it wouldnt go bad because of the use of the wrong octane it goes bad cause its old

 

wheres your dad a mechanic at if you dont mind me asking?

 

Exactly. No rush to replace it. You can drive from NY to California with a bad knock sensor and no harm will be done to the car. The ECU just dials back the air/fuel ratio and chills.

The only reason you want to replace the knock sensor is to maximize your performance when you use premium gas, 91 octane or better. If you plan on sticking with 87...leave the knock sensor until some other time. It is no biggie at all.

The knock sensor code does not generate a check engine light. It's a ghost code that hangs out until you're ready to deal with it

DW

 

UPS facility in Addison, or... another place, I forget which one. He switches around between the two of them though. Hes been working for them for 32 years.

 

Alright good, thats what I thought. I received a bunch of old service records when I bought my car. So I was looking at them last night and the knock sensor was actually replaced less then 30k miles ago. So more likely then not, thats not the culprit here. I also noticed that two oxygen sensors on my car have been replaced within the last 50 k, accept... the one near the front of the engine. I've got a hunch I know what the problem is . Filling her up with premium later today too, we'll see how it goes.

 

That's too funny.....all the O2s were replaced except the one that really matters

DW

 

haha my roommate used to work there, i didnt realize your like a half hour away from me

 

maby it wasnt bad whn they replaced the others

 

Haha sweet. If I was going for the mechanic profession, I would definitely want to work for UPS, the company has been great to my dad. Yeah man I pass through Carol Stream all the time.

 

Alright well I changed out my fuel filter today. Good thing I did too, when I turned it over a good amount of brown and black gunk came out. I'm pretty sure it was the original filter too, it was corroded and said made in japan on the back of it. If it had been changed at all in the last ten years it most likely would have said made in china on it. As soon as I got in my car and pulled out onto the road, I immediately noticed a difference in my cars performance, it was much more responsive. I can't tell yet how much it'll affect my fuel economy but it feels good to get that done. Tomorrow I'm changing out the front o2 sensor and already have a cat delete pipe and resistor shipping in the mail. The cat on my car is definitely the original one, it looks like total ****. As soon as I get that changed out I'm sure its going to make a huge difference in my cars performance. I'll update again once I get all that done.

 

Curious for your results tomorrow. My car has horrible mileage as well. May follow suit on fuel filter and front O2 this summer.

 

When CATs go bad, they clog. Clogged CATs lose power, especially on the highway. If you feel some decent power, it may still be OK.

Original fuel filter, huh? Wow I feel sorry for your fuel pump.

DW

 

Good that you changed the fuel filter. Not sure that it will solve your problem entirely but it may, and certainly won't hurt. Remarkable that it possibly hadn't been changed, ever (I have a really hard time believing that but who knows, it's possible).

I didn't read the whole thread because I'm not that dedicated, but gas mileage usually deteriorates in the winter months. Just something to be aware of. Now, 26mpg to 18mpg or whatever you said it was now is pretty significant and much more of a change than I've ever seen, but it is a factor you might think about and see what happens with your mileage as they get away from winter blend gas around here.

 

The fuel filter that I had on there before was an OEM filter, I checked at a Nissan dealership and they were both the exact same. I have service records for my car going back to 3k miles, and none of them show the fuel filter was changed. So I'm pretty sure its the original filter. I'm not going to be able to get my o2 sensor changed or cat changed out till later this week, my dads using the garage to rebuild an engine . As soon as I get everything done though, I'll make sure and update.

 

Problem solved! It was the fuel filter! I calculated my fuel economy before changing it using premium gas with conservative driving and averaged 19 mpg. This is my first time calculating it after changing the fuel filter, and using premium gas with the same conservative driving averaged 24 mpg . I haven't even changed the oxygen sensor or the 15 year old cat yet though. I'm still debating whether or not to change the o2 sensor, it looks fairly new, but I'm definitely changing out the cat. Hoping to gain another 2-3 mpg from just that. Thanks for all the advice everyone.

 

DEFINITELY change out that front O2 sensor. My front O2 sensor appeared very clean and new looking as well. I was getting 22 mpg highway, so after reading this thread I decided to change that front O2 sensor.... I bought the O2 sensor on eBay for $23 and installed it in a couple minutes. Couldnt be easier.

After driving 300+ miles back to school today, I calculated 28 mpg (going 75-80 mph most of the way down i95). For me, a 6mpg improvement for $23 and a couple minutes of my time was definitely worth it.

Here's the link for the sensor i purchased: http://www.ebay.com/itm/NEW-DIRECT-F...0b393d&vxp=mtr

 

Agreed.

Change the o2 but leave the cat. Alone

 

I'm on it

 

Well I changed out my O2 sensor, even though my dad said it was a waste of my time and money if it wasn't throwing a check engine light . It was only $23 for a brand new one, and I couldn't resist an opportunity to toy with my car. I took it for a drive right after changing the sensor and just like after changing my fuel filter, noticed an immediate difference in my car's driveability. It was much faster, more responsive, and actually shifted quicker then before. Very happy that I changed out that part for a new one, well worth the time and money. When it comes time to fill up the tank again, I'll calculate my fuel economy and see if it makes a difference. Thanks for the suggestion.

