SO I recently moved to another state (Arkansas). Since being here, my truck has been running like crap.. stalling, poor idle, sometimes hard to start.... almost like it doesn't get enough "boom" to "fire" it up.

2004 F150
5.4 3valve
Supercharger 7.5 PSI

So I have been deducting the possible causes. I already replaced the throttle positioning sensor.. no help.

So I deducted what has actually changed in the last month.

1. The air has gotten warmer. I know my truck is running rich and I thought maybe since the air contains less oxygen, it may be running too rich to run good. (Getting new dyno tune tommorow)

2. Gas change. While filling up today, I got about 1 gallon into the fill-up and noticed "Up to 15% ethanol". WTF?!?

I know that most of the gas in the nation contains 5-10% ethanol.. but up to 15?

My question is... could this be what is causing my problems?

I left there and scavenged the county for a place that sells 93 octane and doesn't mention ethanol. I found a place and filled up. I drove about 15 miles to fully mix the small ammount of "ethanol gas" with the new gas.

It "seems" to idle better.... It could be in my head.

COuld the ethanol gas be causing the problems? Anyoneelse have a similar situation?

 

Is your truck tuned? I've recently switched to Shell gasoline since they are on of the few selling 93 octane now. My car is tuned for 93 octane and runs like *** when using gas that has an ethanol mix. It is very possible that the ethanol is the problem.

 

It's tuned for 93 octane performance.

I used to use only Shell gas back in Kentucky, but i this city, every Shell gas station is closed down.. there's about 5 of them and they're all down.... of the other stations, ony a couple sell 93 and they were both out of it.

I had to nearly drive to another county to find 93 octane gas.

 

ETOH (ethanol) actually has a higher "octane" rating. Adding ETOH to gasoline raises the octane rating. As a point of reference E85 has an octane rating of 105. This is also the reason why top fuel dragsters, with extreme compression engines, run on alcohol.

 

Ethanol does not yield the same performance as gasoline. Take race gas with an octane rating of 105 and E85 ethanol and see which one yields more HP. If your vehicle is not "tuned" to run on ethanol it will not perform as well as gasoline. You need larger injectors along with a host of other upgrades to yield the performance. Taking a car that is tuned for 93 octane and running gas with a 20% mix of Ethanol is a bad idea.

 

What he said.

I don't know much about ethanol, but I do know that it takes more fuel to yeild the same HP as compared to gasoline. Liek he said, bigger injectors.

I found a station that had 93 octane and didnt mention ethanol... so I'm hoping that was my issue all along and it's nothing worse. We'll see tommorow when I actually drive it more and take it back to the dyno.

 

E85 does not burn as efficiently as Gasoline; especially in vehicles that are not set up to run E85. Running E85 in a conventional gas engine will in time destroy the internals. E85 contains approx 70% of the energy of gasoline when compared gallon for gallon. If you have larger injectors and are set up to run ethanol then it may work for you, but most vehicles are not set up this way. Ask anyone running E85 how their gas mileage is... I bet it's around 20% worse. This is an intersting comparison of E85 and Gas in a flex fuel vehicle.

http://www.edmunds.com/advice/altern...3/article.html

 

I knew that.

I'm hoping that was/is my problem; bad gas.

Like I said, I'll find out tomorrow.

Thanks for the response s2krn! It makes me feel better.... whether it's the case or not.. it makes me feel better.

 

My truck doesnt seem to perform at its best on 10% ethanol. But i never run 87oct. always 93octane. I too have to drive about 10miles to get 93octane without ethanol.

 

Glad to hear you're feeling better, now hopefully you'll find out it's the ethanol! If not post back and I'll make something up to make it seem OK. Anyway, hope everything works out.

 

Something is wrong mechanically with my truck. Somthing fuel related.

The dyno diagnostics were done today and the air fuel is nice and safe, but the fuel delivery is not good. The voltage reading on the fuel pump is all over the map... up and down and up and down. Like a roller coaster.

It's safe to drive, but it's not problem free... by a long shot.


This truck is history.. I'm tradin' it in. I'm tired of messing with the problems.

 

Not trying to be a smartass, but how much do you think you can get for a supercharged truck that needs 93 octane gas today?

 

I agree ... Fix the problems. At worst, a new fuel pump is in need. A lot easier than trading it in.

 

x2

Selling it only masks your problems.