v_man

The past few days I've been driving around the eastern sierra at altitudes up to 8,200 feet , a lot of driving between 5,000 and 7,000 feet . My 'runner has been noticeably more sluggish and MPG dropped by about 15% over three tanks.

I understand that on carbed engines you can easily adjust the air/fuel mixture to compensate for less air at higher altitude, my Honda motorcycle has a screw that can be adjusted for this .

I guess I was under the impression that a fuel injected engine would better 'adjust' , or compensate for higher altitudes than a carbed engine . Is sluggish performance and decreased MPG just par for the course at higher altitudes on these engines ??

Your observations on the 22re at high altitudes?

Vang530

all i can say is don't be afraid to rev the 22re up..it can handle 3.5k rpm all day long if its in good running order

thebeeler

I've noticed that whenever I have been at high altitudes with my 22RE I have had to adjust the idle air bypass screw on the throttle body so it would even idle, and yes the gas mileage will drop. There is only so much adjusting the outdated ECU can do.

v_man

...good point , I guess having it loaded down with camping gear and presents didn't help either.

[IMG][/IMG]

lim50

I just completed (got home last night)a 4 thousand mile trip in my 87 4runner 22re ( 20,000 on rebuild). Left SE Texas (sea level) truck ran great 22mpg on freeway at 70 mph. Drove to kc,mo idle dropped about 150 rpm(1000 above sea level , ASL)mpg down to 20 performance dropped a little. left kc and drove to cedar crest ,nm (7,800 ft ASL) BIG drop in performance, mpg down to 17 miles, idle dropped to 200 rpm. had to readjust air screw. really felt a big difference when I reached around 3500 ASL. Of course on the trip back to sea level had to readjust air screw or the engine would have been idling around 1500 rpm. Going from sea level to 7800asl really showed what thin air does to this engine.

snobdds

I live at 6,800 feet and have a cabin at 9,500. I drive back and forth between those altitudes a lot without adjusting the idle. The ECM, while outdated, will function to set fuel/air trims based upon the inputs from the 02, TPS, coolant sender, etc, reguardless of altitute. If all the sensors that communicate with the ECM are in proper working order and the timing is correct...the ECM is making the engine run at it's proper setting.

That being said, there is still physics involved and air is less dense at altitute. There is no sensor to detect the density of air. So the engine is started of 02 in density and not volume. The easiest way to compensate for that is to increase ignition timing and allow for a little bit more time before ignition. I run my ignition timing at 8* BTDC and it fixes the altitute problem...but I am already at a pretty high altitute to begin with. So if your up high for long periods of time...run your ignition time a little more advanced than 5* BTDC.

lim50

snobdds thanks for the tip. I am going to be moving back to new mexico this spring and will try advancing the timing .any tips for improving my lungs?lol

toastyjosh

iTrader: (1)

My old 91 22re I had I lived at about 7500ft. I drove up 12K often. Yea she will lose a bit of guts at elevation, but not a ton. I still got about 20mpg. A old timer had me adjust my timing to 10, then we readjusted the idle screw. Then cleaned the TB with carb cleaner, to get out all the junk.
Worked great!

thebeeler

I live right above sea level. Whenever I drive up to Red River, New Mexico I have to stop in Eagles Nest, 8250', to re-adjust the idle because whenever I let off the gas the truck will just die, it will not idle. And everything on my truck is in perfect working order.

christoph8_21

Fuel trim will need to be adjusted.

Mraolguy@Gmail.com

so on that note would you still run 5* even at 5000 feet ?

BushPig

Have any of you been up over the high passes in Colorado, like Imogene, Engineer, etc in your 22RE's? How did they do? Planning a trip up that way and wondering if I will make it over the passes on 31" tires, moderately loaded, in 4WD low.

thefishguy77

iTrader: (1)

Went over Lookout and 4th of July in Montana on 33's with a 2k pound trailer I had 5:29's gears. So more gear than a stock gears. I had no problems. Not sure how high the passes your talking about are. But just find your gear and liver your gear. Relax and take your time. Remember the art of pulling hills and trailers is stopping not going.

mountainbrew

I go Denver to mountains over all sorts of passes and the 22re is...well, it's slow. But then again, it's a sizable truck with a hundresish hp at the wheels, and lord knows we all like to bring our heavy toys with us.

