: '03 DeVille - Slight shudder under initial acceleration



Mojo88
01-24-12, 04:15 PM
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.

Ranger
01-24-12, 10:06 PM
Might start with a good TB cleaning. It's more important than you would think.

Mojo88
01-25-12, 11:44 AM
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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Caddys 32
01-28-12, 09:18 PM
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.

Mojo88
01-29-12, 10:18 AM
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...... :cool2:

Dave

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Submariner409
01-29-12, 10:28 AM
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.

Caddys 32
01-29-12, 10:58 AM
02 Deville premium or unleaded ? I know my 93 Deville was premium cuz it said it on the dash. But the 02 doesn't?

Ranger
01-29-12, 12:31 PM
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.

Caddys 32
01-29-12, 04:48 PM
U the man! Thanks ranger!! :)

Submariner409
01-29-12, 05:16 PM
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.

Mojo88
01-29-12, 06:04 PM
..... 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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Caddys 32
02-02-12, 10:06 PM
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!