Transmission Temperature Question (Again)

[jonroe]

Folks,

Since installing my OBD2 gauge last August I have been closely monitoring my transmission temperature (that's why I added the gauge) to decide whether to get an extra cooler or not. I am mystified by the temperature behavior I see. I see quite different behavior with and without my performance tune. I have Lidio's tune and the converter lock-up is set at about 66-67 mph.

A. With the tune installed I consistently see higher operating temperatures and quicker rises. In the past two weeks I have comparable data. With outside temps about 35F and a drive to work of 30 (mostly) highway miles at a steady 60 mph (4th gear no lock-up) I see a rise to the low 180s topping out at about 184 when I get to work and shut her off.

B. With the stock tune back (I have to go to the dealer next week) I consistently see lower operating temperatures and slower rises. For example, this morning with the same 35F outside temps and the same drive to work at the same speed I saw a slower temperature rise which did NOT crack 150 until I was nearly parked in the garage at work. It peaked at 154 when I shut her off.

Why are these temps so different? Is it the converter lock-up or the tune or both. I was not aware that a performance tune would modify any parameters about transmission temperature other than lock-up. Does it? Is it all due to the lock-up? It certainly makes sense that non-lock-up will be warmer, but 30F????

By the way, these test drives did not include any "spirited" driving - very grandma-like - so there was no extra load put on the trans.

Please let me know if others have seen this behavior.

Thanks.

Jon

[magindat]

It's mostly converter lock up. When the converter is not locked fluid is flowing through many vanes in the TC. This causes fluid friction and temp rise. Totally normal.

You are in range. Normal fluid temps should be 160-180.

[Marauderjack]

I lock my TC at about 45 MPH at light throttle for fuel economy only.....I think 63 MPH is too high for normal street driving but fine for "Sport" driving!!:bows:

You are WAY fine at those temps!!!:beer:

See attached chart for a good explanation of trans life expectancy at various temps!!:D

BTW, I have 157K miles on my trans now with the last 73K miles supercharged....drained the pan every 20K miles or so and added back 3.5 quarts...that's all.....and my fluid temps run between 195* and 210*!!!!

Good Luck and MERRY CHRISTMAS!!!:banana:

Marauderjack:burnout:

[magindat]

My temps run 185-215. The highest only when working the highway at 110+.

Cruise at 85 is 184.

[RF Overlord]

jon, as Rich and 'jack said ^^^, your temps are normal. With the T/C unlocked, you WILL get higher temps all the time.

Jerry Wroblewski, ex-Ford transmission design engineer and father of the 4R70W has stated that temps in the 170° to 190° range are normal and that for every 20° above that, ATF life is cut in half. If you normally keep Lidio's tune installed, then do a fluid drain-and-fill as 'jack does ^^^ every 15-20,000 miles and you'll be fine.

[Stranger in the Black Sedan]

I also think 63 mph is rediculous for lockup on a street car. It is just going to help cook the fluid faster. My tune from DR locks in 3rd around 35 mph at light throttle. It is perfect. The lockup occurs almost simultaneously w/ the light throttle 2-3 shift, so it is seamless. Not like before w/ 25 mph chugging piece of crap lockup schedule that the factory gave us. Plus w/ light throttle 35 mph lockup I am not heating up my fluid.

See if you can get your tune re-done. It is unnecessary to hold lockup off until highway speeds for a street, non road race car. There is nothing obtrusive about 3rd gear lockup when it is done properly. Your transmission and transmission life will thank you. I am glad others on this board warned me about not going w/ the late TC lockup schedule.

[jonroe]

Thank you all for the good advice. I was just a little surprised at the 30F difference. I agree that running 185F is no real problem and I do drain my 6qt deep pan every other oil change (10K miles) so I should be fine. I am going to get Lidio to drop the lock-up speed so it is usable when I am cruising and will allow cooler highway runs. I would not want to run all day at 60 at the higher temp if I could be locked up and run the cooler temps. What this tells me is that if I get the lock-up speed lowered, then I may not put in the aux trans cooler.

