Charlie Posted August 22, 2011 Share Posted August 22, 2011 I have a 1993 Pathfinder XE 4x4 5spd, 30x9.50 BFG M/Ts. I bought it for $300 knowing it would need work, and have put about $1300 into it so far. I have replaced the O2 sensor, plugs, cap, rotor, wires, air and fuel filter, coolant temperature sensor (both), thermostat, knock sensor, catalytic converter, cleaned the MAF, ohmed and leak tested the injectors, new PCV, fixed the leaky manifolds, and it still only gets 13 mpg. Passed emissions with flying colors, runs great, starts right up, and has plenty of power. I have put three tanks through it now after everything has been replaced. The first one was 12 mpg, which I attributed to lots of idle time while I installed the stereo with the A/C cranked, the second one was 15 mpg babying it, never going above 3k rpm, and not running the A/C, and the third was 13 mpg, driving normally, A/C on in town, with a small 2-3 mile 4x4 trip. I know for a fact that it isn't supposed to be this bad. I had one in high school and I averaged 18 mpg on 31x10.50s with an auto. What am I missing here? Link to comment Share on other sites More sharing options...
Slartibartfast Posted August 22, 2011 Share Posted August 22, 2011 (edited) Did you do the timing belt? If it's a tooth or two off, that would hurt the milage. (All I can think of, but then, I'm no mechanic.) Edited August 22, 2011 by Slartibartfast Link to comment Share on other sites More sharing options...
Charlie Posted August 22, 2011 Author Share Posted August 22, 2011 Didn't replace it, but tore it down and inspected it. Looked like it had been recently done, along with a new balancer, so I didn't bother replacing it. If I remember correctly, it was timed right. Link to comment Share on other sites More sharing options...
nige Posted August 22, 2011 Share Posted August 22, 2011 Brakes aren't dragging are they? Could be toe-in or toe-out too, when was the last time you had an alignment check? Tire pressure? Link to comment Share on other sites More sharing options...
sewebster Posted August 22, 2011 Share Posted August 22, 2011 I dunno, 13 mpg in town with some 4wd might be normal. Also, I'm not sure if you'll get the best mpg by keeping it below 3000 rpm, the engine could be lugging a lot trying to move around that much weight at low rpm. Link to comment Share on other sites More sharing options...
Charlie Posted August 22, 2011 Author Share Posted August 22, 2011 There's now way this thing is getting normal mileage. My old TBI pathy got better than this by a lot. When I said babying it, I'm talking barely accelerating at all, slowly getting to my target speed. Should have been way more than 15mpg. My friend has a wideband O2 sensor for tuning cars, so I think this weekend were going to stick it on and see what the AFR is like. At least that will tell me if it is related to the way the engine is running or something else. Link to comment Share on other sites More sharing options...
Charlie Posted August 22, 2011 Author Share Posted August 22, 2011 Also, brakes are good, and there is no excessive toe in or toe out. Little bit of negative camber but that's it. Link to comment Share on other sites More sharing options...
5523Pathfinder Posted August 22, 2011 Share Posted August 22, 2011 (edited) Lets see, you have replaced a bunch of stuff! I would check your EGR valve for proper operation. If its opening at the wrong time, it will kill mileage. Have you checked for vacuum leaks? This would lean things out causing extra fuel usage, hurting your mileage. How about tire pressure? What pressure are you running? You said timing is good, did you check it with a timing light? if its advanced a bit, you might get more power, but mileage will drop(I did this for a while, but put it back to spec). How does the inside of your intake look? Lots of carbon buildup? Carbon will build up on the valves over time(VG's are real good at this), causing lack of power, low milage, idle issues. You clean them with a chemical, or as some guys do, use water. One more...What grade fuel are you using? Oh, and have you checked for codes? The check engine light may not be on, but a code can get stored. Edited August 22, 2011 by 5523Pathfinder Link to comment Share on other sites More sharing options...
silverton Posted August 22, 2011 Share Posted August 22, 2011 I would get 18 pretty regularly with my old XE auto with 235's. The mud terrain is a fairly heavy tire, even at 30x9.50. I have 33x10.50's on my current SE auto, and I seem to be getting about 10city/15hwy. Link to comment Share on other sites More sharing options...
Precise1 Posted August 22, 2011 Share Posted August 22, 2011 What type of wheels do you have? How many miles on the truck? How much do you usually carry in it? Is this city or highway driving or a mix of both? If so, what ratio?? Do you have a roof basket or lights? What is the vehicles gearing? (Passenger fender info plate, 1/2 way down HG43 or HG46.) How are you calculating your mileage?? B Link to comment Share on other sites More sharing options...
JamesRich Posted August 23, 2011 Share Posted August 23, 2011 My 87 TBI gets around 13 to 14 in town too. I have also replaced everything I could, wires, cap, rotor, plugs, O2 sensor, T belt. It runs great just doesn't have much power but then again I'm used to driving a titan. It kind of sucks though that the pathy is a slug and drinks the same amount of gas as the titan. James Link to comment Share on other sites More sharing options...
