We wanted to give everyone a heads up. Especially those in Maryland. Some of the cars we have been tuning recently have required a significant reduction in timing. This seems to be due to the different formulations of fuel they are using (i.e.-oxygenated or higher ethanol content). We recommend that everyone that is running FI in our area or in areas that use modified winter formula fuels to get a baseline. If you can, find a way to watch your factory timing. To give an example I've been testing the Txs UTEC on the shop car. Normally I would be running 19 to 20 degrees of timing near redline. I've only been able to run 13 to 15 degrees with just a fresh tank of gas (the previous tank was about 3 weeks old). We've also confirmed this change with some of the tuners that use our dyno.

I'm doing some research to see if Maryland has implemented an emmissions change. This was not something that has happened in previous years so I think its a new regulation.

 

Was the car pinging before you brought back the timing?

I had a customer report to me that his car has been running a half point or so leaner since the tune we did when it was a little warmer out. Stock ECUs and piggy backs and 450rwhp just dont add up for the greatest in consistency thruout the seasonal changes and winterized fuel I guess.

 

Good point Dave/Phunk. It's so important for customers to monitor things like wideband AF gauges, and engine sounds....to the best of their ability...as tunes can change from time to time.

 

I had my car tuned since Feb of this year and have had 2 retunes to keep the Ecu happy. I like to run 100 oct to reduct Detonation so the cold weather really makes things intersting

 

My AFRs according to my AEM wideband have gone from 11.0:1 a few months ago (70-80 degrees ambient) to about 11.5:1 now (30-40 degrees ambient)...I'm pretty sure IL switches to winter gas too....

 

Subscribing.........

 

I also live in IL. How do you know if you are pumping modified winter fuel?

 

i have retuned my car twice this year, my latest tune was originally producing a smooth a/f at 11.2-11.4:1... then, the 350z gremlins took over and i was seeing mid to high 12's...so, i had to rescale my entire map (cause i was at "99" in some of the cells-maxed out in how much fuel i could add)...anyway, i retuned, running good a/f...the temp here when i tuned was around 80degrees, now it is a low of 20 degrees at night, around 40-60 during the day, so the cold air probably played part of the role in the dramaric change in the a/f

also, off topic, i am having issues with my boost...it has dropped from 16psi to 14ish psi, i have played with my boost controller settings-profec e-01...even maxed it out with a set of 100 (i use manual mode, i could never get auto to work properly)...i called greddy, they said that if the solenoid were to go bad, it would not make any boost over the wastegate spring setting, not just drop a few psi...any ideas? i ordered a cheapo manual boost controller that will be here next week to hook up and see if i can make 16psi to further troubleshoot...any ideas are greatly appreciated!!!

 

Basically with the "summer" gas I could run 8 to 9 psi with no knock counts on the UTEC. Right after the 5 gallons of "winter" gas was added knock counts started showing up across the board at 6 psi. Also other cars on the syno have been showing that same issues. While logging the factory ECU on other Z's I've seen the ECU dropping the timing significantly. This was also confirmed with local proffesional tuners, like Phil from Element Tuning who used to be with TXS.

 

PS- None of this is really scientific at all its just based on what the UTEC is doing and what other cars and the factory ECU is doing. I assume the factory ecu knock algorithims and frequency filtering are much more accurate then my ear or the UTEC sensor could ever be.

 

By now you definitely are...I think they change it around late october to early november. I don't have to worry about it since my car is put away for the winter...but if your drive your car all year round...I'd get it on the dyno with the fuel that's available now and make sure everything is cool.

 

What are other feasible options to decreasing knock counts, other than retuning......mixing race gas to increase octane?

 

You could mix race gas...only problem is FINDING race gas this time of year. Lots of stations stop selling it in the winter months.

 

I have a gas station that sells 100 octane 5 min from my house. It sells for $5.99 a gallon. I don't drive my car during winter other than the days that have no snow or salt on the roads. Should I put a few gallons in with the 93 I use?

 

That's cool. You're free to do whatever you want. Putting a couple gallons of race gas in definitely won't hurt anything.

Didn't you just have your car tuned @ GRD recently??

 

So Sharif, does NC change their gas to a winter mix?

 

Car should be done on Monday.

 

DBZ33, where is this station located?

 

Not to my knowledge. Typically, you will see a sticker on the pump that will say that the formulation has changed....or that they have oxygenated the formula. That is what they did in Los Angeles when I lived there.

 

In Illinois I don't think they give any indication at the pump that the gas has been changed. At least none that I have notice. Only way for me to tell each year around this time is when customers come in for a tune and AFR's are a little leaner than usual.
DBZ33, $5.99 is a little steep for 100 octane. At our local pump it was about $4.00/gallon. The wonderful thing about the UTec is that you can run a winter map and switch to a summer map when the gas changes back.

-Tuan