95 Nissan bogging out in high alt?

nissan95pu · Apr 28th, 2005, 07:21 PM

Hello,

I am a new member and I seem to have found the right site for my nissan questions. I recently moved up in elevation from about 1500 ft to about 7000. I am happily living in Utah but my truck is very unhappy. The minute I got into the high country my truck started idling really low and putt-putting up the high passes. I talked to some mechanics who told me that my truck is equipped with a computer chip that automatically adjusts to altitude changes but it has been two months and I am still bogging. It is a 1995 four by four pick-up with a 4 cylinder, 2.4 engine, not exactly a huge powerplant, but it always hummed right up the hills in the lower elevation. I suppose it could be sensor that is not working. I changed the plugs and checked the air filter and that is not the problem. The guy at the dealership wants to charge me an arm and a leg just to check it out. Does anyone have any advice?

I am also looking into a cold air intake and getting my computer chip re-worked for some more horses. Any input would be welcomed. Thanks.

jerryp58 · Apr 28th, 2005, 08:52 PM

Quote:

Originally Posted by nissan95pu

Hello,

I am a new member and I seem to have found the right site for my nissan questions. I recently moved up in elevation from about 1500 ft to about 7000. I am happily living in Utah but my truck is very unhappy. The minute I got into the high country my truck started idling really low and putt-putting up the high passes. I talked to some mechanics who told me that my truck is equipped with a computer chip that automatically adjusts to altitude changes but it has been two months and I am still bogging. It is a 1995 four by four pick-up with a 4 cylinder, 2.4 engine, not exactly a huge powerplant, but it always hummed right up the hills in the lower elevation. I suppose it could be sensor that is not working. I changed the plugs and checked the air filter and that is not the problem. The guy at the dealership wants to charge me an arm and a leg just to check it out. Does anyone have any advice?

I am also looking into a cold air intake and getting my computer chip re-worked for some more horses. Any input would be welcomed. Thanks.

Hmmm... the first thing I thought of when I read your question was atmospheric pressure. It was an interesting question so I did a quick Google search on "automobile high altitude" and read a couple of interesting things on a Saab website. Apparently, low atmospheric pressure and thinner air really sap an engine's energy output. They were talking 15% to 35% based on the altitude. Some of their suggestions were advancing the timing, adjusting the fuel mixture (not sure how you could do that unless someone can program your computer -- actually, would one of those eBay resistor chips on your intake air temp sensor make the truck run richer?), and getting as much cool air into the system as possible. Please don't take anything I've said here as gospel because I'm just paraphrasing what I've read. Hopefully, someone will chime in with personal experience, but you may want to check some of the websites and maybe even some of the local auto shops or local car clubs and ask their advise.

Good Luck and please post what you find out; it'll be more practical and probably more interesting than high school physics was

**88pathoffroad** · Apr 28th, 2005, 11:14 PM

Mine does the exact same thing. It sucks, but you can't really do anything about it, as far as I know.

zimmer_kole · Apr 30th, 2005, 02:24 AM

Do you think maybe if the ecu was reset, it would be like starting from scratch and the ecu could accquire a fresh taste of the new altitude? Maybe try disconnecting the battery for a while to reset?

**88pathoffroad** · Apr 30th, 2005, 04:14 PM

That will reset the ECU, yes, but I doubt it'll have any effect on performance. It'll still be reading the same air at the same atitude. It's simple physics: the higher you go, the lower the atmospheric pressure gets. The less pressure there is, the less air there is for your engine to run on. The only way to compensate for that is to use forced induction.