Probably just about the dumbest question you'll see today, but it needs to be asked.

I just bought a 87 Maxima with 80,000 mi. Was reading the fuel recommendation out of the owners manual, and it said that the fuel used should have a minimum of a 87 AKI number (91 Research Octane). My question is, which of these numbers is the one seen at a gas station? Is the manual basically saying that I should only use premium gas with the car?

The car just recently developed a knocking problem (I used premium at first, then started using regular for the past week or so) that I attributed to the very old fuel filter (just changed it out 3 days ago). As of this morning, the knocking problem has ceased, but I wonder if I've been using the correct gas?

Other 2nd gen owners, does your Maxima react badly to regular?

 

yeah
If i buy 87 the car will knock because of the carbon deposits. I switched to 89 and that helped a lot. Recently Ive been using 91 and the car feels a little quicker. But generally I stick with 89 from 76 stations.

 

Depending on if you car is tuned up, and timed properly, it should run on 87. If you are like me and run a little advanced timing, then you probably stuck using premium or the car runs like total crap. I runs 92 all the time. My car didn't take well to 87 or 89. Especially when it was warm out and the car was running a little warmer.

S

 

my car used to knock no matter what, i think it was running 15%+ rich though so i just stuck with 87

 

First off, thanks for the great responses.

Drjmaxx88: After hearing that, I definately think octane was the problem; I was originally using Hess regular (which has a octane rating of 89), then switched to regular at the local "Gas N' Gulp" that bottoms out at 87. I'll have to make an effort to have the carbon cleared out of the throttle come to think of it. Would you recommend the use of Seaform for an engine of this age, or should I take it to a dedicated shop?

maximase86: Did the tune up myself recently, changed out your standard parts except for the distributor cap/rotor, and the O2 sensor (going to replace the PCV valve tomorrow. Having a bit of a time fiding it in the manifold though.) Your absolutely right about temperature being a factor. The car just stopped knocking when I got off of work 6 this morning, when it was about 50F out, and it wasn't an issue. About to hit the road in a few minutes, wonder if it'll be an issue. I'm at 80,000mi I would guess I should have the timing redone.

What are the benefits of a more advanced timing?

 

I used seafoam in the throttle body to just clean it out and it worked so far. I haven't used it in the motor oil, but I will when I go for my next oil change. My car has about 240K on it right now and it still can haul A S S.

 

Running rich doesn't cause you car to knock. What causes it to knock is either running too lean, or running too advanced timing, or the engine is running far to hot plugs.

S

 

Seafoam is awesome, I used it on my car and it currently has 205k miles on it.

When you did the tune up, did you check the timing? I can't remember exactly, but the stock timing is about 20-22 degrees...but don't quote me on that. I do advance timing to get a little more out of my motor in combination of the mods I have running. You can advance the car to 24 degrees, and squeeze a couple ponies out of the car. Downside is you HAVE to use 91 minimum octane to keep from detonation (knock).

S

 

I neglected to check the timing. I'll set aside some time for that next week.

Also, your comment about running too hot plugs made me realize something. I was actually running an old set of NGK plugs (probably the set that originally came with the car in 87. Owner was very "guh?" about maintenence), then swapped those out for a new set of Bosch Platinum plugs and wires. Come to think of it, I think the knocking problem started about an hour after I changed them out...

Could the problem lie there?

**Edit**

After doing at little web research, it starting to look as though the Bosch Platinum plugs are pieces of junk compared to the same NGK plugs. Looks like I'll be paying a visit to the Nissan dealer to buy a new set of plugs this weekend...

 

I use 87....I am sure my car would run a little bit better with higher octane, but I do not use my 87 as a performance machine at this point. I am also very good about regular maintence, I do not see myself changing fuel grade unless I have big problems associated with it.

Also about running rich, a bad PCV valve can cause that. When standing at the front of the car the PCV valve is located in the center on the back of the Intake manifold...its easy to see...it just screws in.

And for your correct timing setting it is posted under your hood on one of the stickers. And beware of what the Haynes manual says for you timing setting, because when I compared that to what my car actually called for it was off by 5 degrees.

 

It could be the NGK plugs are one step too hot. You might try running a colder plug.

S

 

Okay, maybe this is a dumb question, but can some one explain "hot" and "cold" plugs?
Thx

 

I forgot which one is what, but it actually is dependent on how long the threading is for the plug. That will effect how hot the plug operates. I notice that the boosted guys go with one or even two step colder plugs than stock. I believe running hot plugs is for if you do a lot of short driving, and the colder plugs are for longer driving, or for more heavily modded cars.

