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Discussion Starter #1 (Edited)
Hey guys. This might end up being a silly idea, but I've been pondering it for awhile and thought I'd pursue it.

I remember reading somewhere on these forums that the ECM's for the R/T and the 300m Special are programmed for more aggressive throttle responses/gear changes/overall more "sportiness" (whatever that might entail.) Sounds nice, if true. In the last year, I've fitted a low restriction air intake and dual exhausts to my 2002 ES 3.5, and while those did make noticeable improvements to low-end grunt, it seems like an engine computer with sportier programming would... be even better.

I clearly don't know what the hell I'm talking about - however, I think there might be something to this. Before I even think about doing anything based on this largely uninformed hunch, I have a few questions for you guys:

Is any of this true? Are the R/T and 300M Special computers programmed any differently from the ES? Would it be at all worthwhile to swap them?

I am aware (I think) that the 2002 and later LH cars have just one unit controlling all of the engine and transmission management stuff. Thus, it seems like a relatively simple matter to swap the units so long as I get one from a 2002 or newer car. Are the wiring harnesses and mounting the same between the ES and the R/T or 300m units?

Also, I know that there are differences between the HO and standard 3.5's, specifically a little electronically controlled intake valve which opens at high RPM's to deliver more awesome. I know that somewhere on the computer wiring harness there are wires to control this valve. Will an HO computer even work with a standard 3.5, given that it lacks this valve?

Thanks for putting up with a barrage of what might seem like obvious questions.
 

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An HO ECM requires an HO upper intake and engine wiring harness.
Does no good without the intake and harness.

If you have a black ignition key, then get on down to the pull-a-part and pull these parts from another black key car.
(Although, I don't know if this is something you want to do at this time of year)

You'll notice a little bit more awesome....it's still a 4 door family sedan.
 

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I believe most if not all 2002 R/Ts had Sentry keys. Mine did so you might run into an issue there. That's assuming your ES doesn't have a Sentry key.
 

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Discussion Starter #4 (Edited)
As it happens, my ignition key is olive colored with a pentastar logo, not black with the ram's horns. I'm guessing this means I don't have a sentry key, which I assume also means I can't use an R/T or 300m ECM (apart from having the wrong upper intake and wiring harness.)

I know it's a family sedan, but it's my first car, so it's an M5 as far as I'm concerned. :)
 

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With your ES having a Sentry key and being able to get an R/T PCM with Sentry....you'd still need a trip to the dealer to program the R/T PCM for the SKIM/Keys in your car. You'd need the PIN for your car and your dealer should be able to provide that.
 

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Discussion Starter #6 (Edited)
So the ES does have a sentry key, even if my key is olive colored? Alrighty then!

Okay, so to make this happen:

Upper intake manifold from R/T. PCM and wiring harness from R/T. Trip to dealer to reprogram PCM to match my sentry key.

Does it matter which year R/T I take the intake manifold from? This thread implies that there are differences. Also, can I take any or all of these parts from a 300M, provided it has the HO? Or an SXT, for that matter?

http://www.lhforums.net/forums/showthread.php?18217-Intake-Plenum-Differences

I'm assuming the dealer can reprogram the PCM for my key before I install it in the car? Otherwise I'm not sure how that'll work.

Thanks for holding my hand through this one, guys. I am a complete novice, but always open to learning more.
 

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M5 it is!! (good comeback).

You should verify that you have a Sentry key system (SKIM).
Take a look inside the steering column cover with a flashlight.
Look through the opening by the tilt handle (lower left).
The SKIM (Sentry Key Immobilization Module) has two wires that connect to it
right on the bottom of the steering column.
If you can see those two wires AND they are NOT hanging loose with a piece of
foam tape over the connector, then they must be plugged into the SKIM and you
have a Sentry key.

You need to stay within 2002 - 2004.
Any HO from those years will work; 300M, Concorde or Intrepid.
(An HO is an HO is an HO)

There are some differences in PCM programming and a 2002 300M Special is the one to get
but, there again, it only gives you a few more enhancements.

All 300Ms were HOs. Some Concordes and some Intrepids were.
 

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1. I was under the impression that all 2nd gen. 3.5's were HO (i.e, have MTV and SRV).
EDIT: Incorrect - see Ronbo's post below.

2. Is a better plan to get the skim module and key from the same car you get the PCM from (rather than pay the dealer for programming)?