I would be happier with a lock-up between 50 and 60 rather than having it lock and unlock around town. I just don't like that. By the way, it is a major pain to be running the stock tune this week - I can't wait to get back to proper shifts! What a crappy shift pattern for stock!

Thanks again.

Jon

[Marauderjack]

Thank you all for the good advice. I was just a little surprised at the 30F difference. I agree that running 185F is no real problem and I do drain my 6qt deep pan every other oil change (10K miles) so I should be fine. I am going to get Lidio to drop the lock-up speed so it is usable when I am cruising and will allow cooler highway runs. I would not want to run all day at 60 at the higher temp if I could be locked up and run the cooler temps. What this tells me is that if I get the lock-up speed lowered, then I may not put in the aux trans cooler.

I would be happier with a lock-up between 50 and 60 rather than having it lock and unlock around town. I just don't like that. By the way, it is a major pain to be running the stock tune this week - I can't wait to get back to proper shifts! What a crappy shift pattern for stock!

Thanks again. Jon

When I had the SCT tuner I got Mike and David at SCT to rearrange my shift points and TC lock in several tunes!!:beer: I finally ran the one that locked only in 4th gear at 50 MPH and had the same thing done for my DiabloSport blower tune!!!:bows:

Dave Lamberson who tunes the FIT kits sent me the trans schedule he likes which does lock the TC in 3rd/4th at 43 MPH under light throttle.....I really like it since I can cruise around town in 3rd with the TC locked above 43-45 MPH!!!:beer:

The key factor in TC lockup management is to MAKE SURE the tune disengages the TC BEFORE the down shift from 4th to 3rd or you may be picking up some pieces off the road!!:eek:

I believe Dave has it setup so the TC releases above half throttle well before the down shift......eliminating the need to remember turning the O/D OFF before romping on it!!!:bows:

Just a little safety feature you may wish to consider??:D

Marauderjack:burnout:

[ctrlraven]

That's one of the next things I want to do is add in a temp gauge for the trans before warm weather rolls around again and a addition trans stack cooler since I have a PI 3500. The DR tune I had would lock my TC up at 30mph in 2nd or 3rd gear, ended up actually making me run .2-.3 secs slower in the 1/4 mile and really started giving me a headache while driving with it unlocking and locking all the time. Got some help from another member now it only locks up at 50mph 3rd gear at light throttle otherwise it stays unlocked until I let off, it's a dream to drive again with the new tune.

With the larger trans pan (Art Car) how much fluid should actually come out. Last time I did it myself and wasn't sure how much it would need to I put one qt in then filled that container with the old fluid until it was gone. About 5.5qts, is that normal? Amount on the dip stick was right on the money with the proper level.

[RF Overlord]

jonroe, Lidio also developed the tune for Trilogy. When he dyno'd my car after I had the blower installed locally, I had him drop the T/C lockup to around 50 or so due to the type of use the car gets and he had no problem with that. I've been very happy with it.

[RF Overlord]

With the larger trans pan (Art Car) how much fluid should actually come out. About 5.5qts, is that normal? Sounds about right. Draining the stock pan will net about 3.5- 4 quarts and the Art Carr holds 2 extra, I believe.

[ctrlraven]

Yeah that's what I figured up also 5.5-6qts.

[Marauderman]

Damn.....mine must be real diff..it hardly ever gets above 150--maybe 155 and thats on a hot day when in USE........I never seen it above 160--either I am not paying attention as I should or my tranny temp is great.....now do I have the cooling thingy..maybe---don't know--at this writing.I have done so much--I may have and don't remember--guess so---cause what ya'll are saying --mine has never seen those temps yet--even at the strip as far as I know----oh well--another thing to re-check more and more --and I use to get alarmed when the temp when to 150.........gheeee!!-I guess this built motor is truley ready for more..........in time.........

