Re-mounting PCM - Idea?
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Northstar Engines and System Technical Discussion Discussion, Re-mounting PCM - Idea? in Cadillac Engine Technical Discussion; I've been toying with how to re-mount the PCM in order to run a different and/or more efficient intake setup...the ...
  1. #1
    fubar569 is offline Cadillac Owners Fanatic
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    Re-mounting PCM - Idea?

    I've been toying with how to re-mount the PCM in order to run a different and/or more efficient intake setup...the stock one is very good, but i want to evaluate the difference and see if any power is to be had...

    if i mount the PCM in its own enclosure, it gets no airflow
    if i put it in a new airbox/etc...that presents a restriction...both the PCM and the "airbox"

    well...dur...i'm a computer nut and know all about overdoing cooling...

    make a new enclosure, mount PCM in enclosure, add small vents...for airflow, run XYZ size tubing to air source and put a 92mm or 120mm size fan flowing 100+ CFM inline with that tube...should be plenty of airflow to keep the PCM happy. the fan runs off 12v and usually take less than 1 amp draw to run (the particular one i have in mind is 650mA and 6 watts)

    this would allow almost total freedom for any sort of revised intake setup should one choose to do it while keeping PCM nice and cool...

    thoughts?

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    Submariner409's Avatar
    Submariner409 is offline If it won't run, chrome it
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    Re: Re-mounting PCM - Idea?

    I like the idea. Especially after discovering (this AM) that the PCM runs hot enough to cause pain if you try to pull it right after a road run. If you really think about it, just how much air flows through the air box at, say, 35 mph? Not much, because the throttle butterfly is barely off-idle and engine vacuum is up around 20". There's 8 or 10" of PCM pigtail to fool with, so there must be a solution.........OR go into the top of the existing box, through the cover held on by the resonator bolt.........

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    Re: Re-mounting PCM - Idea?

    I surmised in the other thread where submariner409 was asking about temperatures that the next step in automotive PCM cooling is active cooling (with a cooling fan, a la your home PC). I think the best deal would be to build your own PCM enclosure, and install two large muffin fans. They'd have to be pretty high capacity I'm sure, but it would probably provide the best alternative to the passive cooling it gets in the intake tract.

    The '97 DeVille box is a bit different than the newer ones (or at least the one in my '01 STS). The air box actually sits "on top" of the PCM and all the air is drawn over the PCM (or at least most of it). In my '01, the PCM sits "in" the air box, and you can easily draw a direct path of air flow that doesn't intersect the PCM. It would seem that the newer design doesn't provide as much PCM cooling, but who knows.

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    airfuel2001 is offline Cadillac Owners Member
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    Re: Re-mounting PCM - Idea?

    What I did was, I had a 3.5 in mandrel piece of pipe from the mass air 90 to my 4 in K&N where it stuck in the corner and was wedged there. I thought it would feed more reasonably cold air to the motor via a heat shield to block rad heat. I placed the computer between the fuse box and the filter and it wouldnt go anywhere, the problem was it would get HOT and that concerned me, after experimenting with that I now have a modded air box and am surprised it is more "crisp" and didnt feel any loss. I also have the peace of mind that the computer is air cooled.

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    Re: Re-mounting PCM - Idea?

    I may duplicate this up in the Seville forum....anyhow, take a flashlight and look outboard of your Seville airbox, and you'll see a rather large hole in the sheetmetal of the side body panel which opens into the area behind the headlight and above the fender liner and lower air deflector panel. If you accurately cut the side out of the airbox and use some 1" foam weatherstripping to form a gasket, you have now more than doubled the air intake area from outside the engine compartment and increased the flow past the PCM.

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    Re: Re-mounting PCM - Idea?

    Quote Originally Posted by airfuel2001 View Post
    What I did was, I had a 3.5 in mandrel piece of pipe from the mass air 90 to my 4 in K&N where it stuck in the corner and was wedged there. I thought it would feed more reasonably cold air to the motor via a heat shield to block rad heat. I placed the computer between the fuse box and the filter and it wouldnt go anywhere, the problem was it would get HOT and that concerned me, after experimenting with that I now have a modded air box and am surprised it is more "crisp" and didnt feel any loss. I also have the peace of mind that the computer is air cooled.
    Can you upload a picture of this, I'm very interested. Thanks

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    Re: Re-mounting PCM - Idea?

    Quote Originally Posted by submariner409 View Post
    I may duplicate this up in the Seville forum....anyhow, take a flashlight and look outboard of your Seville airbox, and you'll see a rather large hole in the sheetmetal of the side body panel which opens into the area behind the headlight and above the fender liner and lower air deflector panel. If you accurately cut the side out of the airbox and use some 1" foam weatherstripping to form a gasket, you have now more than doubled the air intake area from outside the engine compartment and increased the flow past the PCM.
    Have you done this on yours?

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    Re: Re-mounting PCM - Idea?

    Quote Originally Posted by lisekpl View Post
    Can you upload a picture of this, I'm very interested. Thanks
    Very interested.

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    Re: Re-mounting PCM - Idea?

    The PCM is a digital device. It either works or it doesn't. As long as it doesn't throw codes or cause random problems it's working just fine. If it ain't broke don't fix it. What I'm trying to say is that the PCM functions just fine in its present environment. It may seem extreme for various human body parts but the PCM seems to tolerate it well. You're focusing on a problem that doesn't exist.
    Don't mess with Binky Bear!


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    Re: Re-mounting PCM - Idea?

    dkoz......After some surfing, found out that most PCM's, no matter what mfr., seem to run around 120-130 degrees. Lotsa brainwork there.....(PCM - the big ones, not the chipsets out in the left fender area by the driver's foot......)
    Jadcock.......yep, the outboard side of my airbox looks like Swiss cheese. Didn't make a whit of difference anywhere that I can tell with a stopwatch and speedo.....pretty primitive. The PCM still hits 123 degrees measured with an IR thermometer. I'll probably score a used airbox online in case I need to restore things to close-to-stock.

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    Re: Re-mounting PCM - Idea?

    Quote Originally Posted by submariner409 View Post
    dkoz......After some surfing, found out that most PCM's, no matter what mfr., seem to run around 120-130 degrees. Lotsa brainwork there.....(PCM - the big ones, not the chipsets out in the left fender area by the driver's foot......)
    Jadcock.......yep, the outboard side of my airbox looks like Swiss cheese. Didn't make a whit of difference anywhere that I can tell with a stopwatch and speedo.....pretty primitive. The PCM still hits 123 degrees measured with an IR thermometer. I'll probably score a used airbox online in case I need to restore things to close-to-stock.
    It might be interesting to find out what the worst case design specs are for the PCM. Because the car seems to run fine in desert environments it must be pretty tough.
    Don't mess with Binky Bear!


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    Re: Re-mounting PCM - Idea?

    When solid state electronic ignition systems first appeared on factory Detroit automobiles in the 60's they were all plagued with reliability troubles except for the GM DelCo systems that were mounted on the front side of the radiator support. MoPar systems in particular were problematic. Delco used a magnetic pickup and the Mopars were optical. The Delco black box was heavily finned and in a direct airflow path. I never saw one fail.
    Don't mess with Binky Bear!


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    Re: Re-mounting PCM - Idea?

    http://www.amerigon.com/index.php
    click on the 1 2 3 4 tabs

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    Re: Re-mounting PCM - Idea?

    Don't mess with Binky Bear!


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    Re: Re-mounting PCM - Idea?

    Quote Originally Posted by dkozloski View Post
    I have one.

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