Cold weather behavior...

[derfdog15]

Hey guys,

As most of you know, I have a 2015 SHO which is my DD. I currently am running tuned, with an E20 blend, and mild bolt ons.

I noticed in the onset of full on winter weather (sub 32 degree temperatures all day) that my trans takes a long time to warm up(expected). Anyone know what the normal operating trans temp is on 6F55?

I also have noticed, when cruising, that RPM (in 6th) is higher at cruise, close to 2.5-3k, at 75-80mph. I am sure some of this has to do with the trans temp.

The final thing I noticed, Fuel Pressure is obnoxiously high IMO, like 4-6k high, while idling, and goes between 3-6k during cruise. I again, assume this is due to the cold, as it drove fine and never had issues in slightly warmer (35-40 ambient) or temps higher.

LTFT is also "stuck rich", since my STFTs are at 1.00 and LTFT stays greater than one.

This behavior all makes sense to me based on the weather, but I just wanted to see how other peoples ecoboosts behave in the cold.

Thanks guys.

 

[SHOdded]

Trans warmup time can take a LOOONG time if mostly highway.  City driving, maybe 10-15 minutes.  In cold weather.

The N.O.T. is listed in the owner's manual as around 180-200F.

 

[derfdog15]

Trans warmup time can take a LOOONG time if mostly highway.  City driving, maybe 10-15 minutes.  In cold weather.

The N.O.T. is listed in the owner's manual as around 180-200F.

Thanks for the reply. That certainly explains it, as my commute to work is only about 10 minutes in city traffic, and I let the car warm up about 10 minutes before leaving, and it seems to behave normally near the end of the drive. On the weekends when I go out and about on the highway (maybe 10 miles one way at most, same warm up time) it takes a LOT longer to get to normal.

I think the best trans temp I have seen this past week is 135 degF. So definitely cold transmission.

That FL weather for Christmas is going to be wonderful.

 

[Gjkrisa]

I think as long as them trans temp get over 70 it will be alright but I'm no mechanic... At -9 today my warm up temp is 127 only after doing some sliding in the snow I got the temp up to 170 after 5 minutes but watching the temps from a cold start the initial start the temp goes up a degree every second didn't wait very long to see when it slowed it was -30 that day.

Sent from my Nexus 6P using Tapatalk

 

[ajpturbo]

The torque converter may not be fully locked when cold which can raise the rpm a little...it may allow it to slip to help heat the fluid.

What do you mean high fuel pressure of 3-6k?..you logging in kpa?..usually part throttle fuel pressure is a few hundred psi

I dont think the bypass valve for the trans cooler opens until at least 180 and when it does open the fluid that goes to the radiator will get cooler too because you have the lower stat so rad temps may be down too

What do you mean stuck rich?...at warm up sometimes you are in open loop and there is no 02 feedback so stft will show 1.00 until they get warm or you enter closed loop

 

[derfdog15]

The torque converter may not be fully locked when cold which can raise the rpm a little...it may allow it to slip to help heat the fluid.

What do you mean high fuel pressure of 3-6k?..you logging in kpa?..usually part throttle fuel pressure is a few hundred psi

I dont think the bypass valve for the trans cooler opens until at least 180 and when it does open the fluid that goes to the radiator will get cooler too because you have the lower stat so rad temps may be down too

What do you mean stuck rich?...at warm up sometimes you are in open loop and there is no 02 feedback so stft will show 1.00 until they get warm or you enter closed loop

I can get a log of it later, and post it here/send it your way. I have been looking at the fuel rail pressure parameter which I believe is in KPA.

By stuck rich, I mean that even though STFTs are leveled at 1, the LTFT is greater than 1 constantly, and fuel economy has dropped off a bit (which I attribute to higher RPM and the fuel being commanded in a richer mixer). I know the E blend has affected economy a bit as well, but since I have been running it for a while now, I have gotten used to the E20 economy.

I was briefly watching the fuel rail pressure parameter and seeing high numbers the last few times I drove, which is why I posted here. There is no performance loss it seems, though I am not getting on it much due to weather/road conditions and the car still being somewhat cool.

As far as RPM/torque converter slip, that makes total sense, and I assumed it was holding a higher RPM to warm quicker.

I think as long as them trans temp get over 70 it will be alright but I'm no mechanic... At -9 today my warm up temp is 127 only after doing some sliding in the snow I got the temp up to 170 after 5 minutes but watching the temps from a cold start the initial start the temp goes up a degree every second didn't wait very long to see when it slowed it was -30 that day.

Sent from my Nexus 6P using Tapatalk

Yeah it is typically warmed up to about 80 degrees before I leave home but takes a while to get up to/past the 120 mark. 

 

[ajpturbo]

Rail pressure pid can be changed to psi...it should already be though from the config i sent

I wouldnt worry about the rail at part throttle its just following stock values

The fuel economy drop is all from E blend and idling

As long as the idle ltft is less than 1.05 i wouldnt worry...but i think you are mis interpreting the commanded afr.....you are not commanding a richer mix due to cold or E20....look at LAMBSE at idle it should be 1.00 meaning your afr commanded is about 13.75 or so because of the E blend

Your trims will do whatever is necessary to achieve the commanded afr which is also called LAMBSE....so if your fuel tuning was completely jacked up and ltft and stft was 1.15 but your lambse and lambda was 1.00 then you are getting the exact afr that is commanded

 

[derfdog15]

Rail pressure pid can be changed to psi...it should already be though from the config i sent

I wouldnt worry about the rail at part throttle its just following stock values

The fuel economy drop is all from E blend and idling

As long as the idle ltft is less than 1.05 i wouldnt worry...but i think you are mis interpreting the commanded afr.....you are not commanding a richer mix due to cold or E20....look at LAMBSE at idle it should be 1.00 meaning your afr commanded is about 13.75 or so because of the E blend

Your trims will do whatever is necessary to achieve the commanded afr which is also called LAMBSE....so if your fuel tuning was completely jacked up and ltft and stft was 1.15 but your lambse and lambda was 1.00 then you are getting the exact afr that is commanded

Gotcha. Thanks for the clarification. I may still grab a log just for peace of mind, but believe this to be 100% due to sub freezing temperature.

