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TacomaGeneral discussion forum for the 2005 and later Toyota Tacoma.
This is a discussion thread titled "'05 Tacoma V6 needs 91 octane premium gas!", within the Tacoma forum, part of the Truck Forums category.
With a 10.1 compression ratio engine and an ECU programed for 91 plus octane fuel to keep the engine from pinging, you have two choices.
01) Use 87 octane fuel. The engine will ping. More in hot weather than cold. The knock sensor will automatically sense pre ignition and cause the ECU to retard ignition timing until pre ignition is no longer detected. (All automatically. You won't even know it's occuring !)
The problem is, with retarded ignition timing you loose HP. This equates to a loss in fuel milage also, as with less HP you will have to get on it harder to accelerate at the same rate as you would running premium fuel.
02) Use 91 plus octane fuel. Get the best fuel milage and performance the engine can deliver.
So. Which method is best? Cheaper initial cost of fuel resulting in retarded ignition timing that will cost you HP and fuel milage, or more expensive fuel resulting in advanced ignition timing that will get the HP and fuel milage the engineers designed the engine for.
It's a toss up. One way you use more cheaper fuel, the other way you pay for more expensive fuel initially and get better fuel milage and performance. Go figure.
With a 10.1 compression ratio engine and an ECU programed for 91 plus octane fuel to keep the engine from pinging, you have two choices.
01) Use 87 octane fuel. The engine will ping. More in hot weather than cold. The knock sensor will automatically sense pre ignition and cause the ECU to retard ignition timing until pre ignition is no longer detected. (All automatically. You won't even know it's occuring !)
The problem is, with retarded ignition timing you loose HP. This equates to a loss in fuel milage also, as with less HP you will have to get on it harder to accelerate at the same rate as you would running premium fuel.
02) Use 91 plus octane fuel. Get the best fuel milage and performance the engine can deliver.
So. Which method is best? Cheaper initial cost of fuel resulting in retarded ignition timing that will cost you HP and fuel milage, or more expensive fuel resulting in advanced ignition timing that will get the HP and fuel milage the engineers designed the engine for.
It's a toss up. One way you use more cheaper fuel, the other way you pay for more expensive fuel initially and get better fuel milage and performance. Go figure.
This is interesting. I never thought of this before - does that work with the 3.4 V6 as well? If so, would I need to reset my ECU to get it to recognize the higher octane fuel?
This is interesting. I never thought of this before - does that work with the 3.4 V6 as well? If so, would I need to reset my ECU to get it to recognize the higher octane fuel?
Thanks - Jeff
Yes this is how all ECU systems work with knock sensors. You never know when you will get a bad batch of fuel causing the engine to ping. That is why the factory put a knock sensor on the engine in the first place.
No, you don't need to reset the ECU to recognize higher octane fuel. The ECU won't advance ignition timing beond the preprogramed limits it came with from the factory, no matter how high of octane fuel you run.If your vehicle came from the factory programed for regular fuel, your just wasting your bucks using premium fuel. The higher the octane level of a fuel, the slower it burns to prevent pre ignition. This is why higher compression engines produce more HP, but need a slower burning fuel to prevent pre ignition.
That is why premium fuel is required when a performance chip is installed. The performance chip is programmed for more ignition timing than the stock program, along with modified fuel curves, requiring higher octane fuel to prevent pre ignition. If you don't run premium fuel, the ECU will retard timing when the knock sensor tells the ECU it has detected pre ignition. Retarding the timing causes your engine not to put out the HP that the performance chip was intended to produce.
The bottom line is, if your vehicle requires premium fuel you should use it if you want all of the performance the factory designed into the engine. If you use regular 87 octane you will loose HP and fuel milage. Once you switch back to premium fuel, the ECU will not retard timing unless it senses pre ignition.
I have always had trucks that use 87 gas. Can any one tell me if it would make a difference if I alternated between 87 and 91 octane. The salesman I bought my truck from said it would be okay. Would I lose hp or gas milage if I done it that way.
