Slip from lock up

[Truckie117]

Well I used obdII scanner and there are no codes. Is that the type of scanner you are referring to? Next step is to change filter and fluid and you mentioned some selinoid that might need changing is that internal or on the case?
Taking care of a sick wife and sick truck at the same time is no fun.
Thanks
Mike

[convert2diesel]

Mike:

I noticed you are using veggie. While many have been successful using the straight stuff, the temps required do have an adverse efect on these pumps. Does your problem happen even when running on #2 (no veggie) or is it a universal problem?

I run bio-diesel in my vehicles in the summer with no problems, but in my opinion, these pumps don't really like the straight vegetable oil as you have to get the fuel temp too high to get it to work. The DS4 and the older DB2 pumps don't like heat and can give some wonky problems if they are not cooled properly. They depend entirely on the fuel for cooling and if the fuel is hot coming in then it can only get worse.

Bill

[JohnC]

If there are no codes then the PCM is not seeing it drop out of lockup unexpectedly. So, if it is dropping out, it is expected. Look for a flaky brake pedal switch or a flaky coolant temperature sensor.

My experience is that the #9 resistor can make the throttle on some trucks touchy. Whether or not it could be the cause of the trans issues is a good question...

[Truckie117]

Hi
I think I may have stated my problem wrong. What I thought was the OD dropping out is in fact a throttle problem. Tranny shifts fine but when I travel on side streets everything is fine.
When I go about 45 thats when the trouble starts truck accelerates but when I get to 60 I am hardly touching the pedal but when I try to back off the pedal truck bucks and its hard to keep steady without going faster. That is when the tranny drops out of OD like you are pressing the accelerator to pass. Going to check all the grounds and connections I have 2 new batteries and good battery connections.
Thanks
Mike

[Truckie117]

Could you tell me where the coolant temp sensor is located and what kind of reading it should have?
Thanks in Advance
Mike

[Truckie117]

I found the 2 temp sensors and replaced them the dash gauge seems to be working better more in line with the odb reader for live data. Still truck runs great from Idle to 45 good throttle response can ease off and go slower no problem, When I get to 45 or better when I ease off throttle its like it just wants to drop to idle.
Still no Codes but on hard acceleration a lot of black smoke even when I drop out of od to passing gear. Truck shifts fine through all gears.
Waiting for my manual to arrive so i have the proper books.

[JohnC]

The 4L80E has an over-running clutch when in OD. If you let off the throttle the RPM's will drop down close to idle. (A little higher for emissions purposes.) The electronic throttle is very difficult to hold at a specific RPM when there is no load on the engine, so if you are trying to hold the RPM at road speed when you are overrunning the trans, it will go back and forth from "too slow" to "to fast" and this could be what you are experiencing. It may be normal operation.