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Hard starting 2011 GMC Sierra 1500 5.3

MajTomRet

By MajTomRet
in Ask A GM Technician

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MajTomRet New Member

MajTomRet

Posted
Posted

I added a K&N 63-3070 Performance Air Intake and a Throttle Body Spacer to my truck and now it starts REAL hard but up till now always starts... This happens ONLY on cold engine starts after the truck is warmed up it starts just fine...? The performance is great response and power are what I was looking for and it has it...
Any Ideas as to why it is a cold hard starter now?

Danthaman69 Enthusiast

Danthaman69

Posted
Posted

Sometimes throttle body spacers will do this. I would go ahead and get a custom tune done. Your A/F mixture has adjusted now. The computer may not realized the difference yet. Getting a tune done will take care of this.

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

I am surprised people still fall for the throttle body spacer idea. If extending the air intake half an inch made even half a mile per gallon difference in mileage the manufacturers would be all over it to help them meet CAFE numbers. As for power increase, again, GM adding a half inch more plastic in the manifold to get the claimed hp increase would also be a no brainer for them.

Most spacers have CARB exemptions. That means that the spacers do not alter the emissions enough to make a difference. If there is no difference in emissions, there cannot be a change to either mileage or power.

 

I would really like to find a deaf truck owner that knows his vehicle well enough to know if there was an actual power increase after adding either a CAI or throttle body spacer. The change in sound alone from the CAI tricks most people into feeling more power.

Silverado4x4 Senior Enthusiast

Silverado4x4

Posted
Posted

I am surprised people still fall for the throttle body spacer idea. If extending the air intake half an inch made even half a mile per gallon difference in mileage the manufacturers would be all over it to help them meet CAFE numbers. As for power increase, again, GM adding a half inch more plastic in the manifold to get the claimed hp increase would also be a no brainer for them.

Most spacers have CARB exemptions. That means that the spacers do not alter the emissions enough to make a difference. If there is no difference in emissions, there cannot be a change to either mileage or power.

 

I would really like to find a deaf truck owner that knows his vehicle well enough to know if there was an actual power increase after adding either a CAI or throttle body spacer. The change in sound alone from the CAI tricks most people into feeling more power.

 

Well said, throttle body spacers do nothing as the same as aftermarket CAI. Your truck already has a CAI from the factory and all the aftermarket ones do is give you more noise and making you think you have more power by the sound.

gmtech4 Senior Enthusiast

gmtech4

Posted
Posted

 

Well said, throttle body spacers do nothing as the same as aftermarket CAI. Your truck already has a CAI from the factory and all the aftermarket ones do is give you more noise and making you think you have more power by the sound.

awesome !!!! lmao !!!

demech23 Enthusiast

demech23

Posted
Posted

Well said, throttle body spacers do nothing as the same as aftermarket CAI. Your truck already has a CAI from the factory and all the aftermarket ones do is give you more noise and making you think you have more power by the sound.

 

awesome !!!! lmao

 

BlackBear did prove that a CAI can be benifitial, and this was before they were tuned for optimal performance.

http://www.gm-trucks.com/forums/topic/98172-how-to-shop-for-an-intake/

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted

 

BlackBear did prove that a CAI can be benifitial, and this was before they were tuned for optimal performance.

http://www.gm-trucks.com/forums/topic/98172-how-to-shop-for-an-intake/

 

Don't think they said CAI was beneficial. The final paragraph says:

 

"This all being said, intakes (as well as exhausts) are a matter of personal preference, just taking off the stock tube takes off a lot of restriction. Realistically, the differences between intakes (ie. open vs. open and closed vs. closed) will be minimal. One thing I do encourage anyone who purchases an aftermarket unit to do, is check the fitment every couple hundred miles, these things find a way to wiggle loose and can cause a drop in performance as well as MPG"

 

The stock air tube is designed to control intake resonance, not air flow. That being said, by screwing with resonance you can actually create a restriction by having the resonance cancel itself out. Take a look at any modern motorcycle airbox to see the science in using resonance to make optimal airflow. Simply cutting a hole in a motorcycle airbox can kill the torque, thus killing horsepower as well.

 

Chrysler found a way to use intake resonance to actually create a boost condition in the intake runners back in the late 50.s, early 60's. It was called either "long ram" or "cross ram" at the time. It is not the traditional cross ram though.

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