I have a '98 4.2l with 122,000kms on it. I changed my plugs, filter, fuel fliter recently and all was well. Two days ago I started the truck and began to drive off when the truck started to stutter. The weather has been a bit cool but not unusual. One i drove for about 1 minute it was smooth like normal. I also hace a sound in the engine (like a card in a bicycle tire) only on acceleration. Could it be by o2 sensor, or my plug wires
Thanks for any help

 

First, check the oil level and condition. When was the last time you changed it?

 

Look for something simple like a plug wire loose or bad. It sounds like a wire arcing to the block to me. When the engine is cold, it is running richer and richer fuel mixtures are harder to ignite. This may be when the wire is grounding to the block. Especially on acceleration when the timing advances. Also, this can explain the noise you are hearing. You can also try starting it at night. Lift the hood and take out the bulb. When it is dark out, have someone start the truck and rev the engine. Then you can see if you get any arcing.
Good luck.

 

I changed the oil 3 days ago.

If understand all, I should change the spark plug wires then?

 

you could try changing IAC valve (mounted on throttle body)
some peole have even cleaned those, but i think that should be done with caution.

 

You'll know if it's the o2 sensor because the engine will gradually run worse day by day until no one will dare follow behind you in traffic for all the smoke and smell because the computer doesn't know what fuel/air mixture to use.

 

gsdindy,
Check the wires. If they look bad then change them. It may be as simple as a plug boot not seated properly. Also be sure to use spark plug boot (dielectric) grease.

 

I changed my spark plug wires ( pain in the clASS ) No more chugging. I went to Canadian Tire and asked them about the sound, the technician there told me it was due to low octane levels in the gas. He claims that regular gas ( octane 87 ) is closer to 65. He suggested that I run a tank or two of High Test to boost the engine. Hope it works
Thanks for all the tips

 

Sounds like what my 97 4.2 was doing just before I found coolant in #4 cylinder. Sounds like you might have a gasket problem, get ready for a hydro-lock and the kiss off from our friends at FORD> Hope I am wrong but sounds just like my symptoms.

 

What is a hydro-lock?

 

hydro-lock is when water gets into a cylinder and water doesn't compress and POP goes the valve and maybe even a crank bearing. I doubt that is the problem. Do you notice your coolant level going down? Or a strong coolant smell from the engine? White foam on the dipstick? Non-stop thick white smoke from the tail pipe? If none of the above don't worry too much.

I also don't think you should run higher octane, just try a different (Name) brand of 87.

The sound you described sounds more like a plug backing out. The sound you hear could be the compression leaking around the loose plug.