Hi everyone,

I don't really know how to describe it, but when I am running at highway speeds, I get a sound similar to small pea gravel in a can (best as I can describe it). It's not real loud, and if I let off the gas, then press back into it it stops. After a few minutes, it starts again.

Truck has about 91000 on it. Any ideas? Thanks. Kevin

 

Maybe a loose heat shield on the exhaust system?

 

My '02 5.4L with 96K was making a lite knocking noise under acceleration. Kind of like the old "bad gas" knocking sound. I switched brands of gas (from Shell/Texaco to Chevron) and the problem has stopped.

A couple of other suggestions I was given when I posted a thread asking after the same matter as you: EGR valve; piston slap; timing chain; may need a valve adjustment (huh?); and also the exhaust system heat shield rattle.

Daryl

 

I've ruled out the gas and heat shield. It is definitely in the engine though. It doesn't sound like piston slap either.

Thanks, Kevin

 

How long have you noticed the problem? Does the "pea gravel in a can" sound happen continuously, or just under acceleration? Does the sound only occur at highway speeds, or do you hear it from a start and at "around town" speeds as well?

What have you tried as a remedy/fix? Have you had a mechanic look at it yet?

DS

 

Could be carbon build up inside the combustion chambers causing an extra high compression ratio. An engine decarbonizing procedure can help. Professionally done or do it yourself.

 

What is that? And how do you do it???

DS

 

It started a couple months ago. It isn't continuous, usually just comes as I'm traveling at a contstant speed, I believe above 45 or 50mph. If I let off the gas, then give it gas again it stops for a while.

Haven't tried any remedies yet since I don't know what it is. No mechanic yet because I was trying this route first to see if it sounds obvious to anyone.

Thanks. Kevin

 

Kevin,
This is getting Twilight Zone-weird. My "knocking" sound chimes in around 45-50mph, too. VERY strange. Maybe it's something with the 5.4's with 90-100K on them. Are we missing something in the "scheduled maintenance" list?

I was told here on FTE that the valves are hydraulic and therefore don't need adjusting. Do you know anything about that? Is that accurate, or not?

I am going to have new plugs and wires put in, plus have the fuel injection system cleaned out. Also interested in what a "carbon cleaning" is, as mentioned in an earlier reply by another FTE member in this thread. Wonder if that's worth looking into, especially coming up on 100K miles.

Have you tried switching gas brands? Or going from 87 to 89 octane gas? I switched gas brands and it seemed to help.

I'll let you know if I find a remedy, and you do the same, ok?

Catch ya later,
Daryl

 

The carbon build up is normal for engines with at least 60,000 miles. Especially if your light on the throttle. This carbon gets built up on the valves and on top of your pistons. It obstructs air flow, cuts down on power and fuel economy. If you have too much carbon, your engine can star to 'ping' which may be what you have. Believe it or not, Ford reccemends to accelerate your engine at full throttle and let it shift through 1st gear a coulpe times. You should do this a few times every 1-2 weeks when the engine is hot. That helps clean the carbon from the intake and combustion chambers. We have a BG service at work that costs 149.95. It is a carbon cleaning system that works pretty good. It runs a special cleaner through your intake and burns off the carbon. We rev the engine up while doing it and it helps clean it out. Most all service shops have something like this. Or you can get some kind of cleaner yourself and with the engine running you disconect your pcv or brake booster vaccum hose and suck up the cleaner through one of those lines while excellerating the engine. This procedure works very well. Be careful not to suck up too much at once. It should take about 3 minutes to suck up 12- 18 ounces of cleaner. Weather carbon is your problem or not this kind of procedure should be done every 60,000 mile or so.

 

Thanks for the info gents. Mine is definitely not pinging, at least not the typical pinging sound of too low an octane rating.

I'll try the cleaning just for maintenance though.

 

These engines are designed for 87 octane,running any higher is not doing anything to help the performance or eliminate pinging.
I would ask how the orignal poster eliminated the shield or pinging?
Did you crawl under the truck with a rubber mallet and tap on the heat shields?
A rattling or pinging sound can be from a bad knock sensor.
The knock sensor tells the pcm to advance or retard the engine timing depending on its voltage generated.
Now the bad thing is the location of the sensor (under the intake manifold)

Rich

 

Maybe the catalytic converter is starting to break up and rattle?

 

I do have a heat shield rattle that's been going on for a couple years. This is a different sound that sounds like it is in the engine. It sounds nothing like my heat shield rattle sounds. Thanks, Kevin

 

I know..a little late to the game...but hey...I'm having the same noise as I had forgotten about what caused it. I had this on my old 94, and am again starting to get the hints of it on my 'new' 94.

The BG product you want is 44K. Now is a good time to use it since the season calls for (at least for me anyhow) lots of short trips here and there. The 44K works best if you run the engine till running temps are met, then shut her down. The solevant works while you shop...then start her up and she blows the broken down matter backwards out the tail...stop and shop and the process starts anew.

Now...ultimate question I have locally..where to get a can of 44K on a Sunday...or maybe just have the wife grab a can from work on Monday.

Good luck..hopefully by this time your issue has been resolved...