Ignition timing with 87 and 91 Octane Gas

[Iowa4Runner]

After logging, graphing, and interpreting OBD-II data, I was surprised to see no apparent advantage to running 91 octane gas under "normal" driving conditions. Normal being fairly flat terrain at ~700 ft. elevation in 78 degree temperatures with nothing towed.

Since this feeble forum can't handle a whopping 500kb attachment, you'll have to email me at [email protected] if you want to see the graphs of the engine parameters.

 

[Casper]

doesnt surprise me...the engine isnt tuned for 91 or 93 octane and since you are low density altitude and low load, you shouldnt really see a huge difference.

 

[greasefingers]

I would love to see the graphs! I just purchased a ProScan OBDII data logger for my Laptop. The logging function in the software does not work. I can get raw data as a snap-shoot, but when I export the data to Excel I get the same data points recorded over and over again. I will email you. Maybe I

 

[bulldog-yota]

Interesting, but as said makes sense. Would love to see data for WOT runs on it as well.

BTW what OBDII reader did you get? I'm looking for one to plug into the laptops USB port, but it must be able to read 03 (Pre CAN) and 05+ (CAN) protocols.

I'll PM you. If you email me the file I can host it for you.

 

[Bluto]

doesnt surprise me...the engine isnt tuned for 91 or 93 octane and since you are low density altitude and low load, you shouldnt really see a huge difference.

Would the 05 V8 be different? It has a 10:1 compression ratio.

 

[Casper]

Would the 05 V8 be different? It has a 10:1 compression ratio.

It might be but again, with low loads and low density altitudes...the is going to be little difference. the 10:1 does make it want higher octane though. If it was like 10.5 or 11:1, im sure toyota would mandate 91 min for the truck. Anyone know what the Seq. CR is? As yota mandates premium for them but only regualar for us and its the same damn engine

 

[mikes4runner]

[B I did notice a huge change in the MAF reading after I cleaned this sensor. [/B]

This should be cleaned on a regular basis(MAF) many don't and you would be surprised in the difference it makes.

Mike

 

[greasefingers]

This should be cleaned on a regular basis(MAF) many don't and you would be surprised in the difference it makes.

Mike

Yep I agree. I have decided to do it every time I change my air filter, which is usually once a year or 15 k miles. It

 

[Iowa4Runner]

Interesting, but as said makes sense. Would love to see data for WOT runs on it as well.

BTW what OBDII reader did you get? I'm looking for one to plug into the laptops USB port, but it must be able to read 03 (Pre CAN) and 05+ (CAN) protocols.

I'll PM you. If you email me the file I can host it for you.

I sent the file. The scanner I bought was the BR-3 from http://obddiagnostics.com, which at present won't work with CAN unfortunately.

 

[bulldog-yota]

I sent the file. The scanner I bought was the BR-3 from http://obddiagnostics.com, which at present won't work with CAN unfortunately.

You should have the URL for the file, so you can just link the image here.

Thanks for the OBD scanner link

 

[Iowa4Runner]

Bulldog-Yota has graciously offered to host the jpg file showing the 8 graphs from the octane test. You can get it here:

http://www.ezdries.net/Vidpics/temp/Octane Test.JPG

The graphs show three parameters: RPM (x100), ignition timing (degrees), and throttle position (degrees ?). The values on the X axis are unimportant, they're basically the sample #.

Thanks Bulldog-Yota!

 

[Boston_Runner]

Would the 05 V8 be different? It has a 10:1 compression ratio.

I thought the 2005 V6 was 10.0:1 and the V8 was 9.6:1. If this is true, the V8 definitely don't need super unleaded gas. Can somebody confrim these numbers?

 

[Northof49]

I thought the 2005 V6 was 10.0:1 and the V8 was 9.6:1. If this is true, the V8 definitely don't need super unleaded gas. Can somebody confrim these numbers?

2005 V8's indeed went up to 10:1

 

[Bluto]

I thought the 2005 V6 was 10.0:1 and the V8 was 9.6:1. If this is true, the V8 definitely don't need super unleaded gas. Can somebody confrim these numbers?

I can.

 

[iFORCE]

 

[Boston_Runner]

Isn't the BMW M3 designed to take advantage of the premium gas, it has a compression ratio of 11.5:1.