00' Montero Sport Odd Shifting behavior
|
|
Post by russiankid on Dec 18, 2014 19:01:36 GMT -5
I recently acquired a 2000 Montero Sport LS from an old friend who purchased it with 109k on it. At that time he had me do the timing belt,water pump,spark plugs,valve cover gaskets, plenum gaskets,trans service, all axle fluids, brakes, pretty much you name it it has been done. The issue that has been present since the day he purchased the vehicle and I did all the work is that when the truck warms up and it shifts from 2 to 3rd gear and also from 3rd to 4th, the rpms will drop and a split second later drop another 200rpm. It does not matter on the engine speed and whether or not I am at full throttle. However when the trans is cold, it behaves normally so this only happens when it is warm. I did a lot of searching online and everything comes down to improper fluid or a shot trans. However, I am running good ole' Mitsu SP3 fluid with a new filter, the fluid looks brand new even after 13k miles of driving with this issue and it has not got any worse. The only thing left to test is the TPS sensor as the TCU uses it to determine shifting pattern, and also to check the shift solenoids. The question is, has anyone encountered this problem and have a solution?
P.S. It has 123k on the odo.
|
|
|
|
Post by jkdv8 on Dec 18, 2014 22:42:53 GMT -5
Not quite sure what it is doing. So the rpms drop off after it shifts? I know with mine depending on my foot position, in 3rd, the rpms drop a few 100 around 2500-2750 iirc to keep in the torque curve under load/power. Then raise back up before it actually shifts into 4th. Provides a little boost of power before shifting. You can actually cause it to do it as well depending on foot position/engine load so it may or may not do it all the time.
If this isn't what you're referring to then warm it up, park on a level surface, throw the parking brake, shift through all the gears ending in neutral, carefully check to make sure it has proper fluid level with the engine running. Also try unplugging the battery and letting it sit for 15 min or so. Resets the "learned" shift points. TPS is probably the culprit if all else fails.
|
|
|
|
Post by russiankid on Dec 19, 2014 8:43:11 GMT -5
Sorry if I wasn't very clear. When it shifts into 3rd or 4th, the rpms drop down once it shifts and about a split second later they drop another 200. It is if the shift is delayed a bit but it really isn't. What you're describing could be what is happening with mine and I am just not used to it, but I've never seen an auto behave like this. I have checked the fluid a few times already at different temperature ranges and all is within spec.I also have reset the battery and let the TCU relearn shifting and still the same thing. I'll be testing the TPS today after work and fingers crossed its bad and a new one fixes the issue. Using an OBD scanner, the TPS signal takes a good 1/4" of pedal travel to even register.
|
|
|
|
Post by ES_97Sport on Dec 19, 2014 15:53:37 GMT -5
... The only thing left to test is the TPS sensor as the TCU uses it to determine shifting pattern, and also to check the shift solenoids. .... TPS and ECT. Both feed into the TCU. Edward |
|
|
|
Post by russiankid on Dec 20, 2014 8:30:46 GMT -5
... The only thing left to test is the TPS sensor as the TCU uses it to determine shifting pattern, and also to check the shift solenoids. .... TPS and ECT. Both feed into the TCU. Edward I guess that makes sense for the ECT being tied into it. Another thing to test, thanks. |
|
|
|
Post by ES_97Sport on Dec 22, 2014 15:11:50 GMT -5
TPS and ECT. Both feed into the TCU. Edward I guess that makes sense for the ECT being tied into it. Another thing to test, thanks. TPS is the input for shifting based on throttle position. Its used in conjunction with RPM. ECT introduces a variable used to change the shift point based on engine temperature. ECT is the most likely to introduce "strange" shifting behavior as this is the input used to modify the static shifting data. If the ECT isn't reading correctly, this will most certainly introduce strange shifting behavior. Documented fairly thoroughly in the FSMs. RPM is actually derived - there isn't a 'RPM' sensor. Its derived from the crank/cam sensor(s). I forget it its both or just crank. If there were a problem there, you'd have other, more serious issues showing up. TPS is a very low level input. Baring someone having screwed with it, its unlikely there's a problem there. I'm not saying it's not possible, just unlikely. I replaced mine on my big Sport a few months ago and had it set because it was basically worn out after half a million miles. There was some obvious tweakyness in the throttle - basically the same behavior as an out of adjustment throttle on a carburetor. It is possible - having personally experienced this - for the TPS to go 'out of adjustment' over time. I had my big Sport adjusted about 6-7 years ago and I'd recommend if you're hitting 200-250K miles to have that done. One thing with the TPS - I could tell when my TPSs weren't working exactly quite right. Its subtle, but the throttle should be very crisp and clean from idle through off idle past 2K. There should be no pauses, no 'jumpyness'. It should be like stepping on the pedal of a sewing machine. Crisp and rock solid consistent. This assumes that the IAC is in good working condition because an old worn out unit will do some pretty screwy things that SEEM like the TPS. Edward |
|
|
|
Post by russiankid on Dec 22, 2014 19:23:58 GMT -5
Based on what you're describing with the ECT, it makes sense how the TCU will use the engine temp to adjust shifting. Also, my issue happens once the truck is completely warmed up, but when I use an OBD scanner the coolant temp sits at 195-198F. However, I am not sure if that is based on the what the ECT see's on the gauge sensor.