 

[ajpturbo]

Hell yea send a loggy log my way

 

[derfdog15]

Hell yea send a loggy log my way

Will do Mr. Log Warlock.

Expect one in your inbox sometime between 5 and 7pm tonight. Probably won't wait a ton for the car to warm up, but I'll just log from the time I get in until I get home.

 

[SHOdded]

By design, the trans bypass valve opens around 140 or 160F. Will have to check.  Since very little heat actually transfers from the engine to the transmission, only driving hard will raise trans temps quickly.  Which of course we DONT want to do.  So patience is key.

I think the ebs that use the 6f35 trans do have a trans warmer circuit builtin using engine coolant?  To go with the shutter thing.

 

[jbrown9999]

I actually bought this because we've had some chilly temps here in UT this year and I know 75% of engine wear is caused at startup, especially in cold temps because the oil (synthetics also) are thicker and take time to get to the engine parts.

https://www.amazon.com/gp/product/B009Z2H71O/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

I should be able to get it installed and tied down tomorrow for this upcoming sub freezing weekend.

Based on this, maybe I should get a 2nd one for the tranny.

 

[8nutz8]

By design, the trans bypass valve opens around 140 or 160F. Will have to check.  Since very little heat actually transfers from the engine to the transmission, only driving hard will raise trans temps quickly.  Which of course we DONT want to do.  So patience is key.

I think the ebs that use the 6f35 trans do have a trans warmer circuit builtin using engine coolant?  To go with the shutter thing.

To the best of my knowledge the open temp of the trans fluid thermostat depends on model. Cars with PP and aux trans cooler have a 160* and cars without 190*. I can't say this is 100% verified info but i  know i've seen it stated before and it seems accurate from the difference i saw when changing to just the colder trans fluid thermostat.

 

[derfdog15]

I actually bought this because we've had some chilly temps here in UT this year and I know 75% of engine wear is caused at startup, especially in cold temps because the oil (synthetics also) are thicker and take time to get to the engine parts.

https://www.amazon.com/gp/product/B009Z2H71O/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

I should be able to get it installed and tied down tomorrow for this upcoming sub freezing weekend.

Based on this, maybe I should get a 2nd one for the tranny.

75% of my cold startups are from inside my garage, which is usually 15-20 degrees warmer than ambient so not super concerned on this. My engine warms up quick compared to the transmission, but both are not super quick. I sent AJP some logs, so he will probably chime in with what he sees.

By design, the trans bypass valve opens around 140 or 160F. Will have to check.  Since very little heat actually transfers from the engine to the transmission, only driving hard will raise trans temps quickly.  Which of course we DONT want to do.  So patience is key.

I think the ebs that use the 6f35 trans do have a trans warmer circuit builtin using engine coolant?  To go with the shutter thing.

To the best of my knowledge the open temp of the trans fluid thermostat depends on model. Cars with PP and aux trans cooler have a 160* and cars without 190*. I can't say this is 100% verified info but i  know i've seen it stated before and it seems accurate from the difference i saw when changing to just the colder trans fluid thermostat.

Seems reasonable, that said, I took some logs for AJP tonight, and saw a MAX trans temp of 141 degF. started from cold, after sitting 8 or so hours in the work parking lot. Drove to walmart. shopped a few minutes. Drove to Sams Club. Shopped a few minutes. Drove home. Let the car sit about 2 hours. Drove to get food (highway vs. city). Ate (about an hour). Drove back home (highway).

For both of the highway driving scenarios, trans started at ~115 degF.

All told, I think I just am paranoid because of how new this car is (a tick over a year from its build date), and what I have done to it in that time. But, even with the cold it still drives extremely well. You can feel the torque converter slip a bit around 35 mph in the city and lock/unlock causing a slight vibration until it shifts. This is a purely cold weather action, as it has never happened in warm weather. But easily fixed by paddle shifting to the next gear, or slightly pressing the gas.

 

[metroplex]

The highest ATF temp I've seen is about 200F in the summer. In the winter (like 0F ambient), I'll usually see a high of about 130F-140F if I'm cruising. If I get on the gas a lot and the trans is shifting around, it'll go as high as 170F. An unlocked converter will increase the ATF temp more than a locked converter. I found that in the summer, if I keep the converter locked sooner and longer, I can drop the trans temp by 30F-40F in normal driving conditions.

 

[SHOdded]

What effect does a change in converter lockup behavior have on longevity of the transmission?  Fuel mileage?

 

[metroplex]

From the way I understand it, a locked converter reduces the wear on the lockup clutch and helps keep the fluid cooler. It also provides more power transmission (especially at WOT) and would only help fuel economy. An unlocked converter or slipping converter tends to waste energy, but helps with driveability in certain conditions (less driveline clunking).