I have a question have anyone ever tried to remove a knock senson on their maxima?

 

yea, but the engine wont really run without it. You can replace the knock sensor with a resistor that reads the same resistance as the knock sensor itself (when it is in perfect condition) which means the KS will never go bad, you want have to pay for a new one, etc. but that also means that your engine will have no idea if its knocking, and wont be able to fix itself IF it is knocking

 

It will run. The timing will be retarded though so you'll be running in "safe mode".

 

i just meant that u wont want to drive it like that

 

as long as you are running 93 fuel, why should it be an issue? If it's knocking enough, you'll know...and if you're that worried, an SAFC-II will tell you if it's knocking. If you're doing proper preventative maintenence, using good stuff, you shouldn't need it, that resistor will do the trick

 

If i'm suspecting that my knock sensor is bad and if the engine will still run in "safe mode", could I disconnect the sensor to see if it makes a diff and conclude that if it doesnt that my KS is bad?

 

If you think it is bad it most likely is, but unless you want to spend a Min of $90 (installing yourself) to buy a new one on a hunch, then I suggest you scan you ECU. If you don't know how there is a very detailed write up in the stickies, it will take about 5mins even if you have no idea what your doing. or just bring it to a autoparts store, they will prob do it for free.

If you dont want to install it yourself, I have heard outrageous claims of what the dealer will charge... once I heard $750!!!!! This is because when the dealer does it they take off the intake manifold, you on ther other hand don't have to. I plan to do mine this weekend, Ive heard it takes about 1/2 hr

 

because the highest in SOME states (ca) is 91, and it is 2.20 a gallon

 

so where do you get your 93 octane?
the highest octane gas they sell here in AZ is 91

 

get some octane booster, here in FL we have 93 octane

 

does that stuff really help?

 

so i've heard.... tryit out..only a couple of bux..

 

Ha! You guys always make fun of us NorthEasterns for our snow and cold weather, but we get 93 octane and 94 ultra in sunoco. . .. I couldnt even tell you where to get 91 around here.

Look on ebay, you can get an OEM Knock Sensor for $90, alot better than the dealer's $160.

 

If it's diconnected the ECU automatically retards the timing. If you disconnect it there should be a difference, if not it's busted. Even 93 octane can get knock. The resistor is a cheap, unsafe alternative.

 

that is a stupid idea octane booster is expensive, and using it constantly every time is pointless to me. Use 91, thats the best you can get

 

well, i could get 110 octane racing gas for $5.50 a gallon but that stuff is leaded

 

What happens if you use above spec fuel? I always fill up with 96 or 98 (NZ$1.07/L). My ECU gave me the code for a knock sensor the other day, so does this mean I'm pretty much wasting my money filling it with 96-98 if it just assumes I'm running 91?

 

Aside from a bad KS, it's possible that your engine really is knocking and causing your ecu to store 03-04. In my car, I would reset the ecu, and the 03-04 would come back shortly thereafter. I always run 93 octane and figured it was a bad KS because I never 'heard' the engine knock. Before replacing it though, I conducted a TB cleaning as described at motorvate.ca, sprayed AMSOIL intake cleaning foam into throttle body w/ the engine running after the TB cleaning, and ran a can of BG 44k through after that. I haven't seen 03-04 since. I suspect it was the BG 44k that did the trick as it gets rid of carbon in the combustion chamber. The car apparently had a mild knock that I did not notice - the knock was eliminated w/ maintenance.


edit: for those looking to boost their octane, check out THIS thread

 

Since when is 91 octane not good enough?

I was getting the worse mileage on my car until I decided to buy a cheap KS on eBay for 90$. I just changed it 2 days ago, it's just starting to kick in with the ECU now and it feels soooo much better. I never really noticed the power loss until today when I felt the KS kick in.

 

too much octane isnt really bad for the car, it can cause some extra detonation knock, and it is over time bad for the catalytic converter. You should basically run 93 max, unless you go to the track a lot or something. Replace that KS and get some power back

 

Higher octane will help gaurd against detonation and knock. I've heard that higher octane gases can have a slower burn though, so if you have overly high octane (more than you need) it can hurt performance.

