Toyota FJ Cruiser Forum banner

21 - 40 of 104 Posts

·
Registered
Joined
·
846 Posts
Guys, Im a mechanic. I've learned almost everything about a piston engine. Knock sensors do not die from lower rating gas. Knock sensors are always monitoring your engine. All they do is for example:

Engine: How am I doing down there?
Knock: Theres octane 92 in here, looks like you can go full potential on this one.
Engine" Great, but im only doing 30mph in a 45 zone?
Knock : Tell the jackass behind the steering wheel he's wasting his money on this higher grade octane then. Punch him out with an airbag or something.

Knocking or pinging only comes from watered down gas. If the 1GR-FE engine had a distributor to control the sparks, then i'd believe it pings. But no, the 1GR has coils. Each coil adjusts spark according from the data input from the knock sensors.

On my Cressida, when I go get a smog, I adjust the distributor to 10degrees and throw in 87 octane. Owners manual says that the 7M-GE in the Cressida requires 96 octane for maximum performance. It drives just nice with the 87 octane. After it passes smog, I then finish the full tank of gas, adjust the timing back to 18degrees and use 91 octane because I like to do alot of these. Now you jack asses that love to shuffle out an extra 20 cents a gallon for premium gas and you never rev your engine past 2000 rpm, thats your loss. As for me, as long as im not using the FJ for maximum performance, its using 87 octane.


PS, Why the FCK the knock sensors on my 2002 4Runner with 204,000 miles hasn't blew out of the engine block, or the engine pop because I used 87 octane when theres big bold print in the owners manual that says use premium?

Guys get real. Don't be so gullible. You can put sunroofs in rag top Jeeps if you wanted to. Anything is possible. You just have to pull your heads out of your asses and stop listening to people that scare you. I'd take you to politics for examples but then i'd be hijacking the thread.

87 FCKIN OCTANE IS SAFE!!!!!!!
 

·
Registered
Joined
·
2,687 Posts
I agree with CACressida about the robust design of knock sensors. There won't be any difference to longevity of knock sensors between running 87 or 93.

CA you mentioned that your Cressida manual states 96 octane. Could that be 96 Research Octane? Today's pumps post octane at the arthimetic average of Research and Motor octane, hence, (R+M)/2. Research octane is conducted with the engine operating under little more than idle conditions and Motor octane is conducted with the engine under a loaded condition (similiar to ordinary acceleration from a stopped position on level ground). Research octane values are always higher than motor octane values. The difference between the two is known as sensitivity. It is common for sensitivity to be 8-12 octane numbers. Therefore, using a 10 octane sensitivity, 96 Research octane would be 91 (R+M)/2 octane as posted on the pump. I had a 1981 Toyota Celica Supra that used the same engine as the early Cressida's. Both were excellent vehicles.
 

·
Premium Member
Joined
·
1,423 Posts
Not to derail this thread or anything, but has anyone noticed that they've never seen Kansas Law Dog and Rain Man in the same room together?

Just sayin....

Good grief man...you just seem to know EVERYTHING about EVERYTHING. Where do you get all this information from? It's like you're a walking google or something. :D

Sorry, I've been in awe of KLD's knowledge for a while...I just needed to say that.

Back to the topic at hand now.
 

·
Registered
Joined
·
846 Posts
Kansas Law Dog said:
I agree with CACressida about the robust design of knock sensors. There won't be any difference to longevity of knock sensors between running 87 or 93.

CA you mentioned that your Cressida manual states 96 octane. Could that be 96 Research Octane? Today's pumps post octane at the arthimetic average of Research and Motor octane, hence, (R+M)/2. Research octane is conducted with the engine operating under little more than idle conditions and Motor octane is conducted with the engine under a loaded condition (similiar to ordinary acceleration from a stopped position on level ground). Research octane values are always higher than motor octane values. The difference between the two is known as sensitivity. It is common for sensitivity to be 8-12 octane numbers. Therefore, using a 10 octane sensitivity, 96 Research octane would be 91 (R+M)/2 octane as posted on the pump. I had a 1981 Toyota Celica Supra that used the same engine as the early Cressida's. Both were excellent vehicles.
Yes you are right. Just pointing out what the manual says VS real life to these ppl ;) Celica Supra, aye? 5M powered straight six. Nice vehicles.

So yes people, octane 87 wont hurt you. I say go back to the salesman that said theres only 5,000 fjs being made, take off your shoe and smack him right accross the face. Case closed.
 

·
Registered
Joined
·
750 Posts
JLam said:
Not to derail this thread or anything, but has anyone noticed that they've never seen Kansas Law Dog and Rain Man in the same room together?
OMG JLAM!!! My caramel apple empanada almost shot out my nose! Dude I am still laughin. Yer a funny sum-B

Kathie
 

·
Registered
Joined
·
750 Posts
Kansas Law Dog said:
I agree with CACressida about the robust design of knock sensors. There won't be any difference to longevity of knock sensors between running 87 or 93.

