Engine/Transmission (1998.5 - 2002) installed 275 injectors and lost 2.5 MPG!!

[rraulston]

2 weeks ago i installed 275 injectors and my mileage went south. I thought everyone's went up a few. This sucks... ... ... . I guess ill put the old ones back in. Do i need to send them off for a cleaning first????? RRR

 

[RBallard]

I installed mine about 1-1/2 months ago and saw an immediate improvement, city driving and highway averaged a 2mpg increase.



I have 3. 54 gears but I am running 35" tires and 6 speed transmission. I average 70 mph on the highway.



I am not sure ho it reacts with the auto but I would have thought you would do a little better.

 

[WadePatton]

Yeah, dump 'em. Put in some dd2's THAT'LL get your mileage up! Or is it Smileage:-laf :-laf



What about your foot? I found out that I can get a 3-4 MPG increase if I don't swing the boost needle so hard and lift altogether at the slightest provocation. But it's a real drag.



If you haven't put on some serious mileage, I'd stick with them a little bit longer.



Or you may have another issue.

 

[GWHaley]

Have you checked your oil level since the install???

 

[GMocanu]

Originally posted by rraulston

2 weeks ago i installed 275 injectors and my mileage went south. I thought everyone's went up a few. This sucks... ... ... . I guess ill put the old ones back in. Do i need to send them off for a cleaning first????? RRR

My mileage went south after I installed the 275's. I went from 18 down to 13. I know why it did. My foot gained weight while I was installing the things . I backed off a little and I went back up to 16+. I only backed off a little. I figure it's still better then my last Dodge (a gasser) but a lot more .

 

[drifter]

Mine runs great ! Did you put new seals on the connecting tubes? Trq. on the nuts are critical according to the manual. And it is if you want a good seal. Fuel could also be leaking past the injector O rings. This would show up in an oil sample analysis. About 10 bucks on the average at CAT or Cummins. Call around.

Should be an easy fix. .

 

[Chris N5CWM]

Are you sure?

My mileage increased 2 MPG. I managed to drive a 300 mile round trip, 80% highway, right after my 275 install. I filled up at a Flying J truck stop on the way out, and on the way back topped off again at the same pump. I used the trip meter miles driven and divided by the gallons pumped. My trip computer MPG calculator on the overhead console is now really optimistic, sometimes showing my average over 25 MPG! But it's no calibrated to the 275 flow rates so the readings are off. I'd love it if I could recalibrate that sucker!

Maybe you're just to happy to use the go pedal now and it's impacting your fuel mileage? Also like mentioned above, check to make sure it's not leaking into your oil via a bad o-ring somewhere.

 

[Phil Stuart]

I averaged about a 2mpg increase from 19mpg TOPS before the swap to 275's. The power increase is nice and tows much better now the engine has some guts.



check for fuel leaks/oil dilution



Phil

 

[greyghost]

Originally posted by rraulston

2 weeks ago i installed 275 injectors and my mileage went south. I thought everyone's went up a few. This sucks... ... ... . I guess ill put the old ones back in. Do i need to send them off for a cleaning first????? RRR

RRaulston, have you had a chance to fix you mpg yet. I would very interested in what you did.



I've got the same thing going on with my truck too. Before I installed my injectors the truck with the comp on set to 4 x 5 would get the same mpg as stock. If I set it lower than 4 x 5 I could get a 2 mpg increase.

Now to get back to the stock mpg I have to have the comp set to 1 x 1 and if I have it set to 3 x 3 I'm down 2 mpg below stock (injectors have been in for about a month).

Next is to check re-seat the injectors and delivery tubes and have the oil tested. I've been checking it everyday in the morning before work since I installed the injectors. If the injectors are leaking it's not make the level change a bit.



Garrett

 

[rraulston]

thanks guys, i have checked the oil and it seems to be be the same for 7 days running. I dont know, i give up. This truck got 16 mpg when i bought it. after an ATS transmission, valve adj. clean all sensors, synthetics, air up the tires and on and on, i got up to 18. 4 avg. now to drop 2 was devastating. oh well, i guess i will go buy some more front end parts... ... ... . rrr

 

[juicedcummins]

I noticed that mine dropped off real bad at first to but with a little time it came back with an improvement of +2mpg.



I run one stretch of highway which takes 10hr to my fuel point and my old 6. 5"s + 6. 2's did it again and again. When I tried it with this ride the first time it didn't make 6. 5hrs and it was dry. This was the same road and speed so it really made me wonder what kind junk I had just bought. The truck had 18000km on it when the 275's went in,and left on the trip the next day. Now this thing will run circles around anything else I've owned in both mil age and power. There seems to be something in the computer that takes time to learn and longer to learn if it isn't working hard.

Work the snot out of it and give it some time.