3. Be aware that the MTV actuator was electrically operated in some years and vacuum operated in other years - PCM, MTV control module, and MTV actuator have to be made for the same type of actuation (electrical or vacuum) - may not be a problem for the years you're dealing with. I may not have all the details right on that, so someone who knows for sure will either verify or correct as needed.
 

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The 2002 Intrepid ES is NOT an HO engine. Part of the DC cost cutting, etc.

Unsure? Just open the hood and look at your intake manifold. If it's an HO model it'll have a badge on it that states 3.5 HO.
 

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MTV/SRV are vacuum operated for 1998-2001 and electrically operated for 2002-2004. The years correspond to the introduction of the NGEC PCM in 2002.
 

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The 2002 Intrepid ES is NOT an HO engine. Part of the DC cost cutting, etc...
MTV/SRV are vacuum operated for 1998-2001 and electrically operated for 2002-2004. The years correspond to the introduction of the NGEC PCM in 2002.
Thanks for the followups.
 

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The 2002 R/T and SXT will be HO engines. The ES is not.

Now you know! LOL!
 

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From someone who had a special pcm swap from a stock H.O. pcm:
Did I notice a power difference? No, not really at all
Speed in shifts increase? Not really noticeable unless I was hammering on it with 2-3 and 3-4 shifts
Governor increase? Hells yeah. No more stock 108 mph. That was probably the only real benefit and my speedo wasn't off due to the difference in special gears and stock gears. 3.66->3.89 gears
 

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Discussion Starter #14 (Edited)
Right, so as long as I stay within the 02-04 years for everything, I should be good.

From someone who had a special pcm swap from a stock H.O. pcm:
Did I notice a power difference? No, not really at all
Speed in shifts increase? Not really noticeable unless I was hammering on it with 2-3 and 3-4 shifts
Governor increase? Hells yeah. No more stock 108 mph. That was probably the only real benefit and my speedo wasn't off due to the difference in special gears and stock gears. 3.66->3.89 gears
Okay, so that tells me that the 300m special PCM isn't really all that special, and any HO PCM will probably do me just fine, correct? Not concerned about the governor, I'll never track or drag the thing. Won't help me outrun the coppers either now that they all have Chargers in my state.

Has anyone here done what I'm proposing? Is it worth it? Indeed, what might I expect to pay for these parts from Jim-Bob's automotive graveyard? Anyone know what upper intakes and PCM's go for these days?
 

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Getlemen, I have replaced my 2002 2.7 (SE) with a 2002 3.5 H.O. and now want to swap for a 300M PCM/ECM. I have the Black key (non-SKIM?)
My mechanic simply swapped engines and used the existing ECM and harness (I think/engine came shipped on a crate 1/2 way cross the US). This has been almost 2 years ago and all is well. I am wanting the "little bit more" performance the 300M PCM offers and want to purchase this week. 1) How can I be sure the harness I have will take advantage of the change ? 2) I plan on calling a guy we go to church with, he has a salvage yard - Will I have issues if I do not "prove" the pcm was from a Non-Skim vehicle ?
WOW, just read YESIMLDS post, :-( Bummer, if I am not going to realize/notice the change I guess I will not bother......Thoughts ??
 

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Getlemen, I have replaced my 2002 2.7 (SE) with a 2002 3.5 H.O. and now want to swap for a 300M PCM/ECM. I have the Black key (non-SKIM?)
My mechanic simply swapped engines and used the existing ECM and harness (I think/engine came shipped on a crate 1/2 way cross the US). This has been almost 2 years ago and all is well. I am wanting the "little bit more" performance the 300M PCM offers and want to purchase this week. 1) How can I be sure the harness I have will take advantage of the change ? 2) I plan on calling a guy we go to church with, he has a salvage yard - Will I have issues if I do not "prove" the pcm was from a Non-Skim vehicle ?
WOW, just read YESIMLDS post, :-( Bummer, if I am not going to realize/notice the change I guess I will not bother......Thoughts ??
3.89 gears and a special pcm to match it so your speedo is on.
 

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The only thing about switching to a special pcm is that he will have to find the pcm, the skim module, and one of the chipped keys from a 300m special. The skim module will have to be installed and the chipped key zip tied or somehow attached near the ignition switch in order to allow for the car to start and run without the pcm shutting it down after 2 seconds.
 
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