HZJ79 splutter at altitude ??

[Ian H]

Hi guys, im currently driving around the USA in my HZJ79.
over the last few months we have had a recurring problem at altitudes over about 2500 metres.
the standard 1HZ motor (non turbo) runs perfect at lower altitude but over about 2500m she coughs and has low power, its like one cylinder is miss firing.
the last couple of times this is accompanied by puffs of blue grey smoke and a top end rattle from the rocker cover area. if I add a double dose of diesel treatment with cetane booster she picks up a bit but not a cure. as soon as I drop below 2000m she's back to being smooth and quiet.

Im struggling to find a solution having visited 2 mechanics who seam at a loss as well.

my thoughts are:- given the reduced oxygen at altitude I am getting an incomplete combustion in at least one cylinder causing the power loss and miss fire symptom, adding the cetane boost then increases the combustibility of the diesel and partly cures the problem.

this is all my limited knowledge can come up with.

I would really appreciate some of your shared knowledge as I'm heading to South America in a few months where I will be above 3000m for months at a time.

many thanks in advance.
ps im on the road so may not be able to answer any replies for a few days.

 

[Firewout]

Hi ian,
Do you have a hac fitted on the fuel pump? =high altitude compensator
http://ontroerend-goed.be/1HZ fuel pump.html
Is your air filter new/clean?

 

[nick_the_fish]

Hi Ian,

I have a non-turbo 1HZ and have the same problem at altitude, although I have to say haven't noticed any rattling. I've always assumed (i'm sure others will know for sure) its just that there isn't enough air to get decent compression hence the lack of power. I don't think its one specific cylinder its all of them. I've had her up to 3500m where she was struggling but she made it through. Its fairly common I believe. I have heard some people advance the timing which helps, although to be honest thats a bit beyond my knowledge of engines.

We're doing the same trip that it sounds like you are doing in a few years so might look into a HAC as Firewout suggested.

I assume you are doing the pan America or something similar? Do you have a blog or anything?

 

[Paddler Ed]

The H in my HJ45 is supposed to be adjusted for running at 1,000m above sea level, so I suspect that some of the other older diesels would as well.

 

[Shayne]

You can't tune a naturally aspirated engine for altitude because fuel can't burn without air , compressed air from a turbo and an intercooler would help but even then only if fitted without aims of increasing power .

I think your right Ian - fuel additive would be my first thought and secondly sacrificing power by reducing fuel injected .

I have no faith at all in these things https://www.ebay.co.uk/itm/uperchar...aver-Cyclone-Fit-Most-of-Cars-Q-/263855661128 but for the price it could do no harm to test one .

 

[Paddler Ed]

You can't tune a naturally aspirated engine for altitude because fuel can't burn without air , compressed air from a turbo and an intercooler would help but even then only if fitted without aims of increasing power .

It looks like for the H there's 2 adjustments for altitude:

1. reduces the fuel (from the FSM: "Altitude Compensation for Maximum Injection Volume of Fuel Injection Pump")
2. changes the maximum speed of the engine (from the FSM: "Altitude Compensation for Engine Maximum Speed")

So there are some that can be made.

 

[Ian H]

thanks for all the answers, Im just sitting in 36 degrees of heat at 20:30 hrs, near death valley. I can't breath now, never mind the engine
I will look into the suggested hac but don't think its fitted to my fuel pump at present.
ive fitted a new air Genuine Toyota air filter but didn't make any difference, think ill try get a K&N or similar in Mexico.
ill keep adding the diesel additive and hope it gets me through the Andes but will try find a mechanic who knows the engines in central or South America.
and yes Nick im heading for Ushuia over the next couple of years. I did the Pan Am on my Yamaha Tenere 660, 2 years ago and loved it so much I sold the house, took an early retirement from the MOD and came back in the truck (with the missus)
we shipped Liverpool to Nova Scotia at beginning of May, crossed Canada, loop around Alaska and up the Dalton, now heading south through all the western national parks.
don't have a blog just my face book page.
many thanks people, ill keep trying to get her sorted.
keep any good ideas coming.

