Some of you may know that I'm somewhat of a gas mileage freak about my car. This is my daily driver and it shouldn't be getting less MPG than my weekend car, but lately it has. So in an effort to improve the situation, I did 2 things Friday evening before I went to bed. I bypassed my knock sensor and I added a bottle of Gumout fuel system cleaner into my nearly empty gas tank and filled it up at around 11:30 in 51F weather (this could be important...I don't know) The next morning, I set off to Walnut Creek from San Jose which I know is a 55 mile one-way trip and a 110 mile two-way trip on a relatively flat road. When I got back to San Jose I noticed my gas gauge was still above the first notch mark and I thought this was odd. I had gone 132.8 miles according to my odometer and usually by that many miles it has surpassed the first notch mark. So I filled up the car and it stopped pumping at 2.9 gallons of gas. I never do this because you are not supposed to, but I started filling the tank some more after it stopped and it went to 3.3 gallons and clicked off. I got back in my car and the gas gauge showed full.
132 miles on 3 gallons of gas is 40MPG!?!?! That just can't be right. Unless the Gumout is acting like on octane booster and giving more bang for the buck. But that still doesn't make sense. Infiniti specs these cars at 27-28 highway mpg. So somehow my car did 12 more mpg??? I'm going to take a drive tomorrow and see if I can repeat this.
This can't be right...but if it is I can't explain it.
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NewfoundlandDude
- Posts: 244
- Joined: Fri May 04, 2007 10:15 am
- Car: 2001 Nissan Maxima SE - 20th Anniversary Edition
Re: This can't be right...but if it is I can't explain it. (rxm6)
Did you repeat this?
And do you have any advise for a guy (Other than knock sensor replacement) that's getting ~16.5 MPG in an 01Max?
AND How do you bypass your Knock Sensor????? - I want to try ths before I buy another to see if it's worth it.........
And do you have any advise for a guy (Other than knock sensor replacement) that's getting ~16.5 MPG in an 01Max?
AND How do you bypass your Knock Sensor????? - I want to try ths before I buy another to see if it's worth it.........
Re: This can't be right...but if it is I can't explain it. (NewfoundlandDude)
Yeah I did figure it out. The pump at Arco must have been broken
Actual mileage came out to be 28.04 mpg mostly highway with small amounts of urban driving. What I did to determine the mileage was to keep the original odo reading of 132.8 in trip A and I cleared trip B. At the end of 105.5 miles I filled up the gas tank at a station I trust and it filled the car with 5.2 gallons. When I did the math with a 105.5 miles, it pretty much came out to 20 MPG. But I figured the other pump might be in error so I added the mileage and the amount of gas filled and that came to 238.3 miles at 8.5 gallons which comes to 28.04
I bypassed my knock sensor by removing it from the engine and grounding it. Another way to accomplish this is to remove the knock sensor and place a 5.6k resistor (i think, don't remember actual resistance) in its place and ground the resistor.
As far as advice for the 16.5 mpg max, several things jump to my mind. One is, at 140k (which mine is) my pre-cats were clogged beyond belief. Once I removed them and used a y-pipe, my mileage jumped up a good amount. I also think that wrapping my y-pipe helps the engine work less in pushing the exhaust out, which also contributes to good gas mileage. I also noticed a power and gas mileage increase when I switched over to full synthetic, though slight. I would be really interested to see what kinda of mileage gains I would get if I either put on a new cat or used a test pipe in its stead? Also, I think keeping the intake air cool is a big factor. I noticed a marked increase in performance and mileage by cooling my intake temperatures. If you take off the stock air box and stick a filter over the MAF you are sucking in 122F temperatures. That can't be good for power or mileage.
So let's see, a few posts ago I said that I thought my car could make it to LA in one shot which is about a 400 mile trip. So, if I take 28mpg and multiply it by 17, which is about the limit I will let my tank reach, that's 476 miles. Road trip anyone?
Actual mileage came out to be 28.04 mpg mostly highway with small amounts of urban driving. What I did to determine the mileage was to keep the original odo reading of 132.8 in trip A and I cleared trip B. At the end of 105.5 miles I filled up the gas tank at a station I trust and it filled the car with 5.2 gallons. When I did the math with a 105.5 miles, it pretty much came out to 20 MPG. But I figured the other pump might be in error so I added the mileage and the amount of gas filled and that came to 238.3 miles at 8.5 gallons which comes to 28.04
I bypassed my knock sensor by removing it from the engine and grounding it. Another way to accomplish this is to remove the knock sensor and place a 5.6k resistor (i think, don't remember actual resistance) in its place and ground the resistor.
