My engine is very smooth at idle but now at any speed over 25 mph I get shaking and little power. Check engine light came on and I used a code reader. It says random miss-fire and mis-fire at cylinder 3 & 4. I am begining to wish I never had this Roush Supercharger installed.

Anyway is it safe to drive this truck back to the dealer? I hear no knocking just lots of shaking on and off at cruising speed. At idle the engine is as smooth as butter?

Any tips?

Thanks

 

you gummed up the spark plugs with that load of octane booster in the start I think. I'd have one or two of the plugs pulled and checked. I ran into the same problem after using octane booster. When they ran the check at the dealership, it showed two bad injectors but that wasn't the case. The plugs were so bad it wasn't firing.

Hopefully that's all your problem is.

 

But at idle and lows speeds the truck runs fine with no misses. Just at higher speeds. Abad plug or wire would cause a miss at anytime the engine is running. Even if I rv the truck in park......no miss

 

Not exactly, there is no load on the truck at idle or in park/neutral. A bad plug or coil will mostly only show up during load.

 

I could get up to 2500 RPM's no problems. Smooth idle, no problems starting up. The truck would miss bad above 2500, or even lower RPM's while under a load.

I'd start by checking the plugs. Other things that might have problems are your fuel filter needs changed, you need a larger fuel pump, which I doubt, or you have a couple of bad injectors. It sounds like your plugs though, I just went through this with my rig and your symptoms sound identical.

 

That is why I bought my L in the first place. I was tired of tinkering with my Procharged 5.4. I told myself, "I'll buy a Lightning and leave it alone." That didn't last very long. A stock Lightning is just too slow these days. There is a crap load of cars close to it or faster. The days of a mid 13 sec vehicle owning the streets is coming to an end.

Anyway, the point being...

It's just too addicting. You'll be happy once you fix it and have no regrets!

 

If you have a BOV check to see if it is sticking, I had a simular problem w/ a centrifical blower.

 

I was told the new plugs put in during the supercharger install were the wrong type and they had to put OEM plugs in? No more misses but the supercharger seems to whine way much more than it did before? I am still not gonna get down on it yet.

 

The whine will definately be more obvious now that you can get up to power. On my Whipple, it didn't really kick in until I got around 2500 RPM when I had the stock pully on. When I went with the smaller pully, it starts whining alot sooner.

If you've got the right gas in there now, get on it. There's really no break in period needed.

Glad you got it fixed! now go have some fun!

 

Thanks............Whats the best way to get up to speed to open it up.......WOT?

Thanks for all the replies all!!!

 

Took it out today and layed some black stripes..lol I love the sound and the instant power. I notice I dont need to press as hard at all to get up to speed. very quick when you wanna go fast but very civil for normal driving.

keep in ming my other vehicles are a BMW 745i and a Aurora so I dont have any slow vehicles but the truck is just as quick if not quicker than both those cars especially the Aurora.

Trucks so big you cant tell you are going all thet fast till I llok at the Speedometer.