so details. it started when i revved the egine to get someones attention, so i revved it loud. then on the drive home and ever since then has been shaking when im at mid throttle on the peddle. if i barly press the gas its fine .. if i floor it and drop a gear its fine but mid throttle it shakes like im hitting a rumble strip. and idk if this helps but i did a tune up and oil change cuz i thought it might be a misfire and afterwards it not only still did it but a new sound was added on which scared me. because everyone said the new sound was a rod knock, but... a month later the rod knock went away and now im stuck with the shaking... any and all help is appreciated.. tanks

 

have you checked for codes? did you get a cel? i had this happen to me once, but the shaking stopped after a few seconds. i was beating the crap out of my truck and the heat must have caused the carbon on the pistons to pre detonate the fuel. if that was your problem, the skaking would have stopped by now though. have you ever seafoamed it?

 

havnt seafoamed it .. but am going to and if that doesnt help i was gonna use some injector cleanor to see if it helped

 

its possible your harmonic balancer spun on itself. does it do the shaking in nuetral also?

 

no not shaking in neutral or in park only when im driving

 

What tranny do you have? Does it shake on acceleration and deceleration? Do you have a tach?

 

my 1994 ford f150 straight 6 did same thing couple years ago.. it was bad spark plugs, overdue tuneup. so i got new plugs, dis. wires, dis. cap and it ran much better.. take look at your spark plugs and dis. wires.

 

i did the complete tune up allready... thats when the knocking started

 

do you have the plug wires mixed up?

 

hitting a rumble strip..does it at a certain speed or a certain rpm? sounds like torque converter or transmission not shifting. do you have the E4OD or the AOD or a manual transmission ?

 

Edit: I didn't read it was a straight 6. But it sounds like a miss fire at rpm XX. Its hard to diagnose crap over the internet unless its one of those extremely common problems. That and I just woke up for work.


If it were me... I would start pulling plug wires and see if it the idle changes on the truck one at a time. It sounds like you may have a wire that's not seated 100%. The sparks able to jump... some of the time. Maybe a clip got pushed back into a wire.

Or you didn't cross the plug wires at a 90 degree angle and your getting the miss where the plugs share a pulse.

1-5-4-2-6-3-7-8

If 7 plug wire is running parrallel and close to 8. Occasionally it will jump the spark between the wires, so 7 will fire off both 7 and 8. And then 8 can also fire off 7. Makes a slight miss fire. If the spark plug wires are tucked neatly into the plug clip... your doing it wrong.

Check that and report back.

 

plug wires aint mixed .. but idk if there jumpin so ill check on that.. then report back.. thnks for all the help so far guys

 

I doubt it on a straight six. I had just gotten up and was like... oh well that might be an easy one. I am not seeing it being a problem with the TPS. Just trying to think what it might be just sitting here. If I was there would make it a whole lot easier.

I mean there is several things it could be. I wonder if your ignition advance is going to full advance at part throttle. Would not be a problem at light throttle or full throttle. But it sounds to silly we need something more concrete.

So from what information I have. Its missing in gear, so it has some sort of load. It cant be valve springs because it would start missing at anything over a certain rpm. Lets assume the spark plug wires are fine and there is no jump. Since its not running stupid at idle lets say there is no vacuum leak and that you hooked up your wires properly.

I dont think it could be a leaking manifold gasket but... it might be. But that sounds to far fetched it would have other problems at idle... Egr is open at part throttle, if it was sticking open your idle would be all stupid, but under part throttle your egr should be open. But if the EGR is stuck closed at part throttle you will run lean and it might be detonation and make you run like crap.

Do you still have the egr on your truck? Get a vacuum pump and see if you can pull vacuum on the egr valve at idle and see if the truck stumbles. If you pull vacuum on the egr at idle and nothing happens the little ******* is clogged or stuck shut. Your running lean and that's your problem... So after all that rambling check your EGR valve. If its good I will find you something else to check.

Again I have no idea I am just trying to toss something to ya.

 

Mine just started doing it also, it shakes from about 15-40mph. It doesn't shake when I let off the gas though. It started after my front tank quit on me. Also motor is freshly overhauled now have 6k miles since then, damn nylon timing gear smoothed out. Just replaced all tie rods and tires but still shaking.

 

stil no progress on this end.. but mine will do it at any speed.. i just have to be at mid throttle on the gas pedal.. if i figure it out ill post the answer here