I have a 94 f-150 with the straight six and an automatic trans. Motor was rebuilt at a ford dealership before i owned it. Ive deleted the egr, the PCV now runs out the passenger fenderwell, and i put a glasspack on it. Ever since ive owned it its made strange noises, when the motor is lugged down, it makes a knocking noise, it sounds somewhat like when you shut a diesel truck down. At idle its not existant, but it will do it anytime the motors under load and then go away at about 2000rpm. Its especially bad when im about to kick it out of O/D its really loud then, but as soon as it kicks down the noise goes away, and it will not do it in neutral/park. Any help would be greatly apperciated, its starting to worry me and i cannot afford a shop.

 

What you are experiencing is detonation, aka spark knock. It will kill your engine. You have contributed to this by deleting the EGR.

READ

 

Could you explain the item in bold above?

 

Have you checked the timing?

If it's much above 10° try setting it back to factory 10° BTC setting.

 

If you just blocked off the EGR without unplugging it/tuning it, that certainly can cause knocking at low rpm/high load. EGR allows the engine to use less fuel with more spark timing because of the cooler combustion. With it blocked off, you get lean combustion with a ton of ignition advance - which leads to knocking/detonation.

The oxygen sensor can compensate for the lean burning, but not the extra timing advance.

 

Well The PCV was causing a vaccum leak so i blocked it off at the intake and since it smokes a little bit on start up i ran a hose out the fenderwell. Should i try taking a few degrees of timing out of it? but if i do take timing out wont the computer just compensate for it? And do i need to remove the little grey plug when i change the timing? when i first bought it i bumped it up about 2 degrees bub didnt unplug that little plug, ive been told thats a no no

 

The computer can't compensate for timing. Everything it does is either added or subtracted from the base timing. Removing the 2-wire SPOUT connector/plug disables the computer timing advance allowing you to set the timing. Trying to set the timing with the SPOUT connector in is futile at best - engine damaging at the worst. I doubt the 4.9's can tolerate much ignition advance anyways.

...and come on man, fix the PCV system. Do you know how much a PCV valve for your truck costs? 3 Dollars. Not thirty, just three. Do you know how much replacement vacuum line costs? Typically less then 30 cents per foot. You could have fixed the system right for less than $5 and 5 minutes of your time. The engine's breathing system/valve cover was not designed for draft-tube venting, it was designed for PCV.

 

Sorry i just dont like the thought of my truck breating in all those oil vapors, same with the EGR all it does is hurt the motor, and i did leave the egr sensor plugged in but since nothing is pushing in the little rod the motor thinks the egr is shut. i had an 85 with the six and the first thing i did was remove all the emmissions equipment and that truck once setup right ran perfect, much better than with the goverment emmissions b.s on it,

 

EGR does not harm your engine. The detonation from your higher combustion temperatures has done more harm to your engine in the past few months than any amount of EGR would do in 30 years. What does EGR do? It lowers combustion temperatures and puts some soot into your intake. The same harmless soot that your engine already created on its own. Not a big deal.

What does knocking do? It literally dents, punches holes through your pistons and destroys piston rings. It is pretty much the equivalent of hitting the tops of your pistons as hard as you can with a sledge hammer. That is what disabling your EGR valve has done to your engine - thousands of times per minute.

What does the PCV valve do? Constantly brings fresh air into the engine and brings combustion gasses that have leaked past the piston rings as well as oil vapor to be re burned. The engine itself can hardly tell the difference between oil vapor and the very gasoline it's running on. They're both very atomized hydrocarbons.

What does bypassing the PCV valve and having a draft tube do? At low speeds and idling it allows those combustion gasses and oil vapors to build up inside the crankcase. Those combustion gasses will break down the oil and start causing the oil to build sludge all over the insides of your engine.

So you're completely wrong on both counts. You've done more damage to your engine then those emissions components could have ever done. All of that knocking and detonation has done permanent mechanical damage. These engines run just fine with the factory emissions components and EFI doing what they are supposed to do.

I'll leave you with a couple of pictures of what enough detonation can do:

 

It sounds like you have been handed a line of B.S. And, you bit it hook, line, and sinker..

The engineers that designed the "system" were not complete idiots

 

Thanks for the help guys, i went ahead and checked the plugs today, they were all nice and brown with no signs of pre-ignition or detonation. I found out the noise was coming from the EGR pipe that runs to the exaust manifold, got it fixed and no more noise. Also found out why you dont mess with the screw on the throttle body.