Mstg007 Posted September 22, 2017 Report Share Posted September 22, 2017 I was in a traffic jam for 30 mins today. After we got past the wreck, I went to accelerate and as I am driving around 70 MPH i see my TACH is around 3.5000 RPM. Usually, its around 2.5000 RPM. So I went off to a back road and put my transition into 3RD and was going about as fast. Thats how i was able to tell (overdrive) did not work. Now, I dont know if this is a fluke, but hopefully it does not do it tomorrow, but if it does, what am I looking for to fix this? 1994 Cutlass supreme 3.4L with 150,000 miles. Thanks for all the help and advice guys. Quote Link to comment Share on other sites More sharing options...
digitaloutsider Posted September 22, 2017 Report Share Posted September 22, 2017 It's something with the PCM calibration on early 4T60E cars, IIRC. My '94 Bonneville SSE used to refuse to shift into overdrive when the transmission got hot. It's on purpose as far as I know. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 22, 2017 Report Share Posted September 22, 2017 I recently reposted an old posting about this very symptom...you're likely losing TCC lockup, because the TCC apply piston is sticking in the bore when hot. Unfortunately, a common problem with the T460. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 22, 2017 Report Share Posted September 22, 2017 http://www.w-body.com/topic/41994-95-dohc-cutlass-p0740-no-overdrive-no-tcc-when-hot/ Quote Link to comment Share on other sites More sharing options...
Imp558 Posted September 22, 2017 Report Share Posted September 22, 2017 Shouldn't 4th gear and TCC work out to be around or under 2K? This sounds like my old 4T60 that had no 4th or TCC, I thought you posted something a while back specific to this. My solution was a bit more drastic than most would like. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 22, 2017 Report Share Posted September 22, 2017 (edited) My short term solution was to add a transmission cooler from a 3.8 Regal, which slowed down the heating, and meant most days I could drive to an from work before the problem hit... ...the long term solution was to have the transmission rebuilt, and even the rebuilder got it wrong on the first try, even though I correctly diagnosed the problem before leaving it with him.. ..in his defense, though, he went out of his way to make it right, and I doubt many people had ever walked into his shop knowing EXACTLY what was wrong with their transmission. Edited September 22, 2017 by Galaxie500XL Nas Escobar 1 Quote Link to comment Share on other sites More sharing options...
Mstg007 Posted September 22, 2017 Author Report Share Posted September 22, 2017 Interesting. Thanks for sharing guys. The car is basically once a week driven to work on nice days. Yesterday was 95 Degrees and siting in the traffic does not help which explains the temperature for the TCC. So if this were to happen again in the future. The temp fix would be to pull over. Turn off the car and back on and there should be over drive again. (That's if I'm understanding it as best as I can.) Galaxie500XL 1 Quote Link to comment Share on other sites More sharing options...
Imp558 Posted September 22, 2017 Report Share Posted September 22, 2017 An easy mod would be the bar and plate cooler from a ford explorer, late nineties. That would probably carry you for quite a while if the object is to run cool. rich_e777 and Galaxie500XL 2 Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 22, 2017 Report Share Posted September 22, 2017 Interesting. Thanks for sharing guys. The car is basically once a week driven to work on nice days. Yesterday was 95 Degrees and siting in the traffic does not help which explains the temperature for the TCC. So if this were to happen again in the future. The temp fix would be to pull over. Turn off the car and back on and there should be over drive again. (That's if I'm understanding it as best as I can.) You'd think so...but my experience was until the transmission temperature dramatically dropped, shutting down and restarting meant at best a minute or so of normal operation, then the problem repeats itself. Quote Link to comment Share on other sites More sharing options...
55trucker Posted September 23, 2017 Report Share Posted September 23, 2017 Interesting. Thanks for sharing guys. The car is basically once a week driven to work on nice days. Yesterday was 95 Degrees and siting in the traffic does not help which explains the temperature for the TCC. So if this were to happen again in the future. The temp fix would be to pull over. Turn off the car and back on and there should be over drive again. (That's if I'm understanding it as best as I can.) I take it that you did not have the A/C running, even tho the DOHC cars have a trans cooler if the fan/s are not running when it's hot outside & you're not moving then you still won't get any airflow passing thru the cooler to aid the trans temps. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted September 24, 2017 Report Share Posted September 24, 2017 WHY is the fluid getting that hot? This ain't the first time a W-body has been driven in 95-degree temps. SOMETHING is wrong. We just haven't found out what...yet. I would be looking at what has failed, before I slammed a bunch of add-on crap onto the cooler tubes. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 24, 2017 Report Share Posted September 24, 2017 It’s a fair question, but it depends on your definition of hot. Mine would fail at fluid temps above 175...which isn’t hot at all, considering normal coolant temperature on an LQ1 is a little above 200 or so. Quote Link to comment Share on other sites More sharing options...
Mstg007 Posted September 25, 2017 Author Report Share Posted September 25, 2017 Luckily I have not had the problem since. The engine temperature was in normal range. You are right, I did not have the A\C On. I get what you are saying about the adding to the cooler lines, but as Schurkey said, What would cause that to get hot or hotter than normal? Quote Link to comment Share on other sites More sharing options...
cutty collector Posted September 25, 2017 Report Share Posted September 25, 2017 galaxy is right on the money mine does the same thing I have to get into heavy traffic for it to fail. transmissions don't cool as fast as engines they used to teach us in the gm classrooms that the cooler is actually a heater for the trans in the winter time as the coolant in the radiator heats up much more quickly that a transmission does, with the exception of doing a brake torque where trans temps sky rocket in no time Quote Link to comment Share on other sites More sharing options...
cutty collector Posted September 25, 2017 Report Share Posted September 25, 2017 I have been looking into a repair valve for this condition on my transmission it rides in a different portion of the bore that is not as badly worn. Sonax makes several kits Quote Link to comment Share on other sites More sharing options...
