I have had a 95 F150 with a 5.0 for a year now that has been experiencing some engine noises. When I took it out for a test drive (prior to buying), I had noticed a slight rattle coming from the engine when I would really accelerate. I didn't think much of it because it was very slight, and the owner said that he had never noticed it. I figured it was just an exhaust rattle, and went ahead and purchased the truck because I was sort of desperate. Anyways, I had to use the truck to drive back and forth to school (approximately 1,200 miles round trip) The sound never really got worse, but never really went away. I took the truck to a Firestone Shop, and Ford Dealership; both of whom said the truck was fine. The Ford guy actually told me to take it to Meineke to check the exhaust system. Well the Meineke guy told me that it sounded like a low-octane knock, and to try a higher octane gasoline. I took his advise and surprise, it worked (at least for a few months that is). To wrap up this novel, I wanted to say that the sound has never gone away and may have gotten worse. It's kind of a combination rattle/dieseling sound. The truck has got 74K original miles. It does not smoke or use any extra oil, and has plenty of power. Have any of you had or heard of a similar problem? Any suggestions would be greatly appreciated!

Thanks,
Jeremy

 

Sounds like you got some spark knock. It comes from running a little lean. Check fuel pressure, 30-45psi. Check for any codes. Try having the fuel injectors cleaned, or you could add some stp injector cleaner to the next couple tanks and see if it helps. Keep me posted.

Robbie

 

Thanks for the info. I ran some injector cleaner through a couple tanks to no avail. My dad recommended spraying some sea foam in the intake to help eliminate any possible carbon build up, but that didn't work either. You may be on to something, about it running lean. I might try flushing the injectors, and see if that helps. I don't want to spend too much money trying to solve this problem as I'm selling the truck in a few months. My dad said he had the problem with his 87. Any of you all heard of this before? Supposebly this is a problem that GMs normally have...

 

If you drive lightly, accellerate moderately and drive maybe 10 over the speed limit, you can clean it out by driving it hard once a week or so. Warm up thoroughly, then floor it and let the RPMs build to about 3500, slow down and repeat 3 or 4 times. After a couple of times, if carbon in the combustion chamber was the problem, it will clear up.

If it is a clogged injector, low fuel pressure, poor EGR circulation, etc., it won't help. Here's hoping it will clear out for free.