'03 DeVille - Slight shudder under initial acceleration
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Northstar Engines and System Technical Discussion Discussion, '03 DeVille - Slight shudder under initial acceleration in Cadillac Engine Technical Discussion; Recently purchased a beautiful '03 DeVille with 55k miles. It has a slight shudder under initial acceleration, almost like it ...
  1. #1
    Mojo88's Avatar
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    '03 DeVille - Slight shudder under initial acceleration

    Recently purchased a beautiful '03 DeVille with 55k miles. It has a slight shudder under initial acceleration, almost like it needs a bigger accelerator pump shot. Once it gets going, it runs as smooth as glass, very nice. Mileage is good too.

    I am familiar with old school muscle cars, and if I had this kind of stumble, I would increase the accelerator pump shot a little (by swapping parts or pump cams). Of course, this is EFI and a whole lot different.

    Just wondering if anyone has any experience with a fix for this slight shudder? Would it involve tweaking the software? I have a qualified shop that could do this.

    Thanks for any help.

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    Re: '03 DeVille - Slight shudder under initial acceleration

    Might start with a good TB cleaning. It's more important than you would think.

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    Re: '03 DeVille - Slight shudder under initial acceleration

    Quote Originally Posted by Ranger View Post
    Might start with a good TB cleaning. It's more important than you would think.

    Yeah, that's a good idea. And fairly easy too. I'll give that a whirl, thanks.

    Dave

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    Re: '03 DeVille - Slight shudder under initial acceleration

    Mine did that but I have a lot of miles on my 02 Deville .192000 on it. Bought New cat. Converter, & cleaned iac , & intake it helped a lot.

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    Re: '03 DeVille - Slight shudder under initial acceleration

    Well, I cleaned MAF and it does seem better. Plus, I'm also running plenty of fuel injector cleaner through the Northstar. It's almost perfect!

    Thanks for tips gents. Much appreciated......

    Dave

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    Re: '03 DeVille - Slight shudder under initial acceleration

    There is no way to "tweak the software" in our series of PCM engines. No way. We all hope and wait for a CF member (GM Service Tech) and a Canadian shop to come through, but so far, nothing in 6 years.

    Click on my username, open my profile. 2 albums, 6 pages of pictures, graphs and diagrams for our cars and engines.

    For your "fuel injector cleaner" - Get a 20 oz. jug of Chevron TECHRON and dump that in with a fillup of a Top Tier gasoline - Shell, Chevron, Texaco, EXXON, a few smaller names - Google "top tier gasoline" to find out why. Stop pouring various potions into the gas tank, run Top Tier fuels and use TECHRON only once in 5,000 miles.

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    02 Deville premium or unleaded ? I know my 93 Deville was premium cuz it said it on the dash. But the 02 doesn't?

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    Re: '03 DeVille - Slight shudder under initial acceleration

    Your '93 was a 4.9. Your '02 is a Northstar. The 4.9 did not have a knock sensor. The Northstar does. The 4.9 NEEDED premium. The Northstar doesn't.

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    U the man! Thanks ranger!!

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    Re: '03 DeVille - Slight shudder under initial acceleration

    Caddys 32 - A half page on fuels for the 2000 and later Northstars - in the owner's manual.

    The OP who started this thread - Mojo88 - did you do the homework on TECHRON ? The reason I ask is because it is NOT a good idea to constantly use any sort of fuel system cleaners or other magic potions - the stuff is a combination of powerful solvents that pump seals, gaskets, O-rings, rubber diaphragms and composite fuel lines does not like.

  12. #11
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    Re: '03 DeVille - Slight shudder under initial acceleration

    Quote Originally Posted by submariner409 View Post
    ..... Mojo88 - did you do the homework on TECHRON ? .......

    No, I didn't do any 'homework' on Techron, though I have seen it highly recommended on the Corvette Forum (I have a '04 Vette). Honestly, I'm just not sure of what to believe in all the hype and hoopla about the "best" and "worst" additives/oils/gas. My philosophy is simply to change fluids and filters often, always using high-quality parts. I maintain my vehicles very well.

    Thanks

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  13. #12
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    Quote Originally Posted by submariner409
    There is no way to "tweak the software" in our series of PCM engines. No way. We all hope and wait for a CF member (GM Service Tech) and a Canadian shop to come through, but so far, nothing in 6 years.

    Click on my username, open my profile. 2 albums, 6 pages of pictures, graphs and diagrams for our cars and engines.

    For your "fuel injector cleaner" - Get a 20 oz. jug of Chevron TECHRON and dump that in with a fillup of a Top Tier gasoline - Shell, Chevron, Texaco, EXXON, a few smaller names - Google "top tier gasoline" to find out why. Stop pouring various potions into the gas tank, run Top Tier fuels and use TECHRON only once in 5,000 miles.
    I used it 2 day. that stuff. Thanks!

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