82 Vanagon idle drop at elevation in the Andes

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ohmydarlingcharlie
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82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Tue Aug 02, 2016 9:24 am

Good morning itinerant aircooled team:
I am currently having running issues with my idle at elevation as I travel to higher altitudes in the Andes.
Up until 9 500 ft I was running fine. The van ran great.

At 10 000 ft, the idle started dropping when I stopped the van and would eventually shut off unless I pressed on the accelerator. As I climbed, at 10 500 the rate at which it would drop and eventually shut off was more pronounced. This is the highest I have been thus far. I was able to drive the van as long as I was pressing on the accelerator.

When the van shut off I was able to restart it easily. When I got back to 8000 ft, the idle was fine.

I am in the Andes in Southern Colombia and will be climbing even higher as I head into Ecuador and Peru.

Can the timing, FI be adjusted to compensate for the higher elevation. I heard about advancing the timing. Can anyone comment on the amount and if this is the right course of action.

82 Vanagon aircooled, FI, federal edition, Pertronix ignition, 7.5 timing
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
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dingo
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Re: 82 Vanagon idle drop at elevation in the Andes

Post by dingo » Tue Aug 02, 2016 5:35 pm

experiment by advancing timing a degree or so...see if it helps, Supposedly this will compensate for the lower air density.
Good luck..sounds like a great adventure !
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Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Wed Aug 03, 2016 8:48 am

ohmydarlingcharlie wrote:Good morning itinerant aircooled team:
I am currently having running issues with my idle at elevation as I travel to higher altitudes in the Andes.
Up until 9 500 ft I was running fine. The van ran great.

At 10 000 ft, the idle started dropping when I stopped the van and would eventually shut off unless I pressed on the accelerator. As I climbed, at 10 500 the rate at which it would drop and eventually shut off was more pronounced. This is the highest I have been thus far. I was able to drive the van as long as I was pressing on the accelerator.

When the van shut off I was able to restart it easily. When I got back to 8000 ft, the idle was fine.

I am in the Andes in Southern Colombia and will be climbing even higher as I head into Ecuador and Peru.

Can the timing, FI be adjusted to compensate for the higher elevation. I heard about advancing the timing. Can anyone comment on the amount and if this is the right course of action.

82 Vanagon aircooled, FI, federal edition, Pertronix ignition, 7.5 timing
Advance the timing to 40*BTDC at 3,400 rpm (all hoses off the distributor) when you are above 8,000 feet.
REMEMBER TO BACK OFF THE TIMING WHEN YOU DROP BELOW 5,000 FEET!
Lean out the fuel mixture for best idle.
REMEMBER TO RICHEN THE MIXTURE WHEN YOU DROP BELOW 5,000 FEET!

Thse are my recommendations,
Colin (current elevation, 36 feet)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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the miz
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Re: 82 Vanagon idle drop at elevation in the Andes

Post by the miz » Wed Aug 03, 2016 11:12 am

Amskeptic wrote:
Advance the timing to 40*BTDC at 3,400 rpm (all hoses off the distributor) when you are above 8,000 feet.
REMEMBER TO BACK OFF THE TIMING WHEN YOU DROP BELOW 5,000 FEET!
Lean out the fuel mixture for best idle.
REMEMBER TO RICHEN THE MIXTURE WHEN YOU DROP BELOW 5,000 FEET!

Thse are my recommendations,
Colin (current elevation, 36 feet)
Granted I was dealing with 2 big carbs at the time, I can vouch for the Colin Recommended Leaning and Advancement Plan...it certainly seemed to help on my trip through WY and CO last year and got me to over a 12,000'+ pass and an 11,000'+ pass...without the issues you are describing.

miz
1982 Westy- Vana White

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by Ronin10 » Wed Aug 03, 2016 5:30 pm

Amskeptic wrote:Advance the timing to 40*BTDC at 3,400 rpm (all hoses off the distributor) when you are above 8,000 feet.
REMEMBER TO BACK OFF THE TIMING WHEN YOU DROP BELOW 5,000 FEET!
Lean out the fuel mixture for best idle.
REMEMBER TO RICHEN THE MIXTURE WHEN YOU DROP BELOW 5,000 FEET!