 

excessive octane doesnt help detonation at all. if you use too high you need new plugs and new timing, and thats for a reason too

 

Can only get 91, 96 or 98 in NZ, so would 91 work out to be better for it rather then 96 or 98?

 

A higher octane fuel is less likely to detonate. There is no question. IF a car is running a high compression and plugs that are hotter than they should be, a higher octane fuel may be necessary to prevent the damage - not the other way around. This is why boosted cars tend to run higher octane gas, to PREVENT detonation from occuring.

Running higher (more than the factory reccomendation) octane is NOT always good though... It may hurt your performance because of a slower burn. If you have higher than stock compression, or if you are boosted / spray, consider higher octane fuel.

You will not increase your chances of detonation and knock by running the high octane.

 

Octane is a measure of the antiknock quality of gasoline. The octane number posted on service station dispensers and listed in car owner's manuals is an average of two measurements: Research octane number and Motor octane number. These octane numbers are determined using a laboratory test engine operated at different temperatures and speeds to simulate different driving conditions. The average of these two numbers, (R+M)/2, provides an indication of on-road performance. Most car owner's manuals recommend a certain octane but advise owners to increase octane if they detect audible knock or unsatisfactory performance.

Many new vehicles are equipped with knock sensors to prevent engine damage resulting from knock or to enhance performance. When engine knock is detected, the knock sensor system retards ignition timing until knock is reduced or eliminated. When ignition timing is retarded, power and efficiency are reduced so drivers can experience poorer acceleration performance and gas mileage. These vehicles require a higher-octane fuel to provide optimum performance.

 

that was my point if you paid attention. the can require timing change or plug change. the slower burn is an effect for those objects that i metnioned, i said nothing about a compression change or anything else

 

Hmm.. i suppose your comment about higher octane fuels *causing* detonation and knock threw me off.

perhaps we are on the same page though. Higher octane fuel does prevent detonation and knock, but may not be necessary depending on what mods you have done to the vehicle. Running high octane unleaded gas should not require timing or plug changes. The reverse is true though - advanced timing and plugs may require higher octane.

 

i just dont see why you would run 7 octane points about the recomended 91.

 

Hey where can I get a can of BG 44k and how much is it usually?

 

There is 110 octane at a few 76 gas stations around here. It is like 4.75 a gallon though...

 

the question is why

 

First of all, I‘d check how the octane numbers in New Zealand correspond
to USA numbers. It could be different ways to measurement,
hence diff.numbers. In Russia I know for sure, is so.

 

I buy mine locally for around $22.00 / can after tax. You may find it difficult to locate the product in chain auto parts stores, so call before you drive out to them. HERE is one place i saw online that offers the product and HERE is where you can go to get more information. The BG 44k is by far the best product of it's type that I have ever used. Have a funnel with you when it comes time to add a can of it to your tank of gas though - you'll be happy you did.

for your convenience, I ran a quick search and came across THIS thread so you can get some more maxima owner opinion on the product.

 

Octane is measured two different ways in the USA. One is 'research' octane, the other is 'motor' octane. The research number is generally quite a few points higher than the motor number. The USA averages these numbers, and lists this figure on the pump. Many other countries just list the 'research' number, so if you've got a choice of three grades, use premium.

Using more octane than what is needed will NOT harm the engine. It won't help it if there's no detonation with lower fuel, but it's not going to hurt anything. Remember, octane is just the measure of a fuel's ability to avoid detonation. Using higher octane fuel will NOT cause detonation.

Those of you using nitrous, superchargers and turbos need all the octane you can get... especially since the maxima has a pretty high compression ratio to start with.

Those who aren't all that comfortable with disabling the knock sensor by using resistors can simply mount a functional unit to the firewall and hook the wire to it.

However, disabling the knock sensor is not really a good idea for most. Nitrous, superchargers and turbos require the timing to be retarded in order to avoid detonation. This is tough to do with the stock type ignition and no knock sensor. I can program the amount of nitrous retard on the mustang, but I have no idea how to do it on a maxima. I don't even know the amount the knock sensor can pull out. It's probably too sensitive and too much for optimum performance... but is the only choice I know of. A person might get by with a disabled KS for limited track use, or with mildly nitroused or blown engines if straight 100+ octane fuel is used, but regular street cars that need good reliability should never disable the sensor.

Good Luck!