Tuned PCM fuel grade questions [Archive] - GrandAmGT.com Forum

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McFlurrey06
10-18-2008, 04:04 PM
Not sure if this is the right spot to ask this, but, I just got a PCM from MPR that is tuned for premium octane, but my tank is 3/4 full of regular.

Would it be ok to install the PCm or to wait until the next fill up?

Mike Jung
10-18-2008, 04:23 PM
Not sure if this is the right spot to ask this, but, I just got a PCM from MPR that is tuned for premium octane, but my tank is 3/4 full of regular.

Would it be ok to install the PCm or to wait until the next fill up?
IMO, it would be safer to wait for a tank full of premuim gasoline.

& don't forget to be easy on the gas pedal the first 30-minutes of driving; after the PCM is installed, to learn the fuel trims.

McFlurrey06
10-18-2008, 04:52 PM
I usually fill up around the 1/8th of a tank mark, that should be ok right?

Thanks for the 30 minute tip, about the tables.

AaronGTR
10-18-2008, 07:33 PM
Yes, that should be ok. By the time you get down to 1/8th of a tank of regular 87 octane and fill it up with say 93 octane, your end octane will be like 92 after mixing, and your next fill up you'll be straight at 93. That should be plenty safe. And like Mike said drive it easy for at least 30 minutes so it can relearn the fuel trims. Also don't forget to go get a CASE learn done. :thumbs:

hass
10-18-2008, 08:18 PM
what about octane booster?
I always keep a bottle with me especially when traveling, just incase I get stuck on the thruway and low on gas w/ a station that only has 87/89/91.

Would that work for him?
Spending extra money, however.

McFlurrey06
10-18-2008, 09:41 PM
Wouldn't that be alot of octane booster to go from 87 to 93? And on a tank thats 3/4 full.

Metalxen
10-18-2008, 09:45 PM
Don't mean to whore your post, but damn you got your pcm fast dude.:applause:

hass
10-18-2008, 11:21 PM
Wouldn't that be alot of octane booster to go from 87 to 93? And on a tank thats 3/4 full.

Hmm, think one bottle should do it. At least of the stuff I have it will do it... maybe two to be safe.
Says it increases it by 5 points in 15 gallons.
but it's like $3-4 a bottle at least. So... judgment call on how much you enjoy your money and how fast you want that PCM in ;D

McFlurrey06
10-19-2008, 12:02 AM
Well after taking the girlfriend out for sweetest day, and for a long cruise im down to 1/2 so i wil wait until the 1/8 tank mark and fill up with 94. Sunoco gas around here carries it and according to Aaron who knows his sh!t that should do me just fine. Then a case learn, how much do they cost btw?

AaronGTR
10-19-2008, 04:54 PM
Yeah, I read somewhere that mixing octane doesn't split the difference equally between them, but tends towards the high side. ie mixing half a tank of 87 with half a tank of 93 won't give you 90 octane, but closer to 91-92. So mixing 94 in there with just a little 87 should give you 93 or pretty close. Only downside is last I remember sunoco offers 92 and 94 octane and they charge 10 cents a gallon more for 94 than for 93 from competitors. :(

DrFabulous
10-19-2008, 07:01 PM
Then a case learn, how much do they cost btw?

You usually can find someone that can do it for a 6 pack.... it takes less than 3 minutes

McFlurrey06
10-19-2008, 07:14 PM
The sunoco around me has 93. So I'll just fill up as usual with the 93 octane, I'll wait till the gas light is about ot come on, or after it comes on, that should do me just fine. should be by tuesday.