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Discussion Starter · #1 ·
you'd think getting good miles per gallon would be simple on a 4 banger..

anyone have a clue to where I might has missed something, after installing a new wiring harness, plugs, "all sensors", filters, timing put back to specs, new catyailc converter, correct thermostat, 5 tanks ran with berryman B12 fuel carb injector cleaner and still getting crappy mileage. Does the on board computer stay in some sort of loop mode>? No trouble codes show up anytime and my local dodge dealership said everything is up to normal. Makes no sense to me really but I thought I'd ask in case I need to somehow reset the computer or maybe someone here can advise if I've overlooked a spot :help:

thx guys!
 

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how bad of mileage?? What year? I used to get terrible mpg on my 90 with a 2.5L but someone put the wrong rearend gear ratio it was a 2.76 or something like that. I put a 3.55 and I got up to 22mpg.
 

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Discussion Starter · #3 ·
20 mpg, but before I did all the reapirs I was up 26-27 340 miles+ to a tank.. my next guess is intake leaks and the pc is compensating for the added air volume.. soon to find out once I start checking for leaks...
 

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4 cyl trouble

If you had to pay the dealer to look at it, he should have been able to tell if there was a leak.What was it doing that you started all that work on the truck.Did you run the truck with th O2 sencer unpluged.This can put the O2 way out of whack.But then the dealer should have found it if it was off.
 

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Some techs at dealers say "whatever" sometimes it's hard to detect a gas mileage complaint. At the time the truck was in, it may have been running perfect. I am a technican and I have dealt with these sort of scenerios.
 

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Discussion Starter · #7 ·
well no leaks, did it the hard way with starting fluid and a cold engine sprying it in spurts around all the gaskets :) hehe

but the 02's, cat, timing belt and egr I replaced as well and all are tight to specs.. but I did notice a slight sputter from idle but I assume it's also since the temp was 96 @ the time.
it's weird I must say and can usualy figure it out in no time.. I wonder if a wires gone bad or just was not crimped right since I put on a brand new engine wiring harness that plugged into all the sensors etc... guess I'll check that tonight I prob should have compared it to the old harness before tossing it away hehe
 

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The Legendary Cross Ram
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I'm averaging 23mpg, and I have: weak compression in my third cylinder, very bad backpressure, and a messed up feedback carburetor just for starters.

Good luck finding you problem.
 

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Discussion Starter · #9 ·
Well just as I assumed all the wiring was fine so all thats left is to check each and every vaccum line for cracks or build-up inside, AND LASTLY the fuel return line since a pressure regualtor was 12 bucks I went ahead and gave that a shot as well... let ya all know in a few days
 

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Discussion Starter · #10 ·
guess it's time to just let it run rich till it eat the rings away... no cracked vac lines or buildup in any of them.. interestingly enough now once hot after a 30 min drive there si some mad sputters when you give it wide iopen throttle, easing into the throttle does fine... possibly the fuel return line clogged or does that sound like a fuel pump going on the blitz since this only happens once warmed up?
 

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WrenchRat
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It may be the timing....When you put the new timing belt on and "reset the timing to spec", do you remember what the timing was prior. Was it higher or lower? I am guessing that it may have been higher. With the symtoms that are present.. try resetting timing approx. 4-6 degrees higher and see if the problems go away.
hope this helps.
 

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Discussion Starter · #12 ·
well guys all the responses help fix it, the cam gear has one of them adjustable gears on it and was slightly advanced so I got it all set back to spec's and everything worked great... and then Sunday the head gastket blew... the original head had been repaired once so all new going on.... whew fun in the sun I tell ya


maybe it's time to finish this off with a V8, any suggestions?
 

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Discussion Starter · #13 ·
well I'm on my last straw here so I took it back to the shop, they had to put a brand new head on since the one I had was re-welded ( not that I could tell) and now they have put it all back together but after it runs for like 30 minutes it will backfire thru the throttle body and stall for like 5-30 minutes and the starts back up, runs fine for another 10 - 45 minutes and stalls again... Am I missing something here>?
 

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WrenchRat
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My first thought from your description of symtoms is that you have fallen prey of the old intermitant fuel pump problem. The only way that i found mine was to drive it until it dies and get out with a rubber mallet and smack the round circle on the bottom of the gas tank. Then see if it starts right away. If it does start and run then i would say it is the fuel pump. hope this helps
 
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