AMC-MJ Posted April 4, 2011 Share Posted April 4, 2011 I had been mostly driving hwy's 45-65mph my AMC-2.5er been getting 14MPGs. Recently I been bummin around town last few weeks 15-35mph and its been getting 16MPGs. Is this Normal ? ! ? MJ-Configuration: Shortbed 2WD, AMC-2.5 / AX-4 4spd / D35-3.73s. Mike Link to comment Share on other sites More sharing options...
mvusse Posted April 4, 2011 Share Posted April 4, 2011 16 around town is probably right. I'm getting 17. But 14 highway is way off. Should be getting close to double that. Link to comment Share on other sites More sharing options...
Geonovast Posted April 4, 2011 Share Posted April 4, 2011 Did you put the 3.73 axle in? 2.5/4 speed should have rolled out of the factory with 3.55 in the axle. Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 4, 2011 Author Share Posted April 4, 2011 Ya I'm wondering if ol'2.5er is about worn out . . . Enough power to pull the city good but bucking the highway its straining a bit ? Type of deal ? ? Its in tune filters are new no vac leaks . . . Maybe it'll jump up some now that its warming up outside ? It was Re-geared from 3.55 to 3.73 by a Jeep dealership so the OB could tow his boat n lawn mower. Mike Link to comment Share on other sites More sharing options...
mnkyboy Posted April 4, 2011 Share Posted April 4, 2011 I was getting mid 16s up to about 18mpg with my 31s,I don't want to know what I'm getting with the 33s. Your truck should have decent power,I'm running 33x12.50s with 3.55s and it still pulls itself down the highway I can't remember,didn't you already put a new o2 sensor in it? Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 4, 2011 Author Share Posted April 4, 2011 Its got 235/75R15s on it, I'm running 1/2 throttle doing 67.5mph@3000rpm. Oh I gets up an goes good rips 0-75 then fades off fairly quick. Yep O2 is new, TPS is new, MAP is new, Fuel system has less then 10K miles on it, and was Freshly tuned up with new ignition mod n coil pack. Timing chain ? I'm at 198K-miles, The records I got with it don't show it being changed in the past . . . Mike Link to comment Share on other sites More sharing options...
NewfieMJ Posted April 4, 2011 Share Posted April 4, 2011 Thanks for this info . I was worried about running the 2.5l with 32's @ 3:55's . I'd also be happy with the MPG's you've listed . Link to comment Share on other sites More sharing options...
mnkyboy Posted April 5, 2011 Share Posted April 5, 2011 Thanks for this info . I was worried about running the 2.5l with 32's @ 3.55's . I'd also be happy with the MPG's you've listed . It does go down the road but you will want to eventually regear,I'm going to 4.88s real soon Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 6, 2011 Author Share Posted April 6, 2011 Alright something is up with the lil'2.5er, I lose speed majorly in the hills last 2days now . . . Boggin down 7-12mph drop down into 3rd n get after it and it slowly recover's speed ! Hit the base of the hill/incline at 60mph n top it at 53mph@3rd gear or 48mph@4th gear with 700-900lbs in bed . . . Time was this thing could hit a hill at 72mph and top that hill at 65mph loaded@2K-Lbs ! ! ! I think my lil'AMC-150 I4 is finally getting tired its got 198K-Miles of Direct Drive operation, Spending its life cruising 2500-3000RPM's on HWY n 1900-2100RPM's in CTY. Its always humming along . . . Mike Link to comment Share on other sites More sharing options...
jmderyke Posted April 6, 2011 Share Posted April 6, 2011 ouch those fuel mpg hurt I'm squeezing 22 mpg hwy and around 18 in town out of my 2.5. I had to reset the tps before on my rig it was off a bit and it brought my fuel mileage down, did you adjust it or did you have someone else do it? Have to checked the coolant temperature sensors? theres two one for your gauge and one for the ecu, if the one to the ecu is bad you can be getting a rich fuel mixture that will slow you down on those hills. Hows the oil pressure and compression? That will give you a good sign of engine condition also. Maybe something in the drivetrain is causing the mpg decrease? Just a couple thoughts I had sorry for the letter, hope you find out what it is :ack: Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 6, 2011 Author Share Posted April 6, 2011 I haven't checked the compression but I can run it Hot or Cold with the oil cap off and feel no air nor see any smoke or steam rise out. Oil pressure I can't say as its got lights not gauges but the light pops on so I flip the key on and almost instantly goes off after start up. I replaced the TPS was told to set it at .8V n 5V I got it to .86V n 4.93V was as best I could get. Is this something that need to be readjusted / Reset from time to time ? Now as for the rest of the drive train, 2nd / 3rd / R howl n growl a bit have for a while now, Grinds shifting into 4th but once in 4th it cruised along smooth n quiet. Tho I have noticed its got a funny vibration last few day's started once weather warmed up. I kicked into neutral on a down hill, stayed the same as in gear now wouldn't a bad U-Joints made the vibration worse in neutral ? ! ? At least this is how I have always diagnosed them. The fill plug won't come out I fought that a while back n decided to leave it alone and run it. Maybe the trans is about ready to grenade ? ! ? Oh well . . . I guess I will just keep running it. Mike Link to comment Share on other sites More sharing options...
jmderyke Posted April 6, 2011 Share Posted April 6, 2011 no once the tps is set and tight it will usually stay........ as for engine compression and oil pressure the only way to really know what kind of condition they are in is to actually test them. Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 6, 2011 Author Share Posted April 6, 2011 I had a compression tester, I adapted it to a diesel once and wrecked it ! I have NOT seen an oil pressure tester ? ? Where dose one find such a testing kit ? ? ? Mike Link to comment Share on other sites More sharing options...
jmderyke Posted April 6, 2011 Share Posted April 6, 2011 um first id try to find a friend that had one, if not it would depend on what quality you want you can get one from harbor freight for 20 bucks they are always a good tool to have. I hardly ever trust the gauge in the dash. Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 6, 2011 Author Share Posted April 6, 2011 So get a new compression tester ? and a set of gauges ? Or just an oil psi tester ? The PO hacked the dash and installed Voltage n Tach, I'd like to add water n oil but I don't want to further hack this dash, Much less the new replacement one. I'll have to kick around the gauge idea. Mike Link to comment Share on other sites More sharing options...
JeepcoMJ Posted April 6, 2011 Share Posted April 6, 2011 Keep in mind that the torque curve and hp curve meet at just over 3200rpm in an amc 2.5 liter and that is where out will have it's best performance. I got 24mpg interstate at 70 mph with my four cylinder 86 cherokee running 3200rpm Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 6, 2011 Author Share Posted April 6, 2011 Gear it down some ? Swap out the 3.73s for some 4.10s ? ? To bring the revs up some ? ? ? Mike Link to comment Share on other sites More sharing options...
Exgrayxj Posted April 7, 2011 Share Posted April 7, 2011 ;) Don't know if this has anything to do with your problem, but on mine the sock on the in tank fuel pump will clog after driving/running for 30 minutes or so, cuts power, and you would think less fuel would mean less gas used, right? Not so. Makes it struggle, mine used half a tank in 100 miles. Just a thought, this is the 2nd vehicle I have had this problem with, first was a minivan with a plastic tank, but the crud on the strainer was rusty looking, looked like rust to me. Replaced the sock, pump became quiet, and problem solved. Only another possibility. :wrench: Link to comment Share on other sites More sharing options...
AMC-MJ Posted April 7, 2011 Author Share Posted April 7, 2011 Hmmm you may have something there, Certainly worth a look I guess. Mike Link to comment Share on other sites More sharing options...
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