CA you mentioned that your Cressida manual states 96 octane. Could that be 96 Research Octane? Today's pumps post octane at the arthimetic average of Research and Motor octane, hence, (R+M)/2. Research octane is conducted with the engine operating under little more than idle conditions and Motor octane is conducted with the engine under a loaded condition (similiar to ordinary acceleration from a stopped position on level ground). Research octane values are always higher than motor octane values. The difference between the two is known as sensitivity. It is common for sensitivity to be 8-12 octane numbers. Therefore, using a 10 octane sensitivity, 96 Research octane would be 91 (R+M)/2 octane as posted on the pump. I had a 1981 Toyota Celica Supra that used the same engine as the early Cressida's. Both were excellent vehicles.
Thanks for explaining that KLD, now I can chime in again. I work at a refinery, and no, not in the office, (although I have one with 7 different computers in it, all with different things going at once). I work in the Tank Farms. I BLEND GASOLINE! So, I'll try to make this simple. When I blend I have to run the Research and Motor knock engines. When I am blending the engines are set for a certain octane range. I change the setting depending on what octane I'm blending. My blend is tested against a known standard, and if the octane of my blend is too low, the engine/s will knock. KNOCKING IS NOT CAUSED FROM WATERED DOWN GASOLINE! It is caused from running a lower octane than an engine requires. However, if you have water in your gas, it's gonna run like dog pooh anyway, weather it spits, farts, backfires, knocks, or just won't run at all.

If you need a better explanation, ask the Rain Man ;)

Kathie
 

·
Registered
Joined
·
2,687 Posts
Kathie - It great to have another refiner on the Forum. Two compounds define octane: 1) iso-octane (actually 2,2,4, trimethylpentane, which is 100 octane by definition), and normal heptane (straight chain C7), which is 0 octane by definition. The standards you speak of are mixtures of those two compounds, or another pure compound of known octane value approved by ASTM (American Society of Testing Materials). Just for the record, I wasn't me that said "knocking is caused from watered down gasoline".
 

·
Registered
Joined
·
846 Posts
Pinging = Your trying to launch a heavy car from a dead start in 2nd gear. It pings, why? Predetonation. I am aware of this all.

Usually an engine pings if the air+fuel mixture burns before the piston makes it to the top. Predetonation is caused from one, the octane is too weak to survive max compression, two the spark happens before TDC.
 

·
Registered
Joined
·
2,057 Posts
hey i got it...ill get the cheapest, piss filled gas out there and let you know how it runs. isnt this something like that 56th thread on this stupid topic already? no offense to any of you science geeks out there,...but c'mon already...enough is enough.
 

·
Registered
Joined
·
217 Posts
Well, **** - I'll just run right out and get me a bucket of pine sap and make up some fuel from it. I read today that Jap cycles ran on it just after WWII, but they smoked a bit.
 

·
Registered
Joined
·
846 Posts
caliFJ said:
hey i got it...ill get the cheapest, piss filled gas out there and let you know how it runs. isnt this something like that 56th thread on this stupid topic already? no offense to any of you science geeks out there,...but c'mon already...enough is enough.
YEAH, it ticks me off. The same thread, over and over and over and over and over and over and over and over. Just put any gas in there, as long as it runs.
 

·
Registered
Joined
·
342 Posts
I dont wanna risk it. Im keeping my FJ and plan to pass it on to my great great grand children. Im putting nothing but 91 octane.
 

·
Registered
Joined
·
846 Posts
fjarch said:
I dont wanna risk it. Im keeping my FJ and plan to pass it on to my great great grand children. Im putting nothing but 91 octane.
Suit yourself buddy. My FJs running like a champ with 87. When I towed with it it ran pretty good for 20 miles then I had to fill up. But I filled up with 91.
 

·
Registered
Joined
·
342 Posts
CACressida said:
Suit yourself buddy. My FJs running like a champ with 87. When I towed with it it ran pretty good for 20 miles then I had to fill up. But I filled up with 91.
I had an 03 Nissan which the dealer had recommended to put only premium gas. I put in regular gas since I bought it and 3 years later, MPG has dropped significantly and the engine didnt sound the same. I had to get rid of it before it became a problem. So.... suit yourself.
 

·
Registered
Joined
·
846 Posts
fjarch said:
I had an 03 Nissan which the dealer had recommended to put only premium gas. I put in regular gas since I bought it and 3 years later, MPG has dropped significantly and the engine didnt sound the same. I had to get rid of it before it became a problem. So.... suit yourself.
Nissan.. PFFT. Even if you used 91, it still would've gone bad. Its a Nissan.

Your comparing Apples to turds.
Toyota = Apples
Nissan = Turds
 

·
Premium Member
Joined
·
2,888 Posts
CACressida said:
Guys, Im a mechanic. I've learned almost everything about a piston engine. Knock sensors do not die from lower rating gas. Knock sensors are always monitoring your engine. All they do is for example:

Engine: How am I doing down there?
Knock: Theres octane 92 in here, looks like you can go full potential on this one.
Engine" Great, but im only doing 30mph in a 45 zone?
Knock : Tell the jackass behind the steering wheel he's wasting his money on this higher grade octane then. Punch him out with an airbag or something.

