4L80 acting weird AFTER adding wire for TCC

[CDeeZ]

I think I have made some progress on the rich issue. After fiddling around with the injector flow rate what seemed to help the most was to take the VE cell that it idles in, and the surronding cells for I believe 12 in total and reduce them all by a value of 25.

The other strange issue is still present. I'm still suspecting something with the 4L80. You mentioned a possible ground issue, wouldn't that show up in the scanner on the monitors as some form of a voltage drop, even for a split second? Voltage is rock steady. Tonight, for the second time the PCM set error code 73 Pressure Control Solenoid. Maybe this is the problem???? To describe the issue again, it feels like the trans drops in and out of gear, or hunts between gears when it is happening. I think I've even seen the scanner show it flip between 3rd and 4th when this is happening.....


EDIT: I can look at older logs and there is SOMETHING displayed on the monitors for the force motor duty cycle.... The log from tonight and the other night when this issue started, NOTHING for force motor duty cycle.

[CDeeZ]

The first image is what I would expect the force motor to look like on the logs. (The teal line) This is from a previous log before this issue happened.

The second image is of the force motor completely spiking down to zero on the monitors, perhaps a sign it's failing? This log is from a few days ago.

THe last image is showing the force motor duty cycle staying at 0... Doesn't even show up on the monitor now since it's 0. This log is from tonight.

[Terminal_Crazy]

Hi
[QUOTE]
The second image is of the force motor completely spiking down to zero on the monitors, perhaps a sign it's failing? This log is from a few days ago.[\QUOTE]

I don,t know and could be wrong but i suspect the log is showing the “commanded” output from the pcm rather than the actual output of the motor. Ie the log is showing pcm output rather than input data.

Mitch

[CDeeZ]

I think you may be right. I read somewhere that the PCM will shut the force motor off defaulting to max line pressure.

Where does the 4L80 ground??? Or is it the solenoids grounding as provided by the PCM for each shift event?

[CDeeZ]

Gentlemen,

The root of the problem has been isolated..... Wait, almost rolled into a Clutch song... OOps... Anyways, looks like I fixed it.


Today I had some free time and the weather was a beautiful 70*.... Took advantage of this to look over everything....

The first thing I did was to remove the 2 wires going to the Input Speed Sensor on the trans and twist them up... They were NOT twisted when I installed them and I wonder if they were picking up interference causing this weird issue. Those wires were actually pretty loose and sloppy in their routing before I twisted them up.

The second thing I did was I looked at the main trans plug that goes into the case with 11 wires, the round plug. I noticed there was a little bit of trans fluid on it. I coated the plug in "motor assemly lube". Says right on the side of the bottle "excellent for electrical connections". And I have used it before on electrical things.

One of these two things must have fixed the problem... Went on a 30+ mile trip and everything is working perfectly, shifts through all the gears, hits lockup and releases lockup when I touch the brake pedal....

I also put in maybe 4 oz of fluid into the trans, no way it being just barely low could have caused all that weirdness though surely......

It was mentioned by myburb that it could be an electrical issue and I think that must have been the case because sometimes I could hit a bump and cause this issue, pretty indicative of an electrical problem.

I also noticed that when I key on, the speedo in the dash jump up to 10 MPH or so..... Not sure what's going on there, but I will look into that in the future. Possibly I need to check and retwist the VSS wires coming off the back of the T case.


Moving forward my plan is to check the wiring harness (again) inside the pan and possibly replace it or the seal around it since it's getting ATF on it from somewhere.. And, I'm going to figure out what is going on with the speedo jumping, or at least try to..


I love it when something finally works out. Perseverance is the way to accomplish anything. It's easy to get overwhelmed on a project of this magnitude when you're doing it all by yourself. I built the engine, the transmission, the T case, fixed up the wiring harness, and have been working on dialing in the tune.... 1 Man stand alone factory??? Okay I'm getting off my soapbox now.

Thanks to everyone for weighing in and BillyGraves who I have had numerous exchanges in private messages regarding all things OBD1 and 4L80.....

I'm amazed at how effortlessly this little 355 will pull away in 3rd gear say at 35 MPH.... No need to donwshift or rev up if you don't wanna, TORQUEEEEEEEEEEEEEE!!!

[brian617]

The first thing I did was to remove the 2 wires going to the Input Speed Sensor on the trans and twist them up... They were NOT twisted when I installed them and I wonder if they were picking up interference causing this weird issue. Those wires were actually pretty loose and sloppy in their routing before I twisted them up.

I also noticed that when I key on, the speedo in the dash jump up to 10 MPH or so..... Not sure what's going on there, but I will look into that in the future. Possibly I need to check and retwist the VSS wires coming off the back of the T case.

Always twist VSS and Data pairs (later CAN comm) Otherwise they act like a TV antenne and do strange things. I fixed an old first GEN Dodge diesel auto with a wacky speedo by re-twisting the VSS pair someone had pulled apart not to long ago.

[myburb]

I have had a goofy speedo for some time. It shifts fine, the speeds show correct in data log. I changed drac with no help, I changed instrument cluster with no help. Next time I have the cluster out I will look at adding a hard ground. In the mean time I am using an old gps for speed.