Thse are my recommendations,
Colin (current elevation, 36 feet)
Can you elaborate on your rational for the discrepancy in adjustment altitudes going up versus coming down? Something to do with the throttle plate being closed (or nearly so) on the way down and the subsequent AFM flapper position, I presume?
Oscar: 1976 Sage Green Bus, Stock Motor, Solid Lifters, Manual Transaxle

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Wed Aug 03, 2016 10:24 pm

Ronin10 wrote:
Amskeptic wrote:Advance the timing to 40*BTDC at 3,400 rpm (all hoses off the distributor) when you are above 8,000 feet.
REMEMBER TO BACK OFF THE TIMING WHEN YOU DROP BELOW 5,000 FEET!
Lean out the fuel mixture for best idle.
REMEMBER TO RICHEN THE MIXTURE WHEN YOU DROP BELOW 5,000 FEET!

Thse are my recommendations,
Colin (current elevation, 36 feet)
Can you elaborate on your rational for the discrepancy in adjustment altitudes going up versus coming down? Something to do with the throttle plate being closed (or nearly so) on the way down and the subsequent AFM flapper position, I presume?
Going downhill is easier on the engine.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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asiab3
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Re: 82 Vanagon idle drop at elevation in the Andes

Post by asiab3 » Wed Aug 03, 2016 11:39 pm

Amskeptic wrote:Going downhill is easier on the engine.
I see your clear rationale and I would like to raise us one thought:
If you back the timing off before the decent, you may have a tiny bit more engine braking.

Having just plowed down Beartooth Pass, I would have liked more engine braking. :bom:
Robbie
1969 bus, "Buddy."
145k miles with me.
322k miles on Earth.

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Thu Aug 04, 2016 8:14 am

Amskeptic wrote:
Advance the timing to 40*BTDC at 3,400 rpm (all hoses off the distributor) when you are above 8,000 feet.
REMEMBER TO BACK OFF THE TIMING WHEN YOU DROP BELOW 5,000 FEET!
Lean out the fuel mixture for best idle.
REMEMBER TO RICHEN THE MIXTURE WHEN YOU DROP BELOW 5,000 FEET!

Thse are my recommendations,
Colin (current elevation, 36 feet)
Thank you Colin for this reply and thank you to this wonderful itinerant family for discussing this topic and providing your input.

Please bear with me as I want to get this right.

I know how to adjust the timing to 7.5*BTDC with my timing light. I usually connect it to the battery. It is a fairly simple timing light and does not allow me to set an advance.

I have a few questions with setting the timing and mixture.

1. Do I need to set the timing before I start to have idle trouble? If I reach 10,000 ft and have not yet changed the timing will I be able to set the timing to 40*BTDC at 3400 rpm or will I have to drop until my idle is stable.

2. What is the procedure for setting the timing at 3400rpm? Do you get an assistant to press the throttle while you operate the light. (40*BTDC is also the last mark on my scale).
As for the hose coming of the distributor, do I plug the hose part? and do I plug the metal canister part on the distributor?

3. When I set the timing back to normal, should I set it at 3400 rpm or just set it at idle to 7.5* BTDC? If its 3400rpm, what is the timing for normal altitude? (hose off distributor, right?)

4. What are the consequences of not changing the timing at altitude? Can I just keep dealing with a idle that wants to drop.

5. How much should I lean out the mixture. 1/2 turn ccw on the mixture screw on the AFM? 1 turn ccw?

Thank you for helping out with the Oh My Darling Charlie adventure!
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Thu Aug 04, 2016 8:17 am