Knocking or pinging only comes from watered down gas. If the 1GR-FE engine had a distributor to control the sparks, then i'd believe it pings. But no, the 1GR has coils. Each coil adjusts spark according from the data input from the knock sensors.

On my Cressida, when I go get a smog, I adjust the distributor to 10degrees and throw in 87 octane. Owners manual says that the 7M-GE in the Cressida requires 96 octane for maximum performance. It drives just nice with the 87 octane. After it passes smog, I then finish the full tank of gas, adjust the timing back to 18degrees and use 91 octane because I like to do alot of these. Now you jack asses that love to shuffle out an extra 20 cents a gallon for premium gas and you never rev your engine past 2000 rpm, thats your loss. As for me, as long as im not using the FJ for maximum performance, its using 87 octane.


PS, Why the FCK the knock sensors on my 2002 4Runner with 204,000 miles hasn't blew out of the engine block, or the engine pop because I used 87 octane when theres big bold print in the owners manual that says use premium?

Guys get real. Don't be so gullible. You can put sunroofs in rag top Jeeps if you wanted to. Anything is possible. You just have to pull your heads out of your asses and stop listening to people that scare you. I'd take you to politics for examples but then i'd be hijacking the thread.

87 FCKIN OCTANE IS SAFE!!!!!!!
I've been and still am a mechanic in Cailfornia - and something is wrong with your info. You cannot advance or retard the timing more than 3 degrees from factory spec or the vehicle automatically flunks the smog test. Also, knocking is not from watered down gas, but from inproper burn interval of lower octane in a higher compression cylinder. You can actually use water injection to cool combustion chamber temps, usually for pressurized (e.g. turbo or supercharged ) motors, and not cause knocking. With sohpisticated knock sensors, the engine will not noticably "knock", but the computer will put it in a default mode that lowers the HP output to protect itself. So 87 octane maybe safe, but you'll lose power available. At 20 cents a gallon difference, we're talking less than 4 bucks a tank. Most of you will be looking to add better filters, chips, exhaust, etc. - expensive add-ons - while costing yourselves horsepower that's already there for $4... that sounds silly to me...didn't you buy the FJ to use it ? :rolleyes:
 

·
Registered
Joined
·
846 Posts
CACressida said:
Pinging = Your trying to launch a heavy car from a dead start in 2nd gear. It pings, why? Predetonation. I am aware of this all.

Usually an engine pings if the air+fuel mixture burns before the piston makes it to the top. Predetonation is caused from one, the octane is too weak to survive max compression, two the spark happens before TDC.
Cruiser Larry, read the whole thread first :)

If you don't understand the 7M engines, then you know nothing about them. They are headaches. I set the timing at 10 degrees to smog it, then after smog, i set it back to 18 degrees where I achieve maximum performance. I've been doing this for years, I should know.

I know water injection, advertised for performance on turbocharged engines, wich does nothing power-wise. Im not sure about block combustion temp. But if you put alil more water in there, you fark up ur engine.
 

·
Premium Member
Joined
·
2,888 Posts
CACressida said:
Cruiser Larry, read the whole thread first :)

If you don't understand the 7M engines, then you know nothing about them. They are headaches. I set the timing at 10 degrees to smog it, then after smog, i set it back to 18 degrees where I achieve maximum performance. I've been doing this for years, I should know.

I know water injection, advertised for performance on turbocharged engines, wich does nothing power-wise. Im not sure about block combustion temp. But if you put alil more water in there, you fark up ur engine.
My response to you had nothing to do with 7M engines, just a statement for those who might not know better that you cannot pass smog legally in calif with the timing advanced or retarded 8 degrees from factory. As for your lack of understanding of the principles behind water injection, and the power advantages of cooler combustion, (check your emissions licensing manuals regarding air/fuel density and combustion chamber temps / NO2 emissions, etc...) you most definitely have not spent any time building or analyzing performance engines - something I do regularly. My point was not for you, a trained (???) mechanic, but for others reading who might misunderstand you statement and take incorrect and possibly illegal information to heart... nothing personal...
 

·
Registered
Joined
·
165 Posts
CACressida said:
Oh guys give me a farkin break. Gas is gas. If you plan on just commuting with it, use the fcking 87. If you plan on towing or doing something that requires maximum power, use 91. If I was president, I will force the DMVs make drivers take Auto Class courses b4 they get there Drivers Licesnes.

There something called knock sensors. These sensors adjust the timing to you can burn all sorts of gas. Even super low octane fart in a can. Im gonna say this onece more:

If your just cruising around town or in the freeway or doing some lite duty crap, using 87 is safe. If your gonna tow a heavy trailer, 87 is accetable but 91 works for maximum power.
Yah, so there! <Me too. and all that.!
 
21 - 40 of 104 Posts
Top