Shudder under load

[DBlaze]

Has anyone found the cure for the wash board road shudder / dither that you feel under heavy load at part throttle? My 99 5 speed with 275's and an EZ box does it in 5th gear with the horse trailer at about 1800 rpm. This past weekend we went to the horse trials at Flora Lea farm in NJ. When the outside air temp was high the shudder was minimal, as soon as it started to rain and the air temp dropped the shudder came back. At WOT the shudder goes away and as I understand it the IAT sensor is taken out of the loop. My guess is that the IAT sensor alters the timing and fuel curve in some way that at low air temp the ECM is on the cusp of some combination of parameters that causes the hunting or dithering. Has anyone tried a pot in series or parallel with the IAT sensor to fool the ECM into thinking the air temp was something other than actual with any success in eliminating the dithering? I'm also wondering about the sensitivity of the IAT and the effect that small changes in resistance have on the fuel and timing tables under certain conditions. I'm thinking about a fixed resistance value that will tell the engine that the air temp is high but steady.



Dave

 

[C1B1DIESEL]

My best guess for the shudder would be the axle is wrapping up and with a load on the hitch that also changes the normal angle of the differential, and what you are feeling is the drive line is out of running angle which can and will cause a shudder,or vibrating,

This suddering or vibration will happen when the working angle is out of spec. i do not know what the spec. is.



I also get the shudder. but i just back off the throttle a little and til im past a certain rpm or mph the add the throttle.

i think if i put on a ladder bar of some type and keep the axle from wrapping up that the shudder would go away.