I was referred over by a member of f150forum.


I purchased a used Roush Intercooled supercharger for my 2006 5.4 F150. All appeared to go well. After some light cruising I am now getting some engine lights. Misfire on cylinders #3 and #4. I installed new H20 plugs with the kit and just replaced the coil packs on #3 and #4. #3 and #4 also have brand new Roush injectors. I notice a ticking on my passenger side catalytic converter that wasn't there before the supercharger, not sure if that has anything to do with this. I tested all fuel injectors using an ohm test on my multimeter and all seemed to be okay. I had Roush tune the PCM. I'm really battling this thing - does anyone have any advice?

 

Was your PCM updated by Ford before sending it to Roush? Roush has a tune before the Ford PCM update then once Ford came out with the update Roush had a new tune come out. I got to do the Roush tune both times ha. Not sure if that's the root cause of your problem since I know nothing about you or your installers mechanical abilities or how the truck ran prior to the install. Best thing you can do if you have the cash and are sure the install was "successful" is maybe try a new tune from JDM or someone familiar with the Roush system. The factory Roush tune should work obviously but maybe something is off with it...

Do you have the Roush install manual? If not I can give you the link to mine so you can double check what you may or may have not done.

 

I've never ever had any luck with any other plugs other than the Motorcraft stock plug. Roush even sent me a new set of HT0 plugs and that dang thing would misfire on 4 of the 8 cylinders. That's with the proper gap done with the special tool doohickey I spent a lot of mullah on. What a waste of time and money that was. Ended up tossing those things in the trash.

Now, if you didn't gap it to .032-.035 that may also be your issue. Best to try the stock plugs and see if you get detonation. If no detonation and you're putting down good power, you're good to go.