Got a 06 D5G xl, it's started jumping-jerking-bucking while tramming forward & backwards. The engine strays rpm (no stall) only the transmission/drive pauses/stalls. It started so we called the local cat dealer, they hooked it up to computer & recalibrated. I could feel a minor when he got done & while working yesterday it started again. Dealer said until a falt shows up he can't do anything. Does anyone have an idea to repair ?
There is a speed sensor on the flywheel housing that the hystat ecm reads engine speed off of so that it can tell if the engine is lugging and to destroke the pumps. I think you can see it if you pull the LH engine screen off. Unscrew the sensor and see if it has a bunch of crud built up on the tip. It may have crud on the threads inside the housing so don't be surprised if you need some penetrating oil and work it back and forth to get it out. The correct adjustment for this type of sensor is have one of the teeth centered in the hole, screw the sensor in until it touches and then back out 1/2 turn and lock it down. If it's not the sensor it could be the wires rubbing somewhere. It will be a twisted pair of wires most likely.
Thanks, will check that sensor
I found rust attached to the sensor, it must be magnetized. Reinstalled & ran fine for 3-days, until yesterday pm. and started jumping again. I'm going to remove sensor from flywheel to see if it's rust on the sensor. Just cant figure how to keep rust from getting attached to the sensor.
Cleaned the speed sensor & that didn't any, man that thing is about to make me look @ a komatsu or deere ! I did see that when the sensor was tightened down & went to backed it out 1/2 turn the sensor didn't turn exactally with the collar. Could it be broken ?
What do you mean it didn't turn exactly with the collar? The nut on the sensor body is a jam nut.
Tried to back out the sensor the 1/2 turn but the metal housing turned out just a little before the actual sensor turned, I was watching the wires is the way I seen it wasn't turning together.Turned that the wires were out half turn then tightened the jam nut. Just thought since it was still jerking, maybe the sensor was bad. I did notice when the dozer would complete stop I could press the brake petal & it would start again.
Hmm, if the sensor body turned a little but the wires didn't it could be coming apart internally. IIRC those sensors should ohm out around 1100ohms between the two wires. On those machines it's kind of hard to figure out what's going on without a laptop to see what all your sensor inputs are doing.
Have had the Cat tech. to work on it twice. Got to a point that he didn't know because no faults were showing & he said the (50-60%)u.c. needs changed & then let him recalibrated. But I go back to cleaning the flywheel speed sensor. That's what cleared up the problem for a while.
The last time I dealt with a jumping and bucking machine it was on track loader that I couldn't reliably replicate the problem. I put in a new sensor and put in new wires all the way to the ecm and that fixed the problem. The new wires have to be twisted to reduce interference.