S

 

no the o2 had gone bad and we had adjusted a bunch of things....that what came up in the diagnostic...

it wont knock any more...well hell it wont start, but new cylindar heads are on the way and the existing cylindar heads are not to damaged so i am going to keep them and umm...."fix" them up

 

You were absolutely right when you said the engine shouldn't be knocking from using lower octane gas alone maximase. I went ahead an installed a set of standard type NGK plugs over the Bosch Platinums I had in there, and the knocking problem completely disappeared.

I'm going to go ahead and switch to a higher octane gas anyway though, just to see what (if any) performance/efficiency gains there are to be had.

Going to change the PCV valve, check the timing, and throw some Seafoam in this thing on the weekend. Where is the brake booster hose located to suck the Seafoam into the throttle?

 

my opinion, if you are going to use the car like I do (just regular diving) then just stick to 87 and take care of all regular maintenance...I am a big fan of BG44K and I also will use seafoam on occasion. When it comes down to it I am getting better gas mileage than plenty of people on here and I am only running 87. I also run stock timing...if you advance it 800 degrees like sarin then yes you should use higher octane....I am doing fine on 87 myself.

 

Interesting, this is like the millionth person that had problems disappear when they got rid of the Bosch Platinums they had in the car! Either way, glad to hear that fixed the problem. Did you get to play with timing at all?

Niku-Sama: Well a bad O2 doesn't mean you will go 15% rich. It's proven fact that running rich doesn't make your car detonate, else the boosted guys wouldn't be purposely running rich to prevent thier cars from knocking. I could understand maybe a bad O2 causing you to go lean. Either way, you have an entirely different issue going on. Good luck with that.

S

 

Bosch sux for our cars. I just took the bosch O2 sensor out of my car. I can feel the difference in the way the car drives its already smoother. I had those spark plugs come to think of it, when my car knocked it was with the platinums. Thats weird.

I think its the longer the insulator the hotter the plug. I wonder if I'll have to change plugs when adding a MSD SCI? I think Id have to increase the gap a little too.

 

Probably not.

 

I'm wondering if there's even a big enough benefit to my advancing it, as its an automatic with a completely stock setup. Would upping the timing really be worth it?

Also, know of any guides that explain how to go about inspecting/adjusting it?

 

Well if your modded, and want to tweak a couple extra ponies out of the car, yes. But being stock, I don't think it would be as good to do because now you have to buy premium, and that starts hitting the pocketbook....and if your not planning mods in the future, then it's probably a useless deal. However I was wondering if you we're able to check your timing to see if it was off, but it sounds like the plugs were your problem.

S

 

Alright that makes sense. I've heard of 'hot' and 'cold' plugs, but didn't really know what it meant. Thanx.

 

hahaha Carson! 800 degrees should have my car running 9021hp at the lower outside CV Joint!

S

 

Yet another goofy question (sorry, I'm 20 and just getting into cars.)

When checking the idle RPMs to see if the timing is off, should you do so in park, or drive? In D I get about 800rpm, in P I get 1000.

 

Don't worry about goofy questions. I've always been into cars, but I've never had the opportunity to learn how to fix them.

Besides, there are no stupid questions, just stupid people.
j/k

 

To check the timing you will need a timing light....you will have to do this in the dark, and you do it from the front of the car (not while driving)....the procedure is outlined in any of the service manuals...I pulled my passenger side wheel off and marked the pulley at the proper spot to make it easier to see with the timing light....and you correct timing is listed on the inside of the hood on a sticker...hope this helps.

 

I prefer to time my engines by ear, as opposed to with a timing light. The factory spec can even be a little too much advance in a tired high mile engine due to carbon buildup. So what I do is let the engine idle and adjust the timing to get the fastest idle, but without making the engine stutter. Then I take it for a spin, at W.O.T. and listen for detonation. If it doesn't ping, I advance it some more and test drive again. I just keep doing this until it pings, and then back it off a bit. Then I know I'm running as much advance as I can without detonation. It is also quite acceptable to hear a SLIGHT pinging when going up a very steep hill, on very hot days, Or at W.O.T. at a low rpm. Just a very faint ping. If it sounds like you have an engine full of marbles, that's not good, and will destroy your plugs, and in extremely bad cases can melt the tops of the pistons.

