New Caprice - Discussion forums

I see MPG increases on both my B-Body cars and PPV with higher octane fuel. The timing tables shift, which is a good thing. But since my owners manual for my 2011 always said to use 87, I haven't bothered using anything higher. Perhaps I will now if it makes a difference.

One other thing I thought was funny about the user manual pic posted earlier -- read the section about "Use of Seasonal Fuels". Specifically this gem: "Drive the vehicle with the engine running until the fuel is a half tank or less."

Um, let me see someone DRIVE it down to a half tank or less WITHOUT the engine running. LMAO

Silversled wrote:The stock tune Lo Octane spark table have as much as 12 degrees of timing retard compared to the Hi Octane table in the mid throttle areas. On LS engines this area usually corresponds to the peak torque, so what you feel is not imaginary.

Is there also a separate spark map for E85? If so, does it vary the timing with the detected level of ethanol or does it just switch to the E85 table with the ethanol content get over, say, 50%? It's my understanding that these flex fuel vehicles have an ethanol sensor so that they can tell when you got a tank with a mix of regular gas and E85. (And I've also head that E85 isn't always 85%. It can vary all the down to something like 60%.)

Thanks,
Ben

Happen to have a 15 SS tank and a 14 PPV tank to compare.
Found out the tank is actually the same part number (mold number) but the plumbing is different, I assume for the Flex capability.

The PPV tank on the bottom has this extra sensor on the side of the tank is in the path of the fuel output. My guess is that would be the sensor that tells the ECM what fuel is coming it's way from the back. Have to look in the service manual to see if it says what method it uses to determine what fuel is there. Maybe ethanol has a different resistance from gasoline?



Description from the service manual:

Very cool! Thanks for the side-by-side pic.

Now I'm just wondering if the ECU has a seperate timing map for ethanol and if it varies based on the ethanol content.

BP

I have run my car and the track with both 87 and 93 in the tank. There is a difference in both seat of the pants and times/trap speeds. My 1994 9C1 was also this way but not quite as dramatic. The wife's LS2 GTO even has preminum fuel sticker right on the inside of the fuel door and just like the caprice, it runs fine on 87 but really wakes up with 93.

My best is 13.60 @ 105, Sometime in April I'm gonna run a few tanks of E85 and see what I get at the track (Not the pump which I know will be much much worse)

9C1fanatic wrote:My best is 13.60 @ 105

Very nice!

Yeah, I'm really interested in E85. It's everywhere in WI.

There needs to be a Dyno/Drag/Tuning forum on this site. One place to see who got what numbers with what combination of parts/mods and what tuning they did to get there.

Regional Forums would be nice too.

BP