Diablosport Forums

U7151
V9R11
2008 Ford F150 XLT 4X4 5.4 engine
33" tires, Dynomax Welded Exhaust.

What is the best setting for the Spectre CAI with 87 octane fuel? I am not looking for an increase in power, simply an increase in fuel mileage.

You may need a custom tune with that intake. I would load a Diablo performance tune for your octane and see how it runs. If it runs ok, then log your short term and long term fuel trims. Then a custom tune can be written for the modifications based on the info from the datalog.

I'm new to this whole tuning thing... how do I log and read the short and long term fuel trims? And if it is running okay on one of the Diablo tunes, will this cause any damage to the engine in the long run if I continue running it without any further tuning? I know I sound ignorant, but in respect to this, I am..

Can anyone tell me how to do this?

In the diagnostic menu, you can choose the PIDs you wish to record under the live data menu.

Ok, Thank you.

I read in another thread someone with a similar set-up set his to the JLT tune with 16% MAF with 91 octane. His LTFT's were at 0. I tried the same set up with the 87 JLT tune. The truck now has very slight knocking at low rpm, at acceleration from a stop. This is only when feathering the accelerator, on WOT it seems to run fine. My LTFT reading is -3 on both and the STFT vary from 0 to +6. Which way do I need to adjust the MAF to get the LTFT to 0? I would try and play with it, but I am afraid to ruin something on the engine. Any help from anyone on this would be great!! Thanks!!

Well its nice to know that your get answers and help here... thanks for all the replies to my questions.

Id add about 5% more to the MAf curve.

Thank you.

IIRC, if you have a negative LTFT that means the computer is removing fuel from the engine...if you increase the MAF curve wouldnt that make the LTFT even lower because you'd be telling it to add more fuel??

btw JohnTre08f150, if you make small increments, the computer WILL adjust to compensate for a bad tune. Just don't make huge changes when you adjust things. Make sure you check the LTFT and STFT for each change to make sure what you're looking for is happening. When I first tried the K&N tune with my setup, my LTFT was WAY off (20+). Still the truck ran "fine"....just isn't ideal and I wouldn't recommend running that way for long.

Spectre includes a sleeve in the intake kits for using stock tune , did you remove that sleeve ? if you did I would recommend seeking out a CMR dealer for a dyno tune on it

meh...the sleeve chokes the airflow down quite a bit (what's the point of buying a 4" tube if you're going to reduce it down to 3"?). You can still adjust the tune to compensate and add more fuel. It's just a matter of finding the best starting place for the tune. Of course, if you're going to run it as a 4" tube....you might as well upgrade the exhaust since that's now going to be the limiting factor. Then you'll have more air in again...and have to add more fuel... Then once you get that "balanced" you'll need that supercharger so you can get even more air in... then another upgraded exhaust (unless you planned on that earlier), which then requires more fuel. It's a vicious cycle I love it!