hjb981 Posted November 8, 2011 Report Share Posted November 8, 2011 I just read the thread 275/300N*, and in post #7(http://caddyinfo.ipbhost.com/index.php?showtopic=40572&view=findpost&p=198147), Jims_97_ETC wrote: The exact torque of any given engine is a function of many things. The most important is the preloads for tuning conditions and shift points that the dealer can change with a Tech II. After inquiring about "a chip" a few times, I was informed that they had "reprogrammed my PCM" and a little smoothness went away in favor of noticeably better throttle response. I think that's not uncommon. ... That got me curious. Can other parameters be reprogrammed? I am thinking of the behavior of the viscous converter clutch (VCC) - could it be reprogrammed to fully engage earlier, and also allow for more throttle before it starts to loosen up? I.e. if I start going slightly uphill, or just want to accelerate, the transmission would keep the VCC engaged longer. In other words, I would have to push harder on the gas before the VCC started to disengage (which can be noticed as a small increase in engine RPM). In city driving, the VCC would be engaged quicker. This should result in lower fuel consumption, at the cost of decreased part-throttle response and less smoothness. Anytime the VCC (or lockup in applicable cars) engages, fuel is saved because power loss from heating of transmission fluid in the torque converter is eliminated. My question is if it is possible to change the parameters that control when the VCC engages. Would it be safe for the VCC to handle the extra torque (that it normally hands over to the torque converter). Btw, does anyone know if the VCC is engaged or not at WOT in second gear? /Jonas Link to comment Share on other sites More sharing options...
Cadillac Jim Posted November 8, 2011 Report Share Posted November 8, 2011 Yes, shift firmness can be programmed. However, you will find that getting a flush with Dexron VI will get you excellent shifts from the PCM as-is. I'm not sure if the VCC settings can be changed. My experience with the VCC is that it engages instantly when you let the RPMs match at 41 mph or faster in any gear (I've tried it in second and third, but not low gear), but there is no pull-in VCC engagement that pulls down the RPM. If there is a pull-in VCC engagement, I don't feel it. If you want the VCC, it will engage when you stop accelerating. If you want it while accelerating, ease up just a second to engage it. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
sprinter10 Posted November 12, 2011 Report Share Posted November 12, 2011 I spent time and learned every shift point and torque converter lock up point on my 2000 sts. The minimum speed for the torque converter lock up is 38mph I can get it to shift to 2nd around 8-10mph shift to 3rd around 20mph and 4th I foget exackly where because its been months since I drove it but I completly agree and have wanted to change the torque converter lock up since I started driving the car. It gets such great mialage and watching the mpg on the screen you can see what saves gas and you just keep wanting the torque converter to lock up earlier. After the torque coverter is locked it will stay locked as low as 32mph before it will unlock. If you ever hit the brakes the torque converter will unlock. and if you press the gas past a certain point depending on load and speed it will unlock. I hate the hitting the brake unlock deal. I have to hit the hils around here (going down) at 33 at the top to keep the torque coverter locked and go as slow as possible. To go down the hill using engine braking and not over heating the brakes witch are severly warped. and without hitting brakes I hit the bottom of the hill doing 50. 45mph zone. If I was able to use a little brakes while keeping teh converter locked I could hit the top of the hil at 45-50 and use brakes easy a couple times to keep it from speeding up. Now if I tap the brakes Im stuck riding the brakes all the way down it feels like or it takes off to 60+ I will do some research later and will be watching this thread. Something I want to change myself. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted November 12, 2011 Report Share Posted November 12, 2011 The PCM has lots of presets that can be changed but the software itself cannot. I believe that the PCMs from 1992 through about 2004 the software is a PROM that is an integral part of the PCM and requires an aftermarket PCM to program, which would not be OBD compliant - i.e. off-road only because you won't be able to pass emissions testing. My 1997 ETC has slightly higher shift points, probably because my premium gas engine needs a few more RPM than your fast-burn engine, but the tranny behavior is much the same. It sounds like what you really want is a paddle shift or even a standard shift. Me too, but on my next car, I'm afraid. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
sprinter10 Posted November 13, 2011 Report Share Posted November 13, 2011 nahh I like the torque converter and auto for its speed and the great smoth full throttle shifting I would just like it to have been programmed by me for me. I know most people would prob say the car would be doggy and feel like it has no power if they drove a car that had the torque converter locked when i would program it though witch is why the gm engineers have it set wear it is to please the buyers the most. It runs great its just some fine tuning that I wish I could do. I also drive a 1997 audi a4 quattro witch is a 5 speed standard. No power at all you have to twist it hard to get power. Slow leaving red lights unless you abuse the car. You feel like you are taking off the same or faster but really all in all its slower. That 2.8L with 185hp has no power eather especially with clogged cats and engine codes but while my caddi is down thats what Im running. babying the stock clutch with 170,000 miles. The quattro all wheel drive being a stick shift is very fun though just run around the streets in 2nd with nice controlled slides!! haha If someone finds a way to reprogram the torque converter and shift points on the PROM without messing up the OBD Let me know. It really stinks that we can't adjust things to make these older cars run better and save gas, pollution, and all of the other bs that laws are being made to save because of the other bs laws with the OBD computers that make these cars a wiring nightmare and less fuel effecient. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted November 13, 2011 Report Share Posted November 13, 2011 The PCM for the Northstar watches your driving habits and adjusts the shift points and shift firmness accordingly. To activate this, use your key fob to unlock the car every time. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
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