HAC high elevation to low elevation. (1 Viewer)

[Cruiserompin]

Hey everyone, so quick question!

were moving from new mexico at about 5200 elevation to new york about 180 elevation. The truck has been in NM its whole life and im curious to know if the HAC might be stuck open and wont close when its shipped up to NY.

Also i had a problem with it earlier last year drove about 2 hours on the highway and got into some light traffic in town and it felt as if it went into limp mode. The truck would idle above 1k rpm and if it did it just died. That was at about 6k elevation. Got it back home at 5k elevation and it starter right up and drove no problem.

just looking for some help to see if this will be a problem when it gets to low elevation.

thanks all!

 

[4runner2FJ60]

I am a novice, but I believe at sea level you don't need the HAC. Mine does not have it.

 

[Cruiserompin]

Oh cool ok thank you!

 

[1911]

Hey everyone, so quick question!

were moving from new mexico at about 5200 elevation to new york about 180 elevation. The truck has been in NM its whole life and im curious to know if the HAC might be stuck open and wont close when its shipped up to NY.

Also i had a problem with it earlier last year drove about 2 hours on the highway and got into some light traffic in town and it felt as if it went into limp mode. The truck would idle above 1k rpm and if it did it just died. That was at about 6k elevation. Got it back home at 5k elevation and it starter right up and drove no problem.

just looking for some help to see if this will be a problem when it gets to low elevation.

thanks all!

It's extremely unlikely that the the HAC would "stick open", as that would require constant vacuum to the distributor, or for the distributor advance mechanism to freeze in the advanced position. The opposite is what usually happens, i.e. the distributor advance mechanism rusts and won't advance.

 

[g-man]

testing procedures for the HAC are in the 81 2f emissions manual.

 

[Cruiserompin]

ok thank you. I gotta get out there and jump into!

 

[GeologistFelix]

I have a desmogged 60 without ports on the (Trollhole) carb to run HAC, and I never bothered to fool with the secondary advance on the dissy.

Long story short, it runs 'fine' at all altitudes, but it's noticeably slower when you start to head up above 5 or 6000 feet. Even with my old dissy which apparently had a seized advance, I got the poor old thing up to 80 mph (confirmed by GPS) at 7500 feet with a bunch of crap on the roof and probably well over GWVR with camping gear and four grown-assed adults.

Basically, it's definitely helping the engine run to get closer to ideal timing and AFM, but I get the impression that HAC is 95% to minimize stuff like NO2 etc. out the tailpipe. Plus, the loss of power from loss of air pressure is both unavoidable without forced induction and gonna affect perceived power many, many, many times more than a broken HAC ever would.

That's my long way of saying 'it almost certainly doesn't matter in real life, even if HAC is objectively better for the engine than no HAC.'

 

[himhj60]

HAC landcruiser 60