Gas consumption up with shorty headers
Thread Starter
Instructor
Joined: Jan 2006
Posts: 156
Likes: 12
From: Silverlake Washington
Gas consumption up with shorty headers
I have been running a Jantzen throttle body and a ported and polished MAF with great results. Installed BBK shorty headers and my mileage has dropped considerably. My engine is a stock LS1. Any ideas? Put the stock MAF back on? I am driving it a little harder than usual and see the gas gauge drop in a very short distance. No problem prior to headers. What combo is suggested? Thanks in advance for any help.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Your engine is breathing a lot better. Your Volumetric Efficiency table is no longer calibrated properly to deal with the new air flow thru the engine so the Long Term Fuel Trims are reacting to compensate to keep the AFR at 14.7:1
When the LTFTs are way positive, your fuel efficiency will drop some. The positive value is added to your Power Enrichment (PE) table when you go WOT and hat make things really rich.
You just need a good tune!
If it were me (Ive been down this same path
) I would do all the mods that you can afford that effect engine breathing and have the PCM tuned using a wide band O2 sensor and have the tuner do a AUTO VE Tune.
That will address the drop in fuel economy and maybe even make the fuel efficiency BETTER! My tuner Corvettes Of Westchester (Chuck) fixed my mileage issue and I gained 3 mpg over stock!
BC
When the LTFTs are way positive, your fuel efficiency will drop some. The positive value is added to your Power Enrichment (PE) table when you go WOT and hat make things really rich.
You just need a good tune!
If it were me (Ive been down this same path
) I would do all the mods that you can afford that effect engine breathing and have the PCM tuned using a wide band O2 sensor and have the tuner do a AUTO VE Tune. That will address the drop in fuel economy and maybe even make the fuel efficiency BETTER! My tuner Corvettes Of Westchester (Chuck) fixed my mileage issue and I gained 3 mpg over stock!
BC
Pro
Joined: Dec 2003
Posts: 654
Likes: 1
From: chandler az
Every car I have every put headers on have helped improved mileage, including newer cars with fuel injection. I had a 2000 chevy silverado and 02 toyota tacoma both had shorties installed and I saw about a 10-20 percent improvement. I agree, try the tune first.
Thread Starter
Instructor
Joined: Jan 2006
Posts: 156
Likes: 12
From: Silverlake Washington
Your engine is breathing a lot better. Your Volumetric Efficiency table is no longer calibrated properly to deal with the new air flow thru the engine so the Long Term Fuel Trims are reacting to compensate to keep the AFR at 14.7:1
When the LTFTs are way positive, your fuel efficiency will drop some. The positive value is added to your Power Enrichment (PE) table when you go WOT and hat make things really rich.
You just need a good tune!
If it were me (Ive been down this same path ) I would do all the mods that you can afford that effect engine breathing and have the PCM tuned using a wide band O2 sensor and have the tuner do a AUTO VE Tune.
That will address the drop in fuel economy and maybe even make the fuel efficiency BETTER! My tuner Corvettes Of Westchester (Chuck) fixed my mileage issue and I gained 3 mpg over stock!
BC
When the LTFTs are way positive, your fuel efficiency will drop some. The positive value is added to your Power Enrichment (PE) table when you go WOT and hat make things really rich.
You just need a good tune!
If it were me (Ive been down this same path
) I would do all the mods that you can afford that effect engine breathing and have the PCM tuned using a wide band O2 sensor and have the tuner do a AUTO VE Tune. That will address the drop in fuel economy and maybe even make the fuel efficiency BETTER! My tuner Corvettes Of Westchester (Chuck) fixed my mileage issue and I gained 3 mpg over stock!
BC
Thanks for all of the information. Very informative. This morning I removed the ported and polished MAF and installed the original.
At start up I could notice a difference. The idle was constant and after reving the engine, idle came down immediately without staying up and then dropping.
Took it out and drove it normally for about a half of an hour. Then I took it out to my favorite straight away. From dead stop, nailed it and it fried the tires. I hit 2nd gear and there was not a chirp, it dug in hard and fried the tires with a little sway to and fro. This is the strongest it has run in a year. LOVE IT!!!!!
I believe the MAF was the problem as I did nothing more. The question to MAF or not.........stock engines like the original MAF and no tune required.
Thanks for all the blogs that I read as they were really, really helpful.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I didnt quite catch that you CHANGED MAFs and the airflow thru the MAF by altering it. YES,, That will goof up the fuel mileage for certain!! The new MAF needs to be rescaled and then it will work like the old one.
Glad you NUKED it out!
Bill
Thread Starter
Instructor
Joined: Jan 2006
Posts: 156
Likes: 12
From: Silverlake Washington
Thanks,
Val
Thread Starter
Instructor
Joined: Jan 2006
Posts: 156
Likes: 12
From: Silverlake Washington
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From: East Meadow NY
St. Jude Donor '12
Skip the new MAF, it won't help with anything and many people have had problems. The stock MAF is more than sufficient. Return that MAF and get your money back.
