{
    "lazyNodes": false,
    "abFitnotesFlag": false,
    "abCrawlReviews": false,
    "productOptionsCookie": false,
    "orderDelayFlag": false,
    "skipSessionCookie": false,
    "covidMessage": false,
    "fullTitleCookie": false,
    "nrLoggerCookie": false,
    "checkoutReviewCookie": false,
    "productOptionSeqCookie": false,
    "maintenanceFlag": false,
    "bufferETACookie": false,
    "multiShippingDiscountFlag": false,
    "newFitmentFlag": false,
    "surveyOptInFlag": false,
    "crossSellFlag": false,
    "skuMappingFlag": false,
    "paySplitCookie": false,
    "callDisableFlag": false,
    "zipPaymentFlag": "u",
    "hassleFreeReturn": false,
    "lifetimeReplacement": false,
    "cpn_off": false
}
1999 Chevrolet Silverado 1500
1
0
Price Match Guarantee
60-Day Returns
Lifetime Replacement
Price Match Guarantee
60-Day Returns
Lifetime Replacement
1999 Chevrolet Silverado 1500

1999 Chevrolet Silverado 1500 Cold Air Intakes

Refine by:

Shop Catalog

Showing 1 - 15 of 16 results
Display item:
15
30
45
Sort by:
Cold Air Intake, 5.3/4.8L Engine -
aFe®
Cold Air Intake, 5.3/4.8L Engine -
Part Number: A155474101
Guaranteed to Fit
$416.00
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
Product Details
Notes : Includes aFe Pro 5R Air FilterEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton FilterWarranty : 2-year AFE limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Power Momentum GT Stage 2 SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine -
aFe®
Cold Air Intake, 5.3/4.8L Engine -
Part Number: A155410092
Guaranteed to Fit
$357.00
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
Product Details
Notes : Includes aFe Pro 5R Air FilterEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterWarranty : 2-year AFE limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Power MagnumFORCE Stage-2 Pro 5R SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine
Volant®
Cold Air Intake, 5.3/4.8L Engine
Part Number: V31358531
Guaranteed to Fit
$491.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
Product Details
Notes : Includes Filter Box/Air Duct/Ram Filter/Connectors/Clamps/Air ScoopEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterWarranty : 1-year Volant limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Pro-5 SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine
Spectre®
Cold Air Intake, 5.3/4.8L Engine
Part Number: S719900
Guaranteed to Fit
$199.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
Product Details
Notes : 10.25 in. height; Red filterEmissions : 50-State LegalAir Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Aluminum TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterEO Number : EO Number: D-629-4Warranty : 90 DaysProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Muscle Car Series
Cold Air Intake, 5.3/4.8L Engine, with Red Dry Air Filter -
Airaid®
Cold Air Intake, 5.3/4.8L Engine, with Red Dry Air Filter -
Part Number: A86201712
Guaranteed to Fit
$249.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L with Red Dry Air Filter
Product Details
Emissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : DryQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Synthetic FilterWarranty : Lifetime Airaid limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Jr. Kit Series
Cold Air Intake, 5.3/4.3/4.8L Engine, Low Profile Hood, without Intake Tube, with Red Dry Air Filter -
Airaid®
Cold Air Intake, 5.3/4.3/4.8L Engine, Low Profile Hood, without Intake Tube, with Red Dry Air Filter -
Part Number: A862011121
Guaranteed to Fit
$299.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LT 6 Cyl 4.3L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LS 6 Cyl 4.3L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 Base 6 Cyl 4.3L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L Low Profile Hood, without Intake Tube, with Red Dry Air Filter
Product Details
Emissions : 50-State LegalAir Filter Type : DryQuantity Sold : Sold individuallyTube Material : Without tubeType : Without tubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Synthetic FilterEO Number : D-609-18Warranty : Lifetime Airaid limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : CAD Series
Cold Air Intake, 4.3L Engine, with Heat Shield
K&N®
Cold Air Intake, 4.3L Engine, with Heat Shield
Part Number: K33573038
Guaranteed to Fit
$349.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 6 Cyl 4.3L With Heat Shield
  • 1999 Chevrolet Silverado 1500 Base 6 Cyl 4.3L With Heat Shield
  • 1999 Chevrolet Silverado 1500 LS 6 Cyl 4.3L With Heat Shield
Product Details
Emissions : 50-State LegalAir Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterEO Number : D-269-34Warranty : 10-year or 1 million-mile K&N limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : 57 Series FIPK SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine, with Heat Shield
K&N®
Cold Air Intake, 5.3/4.8L Engine, with Heat Shield
Part Number: K335730211
Guaranteed to Fit
$349.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L With Heat Shield
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L With Heat Shield
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L With Heat Shield
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L With Heat Shield
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L With Heat Shield
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L With Heat Shield
Product Details
Emissions : 50-State LegalAir Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterEO Number : D-269-28Warranty : 10-year or 1 million-mile K&N limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : 57 Series FIPK SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine
Injen®
Cold Air Intake, 5.3/4.8L Engine
Part Number: I24EVO7100
Guaranteed to Fit
$363.95
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
Product Details
Emissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : DryQuantity Sold : Sold individuallyTube Material : Aluminum TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitWarranty : Lifetime Injen limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Color Finish : Black
Cold Air Intake, 5.3/4.8L Engine
K&N®
Cold Air Intake, 5.3/4.8L Engine
Part Number: K33773021KP
Guaranteed to Fit
$449.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
Product Details
Emissions : 50-State LegalAir Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Aluminum TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterEO Number : EO Number: D-269-29Warranty : 10-year or 1 million-mile K&N limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : 77 SeriesColor Finish : Polished
Cold Air Intake, 5.3/4.8L Engine
AEM Air®
Cold Air Intake, 5.3/4.8L Engine
Part Number: A18218000DC
Guaranteed to Fit
$399.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
Product Details
Emissions : 50-State LegalAir Filter Type : DryQuantity Sold : Sold individuallyTube Material : Aluminum TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Synthetic FilterEO Number : EO Number: D-670-15Warranty : Lifetime AEM limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Brute Force Series
Cold Air Intake, 5.3/4.8L Engine
Volant®
Cold Air Intake, 5.3/4.8L Engine
Part Number: V313585361
Guaranteed to Fit
$528.49
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
Product Details
Notes : Includes Filter Box/Air Duct/Powercore Filter/Connectors/Clamps/Air ScoopEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : DryQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Synthetic FilterWarranty : 1-year Volant limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Powercore SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine
Volant®
Cold Air Intake, 5.3/4.8L Engine
Part Number: V3115153
Guaranteed to Fit
$391.99
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
Product Details
Notes : Includes Filter Box/Air Duct/Ram Filter/Connectors/ClampsEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterWarranty : 1-year Volant limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Pro-5 SeriesColor Finish : Black
Cold Air Intake, 4.3L Engine
Volant®
Cold Air Intake, 4.3L Engine
Part Number: V3115843
Guaranteed to Fit
$352.49
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 Base 6 Cyl 4.3L
  • 1999 Chevrolet Silverado 1500 LT 6 Cyl 4.3L
  • 1999 Chevrolet Silverado 1500 LS 6 Cyl 4.3L
Product Details
Notes : Includes Filter Box/Air Duct/Ram Filter/Connectors/ClampsEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : OiledQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Cotton Gauze FilterWarranty : 1-year Volant limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Pro-5 SeriesColor Finish : Black
Cold Air Intake, 5.3/4.8L Engine -
aFe®
Cold Air Intake, 5.3/4.8L Engine -
Part Number: A1551-74103
Guaranteed to Fit
$416.00
Vehicle Fitment
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 Base 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 5.3L
  • 1999 Chevrolet Silverado 1500 LS 8 Cyl 4.8L
  • 1999 Chevrolet Silverado 1500 LT 8 Cyl 5.3L
Product Details
Notes : Includes aFe Pro Dry S Air Filter; Does Not Fit Vehicles with a Mechanical FanEmissions : 46-State Legal (Cannot ship to CA, CO, NY or ME)Air Filter Type : DryQuantity Sold : Sold individuallyTube Material : Plastic TubeType : With TubeRecommended Use : Performance ReplacementProduct Fit : Direct FitAir Filter Material : Synthetic FilterWarranty : 2-year AFE limited warrantyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Power Momentum GT Pro Dry S SeriesColor Finish : Black
Page 1 of 2 | Showing 1 - 15 of 16 results

