This is something I've wondered about since I bought my first chip 3 years ago...

My understanding, that seems to be repeatedly reinforced, is that the PCM does not control fueling, etc. whatsoever once you install a chip. If that is true, then why would a tuner need to know my code? If the chip is handling all those functions, then the PCM is just a big connector, right?

Obviously, I'm lacking in details, and want to know. Not down to the super-nitty-gritty.... but it just doesn't seem to "add up" to me. The one thing I can think of is that the part of the board that we clean off to install a chip must do different things, send different signals, with the different generation of PCM.

Someone please enlighten me!!!

OH, and by chip I'm talking about ones like the TS chip used by PHP, Wildman, Casserly, etc. or DP's F5/F6 chip, and any others that I haven't named. I'm not picking or bashing AT ALL, just trying to figure out a bit of the electronics side of things without becoming too much of an engineer. Thanks all!!

 

Subscribing, always willing to learn...

 

Brendan, according to your sig, you don't have a chip. Or, are you being politically correct?

That is a good question.

 

I don't worry so much about politically correct; It's a techie question that I've wondered at many times and I'm trying to avoid a thread that's just a bash on any brand by (hopefully) heading it off from the get-go.

 

Brendan, a rough way of putting it is that the way a chip works is it substitutes the memory bits on the PCM. In order to successfully do that, the tables for fueling, shift strategies, ICP, etc must all match, otherwise there are conflicts with the wrong data being substituted, or not being substituted at all. The end result of a mismatched tune on the wrong chip is incorrect fueling strategies, transmission shift strategies, etc.

For example, on the later models, the BARO sensor is moved into the PCM. If you were to run a pre-2002 programmed chip on an 02 or 03 7.3L, the shifting is extremely harsh. It's weird, but that's what happens.

That's the short and ugly of it.

Cody knows more about it than I do, maybe he'll chime in. I'm still lernin'.

 

Curtis -

It's almost scary how much you know about these trucks!!! But that makes perfect sense and was exactly what I was looking to know!!! When I get back to CO, I definitely owe you a beer!

 

If I had bin files of other PCM codes, I could show you some of the differences. Right now I only have bin files of VDH2 and VDH5 pcm codes, and those are pretty much identical.

This Minotaur software from PHP is great though. It's amazing how much I'm learning from it. And what's really scary is I'm only at the tip of the iceberg here.


On edit: I'm always up for some beer!!!!!!!!!

 

Short and ugly? I've never even met you and you're already bashing me.

Anyway, Curtis is correct on many points. The long and short of it is that the differences in EEC-V PCM codes mainly come down to hardware changes and most importantly, binary addressing changes. By addressing I mean the way the bytes are arranged in the code. Hardware changes allow fetch requests on a "chip" memory chip to retrieve what is requested by the PCM. If the hardware doesn't match the chip code, the results are usually a poorly running truck or one that won't even run because the correct memory allocation on the chip isn't what the PCM is looking for.

All of those contacts on the J3 connector on the back of the PCM (with the exception of half a dozen or so) are used to power up the chip, ground the chip, put the PCM in a permanent "reset" mode so that the internal memory is bypassed, and transfer all of the fetch commands and signals back to the PCM through a CPLD (basically a hard-wired programmable gate setup) and separate memory.

The early 99 PCMs (DPC 401/402) and the OBS PCMs had an external BAROmetric pressure sensor while it is built into the later boxes. Placing one of these PCMs in a 99.5-up truck will cause harsh shifts and a P0107 code due to the PCM having no clue what the elevation is since it's looking for an external input.

The later (02-03) trucks use an additional type of communications interface protocol between body modules and the PCM. Under some circumstances, swapping the PCMs between 99.5-01 and 02-03 PCMs will work....however the glow plugs, tachometer, speedometer, cruise control, as well as some other features will not work. Placing a DPC-422 chip in a DPC-462 PCM will have a similar effect under some circumstances.

Cali-****-fornia PCM codes are different as well due to the glow plug control/monitoring systems. All Excursions fall into this category as well.

All in all, the above text is a bunch of .

 

Hahahaha Cody!!!!!!


You can't be THAT ugly

 

Cody, what about those of us running a newer PCM in an early 99 in regards to the BARO sensor? Any ill effects?

 

X2...Good question Chase.

 

x3 farmb0y is trying to explain to me why he needs a PMT1 to replace the DCP-422 that we put into his E99 F350. A thread a few days ago gave some info on that question but it still isn't clear to me. I still don't know which exact part no. to get for his truck. Hope that this thread can give some insight to this old man

 

Ok, for those of you wondering about swapping in a 99.5-01 PCM into your E99 truck.

Yes, it can be done quite painlessly.

Your E99 truck has an external BARO sensor and the 99.5-up PCMs have an internal one. No big deal. There will be an extra wire in the PCM plug and a BARO sensor under the dash but the PCM is not wired for it and will ignore any signals from the external BARO sensor. Plug and play.

 

Interesting read.