Poor fuel mileage after NV3550 Rebuild.

[CalcityRenegade]

Hey guys, Have been kind of curious about something and thought I might as well ask around, I have a 2003 Renegade with the 3.7L and NV3550 5 speed manual, Jeep has 270,000kms and my transmission/clutch decided to wear out on my (I tell my wife I have no idea why!) So I had a very reputable drive train shop completely rebuild the transmission and replace the clutch about 2-3000kms ago, Drives incredible but I can help notice that my fuel economy has dropped from 15.2 to 13.8 as per my EVIC, I would average 400-425kms to a tank and now get 350kms, My mileage and driving style has not changed but the economy, Is this something I can expect to go away over time as the transmission breaks in?

I don't expect amazing fuel economy in a 4WD but the way gas prices are going I wouldn't mind saving some cash at the pumps!

 

[LibertyTC]

It may be because things are new and a little tight....
I have to ask though how often do u change the spark plugs and what type are u using?
A clean air filter/pcv valve/ clean throttle body/IAC-/fuel filter etc can help.
Using Chevron Techron Concentrate to the fuel can also improve mileage/ clean injectors.
edit note: Would sure like to know if you can get the concentrate in Calgary..
It seems to have disappeared form Canadian Market due to label requirements. US only availability now I believe.
Run some Chevron 94 in it and see if the mileage goes up...No ethanol in 94 and has Techron in fuel too.
Besides Techron Concentrate, I am not sure what injector cleaner to recommend. Many use seafoam. I prefer something milder.
I may just get the dealer to do an emission service with their pro chemicals to clean injectors. That is something worth while once every couple of years.

oh & if you have been running ethanol fuels, since it likes to absorb moisture..and water sits at bottom of tank..get a couple of bottle of water remover & put that in fuel!

 

[CalcityRenegade]

It may be because things are new and a little tight....
I have to ask though how often do u change the spark plugs and what type are u using?
A clean air filter/pcv valve/ clean throttle body/IAC-/fuel filter etc can help.
Using Chevron Techron Concentrate to the fuel can also improve mileage/ clean injectors.
edit note: Would sure like to know if you can get the concentrate in Calgary..
It seems to have disappeared form Canadian Market due to label requirements. US only availability now I believe.
Run some Chevron 94 in it and see if the mileage goes up...No ethanol in 94 and has Techron in fuel too.
Besides Techron Concentrate, I am not sure what injector cleaner to recommend. Many use seafoam. I prefer something milder.
I may just get the dealer to do an emission service with their pro chemicals to clean injectors. That is something worth while once every couple of years.

oh & if you have been running ethanol fuels, since it likes to absorb moisture..and water sits at bottom of tank..get a couple of bottle of water remover & put that in fuel!

I am hoping its just due to the transmission, Approx 10,000kms Ago I replaced spark plugs with Champion Copper, Replaced all coil packs, New K&N Air filter, PCV Valve, Cleaned intake and I usually put in a Lucas Injector Cleaner in the tank ever 2-3 fill's and always up to date with oil changes, I will have to get to the fuel filter right away to make sure its not that, I will just give it some more time to break in the transmission, I am heading out camping today so can put some more mileage on her, Thanks for the feedback man!

 

[Porkchop]

Other things that can affect mpgs are a/c on maybe a bad brake caliper a hung park brake low tire pressure things like that so you might want to give it the once over and do a complete check over. How does it costs.

 

[rockymountain]

O2 sensor could've been knocked when they were in there doing the trans?
If it was immediately different when you drove it away from the garage. If you have a scanner you can check to see if they are working right. That's a big drop.