I do not have any other issues with throttle response (crisp) or idling issues. It has 123k on the clock so a worn out TPS is unlikely like you have mentioned, but you never know. An ECT is about 5-10 bucks versus a TPS being $100, so I may just pop a new one in since its so cheap.
|
|
|
|
Post by ES_97Sport on Dec 23, 2014 18:06:51 GMT -5
Based on what you're describing with the ECT, it makes sense how the TCU will use the engine temp to adjust shifting. Also, my issue happens once the truck is completely warmed up, but when I use an OBD scanner the coolant temp sits at 195-198F. However, I am not sure if that is based on the what the ECT see's on the gauge sensor. I do not have any other issues with throttle response (crisp) or idling issues. It has 123k on the clock so a worn out TPS is unlikely like you have mentioned, but you never know. An ECT is about 5-10 bucks versus a TPS being $100, so I may just pop a new one in since its so cheap. The ECM/PCM will output the ECT reading to the OBD port as the computer sees it. So, basically, you're getting exactly what the ECM/PCM sees. Can you do logging with your OBD scanner? The big problem when troubleshooting sensors, as I was pointing out in a previous, different post about the EGR and Evap solenoids, is that they may work inconsistently and that's impossible to trace by doing a spot check.  I HAVE had ECT sensors work inconsistently, so .... The idea would be to correlate the OBD data with the shift weirdness. If I were tracing this, I'd use a OBD logging package to log all the OBD data and then note when the shifting weirdnesses happen and locate the instances in the logs and see what things look like. Oh, 5-10 bucks for an ECT? Are you sure you're looking the ECT and not the sensor for the dash gauge? That one is usually cheap. The ECT is more expensive and certainly more than 5-10 bucks. Yea, with that kind of mileage I seriously doubt its the TPS. MAYBE out of adjustment slightly. Edward |
|
|
|
Post by russiankid on Dec 24, 2014 8:57:50 GMT -5
Based on what you're describing with the ECT, it makes sense how the TCU will use the engine temp to adjust shifting. Also, my issue happens once the truck is completely warmed up, but when I use an OBD scanner the coolant temp sits at 195-198F. However, I am not sure if that is based on the what the ECT see's on the gauge sensor. I do not have any other issues with throttle response (crisp) or idling issues. It has 123k on the clock so a worn out TPS is unlikely like you have mentioned, but you never know. An ECT is about 5-10 bucks versus a TPS being $100, so I may just pop a new one in since its so cheap. The ECM/PCM will output the ECT reading to the OBD port as the computer sees it. So, basically, you're getting exactly what the ECM/PCM sees. Can you do logging with your OBD scanner? The big problem when troubleshooting sensors, as I was pointing out in a previous, different post about the EGR and Evap solenoids, is that they may work inconsistently and that's impossible to trace by doing a spot check. I HAVE had ECT sensors work inconsistently, so .... The idea would be to correlate the OBD data with the shift weirdness. If I were tracing this, I'd use a OBD logging package to log all the OBD data and then note when the shifting weirdnesses happen and locate the instances in the logs and see what things look like. Oh, 5-10 bucks for an ECT? Are you sure you're looking the ECT and not the sensor for the dash gauge? That one is usually cheap. The ECT is more expensive and certainly more than 5-10 bucks. Yea, with that kind of mileage I seriously doubt its the TPS. MAYBE out of adjustment slightly. Edward I went ahead and tested the restitance on the ECT with the engine hot and it was jumping all over the place. Purchased a new one for 18 bucks and that seems to have helped the shifting a little bit. However, I think the TCU still needs time to relearn shift patterns with the new sesnor as it didn't completely fix the issue. With my scanner I can't log any data, I can only have live. P.S. On rockauto, the cheapest ECT is about 6 or 7 bucks, but you also get what you pay for. It also looks like the previous owner had the ECT replaced as it is not the original sensor and they used RTV sealant on the threads.  |
|
|
|
Post by ES_97Sport on Dec 24, 2014 12:51:15 GMT -5
