Fuel Economy

[famouslee99gt]

I have a 99 Chevy Silverado, 5.3L, auto, Z71 4WD, ext. cab. This past summer, I tuned up my truck. I put on MSD plug wires and NGK spark plugs. I have noticed that my fuel mileage has somewhat decreased since then. Has anyone else every ran into this problem? I'm thinking about going back to AC Delco plug wires in the spring.

[C & A s Dad]

Lee, I cannot imagine the MSD's hruting your mileage unless you have some defective wires. I am about to change my plugs with NGKs and Taylor wires. I have nothing agains the factory wires but I knew they would likely come apart while changing the plugs and I really wanted some red wires anyway.

 

I have never read or heard any negative comments on the MSD or Taylor wires so I do not feel this is your problem.

 

How many miles on your truck? You may need to be looking at your O2 Sensors.

[hoorders]

Lee, I cannot imagine the MSD's hruting your mileage unless you have some defective wires. I am about to change my plugs with NGKs and Taylor wires. I have nothing agains the factory wires but I knew they would likely come apart while changing the plugs and I really wanted some red wires anyway.

 

I have never read or heard any negative comments on the MSD or Taylor wires so I do not feel this is your problem.

 

How many miles on your truck? You may need to be looking at your O2 Sensors.

 

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I put Taylor wires and NGK's in to my truck with no adverse effects..............in fact, the truck is running better..........smoother idle.........

[famouslee99gt]

Back when I had a Flowmaster muffler with stock single exhaust, I was getting anywhere from 16.5 up to even 18 mpg. When I cut out the muffler and went to cat-back dual exhaust, the mileage was still around the 16 range. I would think that opening up the exhaust would help the flow and fuel efficiency. At the same time though, maybe I just can't keep my foot out of the pedal enough because I want to hear it. I am putting a Magnaflow muffler on it and I'll see what happens from there.

Thanks guys