Question for Fast,Joe,Injuneer,Perf,,,,,,,

[TimeLord]

My friend has a little problem,wonder if you can help please!!

trying to get the stock pcm to run trany while running a Holley Pro DFI

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I don't know if any one has done this but I have installed a Holley DFI and I still need the stock pcm to run the 4L60E. I think it can be done if I supply the pcm with the needed information. I think it will only need the RPM and MPH input to be able to shift the trany and it did before going to the dfi.

My question is where does the stock pcm pick up the rpm signal? Is it from the opti ? What pin on the pcm connection do I need to supply the signal to.

[Injuneer]

I already responded to Drag Bear's post of this problem on CZ28.com Advanced Tech board.

Does he still have the Opti? Without that, he may be SOL, since the PCM looks for the low res pulse form the Opti, and it derives the RPM from that signal. Without it, it shuts things like the fuel system down. Not sure if it will still operate the 4L60E at that point. But the question would be..... why does he want the PCM to control the tranny?

I also think its going to need TPS input for shifting, but I'm not sure.

[TimeLord]

He still has the opti,he is running Ed programming for the tranny & motor right now but is limited by the 7000 RPM ceiling in the stock PCM.

He is running a 383 now and is getting 1.30 60FT and 10.20-10.30 E.T with about 130-133 MPH( dependant on D.A.),he is very busy in the 60Ft and wants to keep the tranny controled by the computer for consistency.



That picture is from last year,he wants to get into the 9.s and thus wants to ditch the PCM controling the engine.

Is this info any help!!

[Joe 1320]

You got me thinking on this one. Keeping the tranny electonically controlled would be an asset, but I'm not sure how to go about doing it without the opti. In theory, keeping the stock opti electronics in place would allow it. You'll still need to be able to edit the parameters via laptop. This should prove interesting...........

[TimeLord]

Joe !!

He still runs the opti and will with the DFI set up also.

Ed Wright does all his tuning codes and Rick plays with them at the track as conditions warrant.

So he is looking for the hardware part ( pins & wires) that runs from the opti to the PCM to the tranny I guess,the shifts will be Eds problem

[fastTa]

He should really consider using a vacuum modulator. The PCM will still actuate the shifts but he would use the VM to control the line pressure. The factory programming in the PCM does not do a very good job at accurately estimating the real load being placed on the motor and hence accurately controlling the line pressure. The PCM looks at vehicle MAP and TPS data to estimate the real time load and then attempts to control line pressure based on that.

However with good knowledge and experience, a good tuner will be able apply fairly accurate maps to control the shifts while the VM is left to control line pressure. Vacuum modulation changes line pressure as soon as the vacuum or manifold absolute pressure changes (throttle opening). When the vaccum is high, the VM will keep the line pressure accordingly low. Aftermarket vacuum modulators have a wider range of line pressure than the EPC solenoid. So you basically program out the parameters within the PCM that are normally responsible for line pressure application and leave that to the VM.

But, I have to ask also, why doesn't he just go to a manual valve body? His tranny would last longer, he would get a better 330, and he wouldn't have to worry about overcoming the PCM RPM limitations.

[TimeLord]

He uses VM on his and on the one he built for me.

My tranny has 250 runs this year and 6k highway miles on it,his has 400 runs since his rebuild 2 years ago (he builds them himself),lasting is not a problem.

The VM is very important and that is how his trannys last so well,wish more builders knew this

I did not know they had Manual VB for 4L60e,

He loves the way the tranny works,he just wants to ditch the PCM for engine control.

[Injuneer]

I did get a PM from Rick on another forum, and he explained that he feels he will get more consistancy out of the electronic shifting..... I guess he's a die-hard bracket racer and prefers consistancy.

That said, why doesn't he just ask Ed Wright what he needs to keep the stock PCM "happy" ..... if Ed doesn't know, its not likely mere mortals are going to have the best answer.....

[TimeLord]

Makes sense,did not think to ask him if he had asked Ed !!!!!!

[fastTa]

He uses VM on his and on the one he built for me.

My tranny has 250 runs this year and 6k highway miles on it,his has 400 runs since his rebuild 2 years ago (he builds them himself),lasting is not a problem.

The VM is very important and that is how his trannys last so well,wish more builders knew this

I did not know they had Manual VB for 4L60e,

He loves the way the tranny works,he just wants to ditch the PCM for engine control.

If he absolutely is sold on using the factory PCM for controlling shifts. He will need input from the VSS, TPS, and a RPM signal. But it sounds as if he is wanting to spin the motor higher than 7,000 RPM. In that case like I said, I think he would really benefit from going to a manual VB. They even have reverse pattern VB's as well for the 4L60E.

Jetchip also makes a stand alone computer for the 4l60E, but they are a bit pricey:

http://www.jetchip.com/products.asp?pid=23408