I asked my tuner if my downshift MPH could be raised while coasting. My car will start down shifting about 20 mph from 4th gear without stepping on the gas. My tuner said the car will not downshift unless you step on the throttle, is this true? I would rather it down shift and already be in a lower gear when I step back on the gas. There are no issues with the transmission, it's just my personal preference. Does the PCM need data from the TPS Is that why?

 

You do NOT need to apply throttle to get the trans to downshift while coasting/decelerating. I'll give your tuner the benefit of the doubt and say that he misunderstood the question. Think about it-if I accelerate from a dead stop up to 60 mph-and the trans has shifted into 4th gear, and the T/C is locked up, if I remove my foot from the gas and apply the brakes and slow to a stop.. The trans WILL BE in 1st gear as I'm stopped. It got into 1st because as I was slowing down the trans was downshifting on it's own. However, if you are say rolling along at 15 mph and you step on the gas and the trans is in 2nd gear, and you want it to be in 1st, then you can adjust the settings to have it downshift to 1st as soon as you step on the gas. Hopefully that answers your question.

 

there are part throttle down shift tables just like part throttle upshift tables

 

https://photos.app.goo.gl/u9q5C7viErik76y7A

Thank you both, I kind of thought so. I'm a big familiar with the part throttle shift tables but I do not have HP tuners. conversation with the tuner. Maybe I did not articulate myself well enough. Below is my conversation.

Thank you, my car up-shifts much better. It still stays in 4th @ 0 tps until about 15mph (please see gear and mph on vid). If I step on the gas enough it will downshift. Can I raise the shift points so 4-3 & 3-2 will down shift while coasting? Let me know whenever you're not underneath a car. Ty.

It won't downshift without throttle

 

You can raise the downshift points. Depending what your tune will charge just for adjusting this to your liking it may be a good time to buy hptuners. Adjusting downshift mph is super simple and you could nail it down to your liking in 1 hr or less. And better yet you could use the tow/hual function in your computer to set up pretty much your "sport mode" shift points. That way it cost down nice and easy like it does now for normal driving and when you want it to be in sport-tow/haul mode you just flip a switch and it changes the shift parameters. I dont remember which pin on the ecu needs grounded to activate tow/haul but it will pop up with a google search.

 

I'm too far in and not knowledgeable enough to buy HP tuners at this point. If I had a friend who had it I would just buy the credits but nobody is local enough. I guess I am able to raise the downshift points and I need to contact my tuner. I just have to figure out if it's worth it to pull out my PCM because it's a pain.

 

If you don't want to buy HPTuners, you could just use PCMHammer and TunerPro to do everything for free. You just need a 15$ cable or 50$ Bluetooth adapter

 

That would be absolutely amazing. Is it an app and is it user friendly?

 

Seconding this

 

There is an android version and a PC version of PCMHammer. That will just read the .bin file. You do the actual editing with PCMHammer or UniversalPatcher. Then you write the modified .bin file back to the ecu.
I would recommend the PC version as you have to edit on a computer anyways. I've flashed my Cadillac countless times this way.

There is also a version of PCMHammer on the Microsoft store, but it only works with the newer Bluetooth adapters.

https://github.com/LegacyNsfw/PcmHac.../2022.05.14.01
https://github.com/BoredTruckOwner/L...ine_Repository

 

I have an Android and the laptop so that's no problem. Is the only way to do this pulling out the PCM or can if he done through the OBD2 port like HP tuners?

 

In a stock application you might have to pull the BCM fuse but other than that it just reads through the OBD2 port

 

Is there a good source aside from YouTube to read and learn if this is for me? To pull the PCM out of the fender is a real pain. I would much rather do it from the old II port.

 

https://github.com/LegacyNsfw/PcmHacks/wiki
This wiki should have most of the info needed

I use an OBDLink LX. A full write takes about 10 minutes, config only takes 2:30.

Here is a list of all the supported devices,
https://github.com/LegacyNsfw/PcmHac...pportedDevices

No need to pull the ECU, worst case scenario you have to pull the fuse for the BCM, but most likely not.
i would download the program and have a look around

 

Let me do some reading, thank you very much and I guess I'll be back.

 

Advice: Get HPTuners.
Own your tune.
you will REALLY like the ability to fine tune shift points to YOUR driving, terrain, etc.
Really, the vehicle experience is dramatically enhanced when you OWN it

 

I agree with you but I should have did it years ago b/c I am too far along to justify. My shift points and lock up are very altered currently. I realized I may know someone w/ HP Tuners. I think he will let me buy the credits and I can dial it in.

 

Advice: Get PCM Hammer and/or LS Droid.
For all of the same reasons.

I'll admit that they're more cumbersome, and limited in some ways, but they're cheap to try and sufficient for a lot of DIY scenarios.
The biggest issue is that they only work well with a small number of GM's PCM operating systems.

 

All the videos I see are being done on a bench with the PCM out. I really do not want to wrestle my PCM out again like a crocodile. Maybe I'm missing something, can they be hooked up to an OBDII port now?

 

yeah it goes through the obd port its the same as hpt or efilive. youre seeing the bench stuff because thats how people develop the software and do testing. i have the same setup but both cars ive tuned lately were physically untouched, everything goes through the obd port like any other tuner.
i use and highly recommend the OBDXpro hardware.