Schurkey Posted September 25, 2017 Report Share Posted September 25, 2017 Mine would fail at fluid temps above 175...which isn’t hot at all, considering normal coolant temperature on an LQ1 is a little above 200 or so. HOW do you know that the fluid temp was 175? WHERE is the sensor? In the pan, or in the cooler circuit? they used to teach us in the gm classrooms that the cooler is actually a heater for the trans in the winter time as the coolant in the radiator heats up much more quickly that a transmission does There are multiple ways to connect add-on trans coolers. In a cool-to-cold climate, the add-on cooler would get the transmission fluid first, with the in-radiator cooler between the add-on cooler and the return port in the transmission. This allows the in-rad "cooler" to warm the fluid as needed in cold weather. I have been looking into a repair valve for this condition on my transmission it rides in a different portion of the bore that is not as badly worn. Sonax makes several kits Which valve are we talking about? Part number for this Sonax "Kit"? I am aware that Sonax makes a heaping pile of repair parts for automatic transmissions. They seem to be a-reputable company with clever "fixes" for OEM trans-design failures. Imp558 1 Quote Link to comment Share on other sites More sharing options...
Imp558 Posted September 25, 2017 Report Share Posted September 25, 2017 The 4XXX Transmissions all have a TFT sensor internal, when I take a reading it's via DLC with my scangauge. It's not ludicrous to think someone may have a dedicated TFT Gauge reading an inline sensor or with an IR thermometer somewhere but that's a really good point. It would be more thorough to know how and where the temp is measured. Good catch Schurkey. Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 25, 2017 Report Share Posted September 25, 2017 My old Actron scantool read the internal sensor as part of the live data...it really wasn’t a problem. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted September 26, 2017 Report Share Posted September 26, 2017 It's a problem if the sensor is faulty and giving incorrect readings. I have a tough time believing that the trans can have fluid-temperature related problems while the sensor is showing "175 degrees". It might be a problem if the sensor isn't reading the temp of the fluid in the pan. The Old Wisdom about fluid temperature assumes that the temperature reading is from the pan, not the torque converter, or somewhere buried in the line-pressure circuit. Quote Link to comment Share on other sites More sharing options...
Mstg007 Posted September 26, 2017 Author Report Share Posted September 26, 2017 Could I ask. where would the sensor be located and is it a pain in the but to replace? Quote Link to comment Share on other sites More sharing options...
Galaxie500XL Posted September 26, 2017 Report Share Posted September 26, 2017 (edited) It's a problem if the sensor is faulty and giving incorrect readings. I have a tough time believing that the trans can have fluid-temperature related problems while the sensor is showing "175 degrees". It might be a problem if the sensor isn't reading the temp of the fluid in the pan. The Old Wisdom about fluid temperature assumes that the temperature reading is from the pan, not the torque converter, or somewhere buried in the line-pressure circuit. Actually, Shurkey, it doesn't do that at all...the temp reads 175, but what causes the lack of overdrive is the ECM detects excess slip from the TCC ( because the TCC apply piston is sticking, meaning insufficient pressure to lock the TCC), and sets a DTC (but doesn't light the check engine light), and then disables overdrive. With a proper scantool, you can see the DTC that's set, P0740. Edited September 26, 2017 by Galaxie500XL Nas Escobar 1 Quote Link to comment Share on other sites More sharing options...
cutty collector Posted September 28, 2017 Report Share Posted September 28, 2017 100% right on Galaxie mine packs it in at about 160 on the scan tool like clock work .Sorry haven't got the sonax part numbers on hand haven't repaired mine yet either .She needs lots of tlc over the winter Quote Link to comment Share on other sites More sharing options...
Mstg007 Posted September 28, 2017 Author Report Share Posted September 28, 2017 Got some more to the story. I was driving home on the interstate yesterday. Top down and windy day. Anyways, I think I felt the transmission thump (change gears) alittle while going around 70 MPH. When it did do it, the engine would rev up just a little. I then had to push harder on the accelerator and let off to get it back to over drive. It did it a couple of times. Is this still linked about to the TCC Piston possibly getting stuck? Quote Link to comment Share on other sites More sharing options...
55trucker Posted September 28, 2017 Report Share Posted September 28, 2017 Are you absolutely sure that what you felt was the trans shifting from 4th to 3rd or was it the TCC unlocking and what you saw on the tach was the engine rpm rising. The trans shifting from 4th to 3rd at that speed WITH the converter locked up is hard on the clutches without the 4th clutches first releasing before the downshift takes place, at that speed the 4th clutches are applied by a signal from the TPS & the VSS that intern the ECM allows shift solenoid *A* to energize, the clutches won't release unless there is a command by the ECM to do so by downshift via accelerating. The TCC will stay locked up unless the driver relaxes their foot on the throttle pedal or depresses it to accelerate. Quote Link to comment Share on other sites More sharing options...
cutty collector Posted October 8, 2017 Report Share Posted October 8, 2017 sure sounds like a tcc going in and out the shift from 4-3 would be fairly violent compared to the tcc going in and out .If youre sure it was a gear shift pull it into third from overdrive and nothing should happen unless it is still in fourth Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.