I have always had trucks that use 87 gas. Can any one tell me if it would make a difference if I alternated between 87 and 91 octane. The salesman I bought my truck from said it would be okay. Would I lose hp or gas milage if I done it that way.
You would lose neither,,,,just your money. Again,,higher octane fuel burns slower to prevent pre ignition on engines that require it. IE., high compression, remapped performance ECU chips, ETC.
wrong. the 05 v6 is designed to run on preimum, although 87 is ok. on a engine designed for 87, there will no benifits from 91. this engine in specific will gain from 91.
wrong. the 05 v6 is designed to run on preimum, although 87 is ok. on a engine designed for 87, there will no benifits from 91. this engine in specific will gain from 91.
I believe he was refering to the 3.4 V6 in his post.
I didnt take the time to read this entire thread so forgive me if I am reposting something that was already said.
I own a 2005 Tacoma 4x4 D-Cab/TRD-Sport/Standard-Bed... I have the 4.0 V6 and 5-speed auto.
I have tried low grade gas, mid grade gas, and premium gas in my truck. Using the lowest grade gas I notice the engine is much louder, doesnt sound healthy at all.. a slight knocking sound. I put premium in for the next tank and the sound went away within about 10 miles and the truck performed noticably better. Next I tried the mid grade gas to see if the noise came back and it did NOT. Then I tried another tank of the low grade gas and the noise came back. So I came to the conclusion that the lowest grade gas isnt all that great for the truck, the premium is better but probably not 100% needed, and the midgrade gas is juuuuust right.
I will be using midgrade gas from now on. I get slightly better performance and the engine seems to sound much much better. I may switch to running premium full time, but for now the midgrade seems to be doing the trick!
P.S. I have had my 05 Tacoma for about 3 months now... and I am absolulty loving it.
I didnt take the time to read this entire thread so forgive me if I am reposting something that was already said.
I own a 2005 Tacoma 4x4 D-Cab/TRD-Sport/Standard-Bed... I have the 4.0 V6 and 5-speed auto.
I have tried low grade gas, mid grade gas, and premium gas in my truck. Using the lowest grade gas I notice the engine is much louder, doesnt sound healthy at all.. a slight knocking sound. I put premium in for the next tank and the sound went away within about 10 miles and the truck performed noticably better. Next I tried the mid grade gas to see if the noise came back and it did NOT. Then I tried another tank of the low grade gas and the noise came back. So I came to the conclusion that the lowest grade gas isnt all that great for the truck, the premium is better but probably not 100% needed, and the midgrade gas is juuuuust right.
I will be using midgrade gas from now on. I get slightly better performance and the engine seems to sound much much better. I may switch to running premium full time, but for now the midgrade seems to be doing the trick!
P.S. I have had my 05 Tacoma for about 3 months now... and I am absolulty loving it.
If that noise you refer to while running regular 87 octane fuel is what I think it is, pre ignition, you need to take that truck back to the dealer ASAP, as the knock sensor should cause the ECU to retard ignition timing to the point where you have no pre ignition on regular fuel! Period.
Its probably not preignition... i knew by saying "knock" I was asking for a reply like this... lets just say the motor sounds/acts slightly different when running 87 octane. Its a noticable difference in sound and performance on premium.
I have now run 2 tanks dry on my X. First tank was with 87 octane and the second was with 93. The Dealer filled the tank up with 87 octane and said it was sufficant for the engine. I enjoy cruising at a low RPM at all gears. What I noticed is I was able to run between 3 and 500 RPM lower with the higher octane without the engine making a grumbling sound. Purrs like a kitten. I do not claim to know much about octanes and engines, but as for me the I would recommend the higher octane because if it run better at a lower rpm, I could just imagine how much better and efficient the engine is running at higher rpm's givin the stress the engine is experiencing. Just a though.
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