Charlie Posted August 23, 2011 Author Share Posted August 23, 2011 (edited) What type of wheels do you have? How many miles on the truck? How much do you usually carry in it? Is this city or highway driving or a mix of both? If so, what ratio?? Do you have a roof basket or lights? What is the vehicles gearing? (Passenger fender info plate, 1/2 way down HG43 or HG46.) How are you calculating your mileage?? B -Stock chrome steel wheels -164,xxx -nothing but myself and my school stuff -mostly city, but then again, my commute contains some "country roads" where the speed limit is 55, so technically a mix. Probably 50/50 stop and go and cruising. -no roof rack, no lights, all stock. -vehicle gearing is HG43 -I am calculating my mileage by filling up the tank, resetting the trip odometer, driving until I have about 1/4 tank, and then filling up. I divide the miles driven, by the gallons used, and then multiply by 1.026 to calculate for the 2.6% difference between 235/75r15 and 30x9.50x15 tires. I should probably verify mileage with a GPS but I don't own one. That said, as I was double checking the ignition timing, I noticed that every once and a while, the timing light would not fire, indicating a miss. The truck does not run poorly, and it isn't detectable by feeling the body of the vehicle, so I moved the pickup around to each cylinder, and it did the same thing. I then hooked the pickup to the coil wire, and the same again. Moving to the back of the truck, every time the light showed a miss, I could hear a slight stumble in the exhaust. To me this indicates either a bad coil, or a bad distributor pickup. Watching the tachometer function on my timing light, (again hooked to the coil wire, so really showing RPMx6) the reading would show around 4200, and then every time it missed, would drop down to about 3000. A random miss would definitely contribute to poor mileage, as the extra oxygen in the exhaust stream is picked up by the O2 sensor, and tells the computer to richen the mixture. Any thoughts on this one? Edited August 23, 2011 by Charlie Link to comment Share on other sites More sharing options...
adamzan Posted August 23, 2011 Share Posted August 23, 2011 Mine had that random miss and crap mileage too and it turned out I had a defective o2 sensor. Try unplugging the o2 (little tree of plugs near fuel filter) and check for the miss. Couldn't hurt. Does it only miss when warm or does it do it when you first start it as well? If it only does it when warm I would lean toward a sensor issue. Link to comment Share on other sites More sharing options...
5523Pathfinder Posted August 23, 2011 Share Posted August 23, 2011 I would pull the cap, rotor and inspection plate on the distributor. I have seen the distributors begin to eat themselves and distribute aluminum shavings inside the distributor. These shavings get into the optical sensor ring and can cause issues. You can try blowing it out with some air, or vacuum it out. I ended up replacing my distributor when I found this happening while searching to a different problem. Link to comment Share on other sites More sharing options...
Precise1 Posted August 23, 2011 Share Posted August 23, 2011 -Stock chrome steel wheels -164,xxx -nothing but myself and my school stuff -mostly city, but then again, my commute contains some "country roads" where the speed limit is 55, so technically a mix. Probably 50/50 stop and go and cruising. -no roof rack, no lights, all stock. -vehicle gearing is HG43 -I am calculating my mileage by filling up the tank, resetting the trip odometer, driving until I have about 1/4 tank, and then filling up. I divide the miles driven, by the gallons used, and then multiply by 1.026 to calculate for the 2.6% difference between 235/75r15 and 30x9.50x15 tires. I should probably verify mileage with a GPS but I don't own one. That said, as I was double checking the ignition timing, I noticed that every once and a while, the timing light would not fire, indicating a miss. The truck does not run poorly, and it isn't detectable by feeling the body of the vehicle, so I moved the pickup around to each cylinder, and it did the same thing. I then hooked the pickup to the coil wire, and the same again. Moving to the back of the truck, every time the light showed a miss, I could hear a slight stumble in the exhaust. To me this indicates either a bad coil, or a bad distributor pickup. Watching the tachometer function on my timing light, (again hooked to the coil wire, so really showing RPMx6) the reading would show around 4200, and then every time it missed, would drop down to about 3000. A random miss would definitely contribute to poor mileage, as the extra oxygen in the exhaust stream is picked up by the O2 sensor, and tells the computer to richen the mixture. Any thoughts on this one? Ok, pretty much stock with average miles on it (not much) and you are calculating the mileage correctly (assuming your speedo was spot on with the 235s) so no culprits there. My guess is that the lower gearing ratio, the amount of stop and go driving and MT tires that you are running are contributing to the low gas mileage. Obviously, if there is an engine system issue it will lower it even further. Fyi, I have a 1995 with 31" MT tires that doesn't have too much added weight and when I just commute to and from work (5 miles/50 mph max) by gas mileage can be really low (12 mph). It runs perfectly and passes California smog tests so I cant imagine it has much wrong with it. B Link to comment Share on other sites More sharing options...
dmag23 Posted August 24, 2011 Share Posted August 24, 2011 13 mpg here. 1987 tbi, 5spd, 4.3 stock gears. New engine, trans, diff's, etc. Ground up rebuild. New everything. Running Thorley headers and 265/75/16 BFG's. 13 after taking into account the larger tire size. Great ride, just doesn't get the mpg's. Link to comment Share on other sites More sharing options...
Trogdor636 Posted August 24, 2011 Share Posted August 24, 2011 http://www.nissanpathfinders.net/forum/index.php?showtopic=30745 That sticker pretty much sums it up. I mean, they got 15/18 when new, so you really cant expect much more than that. I've had a few freak tanks on long trips where I have gotten up to 20-21, but around town I'm happy to get 15. Link to comment Share on other sites More sharing options...
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