I still think it’s the oil!
What I am assuming is that the engine is in proper working order.
You have just had an oil change done on the transmission. You have found that this has improved the performance in general.
However when it is extremely cold the engine stalls when you engage the transmission; BUT when the vehicle is at operating temp there appears to be no issues. Is that right?
So it’s the oil! How come? Things we don’t know: how much oil was replaced? Was the transmission flushed? What if anything was found in the filter? What was the “sludge” like on the inside surface of the pan? (an indicator)
Sludge is not just privy to the pan but throughout the transmission and torque converter. Now as we know transmissions are finally machined units, and the characteristics of the oil used are carefully selected. The stability of the fluid in a new transmission can be predicted (doesn't mean they always get it right) but all bets are off after an overdue oil change!
You can easily remove the fluid however it’s not easy to remove the sludge. Let us say we replaced 11lts, that is a good count and you now have lots of fresh fluid, which is also a very good penetrant! That begins to change the characteristics of the fresh oil as it is now dissolving the sludge and blending with the old! This dissolved sludge now mixes with the fresh oil changing it, and no the filter can’t help as it isn't designed to.
So what is going on that the engine stalls only when very cold?. The short answer is the solenoids are wasting amps because they have to work against the sludge, heaver oil, cold temperatures, and age. Speed is important here; when you engage the transmission the actuators have to respond fast that's there design. If they slow or stall then the torque converter bypass, or slip isn't functioning properly, it cloud be just dragging or not slipping enough, engaged verses engaging, or lockup mode (and no it shouldn't be) at to low RPMs! Here is a quick example, if any one reading this remembers the old “fire ball” cams, or any other high lift, 1st thing we needed to do was find a new stall speed and that also meant a higher stall torque. What that means is a stock torque converter would engage at to low an RPM and cause the engine to stall out! We now had lots of potential HP however we needed to control the engaging at higher RPMs. (a short explanation)
That is what I think is happening, though the cause is different, for one the oil wasn't changed often enough, sludge built up in the valve body, slowing or stalling flow regulation and or path.
Hot oil achieves a better working viscosity; that coupled with the hot valve body mass, things actuate closer to design. I think that if you keep up with the oil changes and perhaps drop some and replace more when the color starts to change, likely you will get ahead of it, or drop the valve body and clean it.
We can also describe the stalling as, dropping the clutch at 6 or 700 rpm!
Try this it won't cost you anything and I don't know for certain it will boost enough but might help, put the air conditioning on 15 seconds before engaging the trans, if it helps drive a couple of blocks with AC on then switch to heat.
Patch
What I am assuming is that the engine is in proper working order.
You have just had an oil change done on the transmission. You have found that this has improved the performance in general.
However when it is extremely cold the engine stalls when you engage the transmission; BUT when the vehicle is at operating temp there appears to be no issues. Is that right?
So it’s the oil! How come? Things we don’t know: how much oil was replaced? Was the transmission flushed? What if anything was found in the filter? What was the “sludge” like on the inside surface of the pan? (an indicator)
Sludge is not just privy to the pan but throughout the transmission and torque converter. Now as we know transmissions are finally machined units, and the characteristics of the oil used are carefully selected. The stability of the fluid in a new transmission can be predicted (doesn't mean they always get it right) but all bets are off after an overdue oil change!
You can easily remove the fluid however it’s not easy to remove the sludge. Let us say we replaced 11lts, that is a good count and you now have lots of fresh fluid, which is also a very good penetrant! That begins to change the characteristics of the fresh oil as it is now dissolving the sludge and blending with the old! This dissolved sludge now mixes with the fresh oil changing it, and no the filter can’t help as it isn't designed to.
So what is going on that the engine stalls only when very cold?. The short answer is the solenoids are wasting amps because they have to work against the sludge, heaver oil, cold temperatures, and age. Speed is important here; when you engage the transmission the actuators have to respond fast that's there design. If they slow or stall then the torque converter bypass, or slip isn't functioning properly, it cloud be just dragging or not slipping enough, engaged verses engaging, or lockup mode (and no it shouldn't be) at to low RPMs! Here is a quick example, if any one reading this remembers the old “fire ball” cams, or any other high lift, 1st thing we needed to do was find a new stall speed and that also meant a higher stall torque. What that means is a stock torque converter would engage at to low an RPM and cause the engine to stall out! We now had lots of potential HP however we needed to control the engaging at higher RPMs. (a short explanation)
That is what I think is happening, though the cause is different, for one the oil wasn't changed often enough, sludge built up in the valve body, slowing or stalling flow regulation and or path.
Hot oil achieves a better working viscosity; that coupled with the hot valve body mass, things actuate closer to design. I think that if you keep up with the oil changes and perhaps drop some and replace more when the color starts to change, likely you will get ahead of it, or drop the valve body and clean it.
We can also describe the stalling as, dropping the clutch at 6 or 700 rpm!
Try this it won't cost you anything and I don't know for certain it will boost enough but might help, put the air conditioning on 15 seconds before engaging the trans, if it helps drive a couple of blocks with AC on then switch to heat.
Patch
