A couple of months ago we had a large snowfall in MICH and I got a lot of snow under the hood. I figured the sputtering was due to excess snow in the engine compartment. It stopped after I pulled into a gas station for a bit and I think most of it melted off. It did this again later in the year when we got measurable snow, but again after a little while and apparently melting it's fine. Now it's sputtering in the rain and I'm not sure if moisture is getting in/on/around a hose? Possibly a crack in the fuel filter? I'm not sure where else the moisture could get that would do this, especially when I just driving down the road, no offroading, puddle jumping. The engine seems ok when maintaining a constant speed or decelerating. But whe I slowy accelerate it's sputtering constanly until I really put the petal down then it does it a little less. So on the road I have to keep my speed up and down to make it bearable. Any idea's

 

Sounds like you have some water in the spark plug wells that is shorting out the spark intermittently. Pull the COPS or plug wires, as the case may be, and dry things out. Sometimes the COP boots or spark plug wire boots are damaged and will need to be replaced. be sure to put a bit of dielectric grease inside the boot with the plug to prevent ti from happening again. Good luck!

 

Since this is happening only recently it would seem more probable that damage to that wire would probably be the culprit, don't you think. It doesn't seem as logical that I'm getting water in the plug housing since every truck would have the same issue wouldn't it. There are only a couple of engine options right? So something is going bad...Does this logic make sense? If so I'm thinking the wire/boot. What about the coil that they hook to?

 

What year truck and engine do you have?

I have a similar problem on accasion when it rains but I have never had the snow under the hood like you did. I originally replaced the spark plugs since they were due. It got better but still isn't fixed. I ordered new COPS for it and have them but haven't installed them yet. I expect that the COPS will do the trick.

 

The lite throttle missing is the give-away there is a bad COP.
There won't be any code to tell you which cylinder it is.
The reasons it does what it does is a long explanation.
Have the coils stress tested by a dealer to find which one is the offender.
Don't believe it's to expensive because you can spend a lot of money and time trying to find it yourself.
You also risk getting a new defective one in a set and really become confused if that happens with a mass replacement of all the coils..

 

I have the '99 F150 4.6 V-8. I put a K&N air filter on it and also put a Tornado in the intake.

If I just replace all 8 of the COP's and I might as well put new plugs in can I bypass dealing with the dealership? The COP's aren't super pricey so wouldn't it cost less to replace those versus dealer testing? And then I'm running all new anyway...What do you think?

 

PS guys thanks for going thru this with me

 

You know what else bothers me about this...The wheel well is not completely enclosed between the the tire and engine. I formally owned GMC and Chevy trucks and on all of them those 2 area's were always protected from each other. It doesn't look like something is missing or off, but something seems off....Don't know if anybody else noticed.

 

They are all open the same way.
There are no ignition parts that low like your old truck.
Often it is a matter of airflow and cooling the engine bay for why the design is as it is.
For example; a poor design back in the day of the 70s Maverick and Comets was the engine bays were too closed resulting in overheating on cars used in the southwest US hot summers.
When the air can't get {out}, it won't come thru the radiator in enough volume to cool due to a pile-up condition.