I mean, I'm not getting passed by semis or anything, but I never have a need for the left lane either. I can keep it at about 55 in all but the worst highway inclines, but I also run 4.88 on 31x10.5

A friend I wheel with has an '85 renegade with about 400hp to the wheels and I can't even begin to keep up in the highway. I always tell him, go ahead and have fun with your jeep, I'll show up eventually to winch you out of the stuff the runner does in its sleep. But bring a sandwich because I'm not gonna be there for a while...

We are the tortoises of wheeling!

Edit: I kinda went off topic, Imogene and Engineer are not passes I would ever do remotely fast. You shouldn't have any problem at all. Take your time and enjoy the scenery, you will have plenty of low end power at that altitude. Loveland pass is about as high as it gets I believe and I never have issues there.

derockus

iTrader: (1)

Haven't done Imogene but we did Engineer and Cinnamon passes (Alpine Loop) in 2014. I have '89 4Runner 22RE (It had about 8K on a full rebuild at that time). I had 31x10.5 tires (Kenda MTs). Not regeared, stock 4.10s.


I did most of the drive in 4lo. It's just so damn bumpy you need to just crawl along to avoid your teeth falling out. There's some steep stuff back there but I was able power up it all. We camped and did a couple 14ers so we were fully loaded.


We went Lake City - camped at Red Cloud TH - camped in American Basin (Handie's TH) - Cinnamon Pass - Silverton - Back up over Engineer to Lake City. We also took a side trip up to Carson ghost town.

BushPig

Very helpful posts, thanks guys!

Love your 4Runner, derockus - we used to have one just like it, in the late '80's, I'll post a pic shortly. Obviously you made it to the top of Engineer, which is great - how did it do on the climb? I think it goes without saying that at that kind of altitude, 4-Low is required, along with low speeds. Was it breathless or were you able to drive the truck with some authority? Any special setups with regard to igntion timing, etc, prior to going on the trip? What kind of MPG did you get?

BushPig

http://s1336.photobucket.com/user/Su...17bb7.jpg.html

Approx 1989, near the coast of Oman, Persian Gulf.

derockus

iTrader: (1)

It chugged right along on the climb. Like other's said, you can get it revved up to 3.5K-4.5K rpm for a long climb without any problem. My timing is about 7deg advanced. Although, I need to recheck it, I haven't since the rebuild. I would change your air filter before the trip, don't asphyxiate your motor any more than it has to be. Only thing special I've done to my drivetrain is a LC Engineering RV cam and the HD clutch kit that MarlinCrawler sells. The truck was not breathless at all. I remember that I drove from Glenwood to Lake City and got 24mpg! That is the highest I've ever gotten though. I think on the trail it was more like 15mpg. I didn't bother to bring spare gas, you could do the whole loop on a tank (I topped up in Silverton halfway through though).


Don't go on a holiday weekend. We went around July 4th and it was MOBBED with Texans. Seriously, every other license plate in Lake City was Texas. And they all ride around with no helmets like 3 people-to-one-ATV. Lots of Razr UTVs with old folks and their lap dogs too.


If you go to Silverton be sure to go Montanya Distillery and DON'T go to Handlebar's. It is hokey and touristy.

Odin

As an experiment I ran my 2wd truck at close to sea level timed at 12 BTDC and premium in the tank. It picked up a lot of low and midrange torque like that but it did ping.
I'll explain, but first...

Could I have gotten away with running mid grade gas? Because of being close to sea level "Perhaps", but I discovered a vacuum leak with some pinging so I put the timing back to stock until I can fix that. (Sooo much to do on this neglected truck including correcting poorly executed fixes/repairs)

I'd just fill the tank with Premium and set the timing at 12. But I'd bring the timing light with me to accurately retard it a little if ping is detected.

wyoming9

iTrader: (1)

The whole idea of 22Re performance at any altitude is pretty funny.

Speaking of a engine with a little over 100 horsepower stock.

Then the very simple engine management system of that era.

Be a good excuse for a road trip someplace over 10,000 feet in the newer 3.4

I do miss the Mountain west!!