Rich vs. lean: Running a bit rich will do nothing but foul plugs, but running lean can be harmful to the engine. Having more oxygen than fuel will create more power to a small extent but is really hard on the upper cylinder. Lack of lubrication up there will wear things out pretty quick, and do some serious damage. I wouldn't toy with mixture settings, rather make sure the o2 sensor is working and let the ecu figure that out.

 

My dealer only sells the new O2 senors for 2nd gen Maximas, that are mad by Bosch.

Ugh.

I really don't want to do that when I know in advance it will cause headaches. Is there anywhere online I can order the O2 sensor made by NPK? If not, does anyone have experience with the Walker brand of sensors?

Also, I can't remove the sensor with the parts provided by AutoZone. I socket was size 7/8'', I believe 28mm. Do o2 sensor sockets come in smaller sizes?

 

well I have the bosch in my car, and I am getting 300+ mpg in town. The guy that is ******* the Bosch is getting 10mpg...I dont think his problem is an 02 sensor...but thats just a guess. I would have gotten an NGK but they seem to be a pain to find and the local napa store had bosch in stock for 50 bux, and they are not on oxygensensors.com, so I stoped looking.

--also I have the 7/8's 02 sensor socket from auto zone as well, and it works fine...I just had to un screw and bend some stuff out of the way to get the socket on it...also I did this from the bottom of the car while it was on ramps.

 

there is a link to it on the yahoo club site. Sparkplugs.com or something. They sell the ones you want.

 

He drives a car thats the same generation as mine. You drive a '98, for which Bosch O2 sensors are the default. The second gen's come with NGK sensors. I'd be more inclined to listen to him.

Sarin, your thoughts?

 

To be clear my cars man. date is 8/87. I don't know if it has the same O2 as yours. Because yours was changed mid year I think. Im sure sarin knows.
Bosch alone was not the problem. Though it didn't help any. I can feel the difference in the gas pedal. With bosch I couldn't tap the throttle and get the car to move. Like in traffic you can go 5mph for 10+ miles. With the bosch it was go,stop over and over again. With the nissan OEM one it feels much better. I can just coast at 5mph. The car feels more fine tuned so thats why I don't like the bosch. To say it caused my car to run crappy isn't fair, because there were other things that helped. But from my experience I wouldn't use it for the 88 max. JMO

 

Oh, I know the Bosch sensor wasn't the only problem for you. I've been reading alot of your posts and realize that there are other factors affecting your performance. However, going by my experience with using Bosch over NGK with the plugs and getting negative results I'm more inclined to just stick with NTK(NGK) on the o2 sensor as well.

 

I would agree with the NGK thing but I was having touble finding them...and just to clarify I have an 87 as well as a 98....thats why I post here

 

To be honest, usually the only thing that doesn't work well from Bosch in these cars are the plugs. Especially the platinum ones. I've heard it all from rough running, to crappy motor response. As far as other things by bosch, like o2 sensor, they probably aren't bad at all. Of course I would be more inclined to use NTK by NGK, but as Carson said, sometimes not everyone has the luxury of finding them. (For instance, I have a hell of a time trying to find NGK wires). But if we had Bosch o2 sensor for OEM sensors, I would probably be pushing those.

Now as far as Dwayne saying not to use them, it's more of a matter of preference. He seems to notice a difference between the 2 in his car....but his car has a whole batch of other problems to go with it. And I don't think an o2 sensor is affecting it as much as he might say, simply because his problems still exist regardless of what o2 sensor he went with. I mean look at this way, it gets 10mpg before changing the o2 sensor, 10mpg after the bosch one, 10mpg after the ntk one...but it runs a little smoother. The question is, will he notice the same difference if his car didn't have any other problems that could affect this?

S

 

True sarin but for one point.
My car got well over 200 miles on 13 gallons. Which hasn't happend since jan/04. Thats the kicker the trany went out as the mileage came back. So that blows.
Also the OEM O2 sensor is about 98$ from the dealer, but from sprakplugs.com the NGK are about 60$. I would of got one from them but I couldn't wait at the time. I changed the O2 39 miles into a full tank. I went 217 then I filled up. I only needed 13 gallons to fill up. So the next tank I would of gotten much better. But I'll never know.


Dwayne?
Oh yeah the sig!

 

Oh yeah
And about the would I have noticed part. When I changed the O2 I still had the intake leak. There was a noticable difference in the O2 sensors. Like I said before the OEM one felt much smoother. I got resistence back in the gas pedal. The bosch sensor I would have to mash 1/2 way to go. Take it as you will but the NGK/OEM are way better than the bosch.

 

i got one that works well made by some other comany that starts with a B, i cant think of it though