Amskeptic wrote:
Going downhill is easier on the engine.
Colin
You might be dropping in elevation for a while but then going right up again. It's up and down all day in these parts.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Fri Aug 05, 2016 8:48 pm

ohmydarlingcharlie wrote:
Amskeptic wrote:
Going downhill is easier on the engine.
Colin
You might be dropping in elevation for a while but then going right up again. It's up and down all day in these parts.
Yes, and I said, do not worry about backing off the timing until you drop under 5,000 feet. Really. I am serious. Up the hill down the hill, if you are going from 5,000 ft to 11,500 feet down to 6,000 feet up to 8,000 feet down to 4,980 feet back up to 9,960 feet, you can keep the timing advanced and the mixture leaned out. Really.
Colin
(if you forget to retard the timing and richen the mixture, you will know about it as you hit about 2,000 feet elevation and the mixtures is so lean it won't carry the idle. Then you will remember to retard the timing back to factory values)
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Sat Aug 06, 2016 11:38 am

Amskeptic wrote: Yes, and I said, do not worry about backing off the timing until you drop under 5,000 feet. Really. I am serious. Up the hill down the hill, if you are going from 5,000 ft to 11,500 feet down to 6,000 feet up to 8,000 feet down to 4,980 feet back up to 9,960 feet, you can keep the timing advanced and the mixture leaned out. Really.
Colin
(if you forget to retard the timing and richen the mixture, you will know about it as you hit about 2,000 feet elevation and the mixtures is so lean it won't carry the idle. Then you will remember to retard the timing back to factory values)
Thank you for clarifying. Helpful information for sure. I'm not back at elevation yet so I will let you know how it goes. Did you happen to see my other message above the up and down comment. I was asking some questions about the procedure.
ohmydarlingcharlie wrote:
Amskeptic wrote:
Advance the timing to 40*BTDC at 3,400 rpm (all hoses off the distributor) when you are above 8,000 feet.
REMEMBER TO BACK OFF THE TIMING WHEN YOU DROP BELOW 5,000 FEET!
Lean out the fuel mixture for best idle.
REMEMBER TO RICHEN THE MIXTURE WHEN YOU DROP BELOW 5,000 FEET!

Thse are my recommendations,
Colin (current elevation, 36 feet)
Thank you Colin for this reply and thank you to this wonderful itinerant family for discussing this topic and providing your input.

Please bear with me as I want to get this right.

I know how to adjust the timing to 7.5*BTDC with my timing light. I usually connect it to the battery. It is a fairly simple timing light and does not allow me to set an advance.

I have a few questions with setting the timing and mixture.

1. Do I need to set the timing before I start to have idle trouble? If I reach 10,000 ft and have not yet changed the timing will I be able to set the timing to 40*BTDC at 3400 rpm or will I have to drop until my idle is stable.

2. What is the procedure for setting the timing at 3400rpm? Do you get an assistant to press the throttle while you operate the light. (40*BTDC is also the last mark on my scale).
As for the hose coming of the distributor, do I plug the hose part? and do I plug the metal canister part on the distributor?

3. When I set the timing back to normal, should I set it at 3400 rpm or just set it at idle to 7.5* BTDC? If its 3400rpm, what is the timing for normal altitude? (hose off distributor, right?)

4. What are the consequences of not changing the timing at altitude? Can I just keep dealing with a idle that wants to drop.

5. How much should I lean out the mixture. 1/2 turn ccw on the mixture screw on the AFM? 1 turn ccw?

Thank you for helping out with the Oh My Darling Charlie adventure!
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

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Amskeptic
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Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Sat Aug 06, 2016 10:08 pm

ohmydarlingcharlie wrote: 1. Do I need to set the timing before I start to have idle trouble? If I reach 10,000 ft and have not yet changed the timing will I be able to set the timing to 40*BTDC at 3400 rpm or will I have to drop until my idle is stable.
You can adjust the timing anytime, anywhere, the spirit moves you. You pull the vacuum hose, loosen the distributor clamp and push the throttle open with one hand and shoot the light at the scale. In your case, you will likely move the distributor barely 5* counterclockwise to set the timing for high altitude. Check at 3,400 rpm that it is between 38* and 40* (the light does scatter a bit), tighten the clamp, stick on the hose, yer done.
ohmydarlingcharlie wrote: 3. When I set the timing back to normal, should I set it at 3400 rpm?
Yes. Always adjust your timing at 3,400 rpm.
Do not adjust timing at idle.
Sea level timing is 28* BTDC no advance hose installed.
When you do put the hose back on, it should reach 40* BTDC when you run the rpms up briefly.
ohmydarlingcharlie wrote: 4. What are the consequences of not changing the timing at altitude? Can I just keep dealing with a idle that wants to drop.
Low power, lousy fuel economy, sometimes difficult starting.
ohmydarlingcharlie wrote: 5. How much should I lean out the mixture. 1/2 turn ccw on the mixture screw on the AFM? 1 turn ccw?
Lean it out until you achieve the best idle you can get. Be very sure to reset mixture when you come dashing down the hill, say, around 5,000 feet, and check again at sea level.

