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Cadillac Tech Tips - How to fix it Discussion, Performance modifications for the 4.x engines. in Item Specific Cadillac Discussion; Originally Posted by Stealth it is now 4 years later. updates to this great thread? Hehehehe... Sorry, I've been very ...
  1. #31
    illumina's Avatar
    illumina is offline Cadillac Owners Connoisseur
    Automobile(s): '98 Buick Regal LS - '91 Caddy Seville - '87 Caddy Seville!
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    Re: Performance modifications for the 4.x engines.

    Quote Originally Posted by Stealth View Post
    it is now 4 years later.

    updates to this great thread?
    Hehehehe...

    Sorry, I've been very busy with about 2,000 other projects, and an even bigger one is coming up pretty soon (not car related).

    That said, as far as bolt on mods that can be bought off of the shelf and will readily fit, what I've listed here is pretty much it. I still plan to make a picture instruction post regarding a nice clean air intake, and the tranny thread will be posted real soon too (still waiting for my LSD!!!).

    So please hang in there, I have not forgotten this performance business, I just have other priorities at hand right now.

  2. #32
    N0DIH's Avatar
    N0DIH is offline Cadillac Owners Master
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    Knowing GM, they typically run fairly rich at WOT, this is where you often find lots of power @ WOT. If you can lean it out at WOT somehow, then you can likely find on the order of 10-15 hp. That coupled with illuminas's mods might really perk things up.

    Why does GM err on the rich side? Cat Converters, they melt if they get to hot, most GM tunes try not to let the cats exceed 800-830C. I have seen performance cars like CTS-V in the 900-950C range, so it does sound like converter technology is changing to allow hotter exhausts. So anytime you lean out WOT you are putting some risk of the converters melting. This is not to scare you, if you tune for WOT power around 13.2-13.3:1, I have NOT heard of people having issues. An engine misfire causes far more damage than a WOT run running @ 13.3:1....

    I had always wanted to get another exhaust pipe for my 91 Deville (that is a sweet one factory isn't it guys??) and tack weld it to the stock pipe and make a dual exhaust option. It might work. But probably more gains for a good muffler design would do more. That large pipe is a nice size for a 4.9L, so the real issue is probably the muffler anyway.

    One of these days if I can get a 90 4.5L car or a 91-95 4.9L car I will do what I can to dissassemble the PCM code and make a true custom tune. I just need the car to start working on, which I don't have at the moment (I do have access to a 90 4.5L, but is isn't mine and it is trying to be sold, so I can't really hack at it too much right now, but if I can get the base code read I might have something to work with, I hope to get the reader today....) and I need the time, the tools for code hacking are the easy part.... Hacking isn't always fun either....

    Oh, a performance mod worth noting, for economy and performance is a Wideband O2 that replaces the Narrowband O2 with a wideband controller that has a Narrowband output for the PCM. I hope to do one soon on my LT1. You can setup for leaner cruise for better economy, or richer cruise for power (this will kill mpg) or whatever you want...

    Did the FastChips chip do anything at all other than remove speed limiter, that is all it looks like it does.

    If anyone has one that they can have read and send me the .bin, I would like to examine and see if they did more than that.

  3. #33
    19Eldorado90 is offline Cadillac Owners Member
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    Re: Performance modifications for the 4.x engines.

    Has anyone cracked a '90 4.5 PCM yet? I plan on either doing some work to the 4.5 in my Biarritz or swapping in a warmed over 4.9. If someone has a bin for it please let me know.

  4. #34
    norfmo is offline Cadillac Owners Member
    Automobile(s): 1988 Eldorado Biarritz 4.5 V8 - 101,000 Miles
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    Re: Performance modifications for the 4.x engines.

    How do you set ignition timing on a 4.5L? Thanks!

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