Major gas milage problems..
Thread Starter
Le Mans Master
Joined: Sep 2001
Posts: 7,928
Likes: 1
From: More cowbell...
St. Jude Donor '04
Major gas milage problems..
Here's the deal.. My gas milage has fallen through the floor in recent months.. For now, it is a stock LT1, and I am getting ~10mpg city, and maybe 16-18mpg on the freeway.. I have the 3.07 gears.. and I know this is TERRIBLE gas milage. I have checked the injectors, and they dont seem to be leaking, besides, I dont think a leaky injector or two would have this big an impact on my gas milage. What other things could be causing this? O2 sensors?? I am doing heads and cam in about a week, and want my car to be running well afterwords.. What should I look for?? How much are O2 sensors, and where can I get them??
-Mark
-Mark
Drifting
Joined: Aug 2002
Posts: 1,857
Likes: 0
From: Yakima WA
Re: Major gas milage problems.. (MarkLT1)
I am only getting about 14-16 miles per gallon overall. I thought that was about right. Am I wrong? I had the injectors cleaned, via additives, pressurized cleaning. Is it possible that it is just my driving habits in town?
Melting Slicks
Joined: Jun 2000
Posts: 2,923
Likes: 1
From: Las Vegas NV
Re: Major gas milage problems.. (dbwade36)
I am only getting about 14-16 miles per gallon overall. I thought that was about right. Am I wrong?
Burning Brakes
Joined: Jul 2002
Posts: 871
Likes: 0
From: Costa Mesa CA
Re: Major gas milage problems.. (MarkLT1)
You didn't install one of those IAT bypass "kits" did you? It amounts to nothing more than a 4.7K ohm resistor put across the plug of the IAT lead after you unplug it to supposedly fool the computer into richening the mixture. Some jerk was selling them on eBay $9.00 and I bought one for my L98. After installation my car ran "bubbery" (is that a word) and was getting 8.6MPG according to the computer.
Even if you aren't as stupid as I was and did this, there might be a problem in that area on your LT1 because I know that screwing with that sensor can kill your mileage. And it wouldn't show up as a trouble code.
FWIW,
BIG JIM
Even if you aren't as stupid as I was and did this, there might be a problem in that area on your LT1 because I know that screwing with that sensor can kill your mileage. And it wouldn't show up as a trouble code.
FWIW,
BIG JIM
Le Mans Master
Joined: Dec 1999
Posts: 8,540
Likes: 1
From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Major gas milage problems.. (MarkLT1)
Sounds like you have a problem.
Sources of poor gas mileage: Dirty Air filter, exhaust leaks before O2 sensors, bad O2 sensors, fuel pressure too high, clogged cat(s), bad ecm tuning.
Looking at your mods:
I would check for leaks in the headers at any point and check fuel pressure.
O2 sensors control mixture, they effect mileage directly. O2 sensor has to about fall off the car to cause a code! A very common fail mode is to get "slow" which will effect mixture and often not set any codes. Also the air vent on the O2 can become clogged with debris which will render it useless, and again may not set a code.
Sources of poor gas mileage: Dirty Air filter, exhaust leaks before O2 sensors, bad O2 sensors, fuel pressure too high, clogged cat(s), bad ecm tuning.
Looking at your mods:
high pressure fuel regulator, SLP shor(t)y headers
I don't think O2 affect gas mileage. Beside if your O2 has problem the engine light would come on.
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