 

give it one or 2 full tanks on the new o2 before you calculate it

 

It doesnt NEED to be replaced just because you use low quality gas but over time when low quality gas has had an affect on the engine internals then it only makes sense that the knock sensor wouldnt be working as well as when it was new. Some people claim their car is almost brand new after the KS install. Probably a placebo effect but it does help

 

So where's my other thank you? I said you're welcome twice.......way back at the beginning of this thread

I bet you get 29-30 mpg easy on your next tank.

DW

 

Got a link to the O2 you bought?

 

Hey now...I called fuel filter before you! Punk!

 

gettin everybody else to find deals for your winter eh? noyce

 

http://www.ebay.com/itm/NEW-DIRECT-F...0b393d&vxp=mtr

 

Alright, will do

 

Yeah your right, over time the sensor does wear out. I have old service records of my car though and mine was replaced about 20k miles ago, so I'm not worried about it failing anytime soon.

 

Haha that thanks was meant as a general thanks to everyone who suggested to change it, but since you were the first to suggest it, thank you Dwapenyi. Realistically, I'm expecting to average 26 mpg, but 30 mpg would be a dream come true. I bet its possible if you draft behind every large truck haha.

 

Yeah, here it is.

http://www.ebay.com/itm/NEW-DIRECT-F...sories&vxp=mtr

I wanted to buy one from a local auto parts store, but the cheapest I could find was one at napa for $85... and it was the same brand as in that ebay listing! Some other stores were asking $110 or $120. Crazy.

 

So now that your dreams of a 4cylinder Maxima have been quashed, how much gas mileage did you get for your 2 tankfuls now that you've changed the O2?

DW

 

The wire on that O2 sensor looked pretty short in the pic, were you able to plug it in- was it long enough?

 

use better fule i use 93

 

I should've known you would bring this thread back up haha. Believe it or not, my fuel economy actually went down to 21 mpg. But that also may be because of the fact that I removed my cat and didn't use an O2 simulator in place of the O2 sensor. I have an O2 simulator on the way so we'll see if thats the culprit. Yes, the O2 sensor has a long enough cord to reach the necessary connector. You may have to wrap it around something to hold the cord in place though instead of using the little clips like on the old cord.

 

Yes, it was long enough. You may have to wrap the slack around something though, like the coolant pipes in front of the engine, because it doesn't come with clips to plug into the spots where the old sensor cord did.

 

So, dwapenyi, funny enough that you catapulted this thread back to the top page because I was going to make a thread about how its possible to average 31.4 mpg in a 4th gen maxima... and I know it possible, because I have done it! I was reading some articles and watching some videos about hypermiling (I know there are guys on here who don't give a **** about fuel economy, so those of you that don't, stop reading. Otherwise, read on.) and I decied to experiment with it myself. Heres what I changed about my driving habits:

1) Maximum speed of 5 mph over the speed limit

2) Very light use of the throttle, don't let your engine rev above 2k rpms for an extended period of time

3) Always keep the momentum of your car going (follow far behind other drivers because they may turn soon, instead of breaking just let off the gas, use the most straight line possible when taking turns, etc.)

4) When you know you are going to be coasting down a hill for an extended range, turn your car off completely, but then switch your ignition back into the on position so your tachometer records the distance you have traveled)

5) When you know you are going to be coasting or sitting still for an extended period of time, shift your car into neutral if you don't want to turn your engine off.

These are the 5 basic rules I used when driving my car on the last tank, and over 502 miles I used 15.982 gallons of gas. Well, when you divide 502 miles by 15.982 galllons of gas, on average, I traveled 31.4 mpg on a gallon of gas. Oh and by the way... none of these miles were highway miles. I didn't drive once on the highway on this tank of gas. Oh, again, by the way... my car is a 4 speed automatic, with no weight reduction at all. It would be interesting to see what someone could achieve with weight reduction, a 5 speed manual, and some highway driving. So, for those of you who won't be racing during the week, and want to get a few more mpg while making the trek back and forth to work, try this method out, and I think you'll be thoroughly surprised.

 

Good to hear. Given that you got this good gas mileage from city driving, you would have done better on the highway. The longer a car stays in top gear, the better the gas mileage.

Also, oddly enough for the 4th gen, the 5-speed manual actually gets worse highway mileage than the 4 speed auto. its only 1 mpg, but still. I dont care. 5-speeds r-o-c-k.

I don't see how, though, removing the cat killed your gas mileage. That's weird.

DW

 

I know it does seem weird. I have been told that if your O2 sensors detect that your cat isn't working properly that they will not retard or modify your timing or engine performance in any way, and I heard that from a couple of people, but that just sounds wrong to me. Anyways once I install that O2 simulator we'll see if that was the problem.

 

number 4..... NEVER turn the car off while moving...holy hell! First of all, IF you do it, you have to do it in neutral, which you don't mention. Also, hope to God you don't have to turn quickly or brake(good luck doing it with no power steering or power brakes)