# Rough Idle



## JohnC (Jul 12, 2007)

I've noticed over the last few weeks that the idle of my 2004 GTO isn't as smooth as it used to be. Seems to run great otherwise.

I've got 35k miles now and had the fuel system serviced by the dealer at 30k.

Replaced the stock air filter with a K&N at 15k miles.

Does anyone think changing the spark plugs might be a good remedy?

Any recommendations for replacement plug part?

How hard are the plugs replacement in this car?

Other things that might cause rough idleing?

Thanks,

JohnC


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## GM4life (Mar 18, 2007)

When did it start? Maybe some bad gas. Your stock spark plugs susspose to last 100K. I put NGK TR55's in my car because I did not like the way the car idled with stock plugs witch was normal. But replacing the plugs was the vary easy, just put anti-seaze on the threads and di-electric grease on the boots.


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## fergyflyer (Apr 18, 2005)

Definately use the NGK TR55's. Changing them is fairly easy. I had my Vette dyno'd with the stock plugs. Then dyno'd with a new company called Pulstar, with their plugs in. Then it was dyno'd with NGK TR55's. The Pulstars picked up like 5-7 hp. The problem was the Pulstars cost $25 a plug and when we put the TR55's in it picked up another 3 hp over the Pulstars. 

That means the TR55's over stock plugs at 23,000 miles picked up 8-10 hp and they cost $2 a plug. My guess is you would see an 8-10 hp increase just by changing to any good plug. The stock plugs will last to 100,000, but I wouldn't take them or any plug that far.


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## ELP_JC (Jan 9, 2007)

fergyflyer said:


> That means the TR55's over stock plugs at 23,000 miles picked up 8-10 hp and they cost $2 a plug.


Ten HP just by changing plugs seems farfetched to be honest, especially if plugs are okay. Maybe it was something else, like different gaps? That's more believable. 
Anyway, what gap do TR55s come with? Stock is 0.040". Thanks.
JC


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## 05GTO (Oct 6, 2004)

Pour a can of Sea Foam into your gas tank on the next fill up. It will remove moisture, clean the injectors and removes carbon.


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## PEARL JAM (Sep 6, 2005)

John, I can tell you that there has been a ration of bad gas around the Chas. area. Also, when you dropped in the K&N, did you oil it? If so, be careful because over oiling can cause engine vacuum to pull the oil onto the MAF sensor causing rough idle and even stalling. 

I too use the NGK's. They seem to provide better drivability.


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## JohnC (Jul 12, 2007)

I've got to stay away from the Kangaroo stations. I've been using Shell since reading GM Bulletin No.: 04-06-04-047G published 11/28/06 that lists what they consider "top tier" fuels. No rough idle since.

For those that don't have access to TSB's here is GM's list from the service bulletin:

Chevron
QuikTrip
Conoco
Phillips 66
76
Shell
Entec Stations located in the greater Montgomery, Alabama area.
MFA Oil Company located throughout Missouri
Kwik Trip, Inc. in Minnesota and Wisconsin and Kwuik Star convenience in Iowa
The Somerset Refinery, Inc. at Somerset Oil in Kentucky
Aloha Petroleum
Tri-Par Oil Company
Texaco

What is TOP TIER Detergent Gasoline?

TOP TIER Detergent Gasoline is a new class of gasoline with enhanced detergency. It meets new, voluntary deposit control standards developed by four automotive companies that exceed the detergent requirements imposed by the EPA.

More current onformation may be found here:

Top Tier Gasoline

JohnC


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## GTO JUDGE (May 14, 2005)

ABC News: Generic vs. Brand-Name Gas: Are They Different?

Drivers turn to generic gas -- baltimoresun.com

Can You Save Money With Generic Gas and Not Harm Your Car?

This topic can be debated until both sides are blue in the face.
It is RARE I use brand name gas, if I ever do so it's because I am out of town and have no choice. Personally, I have never had a problem using generic gas in my 34 yrs of driving.

I use generic medications too and they work as well as brand ones. Of course FDA mandates are different than EPA. but savings is savings.

For my GTO, I don't recall putting any brand name gas in it, unless I was duped at one of the generic refilling stations. I do not buy into the advertising that "zomieizes" many people into brainwashed theories that your car's engine will seize if their gas isn't used. 

Moisture can get into branded gas as it does generic causing coughing and sputtering. 

Exxon BOASTS 42 billion in profits as they dig further into peoples wallets, I won't patronize their boasting gluttony.

Citgo has a madman starving his own people as he uses some Hollywood stooges and poor people (as he gives them oil for heat in our country) has his own propaganda tools as sworn enemy to our leadership and people pump money into his regime because it's a branded gas. Brand X is my choice.

If using Brand X was detrimental to your car's engine, and harm would occur, car manufacturers would void warranties for using off name brands.


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## JohnC (Jul 12, 2007)

I'll err on the side of caution to avoid this; from the GM TSB recommeding top tier fuels:









1.) Intake valve: 10,000 miles with TOP TIER Detergent Gasoline 

2.) Intake valve: 10,000 miles with Legal Minimum additive Gasoline

JohnC


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## JohnC (Jul 12, 2007)

GTO Judge,

You're probably right, butn ote in my post preceding this, the phrase "legal minimum additive". In the articles you've sited a common thread is that all gas is basically the same except for the additives. Admittedly, it's the additives/detergents in top tier gas that make the only difference as they go beyond what is required by law. So, you have to pay a little extra for valve 1 in the picture above or, if valve 2 looks OK, save the money.

JohnC


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## silversport (Mar 23, 2007)

Remember that Top Tier gasolines aren't just what the manufacturers feel are the best but those gasolines that jumped through the hoops for the consortium of manufacturers to become "Top Tier."...others may meet the minimums to be top tier but didn't submit for testing...I would agree with the premise however that if the price were the same or similar, I would rather use a gasoline at least I believed was doing a better job...
Bill


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## GTO JUDGE (May 14, 2005)

JohnC said:


> GTO Judge,
> 
> You're probably right, butn ote in my post preceding this, the phrase "legal minimum additive". In the articles you've sited a common thread is that all gas is basically the same except for the additives. Admittedly, it's the additives/detergents in top tier gas that make the only difference as they go beyond what is required by law. So, you have to pay a little extra for valve 1 in the picture above or, if valve 2 looks OK, save the money.
> 
> JohnC


Nothing wrong with paying for peace of mind. Peace of mind always comes with a price tag.


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