Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - How to over-ride computer RPM while coasting?

bob · 02-03-2016, 10:20 PM

My 87 Dodge Daytona does this and it drove me crazy. Discovered different conditions vary coasting idle from 800-1,200 rpm. But, the biggest is when the front windshield defroster is on with the fan switch engaged then it's 1,500 rpm until almost stopped when it drops to 800 rpm. The easy fix is to press the bi level button and move the fan switch one notch higher. Some drivers run a independent power wire to bypass the computer and/or cut the sensor wire to the computer.
The Daytona has a transplanted 2.5 turbo 5 speed with some mild performance mods and fat 225 tires. Unfortunately it's ganged fuel injected that can only be fixed with a ECU change & that's above my pay grade so it only gets 17 ½ in town, 24 mix if lucky. However, highways a different story.
Aero's Work!
I flared the front nose plastic fascia (easy mod that looks good) to cover the tires and installed a black chloroplast belly pan (almost invisible) from the nose to the engine, about $20. The belly pan slips into & overlaps the front bumper cover and attaches with heavy duty Velcro for fast easy removal. This made a massive improvement not only in highway mileage but wind noise reduction. Also installed is a modified spoiler off a little Chevy S10 pickup using R clips for fast removal. I can remove both pan and spoiler in under 1 minute. Although the spoiler doesn't make any mpg difference it does help handling but also scrapes over every speed bump. This old car won't take a Scanguage without major wiring hacks but came with a primitive version stock that matches the odometer readings. Puget Sound highways are all up and down, rarely flat. In 80 degree weather I consistently get between 36-38 mpg at 58-60mph. Retarding the timing a few degrees, flat ground, good gas, a 5 mph tail wind, 55-58 mph, careful right foot and she does 43 mpg. Today I drove in a 18 wheeler's slip stream and did 59 mpg. In a few months I plan to flair the rear fender skirt and install a belly pan to cover the massive parachute bumper hole. Hoping for another 1 mpg highway.

02-03-2016, 10:20 PM	#38 (permalink)
bob EcoModding Lurker Join Date: Mar 2009 Location: washington Posts: 1 Thanks: 0 Thanked 0 Times in 0 Posts	My 87 Dodge Daytona does this and it drove me crazy. Discovered different conditions vary coasting idle from 800-1,200 rpm. But, the biggest is when the front windshield defroster is on with the fan switch engaged then it's 1,500 rpm until almost stopped when it drops to 800 rpm. The easy fix is to press the bi level button and move the fan switch one notch higher. Some drivers run a independent power wire to bypass the computer and/or cut the sensor wire to the computer. The Daytona has a transplanted 2.5 turbo 5 speed with some mild performance mods and fat 225 tires. Unfortunately it's ganged fuel injected that can only be fixed with a ECU change & that's above my pay grade so it only gets 17 ½ in town, 24 mix if lucky. However, highways a different story. Aero's Work! I flared the front nose plastic fascia (easy mod that looks good) to cover the tires and installed a black chloroplast belly pan (almost invisible) from the nose to the engine, about $20. The belly pan slips into & overlaps the front bumper cover and attaches with heavy duty Velcro for fast easy removal. This made a massive improvement not only in highway mileage but wind noise reduction. Also installed is a modified spoiler off a little Chevy S10 pickup using R clips for fast removal. I can remove both pan and spoiler in under 1 minute. Although the spoiler doesn't make any mpg difference it does help handling but also scrapes over every speed bump. This old car won't take a Scanguage without major wiring hacks but came with a primitive version stock that matches the odometer readings. Puget Sound highways are all up and down, rarely flat. In 80 degree weather I consistently get between 36-38 mpg at 58-60mph. Retarding the timing a few degrees, flat ground, good gas, a 5 mph tail wind, 55-58 mph, careful right foot and she does 43 mpg. Today I drove in a 18 wheeler's slip stream and did 59 mpg. In a few months I plan to flair the rear fender skirt and install a belly pan to cover the massive parachute bumper hole. Hoping for another 1 mpg highway.