS is a piece of cake. Do it yourself.

Update your user cp.

PH98I30

I have a 98I30. I changed my knock sensor in about 10 minutes without removing any other parts. There are you tube videos on this. You might get a few scratches on your hand.

JoshG

What differences did u notice after replacing the knock sensor? Did u use eBay knock sensor?

From my research most cars are hard to get to the knock sensor, and I think the mechanics have the computer giving false labor hours in our cars, luckily on these cars it takes 10-25 mins to replace, but I hear other cars it takes hours to get to and replace, so that's what I think the mechanics are misunderstanding that it takes 10-25 mins for
This car.

And Egr cleaning is an hour from them, which sounds reasonable, but knock sensor.. Hell no

JoshG

Went to a junkyard 60 miles away from my place, called junkyard to junkyard to find any maxima's in their junkyard, many of them had none, some were already parted out, there was not many maxima's in my area surprisingly.

lucky I found one front ended, bought the 97-99 trunk in great condition in black no dents or dings for 150$ she straight up told me $250 until I showed her a text from the yard saying it would be $150 and then she said $150 then. and as well bought the 97-99 bumper she said $159 but since I was buying a trunk she sold it to me for $90, they also gave me a free 97-99 grille too! needed those as well.

Got a really good deal as the condition these parts were in, Ebay they sell these parts for 150+$100 shippin always..saved me $200 goin to the junkyard.

Painting em all pearl white even the chrome grille(not a fan of chrome grille) and putting on the smoke or clear taillights, deciding which one to put on.


And Also trying to find a mechanic to do my knock sensor and EGR Tube 0400 code Job... But what I tell them about the quick method to replace the knock sensor, they wont just listen and say it will take them 3 hrs to do and EGR 1 hr, costin me $300 for the job.. some mechanics dont wanna listen and just want the cash.. But in a couple weeks when I get more cash in then im going to just say fck it and let em do the job for whatever price honestly.. lol

Im not in a rush to do it but I have heard stories that some people on the forums have had the knock sensor and EGR 0400 code for 2 years... no harm to the car just less MPG and less power in the car when accelerating and such. runs fine on the highway and city.

I would do the knock sensor myself, but knowing my luck I would screw something up or drop the sensor somewhere when I try to install it back in. As I have no experience doing under-hood work. For the EGR I have to have a mechanic to do that..

The Wizard

iTrader: (43)

You need to have a little more faith in your abilities. I bet you could do both jobs no problem. Especially the KS.