 

[Firewout]

Hi Ian,
I fitted a turbo on mine. It really transforms the engine. The best mod I ever did.
Just go easy with the right foot.

 

[nick_the_fish]

Hi Ian,

I've sent you a PM to pick your brains about shipping UK to Canada.

Thinking more about your spluttering - How much weight does that camper unit weigh? Obviously there is nothing you can do about that but it will have an effect on the efficiency of the engine when there isn't enough air. Can you reduce weight in your water/ fuel system for the really high passes? Just a thought.

Is the diesel additive helping? You could argue that by adding additive your actually increasing the amount of cetane into a mixture that is deficient of air (not cetane) so you're actually making the mixture richer, which could be compounding the problem rather than helping it??? I guess the proof is in the pudding so if you think its helping stick with it.

Ultimately 1HZ engines are so good I think as long as its well maintained it should pull you over the high bits, albeit with a bit of black smoke and a lack of power. Definitely a situation I can relate to having worried my way through the Ethiopian highlands.

Remember the cooling system might not be as efficient at high altitude so watch your engine temp, especially as the engine is working harder and go easy on her if necessary.

Nick

 

[Ian H]

Hi Ian,

I've sent you a PM to pick your brains about shipping UK to Canada.

Thinking more about your spluttering - How much weight does that camper unit weigh? Obviously there is nothing you can do about that but it will have an effect on the efficiency of the engine when there isn't enough air. Can you reduce weight in your water/ fuel system for the really high passes? Just a thought.

Is the diesel additive helping? You could argue that by adding additive your actually increasing the amount of cetane into a mixture that is deficient of air (not cetane) so you're actually making the mixture richer, which could be compounding the problem rather than helping it??? I guess the proof is in the pudding so if you think its helping stick with it.

Ultimately 1HZ engines are so good I think as long as its well maintained it should pull you over the high bits, albeit with a bit of black smoke and a lack of power. Definitely a situation I can relate to having worried my way through the Ethiopian highlands.

Remember the cooling system might not be as efficient at high altitude so watch your engine temp, especially as the engine is working harder and go easy on her if necessary.

Nick

thanks Nick,

Ive, been thinking when we are in South America the diesel will be higher sulphur content so will not need additive for lubing the engine and pump etc.
this may reduce the problem.
time will tell,
ps ive replied to your other message.

regards Ian

 

[Ian H]

Hi ian,
Do you have a hac fitted on the fuel pump? =high altitude compensator
http://ontroerend-goed.be/1HZ fuel pump.html
Is your air filter new/clean?

Hi, sorry for late reply, im on the road with no wifi.
It looks like I have the HAC fitted but I'm honestly not sure how its supposed to work,(is it manual or automatic comp for altitude)?
any advice wold be greatly appreciated.

regards Ian H

 

[stumog]

On top of the fuel pump I thought there is an adjuster for when traveling at altitude. It moves the diafram in or out don't really know. Have you got the workshop manual or the drivers hand book

 

[Ian H]

thanks, atumog, ill have a look for that.
I don't have the workshop Manual but ill have a look through the hand book.
ive been searching on line but can't find any details on how to operate the HAC manually.

 

[Firewout]

Afaik it works automatically with a bellows which pushes onto a membrane. When you follow the link you can see the different setups for the fuel pumps.
http://ontroerend-goed.be/1HZ fuel pump.html

 

[clivehorridge]

I’m no expert at all on these matters but I’m surprised that 2,500m could be classed as oxygen deficiency due to thin air. 4,500m maybe, but I’m regularly running my HZJ at up to 2,000m and I’ve never noticed any ill effects on me (a smoker) or my truck (another smoker)

Maybe oxygen deficiency kicks in after 2,500m... I know that while skiing in the Alps, I can feel the difference at 4,500m...

 

[Firewout]

When I did alp tours on the motorbike, it began to splutter at 1800 meters. Was better when I took the airfilter out...