Anyone know?

 

PM Masport.The guy selling the learn how to tune book on our forum.

 

LOL sure, he'll probably just tell me to buy the book.

I don't need to know this, it just makes no sense because there is nothing in the trans to measure it.
It would be nice if there was, you could see exactly what your converter was stalling at.

 

I'm curios as well. There aren't any sensors for it in the trans, so it has to be calculated from something.

I made a PID for converter slip after my stall went in. That seemed to work well until after it changed gears. Then it would show more trans input speed than RPM, so something is off somewhere.

 

Lets look at this in reverse.If it know what the output speed is and it knows what gear its in, it then knows the speed of the input shaft. The difference between the the input shaft speed and the motor RPM is the slip of the converter. By the way I've seen seen Dan tell somebody to just buy his book. He doesn't need to, it sells itself, by the people that already bought it.

 

Thats what I said in the transmission forum, I said it must be calculated off output speed.

About the book, my friend tells me about it, not sure if he knows where to buy it. Other than him telling me I wouldn't know such a book exists.

And if it did I'd be damn sure to flip through it first. There are so many write ups on the internet, this site, etc. Seems well educated tuners keep their info private, why would someone write a book....hmmm
Wait I got it, the internet is free=no info? Book=info=money.

 

Ok then how is the output shaft spinning 12 rpm at 0 MPH?

Whats the math formula?

 

How's the motor running at 3592 RPM's and the input shaft spiinning at 24 RPM's, is it braked locked against the stall speed and would it do a full stall at 58% of pedal?

You would just need to know the ratio of each gear to find the differance in speeds

 

Whatever it takes, full stall or not I'm looking for the math on how input speed is determine.
So you don't know the math to figure this I take it? If you know you can give a mathematical equation without knowing specifics, which are:
1st 3.06
2nd 1.63
3rd 1
4th .7
And during the screenshot it was locked in second.

No matter how you calculate it, it's not how input shaft speed is determined.
I'm assuming you don't know either.

I was hoping someone who knew something would chime in, but hptuners board members and people here I guess simply don't know.

 

Sorry if I sound rude but people beating around the bush instead of just saying I don't know, AND not being able to find this information ANYWHERE is frustrating.

 

Personally I don't think HP Tuners calculates the value, it just displays it. The value should already exsist, in the PCM's operating system. If the tranny is locked in 2nd gear, why isn't the car moving?

 

I was doing a brake stall test. What does that have to do with the question!
Post up the numbers and I'll use them against various scan logs I have. I took the screenshot down since it has little to do with the question and it seems to be distracting.

Simple question, how does HP Tuners calculate input shaft speed on a 2002 4L60E with no input shaft sensor?

 

Try emailing Vince at Trifecta Performance (sponsor) he works with HP tuners and is a ex Microsoft guy, he has developed his own products so that might be your source to figure this out. He doesn't spend time on the forum. Interesting question because when he tuned my car he compared my slippage to another A4 my car being a 3000 stall vs a stock converter.

 

HPTuners does not calculate it, the ECM does. If you really want to know, contact Chris at HPTuners on their forum.

Mind you, that test of checking the stall speed in 2nd for these cars is flawed. The only real method to figuring the true stall speed is using a trans brake or some method of locking the input shaft from turning, while going WOT. If you hold the output shaft from turning, the gear ratio will affect the stall speed, much like 2.73 will stall higher then 4.11s.

 

I'm sorry. I know HP Tuners does not calculate it.
I guess I should revise my question and asked what is HP Tuners reading from the VCM to come up with a input shaft RPM. How is the VCM calculating input shaft speed? thats it.

So by what you're saying is if I had a newer 4L60E with an input shaft speed sensor and a competant program to read the input shaft speed a stall test could be performed in second, third, fourth, whatever. As long as the input shaft was not moving? For that matter I could build a dummy trans with a bar through the input drum and case and get an accurate stall test right?
The more I deal with this **** the more I want to get out of performance cars again.

 

Well I guess nevermind. Seriously. Just like the STR post I made.
No one has the answer to this, or it's misunderstood, or not important enough to be a concern (but it's important enough to be a PID in HPT)
Seriously, I have a converter, I like it, I had a question not related to the converter, no one understands me or the way it's worded or no one knows.

So.....moving along, I got most of the tuning done (idle, misfire, etc) including low speed shift points. These are the biggest PITA IMO, I got the higher speed shift points done. Now I'm going to work on the mid range and perfecting general driveability.

 

Basically, yes. We had a huge 24 inch industrial brake rotor attached to our dyno output shaft. If you weren't careful, you could blow up the converter with that brake on and our blown (800hp) BBC at full tilt.

 

I appreciate your input, thanks.

 

It is the VCM itself that calculates the input speed of the trans. It is a long and drawn out process that is nothing more than an educated guess based on output speed, engine rpm, tcc status, temp, gear selection, TPS position, MAF load, ETC. We learned this when we had the 4L60E class years ago. I am a GM tech. Basically the number you see in the data files shouldn't really be relied on.

 

Well, when you look at the 80e it has two speed sensors. The 60 only has output speed. As is mentioned in the quote above me is the case. You [we]don't know what GM's real intentions for that value were, regardless of it's labeling. Knowing that, and what is mentioned (1 speed output) should lead you to the same conclusion. As you noted in the logs, it's clearly not 'real'.