2008 4.2 5 speed. Truck drive fine, new plugs and wires a few months back. Currently has 53k.

When going up a hill on the highway, with the AC on, It hear a strange ticking type sound. It doesn't sound like a normal exhaust leak that ticks along with the timing of the engine. It's a random ticking / clicking sound. Does not happen when I give it gas on a straight away, only going up hills.

Any idea what this could be? Sounds like it's coming from the passenger side of the engine.

 

Might be spark knock - does it go away if you use premium gas?

 

x2.

The symptoms you describe are classic for 'pinging'. This is very hard on your motor.

Maybe you got a bad tank of fuel, or the place you buy your fuel is substandard.

Use higher octane fuel, or downshift to get the revs up.

FWIW, if your cooling system is not operating properly and the motor is running too hot, that can also contribute, but in most cases it is a fuel quality or octane issue.

 

Thanks guys. After doing some research, I do believe this is spark knock. Its happened for a couple months, at least since the dealer changed my plugs and wires. I get gas from different stations a lot so I don't think it's the gas. I will say the truck just has not felt the same since the dealer did plugs and wires. I've brought it up to them, but since I have no codes they will do nothing. Any idea what can cause this besides bad gas? Thanks!

 

Have you TRIED a tank of premium? Did the dealer use Motorcraft plugs and wires?

 

I had just filled up the day before posting this. I still have almost a full tank, so I haven't tried premium. It was a Ford dealer that did the plugs, so I'm pretty certain they used Motorcraft.

 

The increased octane will likely make some improvement. I would absolutely fill up with premium next time to verify that it is insufficient octane for the conditions.

In the old days, you could back the ignition timing off a few degrees.

FWIW, low rpm under load generates the most extreme pressures and heat in the cylinder, so most likely to pre-ignite.

If you don't want to buy premium, you may have to downshift.

Other things that could contribute: Too hot a heat range spark plug, hot weather, Clogged fuel filter.

 

Combustion chamber deposits can do it too - if you use offbrand gas a lot this can do it. If premium gas makes it go away, I'd consider getting a BG or Motorvac job done. Techron in the gas can help clean it up.

 

Thanks for the input. I normally use Shell, never off brand though. New fuel filter yearly, if that means anything. Someone from the Ford dealer is going to come along for a ride. I guess I'll take it from there.

 

Shell should be fine - it's clean gas.

 

Run a can of Techron thru it to decarbon and cut down on spark knock/pinging.

 

I'm going to have the dealer check it out before trying Techron or anything. When driving on the highway tonight, it was doing it a lot. Any slight incline and I'd have that random metallic pinging sound. It would help slightly to turn the AC off and shift to 4th, but even when shifting to 4th and going 70 mpg it was still doing it on inclines. No issues with city driving.

 

sounds like you have a sensor failure and a code probably for it. Techron is one of the best cleaners for carbon after you deal with the sensor. Also seafoam for the intake.

 

I'd get a BG or Motorvac job before I'd dump Seafoam down it.

 

I'd rather use sodium silicate than Seafoam.