[Stranger in the Black Sedan]

You don't want a transmission to run too cold either. Most cars w/ automatic transmissions bypass TC lockup in order to intentionally heat up the trans fluid until it gets to a certain temp, at which point TC lockup will be enabled.

[gmtech]

trans gauge in the pan...ive never seen over 195 with very spirited driving...lidio tune is great ...i love the TQ convertor lockup late :P

[magindat]

Damn.....mine must be real diff..it hardly ever gets above 150--maybe 155 and thats on a hot day when in USE........I never seen it above 160--either I am not paying attention as I should or my tranny temp is great.....now do I have the cooling thingy..maybe---don't know--at this writing.I have done so much--I may have and don't remember--guess so---cause what ya'll are saying --mine has never seen those temps yet--even at the strip as far as I know----oh well--another thing to re-check more and more --and I use to get alarmed when the temp when to 150.........gheeee!!-I guess this built motor is truley ready for more..........in time.........

I think your pickup is outside the trans. We are talking OBD readings from the stock sensor INSIDE the pan. If we don't state where the pickup is, we are not talking apples to apples.

If your pickup is in the line - even the hot line - it will read LOWER than in the pan.

[Marauderman]

I think your pickup is outside the trans. We are talking OBD readings from the stock sensor INSIDE the pan. If we don't state where the pickup is, we are not talking apples to apples.

If your pickup is in the line - even the hot line - it will read LOWER than in the pan.

Thanks Rich---Will soon be having her on a lift for some of those fluid changes and will take a look on those connections....thanks......

[RF Overlord]

If your pickup is in the line - even the hot line - it will read LOWER than in the pan.Rich, I thought the pan held the fluid returned from the cooler and that the output line TO the cooler was after the T/C and would therefore be the hotter reading?

[magindat]

I dunno, RF. I constantly see higher numbers on OBD than on senders.

What you say makes sense, but it's not what I observe....

My main point was to be sure this discussion compares apples to apples. The point is one cannot compare external sender readings with a heat-soaked internal pan readings.

[ahess77]

I dunno, RF. I constantly see higher numbers on OBD than on senders.

What you say makes sense, but it's not what I observe....

My main point was to be sure this discussion compares apples to apples. The point is one cannot compare external sender readings with a heat-soaked internal pan readings.

Since what you're seeing doesn't make sense based on what really happens (line temp should be higher than pan temp), we should question the accuracy of the in-line sensor and the OBD sensor. Anybody know the specified accuracy of the internal sensor in the trans? I also can't find on Autometer's website any statement about accuracy of their sensors. If you're +/- 15F for the accuracy of the system that could account for most of the difference we're talking about.

[magindat]

Since what you're seeing doesn't make sense based on what really happens (line temp should be higher than pan temp), we should question the accuracy of the in-line sensor and the OBD sensor. Anybody know the specified accuracy of the internal sensor in the trans? I also can't find on Autometer's website any statement about accuracy of their sensors. If you're +/- 15F for the accuracy of the system that could account for most of the difference we're talking about.

An excellent point since I have seen wide variations in OBD temps on similarly modded cars.

[Marauderjack]

FWIW mine is OBDII with the ScanGaugeII......

I watched it today and it stayed around 197*-200* cruising at 65 MPH wit the ambient being 60* or so. :cool:

Marauderjack:burnout:

[magindat]

FWIW mine is OBDII with the ScanGaugeII......

I watched it today and it stayed around 197*-200* cruising at 65 MPH wit the ambient being 60* or so. :cool:

Marauderjack:burnout:

That's within a few degrees of what mine runs in similar circumstances.

[rumble]

I am going to get Lidio to drop the lock-up speed so it is usable when I am cruising and will allow cooler highway runs.
Thanks again.

Jon


Please let us know how this works out.

Thanks,
Gary