As far as advice for the 16.5 mpg max, several things jump to my mind. One is, at 140k (which mine is) my pre-cats were clogged beyond belief. Once I removed them and used a y-pipe, my mileage jumped up a good amount. I also think that wrapping my y-pipe helps the engine work less in pushing the exhaust out, which also contributes to good gas mileage. I also noticed a power and gas mileage increase when I switched over to full synthetic, though slight. I would be really interested to see what kinda of mileage gains I would get if I either put on a new cat or used a test pipe in its stead? Also, I think keeping the intake air cool is a big factor. I noticed a marked increase in performance and mileage by cooling my intake temperatures. If you take off the stock air box and stick a filter over the MAF you are sucking in 122F temperatures. That can't be good for power or mileage.
So let's see, a few posts ago I said that I thought my car could make it to LA in one shot which is about a 400 mile trip. So, if I take 28mpg and multiply it by 17, which is about the limit I will let my tank reach, that's 476 miles. Road trip anyone?
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NewfoundlandDude
- Posts: 244
- Joined: Fri May 04, 2007 10:15 am
- Car: 2001 Nissan Maxima SE - 20th Anniversary Edition
Re: This can't be right...but if it is I can't explain it. (rxm6)
Well I have a WarpSpeed -Y, but I also have a Cali-Spec so it doesn't remove the Front Header or pre-cat. My Y-Pipe ends on the horizontal on the bottom of the front pre-cat, as opposed to vertically on the bottom of the header like a fed-spec.
I did notice a gain in power & a sweet sound when I added the Y and CosmoRacing intake (At the same time pretty much). I switched to Mobil 1 Higher Mileage as well, and seafoamed + Deep Creeped the intake manifold & Gas tank a while back.
This gave me an increase from ~12.5 to ~16.5 MPG from last winter when I bought the car, but due to colder temos + Tire spin + general winter driving, the difference may not be a great as it seems.
I may try grounding the knock sensor for a tank of gas, and see what it brings. Are there any ill effects from this? Are there any known problems that may happen when I ground it? And where can I find info on what resistor I can use instead of grounding the KS???
Also, I think I may stick in the stock airbox & cut the front out of the airbox in order to acheive some more flow. Does anyone have any suggestions before I cut the thing. It won't be until the weekend, so I have some time to think about it. I could go GAB, but I think that cutting or drilling holes will get more flow than openint the top of the Airbox if I am not mistaken???
I did notice a gain in power & a sweet sound when I added the Y and CosmoRacing intake (At the same time pretty much). I switched to Mobil 1 Higher Mileage as well, and seafoamed + Deep Creeped the intake manifold & Gas tank a while back.
This gave me an increase from ~12.5 to ~16.5 MPG from last winter when I bought the car, but due to colder temos + Tire spin + general winter driving, the difference may not be a great as it seems.
I may try grounding the knock sensor for a tank of gas, and see what it brings. Are there any ill effects from this? Are there any known problems that may happen when I ground it? And where can I find info on what resistor I can use instead of grounding the KS???
Also, I think I may stick in the stock airbox & cut the front out of the airbox in order to acheive some more flow. Does anyone have any suggestions before I cut the thing. It won't be until the weekend, so I have some time to think about it. I could go GAB, but I think that cutting or drilling holes will get more flow than openint the top of the Airbox if I am not mistaken???
Re: This can't be right...but if it is I can't explain it. (NewfoundlandDude)
Yeah, I have fed-spec so I eliminate both. Might want to think about investing in some headers.NewfoundlandDude wrote:Well I have a WarpSpeed -Y, but I also have a Cali-Spec so it doesn't remove the Front Header or pre-cat. My Y-Pipe ends on the horizontal on the bottom of the front pre-cat, as opposed to vertically on the bottom of the header like a fed-spec.
I think the only ill effects you will find is if you run 87 with a bypassed knock sensor. I believe Nissan put the knock sensor there to deal with the growing number of bafoons who didn't take the dealership's instructions seriously when they said to use 91. If you use 91 all the time, bypassing the knock sensor won't hurt a thing. As far as the resistor goes, I wouldn't do that unless its necessary, like if the knock sensor goes bad. Until that happens, just ground the knock sensor somewhere on the engine where it can't bother anybodyNewfoundlandDude wrote:I may try grounding the knock sensor for a tank of gas, and see what it brings. Are there any ill effects from this? Are there any known problems that may happen when I ground it? And where can I find info on what resistor I can use instead of grounding the KS???