... I went ahead and tested the restitance on the ECT with the engine hot and it was jumping all over the place. Purchased a new one for 18 bucks and that seems to have helped the shifting a little bit. However, I think the TCU still needs time to relearn shift patterns with the new sesnor as it didn't completely fix the issue. With my scanner I can't log any data, I can only have live. P.S. On rockauto, the cheapest ECT is about 6 or 7 bucks, but you also get what you pay for. It also looks like the previous owner had the ECT replaced as it is not the original sensor and they used RTV sealant on the threads. Ouch. Well, at least it was the ECT which doesn't ground through the sensor body (2 wire). Yea, that's not good. The reading should be solid and consistent. I varies but not quickly. I don't know what the refresh cycle is but I do know that if you're seeing any jumpy behavior in the reading there's a problem. Unfortunately, its really hard to tell if its the sensor, the ECM/PCM or the scanner without spare parts and an alternate scanner. That's unfortunate 'cause it's going to be really hard to trace things down if you can't see what's happening while you're driving. If you have a Bluetooth OBD scanner and a smart phone or tablet with Bluetooth, you might want to grab a copy of TorqueScan or DashCommand. I don't like either for logging (even on a tablet), but they're supposed to do it. These work better for real-time and monitoring multiple PIDS and displaying them on a screen. I use ScanXL Pro on a ThinkPad laptop for logging. Something like a T series with Bluetooth/USB (and appropriate matching OBD scanner) and a 250G SSD drive, 2-4G of memory and Windows 7 works well (pull out the DVD drive and turn off any extraneous hardware). Kinda big, but you need the CPU and memory if you're logging a lot of PIDs and the SSD helps tons with battery life and logging. Old software but still the best I've found for real time and logging. The graphing/logging tools are very flexible and very handy. Yes, it takes a while for the everything to relearn. It usually takes about a week of steady driving for my '03 to figure things out, but my TCU is retarded, so YMMV.  Edward |
|
|
|
Post by russiankid on Dec 24, 2014 13:59:52 GMT -5
... I went ahead and tested the restitance on the ECT with the engine hot and it was jumping all over the place. Purchased a new one for 18 bucks and that seems to have helped the shifting a little bit. However, I think the TCU still needs time to relearn shift patterns with the new sesnor as it didn't completely fix the issue. With my scanner I can't log any data, I can only have live. P.S. On rockauto, the cheapest ECT is about 6 or 7 bucks, but you also get what you pay for. It also looks like the previous owner had the ECT replaced as it is not the original sensor and they used RTV sealant on the threads. Ouch. Well, at least it was the ECT which doesn't ground through the sensor body (2 wire). Yea, that's not good. The reading should be solid and consistent. I varies but not quickly. I don't know what the refresh cycle is but I do know that if you're seeing any jumpy behavior in the reading there's a problem. Unfortunately, its really hard to tell if its the sensor, the ECM/PCM or the scanner without spare parts and an alternate scanner. That's unfortunate 'cause it's going to be really hard to trace things down if you can't see what's happening while you're driving. If you have a Bluetooth OBD scanner and a smart phone or tablet with Bluetooth, you might want to grab a copy of TorqueScan or DashCommand. I don't like either for logging (even on a tablet), but they're supposed to do it. These work better for real-time and monitoring multiple PIDS and displaying them on a screen. I use ScanXL Pro on a ThinkPad laptop for logging. Something like a T series with Bluetooth/USB (and appropriate matching OBD scanner) and a 250G SSD drive, 2-4G of memory and Windows 7 works well (pull out the DVD drive and turn off any extraneous hardware). Kinda big, but you need the CPU and memory if you're logging a lot of PIDs and the SSD helps tons with battery life and logging. Old software but still the best I've found for real time and logging. The graphing/logging tools are very flexible and very handy. Yes, it takes a while for the everything to relearn. It usually takes about a week of steady driving for my '03 to figure things out, but my TCU is retarded, so YMMV. Edward I am glad you mentioned the TQ app as I have the BT adapter but I totally forgot about it. The old sensor was very jumpy even after removing it and touching the probe so either way I look at it the sensor needed to be replaced. Sadly I don't have a long commute for work so the 1 week relearn period is probably going to be two weeks haha. I've noticed that the elctronics on this truck are pretty retarded as you have mentioned. Disconnecting the battery on this thing is a tough decision on whether or not you want to go through the idle relearn process and shifting relearn. I will try to gather some data and go from there. |
|
|
|
Post by russiankid on Dec 24, 2014 17:26:21 GMT -5
I tested the TPS and the resistance is pretty smooth throughout the range. I unplugged the TPS and drove around just to put the ECU and TCU in a limp mode, however, no CEL popped up. Upon driving, the trans shifted into gears more rapidly and earlier than needed, but that is expected since it does not know the throttle input. What I did notice is that when it did shift into gear, the same behavior as I described before was not present. This leads me to believe the TPS is somehow causing the torque converter lock up to act up.
