The_Magicians_Eye Posted December 29, 2011 Share Posted December 29, 2011 So the family and I decided to battle out the snow storm that his NM and CO over the Christmas weekend. Something really bugged me during the trip. There was a drastic loss in power in my pathy. Yes I know elevation always plays a factory in engine power. I learned that at a very young age. However even with the truck completely unloaded and only me in the truck it still felt like I was dragging another car behind me. The drop in power was drastic to say the least. Maybe I'm stupid but I always thought Fuel injection systems helped fix this problem. I know for sure it was an elevation issue because even when fully loaded when I got back into Phoenix everything felt great. Or should I say normal lol. There is no way on the planet that Nissan could have sold a single one of these trucks in high elevation cities with the power loss that I felt up there. Keeping in mind that my truck was originally a Colorado truck. Any suggestions, ideas, or ???? that can help me understand and hopefully fix this problem? I have a problem spinning the tires on dirt roads. That's how bad it is. Link to comment Share on other sites More sharing options...
wd21overland Posted December 29, 2011 Share Posted December 29, 2011 (edited) WHen you were going through the high altitude did you ever stop the car durning that time or get gas when in high atittude. I know in my wifes 06 nissan maxima owners manual it says when driving from a low alittitude to a higher alittidue that will be excedding 3000ft difference that the car must be shut off and restarted for the ecu to learn a new fuel map since there less air at high alltidudes. Cars that live in the high alttidues are already programmed for the air up there so they run fine. Also did you get Gas in colorado? I have family that live around colorado springs and up there there normal regualar octane gas is only 85 octane up there since it doesnt need as high of ocatane rating in higher alltitude. Edited December 29, 2011 by wd21overland Link to comment Share on other sites More sharing options...
Nefarious Posted December 29, 2011 Share Posted December 29, 2011 ^ very interesting information! Link to comment Share on other sites More sharing options...
wd21overland Posted December 29, 2011 Share Posted December 29, 2011 Yeah i thought originally they just had horrible gas when i saw the 85 octane for regular at the stations lol. Here is the octane info if any one is curious. United States: in the US octane rating is displayed in AKI. In the Rocky Mountain (high elevation) states, 85 AKI (90 RON) is the minimum octane, and 91 AKI (95 RON) is the maximum octane available in fuel[citation needed]. The reason for this is that in higher-elevation areas, a typical naturally aspirated engine draws in less air mass per cycle because of the reduced density of the atmosphere. This directly translates to less fuel and reduced absolute compression in the cylinder, therefore deterring knock. It is safe to fill a carbureted car that normally takes 87 AKI fuel at sea level with 85 AKI fuel in the mountains, but at sea level the fuel may cause damage to the engine. A disadvantage to this strategy is that most turbocharged vehicles are unable to produce full power, even when using the "premium" 91 AKI fuel. In some east coast states, up to 94 AKI (98 RON) is available.[23] In Colorado as well as parts of the Midwest (primarily Minnesota, Iowa, Illinois and Missouri) ethanol-based E-85 fuel with 105 AKI is available.[24] Often, filling stations near US racing tracks will offer higher octane levels such as 100 AKI[citation needed]. California fuel stations will offer 87, 89, and 91 AKI (91, 93 and 95 RON) octane fuels, and at some stations, 100 AKI or higher octane, sold as racing fuel. Link to comment Share on other sites More sharing options...
adamzan Posted December 29, 2011 Share Posted December 29, 2011 Yeah when I drove my pathy out west it REALLY didn't like being in the high elevation areas ( was there for almost a week) until the truck got used to it. It even spit up a CEL but I never bothered to check it. Link to comment Share on other sites More sharing options...
silverton Posted December 29, 2011 Share Posted December 29, 2011 yeah, like everyone else said, your truck was just used to being in lower elevation. Sadly they don't automatically remap themselves on an elevation change. Resetting your ecu would have made it all better. And you would have had to do the same once getting back to phoenix. Link to comment Share on other sites More sharing options...
The_Magicians_Eye Posted December 30, 2011 Author Share Posted December 30, 2011 Yes I fueled up in Colorado. I was there from Friday after noon until Monday morning. So how do I reset the ECU for next time? Link to comment Share on other sites More sharing options...
Heloflyboy Posted December 30, 2011 Share Posted December 30, 2011 I live at 6200' and drive over a 9500' pass often.It is pretty gut less at high alt. It's funny when you get to sea level,and it feels like a sport's car. Link to comment Share on other sites More sharing options...
unccpathfinder Posted December 30, 2011 Share Posted December 30, 2011 I never really noticed except on climbs...and a lot of times the climb is there but it feels flat...I always watched the GPS to see what my rate of assent is Link to comment Share on other sites More sharing options...
silverton Posted December 30, 2011 Share Posted December 30, 2011 Usually turning the truck off and back on is enough. Sometimes you have to go a far as disconnecting the battery or maybe even pulling the fuse for the ecu Link to comment Share on other sites More sharing options...
unccpathfinder Posted December 30, 2011 Share Posted December 30, 2011 Is the ecu on a wd21 even smart enough to figure it out? I would think it would just run off the MAF and the fuel system shouldn't pressurize too much if all the vents r working right Link to comment Share on other sites More sharing options...
silverton Posted December 30, 2011 Share Posted December 30, 2011 It's still a fuel injected system that "learns" its environment. It may not work as well as the fuzzy logic ECU in the z32, but sometimes just resetting it will fix some issues. I guess you could say it learns how to "run right" then doesn't pay so much attention to atmospheric pressure, and just pays attention to air temp. Link to comment Share on other sites More sharing options...
unccpathfinder Posted December 30, 2011 Share Posted December 30, 2011 That's basically what I was getting at....this truck isn't as critical as newer emissions vehicles...I mean my buddy has different fuel maps for what octane, humidity, ambient etc to optimize his track tines in his ws6 but I don't think its that critical in our application..I would think nits more of the physical load than the combustion...someone go break out their thermodynamics book and run thru the calc's lol Link to comment Share on other sites More sharing options...
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