GOOD NEWS!!!!!!!!! THE MYSTERY IS SOLVED!!!!
Ok guys here is the deal the way it was explained to me. The computer calibration for this truck calls for a whole lot of EGR flow. When the motor is new, this is not a problem because the motor is very efficient. But as the motor gets some age on it,50,000 miles+, it no longer runs as efficient. This causes the exhaust properties through the EGR valve to change from the original calibration, and the motor will surge (RUN LEAN). The computer cannot compensate for the running characteristics of an older motor. Since it is impossible to change this calibration, the only thing you can do to compensate for this is to restrict the amount of EGR flow. HOW???? Put a restrictor plate between the EGR and manifold. This allows the EGR to operate and send feedback to the computer. I asked why I couldnt block off the EGR totally, the answer is that the computer compensates for a certain amount of exhaust gas in the mixture and blocking it off completely will cause the motor to run rich. PROBLEM SOLVED!!!!!!! Hope this helps someone, now that I have pulled all my hair out. YEAH BABY!!!!! Now Im ready for another 100k.

 

i have a 4.9 also and it shakes the hell outta me at higher rpms......but it's the motor mounts going bad......dont think this helps but i thought id add it incase.

 

i also would like to add that due to this extra vibration the motor sounds sick or overworked or something hard to explain....i guess u could say it might sound like it's missing. again im pretty sure this is not ur problem but i thought id add it incase or to help someone else hopefully

 

now i feel dump i hadn't read til the end when i replied. lol

 

Sounds like the cure I need in my 1990 4.9 4x4.
Did you make or buy the restrictor plate? If you made it can you tell me what you did? If you purchased it - where?
Sure glad you solved your problem - hope it fixes mine too.
Thanx - much.

 

BIGWHITETRUCK are you still around?
Did you make or buy the restrictor plate? If you made it can you tell me what you did? If you purchased it - where?
Thanx

 

Sorry dude. Try this hope it helps.
http://www.ford-trucks.com/dcforum/DCForumID9/483.html


[This message has been edited by bigwhitetruck (edited 04-27-2001).]

[This message has been edited by bigwhitetruck (edited 04-27-2001).]

[This message has been edited by bigwhitetruck (edited 04-27-2001).]

 

Have the fuel injectors cleaned, not the stuff you dump in the tank, have them cleaned with bg cleaner and your problem will be fixed, the 4.9 is notorious for clogging injectors.

 

Just a little note. My miss has been gone for about a month now. My kick *** ford truck tech hooked me up with the fix. Now I got a new problem. Im getting horrible spark knock when accelerating on the interstate. I called my ford guru and he said I could have carbon in my combustion chambers. He gave me a can of ford carberator tune up cleaner. Told me to put cardboard over the radiator to get the engine as hot as a firecracker and use the air cleaner hose as a funnel and flood the engine with it till it stalls and let it sit for 15 min. Then use the rest of the can to flush it. It did help but I still have slight spark knock. He said since the spark knock happened overnight, i may have gotten bad gas. ran 2 different tanks still there. Come to find out that the gas formula changed for the summer driving season. Something about oxygenated gas. He told me to enlarge the hole in the plate. I took it off and the spark knock is gone, and it still isnt missing. Go figure. Ill keep the plate and put it back on in the fall.

[This message has been edited by bigwhitetruck (edited 05-13-2001).]