I just had an incident TODAY! where I had not reset my timing and mixture from only from 4,000 feet elevation, and ran 447* CHTs on Interstate 5 in the hot central valley of California until I dropped the timing back down to a proper sea level 28* BTDCand richened the mixture. That CHT number is not good, I was a BAD mechanic. Now my CHTs are a more reasonable 420* but still not too good.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Sun Aug 14, 2016 7:36 pm

I'm currently at 8500ft and I adjusted the timing to 40*BTDC with the hose off the distributor.
The idle immediately improved.
I also turned the mixture screw 1 turn ccw bringing the total turns to 6 1/4 ccw.

With the van warmed up the van ran fine.
The second time I used it, I didn't warm up it up as much and had some acute buckling in all gears. Felt like it could be from air/fuel. Under load and under no load.

I parked the van for a hike, returned after 2 hours and set off right away. I had the most severe bucking at this point. The bucking stopped after maybe 10 minutes of driving. I was able to drive it fine afterwards, go to the grocery store, restart it after 30min without problem.

I did not have this problem before adjusting the mixture screw and timing but I did have terrible gas mileage and bad idle as predicted by Colin due to the elevation.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Wed Aug 17, 2016 6:59 pm

ohmydarlingcharlie wrote:I'm currently at 8500ft and I adjusted the timing to 40*BTDC with the hose off the distributor.
The idle immediately improved.
I also turned the mixture screw 1 turn ccw bringing the total turns to 6 1/4 ccw.

With the van warmed up the van ran fine.
The second time I used it, I didn't warm up it up as much and had some acute buckling in all gears. Felt like it could be from air/fuel. Under load and under no load.

I parked the van for a hike, returned after 2 hours and set off right away. I had the most severe bucking at this point. The bucking stopped after maybe 10 minutes of driving. I was able to drive it fine afterwards, go to the grocery store, restart it after 30min without problem.

I did not have this problem before adjusting the mixture screw and timing but I did have terrible gas mileage and bad idle as predicted by Colin due to the elevation.
That bucking is evidence that you have slipped outside of the ECU's expectations, or programmed map.
I would bring it back incrementially and try to find the most agreeable spot. Nobody said you couldn't experiment . . . :blackeye:
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Thu Aug 18, 2016 5:49 am

Amskeptic wrote:
ohmydarlingcharlie wrote:I'm currently at 8500ft and I adjusted the timing to 40*BTDC with the hose off the distributor.
The idle immediately improved.
I also turned the mixture screw 1 turn ccw bringing the total turns to 6 1/4 ccw.

With the van warmed up the van ran fine.
The second time I used it, I didn't warm up it up as much and had some acute buckling in all gears. Felt like it could be from air/fuel. Under load and under no load.

I parked the van for a hike, returned after 2 hours and set off right away. I had the most severe bucking at this point. The bucking stopped after maybe 10 minutes of driving. I was able to drive it fine afterwards, go to the grocery store, restart it after 30min without problem.

I did not have this problem before adjusting the mixture screw and timing but I did have terrible gas mileage and bad idle as predicted by Colin due to the elevation.
That bucking is evidence that you have slipped outside of the ECU's expectations, or programmed map.
I would bring it back incrementially and try to find the most agreeable spot. Nobody said you couldn't experiment . . . :blackeye:
The timing is what I need to bring back a bit?

I drove 400km the last few days and had 13MPG which was better than I was getting before changing the timing and mixture. I pulled a plug and it was also quite dark.

Does advancing the timing richen the mixture?
How many turns is too much on the mixture screw?
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

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