Top Rated Products

K&N Cold Air Intake, 5.3/4.8L Engine
$449.99( Review)
Quick and easy install. Just followed the directions. Only took about 30 minutes.
Anonymous
VERIFIED PURCHASER
K&N Cold Air Intake, 4.3L Engine, with Heat Shield
$349.99( Review)
Installed on my daily driver, only took about 45 minutes and after one week of drivinSee More
Anonymous
VERIFIED PURCHASER
K&N Cold Air Intake, 5.3/4.8L Engine, with Heat Shield
$349.99( Review)
I took a test drive and was very surprised on how much better acceleration I had withSee More
Anonymous
VERIFIED PURCHASER

Popular Products

Helpful Automotive Resources

Add to Cart! Aftermarket Upgrades to Boost Fuel Economy
Add to Cart! Aftermarket Upgrades to Boost Fuel EconomyA cold air intake is one of the most popular aftermarket upgrades you can buy to boost your daily driver’s fuel economy. The science behind this upgrade is that cooler air means more engine power and better efficiency. 
Must-Have Upgrades Inspired by “Fast & Furious” Cars
Must-Have Upgrades Inspired by “Fast & Furious” CarsJust make sure to abide by the emissions rules where you live, as you can pay hefty fines for modifying your car’s engine. –Anthony Harlin, ASE Certified Master Automobile Technician Turbocharger A turbocharger injects additional air into the combustion chamber, allowing your engine to produce more horsepower and feel like a “Fast and
Best Cold Air Intakes To Improve Your Engine’s Performance
Best Cold Air Intakes To Improve Your Engine’s PerformanceA cold air intake system typically replaces a plastic intake manifold with a metal or plastic tube with a conical air filter at the end. Some aftermarket cold air intake systems replace the intake manifold box with one that has better airflow. A cold air intake system can also have
The Best Car Upgrades For Improved Performance
The Best Car Upgrades For Improved PerformanceYou don’t have to upgrade your engine’s components to get more horsepower and torque from your engine. Most modern vehicles are equipped with engine control units (ECUs) that manage your engine’s ability to produce power in varying conditions. ECUs are generally set to have a torque map that’s meant to
Cheapest Car Mods Under $100
Cheapest Car Mods Under $100Compared to a conventional air filter, a performance air filter can allow in more air into the combustion chambers.
Engine Boosters for Less Than $500
Engine Boosters for Less Than $500Cold air has more oxygen content in a given volume than hot air because it’s denser. As a result, the cold air intake is able to contribute in stabilizing the air-fuel ratio in the combustion chamber.