misfire issue
 

So here is my issue. To start I have a 07 150 with 5.4L. Mostly stock with the exception that I gutted the cats, installed custom dual exhaust which dumps out the side, k&n air filter along with the gotts air intake mod, and a gryphon programmer. If I put my programmer in tranny mode it does ok. If I put it in tow or bump octane to 93 and go with performance it tends to misfire more so when I am holding my speeed below 45. The only thing I can figure is it is doing this because my vehicle is a flex fuel vehicle(blah) and my tuner isn't set up for that. If so, I am thinking of setting up a date to pay a visit to the shop since I would like a custom tune any way(yay) due to the fact my cats are gutted and I would like optimum power. If I do this im slightly confused on how much cash this will set me back. Im sure you guys get tired of answering questions about pricing on stuff like this from nuts like me so pardon my flash of stupidity. Thanks for any input on the issue and time!

Full dual exhaust, no cats and aftermarket intake each need custom tuning. Flex fuel vehicles are also very picky on top of that. I would try calling to set something up asap.

If you bought your gryphon programmer from PHP the tunes will be $30 each. If not then $60 each.

Longshot, the intake is just a drop in filter in the Gotts Mod option, so it shouldn't cause problems. But I agree, the other mods are possibly creating some difficulties.

NITEMARE, when you say it "misfires", this sounds like a spark problem. And, this happens at a steady, low speed below 45? I don't know why you'd have spark problems at such a low load.

Have you cleaned the MAF sensor and the intake area that surrounds it?

- Jack

JackandJanet, I have cleaned the intake system extensively and hasn't had an impact. When I say it "misfires" it simply "skips" like an older carbureted engine. No bucking involved. When I give more gas to the engine it clears out. Im thinking its all in the programmer since it doesn't do it when the programmer is set to transmission only mode. While we are on the topic, what is the difference between flex fuel 5.4 and normal 5.4? Other than injectors and tune.

The difference between the flex and the not so flex is the gaskets and rubberized material is made to better withstand the ethanol. There might be a few other small differences but that is the biggest as far as I know

^^^ What he said ^^^ (That's my understanding, anyway.)

NITEMARE - I can't really think of anything you can do to fix the problem you're having. It sounds to me maybe like the A/F ratio isn't quite right at that no load condition (possibly too lean) and when you open the throttle, it (maybe) becomes richer.

I'd have to say Bill is going to have to adjust your tunes, so you'll need to get in touch with him. (And I know that's sometimes difficult.) :shrug:

- Jack

That's my theory as well. Oh well, just gives me a excuse to pay the guys at php a visit!