|
|
|
|
Post by ES_97Sport on Dec 29, 2014 19:17:25 GMT -5
... I've noticed that the elctronics on this truck are pretty retarded as you have mentioned. Disconnecting the battery on this thing is a tough decision on whether or not you want to go through the idle relearn process and shifting relearn. .... The ECM in the '97s, especially the first ECM, is even worse. Edward |
|
|
|
Post by ES_97Sport on Dec 29, 2014 19:42:27 GMT -5
I tested the TPS and the resistance is pretty smooth throughout the range. I unplugged the TPS and drove around just to put the ECU and TCU in a limp mode, however, no CEL popped up. Upon driving, the trans shifted into gears more rapidly and earlier than needed, but that is expected since it does not know the throttle input. What I did notice is that when it did shift into gear, the same behavior as I described before was not present. This leads me to believe the TPS is somehow causing the torque converter lock up to act up. 'no CEL popped up' - yea, that doesn't surprise me. Did you check for pending and existing OBD codes? 'pretty smooth throughout the range' - expected that, otherwise you'd feel it in the throttle. Hmmmm. Maybe. I may be wrong but I still don't think there's anything physically wrong with the TPS. That drop in RPM like you describe sounds to me like bands slipping and then catching. I've had worn out slipping clutches create behavior like this. I have similar behavior on my '03 but for a different reason. When they put the wrong fluid in my transmission, it messed up the clutch in the torque converter. It slips intermittently sometimes and also locks and unlocks oddly. Anyway, you're description isn't too far off from what I see. The point is its caused by something slipping. There is no reason I can see that the TPS would cause this. If the TPS were returning a flaky/incorrect reading, it'd do it irrespective of whether the transmission was engaged or not and you'd have other problems. The TCU is definitely not the only thing that uses the TPS. Do you have a scanner that will read out real time TPS? Too bad you can't graph it. If there is a hic-cup you'd probably see it. Edward |
|
|
|
Post by russiankid on Dec 30, 2014 12:19:01 GMT -5
I tested the TPS and the resistance is pretty smooth throughout the range. I unplugged the TPS and drove around just to put the ECU and TCU in a limp mode, however, no CEL popped up. Upon driving, the trans shifted into gears more rapidly and earlier than needed, but that is expected since it does not know the throttle input. What I did notice is that when it did shift into gear, the same behavior as I described before was not present. This leads me to believe the TPS is somehow causing the torque converter lock up to act up. 'no CEL popped up' - yea, that doesn't surprise me. Did you check for pending and existing OBD codes? 'pretty smooth throughout the range' - expected that, otherwise you'd feel it in the throttle. Hmmmm. Maybe. I may be wrong but I still don't think there's anything physically wrong with the TPS. That drop in RPM like you describe sounds to me like bands slipping and then catching. I've had worn out slipping clutches create behavior like this. I have similar behavior on my '03 but for a different reason. When they put the wrong fluid in my transmission, it messed up the clutch in the torque converter. It slips intermittently sometimes and also locks and unlocks oddly. Anyway, you're description isn't too far off from what I see. The point is its caused by something slipping. There is no reason I can see that the TPS would cause this. If the TPS were returning a flaky/incorrect reading, it'd do it irrespective of whether the transmission was engaged or not and you'd have other problems. The TCU is definitely not the only thing that uses the TPS. Do you have a scanner that will read out real time TPS? Too bad you can't graph it. If there is a hic-cup you'd probably see it. Edward What you're describing makes sense and I am starting to think it is something internal as it only happen the fluid is hot aka thinner and less pressure. I can get a live reading of the TPS and everything seems to be normal. So that leads me to believe its internal and I just kind of have to deal with it. P.S I don't have any pending codes aside from a P0421 which is for my secondary cat slowly going out. |
|
|
I HAVE had ECT sensors work inconsistently, so ....
