Hey fellas. Here's my deal:

1998 F150 XLT with 95,000 miles. I just bought the truck around Xmas and have noticed a stutter around 1,000 rpm when slowing or accelerating from a stop. It's pretty minor, but definitely there, so naturally I'm bothered by it.

I have since put in a new cold air intake system (Spectre) and had forgotten to disconnect the battery terminal during install. I got a CEL, had the code pulled and it was PO306. Took off the battery terminal and reset the system, and the CEL turned off, but the stutter was still there (still is).

Today, 1 month later, CEL came on and was on my way to get the code pulled when it turned off. I'm thinking I'll change out the plugs and wires. Any other suggestions?

By the way, my gas mileage dropped from around 14 mpg (pre CAI) to just above 11 after the intake install. What the!?!?!

Thanks guys.

 

Forgot to mention that it's a 4.6 V8.

 

At 95k, it's due for spark plugs.

 

I'm going with the Motorcraft platinums for plugs because I hear they're the only way to go. What about wires and ignition coils (not COPs)? Is Motorcraft better for those as well, or will something cheaper do the trick?

 

You may also have a throttle body starting to plug up with carbon.Before you change the plug you need to blow out the sprk plug holes so crap does not fall down in the cylinder.If you have never changed the plugs you will need a 5/8 plug socket and a 5/8 deep well socket and different size extensions too.I use the 5/8 plug socket to remove the plug, and then just light seat the new plug in the plug socket and then turn in by hand to get it started then switch to the 5/8 deep well to tighten it.If you use the 5/8 plug socket, it will stay on the plug when you try removing it.

 

I would stick with Motorcraft wires and coils - Rock Auto has them at a very decent price. They get $70 for the wires, the dealer wants $160. I'd change just the plugs first and see how it goes.

Don't use antiseize on the plugs, and torque them to 28 ft/lb. Use dielectric grease in the wire boots.

 

Thanks for the help guys. I just purchased the Motorcraft plugs and wires from Rock Auto. Awesome prices!

I'll give that a go and see how she runs and then I'll go from there.

Barber, any tips on cleaning out the throttle body? Never messed with that before.

 

Here is a write up on it.

https://www.f150online.com/forums/ar...ttle-body.html

 

I think I would go with the plugs and wires first to see if that changes. It can't hurt! And then if you still get the hesitation do the TB cleaning. If the EGR vent or the MAF sensor get coated or plugged it will cause hesitation or hard starting. If that doesn't do it then try having your injectors cleaned. After 90K they can get gunked up depending on the quality of gas that's been run through. Good luck.

 

As far as cleaning your injectors are you referring to the fuel injector cleaner you put in your gas tank?

 

I did put in a gas treatment a couple tanks ago that's supposed to clean the injectors and increase the gas mileage by up to 10%. My mileage actually dropped by 3 mpg. I did that treatment about the same time I put in the cold air intake. I'm assuming that has something to do with my sudden decrease in mileage.

I just got my plugs in the mail today and the wires should arrive later today as well. If I've got enough time, I'll try and change them out, then report back here with an update.

Thanks again guys.

 

Ok, got the plugs and wires changed over the weekend. I also cleaned the MAF sensor while I was at it. I didn't have the security star bit thing to get the sensor off, so I just took apart the intake tube and sprayed in there with the cleaner. Is that good enough?

I'm off to school and will take note of how the truck runs. I'll post back in a bit with an update.

 

UPDATE:

After just a short drive, the truck runs much smoother. Idle was never really rough but it was close to 1000 rpms. Now it idles even smoother and is around 600 rpms. The stutter is gone as well!

Hopefully we can keep it this way. As soon as I get a couple hours I'll clean the TB because I'm sure it could use it.

Thanks again guys for all your help!

 

Yes, as long as you were able to spray the tip of the sensor directly.