1990Eliminator Posted March 2, 2020 Share Posted March 2, 2020 Hello all. MPG for 1989 20/23 MPG for 1990 17/22 why? Thank you in advance. John Link to comment Share on other sites More sharing options...
89 MJ Posted March 2, 2020 Share Posted March 2, 2020 Gears, driving style, lift, weight, transmissions, tire size, aerodynamics, etc. Link to comment Share on other sites More sharing options...
89 MJ Posted March 2, 2020 Share Posted March 2, 2020 @Pete M, could you move this to tech? Link to comment Share on other sites More sharing options...
1990Eliminator Posted March 2, 2020 Author Share Posted March 2, 2020 Thanks man 🤜🤛 Link to comment Share on other sites More sharing options...
jdog Posted March 3, 2020 Share Posted March 3, 2020 Are you going of of fueleconomy. Org? Or personal experience? Stock 1988 swb 4.0 ax15 np 231. Link to comment Share on other sites More sharing options...
Warren Mohler Posted March 3, 2020 Share Posted March 3, 2020 Just checked mine last week 12MPG average thats after 20 miles 10 city 10 hwy. Link to comment Share on other sites More sharing options...
Ωhm Posted March 3, 2020 Share Posted March 3, 2020 17 minutes ago, Warren Mohler said: Just checked mine last week 12MPG average thats after 20 miles 10 city 10 hwy. That's OPEN LOOP mileage or is it Pb foot mileage? Link to comment Share on other sites More sharing options...
Warren Mohler Posted March 3, 2020 Share Posted March 3, 2020 5 minutes ago, Ωhm said: That's OPEN LOOP mileage or is it Pb foot mileage? I thought it should be better, was disappointed don't have access to a scan tool right now. want to get REM when I collect enough change Link to comment Share on other sites More sharing options...
Dzimm Posted March 3, 2020 Share Posted March 3, 2020 4 hours ago, 1990Eliminator said: Hello all. MPG for 1989 20/23 MPG for 1990 17/22 why? Thank you in advance. John It could be a number of things. If the trucks have different transmissions, gears, 2wd vs 4wd it will make a huge difference. If they have the same driveline, I'd suspect the 90 may just need a tune up or has more mileage/wear/lived a harder life. Something as simple as different sag rate in the springs/suspension could throw off the aerodynamics of the truck and give you worse gas mileage. Keep in mind these things are 30+ years old. Even still 17/22 is pretty decent for gas mileage. My auto trans XJ and MJ get about 19mpg and 21mpg respectively on the highway. My 5 speed MJ gets around 21-23mpg highway if I don't drive it hard. Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3, 2020 Share Posted March 3, 2020 Doesn't sound like you're checking it properly....... Not to mention that gas ain't the same as it was 30 years ago..... Link to comment Share on other sites More sharing options...
OldManComanche Posted March 3, 2020 Share Posted March 3, 2020 Are you talking about manufacture advertised fuel economy or is this the mileage you are getting on 2 trucks you have or know of?? Link to comment Share on other sites More sharing options...
AZJeff Posted March 3, 2020 Share Posted March 3, 2020 13 hours ago, Dzimm said: It could be a number of things. If the trucks have different transmissions, gears, 2wd vs 4wd it will make a huge difference. If they have the same driveline, I'd suspect the 90 may just need a tune up or has more mileage/wear/lived a harder life. Something as simple as different sag rate in the springs/suspension could throw off the aerodynamics of the truck and give you worse gas mileage. Keep in mind these things are 30+ years old. Even still 17/22 is pretty decent for gas mileage. My auto trans XJ and MJ get about 19mpg and 21mpg respectively on the highway. My 5 speed MJ gets around 21-23mpg highway if I don't drive it hard. The amount of lift on a vehicle (above stock ride height) will also decrease fuel economy. I discovered that when I lifted my first XJ. Fuel economy dropped about 1.5MPG by adding 2 inches of lift. Link to comment Share on other sites More sharing options...
omega_rugal Posted March 3, 2020 Share Posted March 3, 2020 1989 -> Renix 1990 -> mopar the older renix had better fuel economy due several factors, camshaft profile etc... 1989 was the transition year for the HO? Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3, 2020 Share Posted March 3, 2020 Same cam. 91 first HO. we're all barking up a tree that isn't even established yet..... Link to comment Share on other sites More sharing options...
omega_rugal Posted March 3, 2020 Share Posted March 3, 2020 1 minute ago, cruiser54 said: Same cam is advanced a few degrees isnt? or was it retarded? to get rid of the EGR, also the HO has the torque peak at higher revs Link to comment Share on other sites More sharing options...
omega_rugal Posted March 3, 2020 Share Posted March 3, 2020 unless the OP is mixing up 4.0 and 2.5 MPGs... Link to comment Share on other sites More sharing options...
cruiser54 Posted March 3, 2020 Share Posted March 3, 2020 4 minutes ago, omega_rugal said: unless the OP is mixing up 4.0 and 2.5 MPGs... My point exactly. Link to comment Share on other sites More sharing options...
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