88 - L98 Poor Gas Mileage - HELP?
Thread Starter
Instructor
Joined: Jun 2003
Posts: 126
Likes: 7
From: Markham Ontario
88 - L98 Poor Gas Mileage - HELP?
My 88 L98 idles fine at around 5-600 RPM. According to the instrumentation, I am only getting 16 MPG. LOW, I'd say. Changed the plugs... slight improvement. Wire are next. However, I have a rattling CAT. It's coming from Mid-America this week, as well as a Y-Pipe with Crossover tube and the Quiet-Flow mufflers I already have. Think this will make a difference?
Whatelse can I do to improve fuel mileage? It has 129,000 KM on it... Hard starts the VERY ODD time. Probably wires, or cap etc.... ???
Thanks
DSSKing
Whatelse can I do to improve fuel mileage? It has 129,000 KM on it... Hard starts the VERY ODD time. Probably wires, or cap etc.... ???
Thanks
DSSKing
Team Owner
Joined: Sep 2001
Posts: 62,171
Likes: 1,735
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: 88 - L98 Poor Gas Mileage - HELP? (DSSKing)
usually when your mpg drops like that, its the Oxygen sensor dying
id replace that before anything else
id replace that before anything else
Thread Starter
Instructor
Joined: Jun 2003
Posts: 126
Likes: 7
From: Markham Ontario
Re: 88 - L98 Poor Gas Mileage - HELP? (vader86)
Just getting back into working on cars again (it's been 7 years since I've had a toy), is it an easy replacement? I had a Mustang where it was right in the H pipe....?
Thanks
Thanks
Team Owner
Joined: Sep 2001
Posts: 62,171
Likes: 1,735
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
Re: 88 - L98 Poor Gas Mileage - HELP? (DSSKing)
Its in the left exhaust pipe, where the front Y pipe meets the exhaust manifold. Easy to replace.
Thread Starter
Instructor
Joined: Jun 2003
Posts: 126
Likes: 7
From: Markham Ontario
Re: 88 - L98 Poor Gas Mileage - HELP? (scorp508)
When I replace the O2 sensor, do I have to clear codes before I fire the engine or will the computer pick up the new sensor and correct itself?
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Every 2027 Corvette Engine Explained
Joe Kucinski
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Verdad Gallardo
10 Ugly Corvettes That We Still Kinda Love
Joe Kucinski
Top 10 Most Expensive Corvettes Ever Sold on Bring A Trailer
Brett Foote
10 Things Every Corvette Owner Needs (2026 Edition)
Michael S. Palmer
8 Most "Only Corvette Owners Understand" Quirks and Problems
Pouria Savadkouei
10 Reasons the C6 Z06 is Still A Performance Benchmark After 20 Years
Joe Kucinski
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Burning Brakes
Joined: Jun 1999
Posts: 862
Likes: 0
From: Auburn WA
Re: 88 - L98 Poor Gas Mileage - HELP? (DSSKing)
Have you calculated your mileage over several tanks? Is this city-type driving or highway? For what it's worth my 89 would get about 16 in normal stop-n-go commuting and 20-something on the highway. Granted I've got aftermarket heads with bigger valves, but I think that's in the ballpark for factory EPA ratings.
