82 Vanagon idle drop at elevation in the Andes

Find/Fix/Report Back

Moderators: Sluggo, Amskeptic

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Fri Aug 19, 2016 10:02 am

ohmydarlingcharlie wrote: Does advancing the timing richen the mixture?
How many turns is too much on the mixture screw?
Advancing the timing advances the timing. There are secondary effects of adjusting the timing, such as slightly better intake air flow which makes the flap move slightly more in the AFM which has the effect of "richening the mixture".

There is no such thing as "too much on the mixture screw", except when it falls out.

Clockwise richens
Counterclockwise leans

It has a limited range, so there are other more powerful adjustments that we are not going into.

Expect dark plugs and rich running at high elevation. We are only trying to give you a driveable vehicle for the short-term, correct?
If you were living above 8,500 feet, then we would adjust the AFM wiper and spring to compensate for less oxygen in the volume of air, and as importantly, reset the spring to compensate for the less dense air.
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

ohmydarlingcharlie
I'm New!
Contact:
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Sun Aug 21, 2016 7:06 pm

Amskeptic wrote: Expect dark plugs and rich running at high elevation. We are only trying to give you a driveable vehicle for the short-term, correct?
air.
Colin
Yes, this is correct. Just looking to have a driveable vehicle as I make my way through the mountains in Ecuador, Peru and Bolivia. I will be traveling from the mountains to the coast and back and want to have the mixture/timing dialed in.

....So this morning, I changed the timing with the hopes of eliminating the buckling was experiencing when the van was cold. It was previously set at 40*BTDC (3400 rpm, hose off). I changed it to 36*BTDC and added 1/2 turn to the mixture screw bringing the total to 6 3/4 turns.

In addition, today I drove 2 hours from 8000 ft to 8500 ft, to Quito, Ecuador, up and down. Along the way I reached elevations of 9500 ft. At one point on the trip, at a light, the van died. The idle dropped and the van shutoff. I was unable to restart it with the key. Luckily I was facing downhill and was able to restart with the clutch.

From this point forward I was careful when I stopped the van. Numerous stops along the way and the van idled fine. When I reached the outskirts of Quito, the van died on the freeway, in the middle of traffic, slightly uphill. I was unable to start with the key and unable to push start it. I tried and tried with the key and was unsuccessful. I tried push starting backwards but was unsuccessful due the traffic. The police pushed me out of the way. (I did cross the equator before this happened!)

Off to the side I tried to start it and it would crank over slowly. I eventually got it started but when I opened the AFM, the wiper looked to be almost stuck. Any gas or any movement of the wiper caused the van to shutoff. The AFM wiper was behaving abnormally.

I checked the temp2, AFM resistances, battery voltage, all good.

I let it sit for a while. I also turned the mixture screw 1/2 turn cw to undo the mixture screw change I had made earlier in the day. I got it to start and idle fine for the most part. Sometimes the idle would start to drop and would return to 900RPM with a little gas.

Scared to breakdown on the freeway again, I called my friendly neighborhood Syncro owner to escort me to his house (*I was on my way to visit this man since he hosts all VW travelers that pass through Ecuador. He escorted me, see photo below.)
DSC_0540.JPG
DSC_0540.JPG (74.93 KiB) Viewed 8966 times
I was concerned about the van dying every time I came to a stop but the idle rpm barely dropped. I made it without shutting off.

My question is, where do I go from here with the mixture/timing?

This is a mixture/timing issue, or am I looking at something else?

What else has changed: between driving it today and last time I drove the van, I cleaned my removal K&N air filter.

Other obeservations, driving it to the syncro owner's house, the exhaust smelled rich.

Thank you for your help. This community is exceptional. Cheers.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Sun Aug 21, 2016 8:31 pm

ohmydarlingcharlie wrote: This is a mixture/timing issue, or am I looking at something else?
I am going to be maddeningly unhelpful here because we need and you need to step up and learn how to ask the engine what it wants.

There is no way we can catch the subtleties of changing environments in the engine and as you drive.

To ask the engine what mixture it likes:

Find the hose to the fuel pressure regulator. Trace it back to the intake manifold. Pull the hose off at the intake manifold at a warm idle.

a) if the idle goes up - the mixture is rich.

b) if the idle goes up when the hose is halfway off then drops into a rough dance with the hose all the way off, it is sort of richish but workable.

c) if the idle drops the instant you start removing the hose and then drops alarmingly as the hose is fully off the intake manifold nipple, we will call that mixture lean.

You do need to look at other issues at this point.
Pull a spark plug. Is it black black black? Is it tan at the insulator? Is it white at the insulator?
Perform a compression test. Readings should vary no more than 20% and clean the spark plug electrodes and adjust the spark plug gaps to .024".

Adjust the valves.

Slow cranking, you need to look at the battery electrolyte to make sure it is covering all the plates. Charge battery slowly and fully.
Checking wiring, security and cleanliness.

You need to feel the engine at work to help intuit if the mixture is rich or lean or the timing is too retarded or advanced.

Retarded timing is noticeable by a strong hot exhaust pulse at idle and low power through the rev range.

Advanced timing is more difficult, because it also has low power on the highway, but the engine revs at rest more easily, (but you can tell it is thrashing the rods) and can cause severe engine damage at speed silently.

I need to know more about the AFM behavior. Were you describing a mechanical resistance in the AFM wiper?
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

ohmydarlingcharlie
I'm New!
Contact:
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Sun Aug 21, 2016 9:07 pm

Amskeptic wrote: I am going to be maddeningly unhelpful here because we need and you need to step up and learn how to ask the engine what it wants.
I forgot to mention that I checked the AFM wiper by moving it 1/4in in cw and ccw direction as per your AFM how-to (forum archives) after the letting the van had sat for a bit and the AFM was working normally. When I moved it ccw the idle dropped (rich). When I moved it cw, nothing happened.
Amskeptic wrote: You need to feel the engine at work to help intuit if the mixture is rich or lean or the timing is too retarded or advanced.

Retarded timing is noticeable by a strong hot exhaust pulse at idle and low power through the rev range.

Advanced timing is more difficult, because it also has low power on the highway, but the engine revs at rest more easily, (but you can tell it is thrashing the rods) and can cause severe engine damage at speed silently.
The engine power seemed fine and I had sufficient power to go up hills when I got the working again. The van was running as per normal. It really seemed to be an at idle, stopped for red light issue.

Previously, when I still had the timing at 28*BTDC it would die at elevation but would start again easily.
Amskeptic wrote: I need to know more about the AFM behavior. Were you describing a mechanical resistance in the AFM wiper?
The AFM showed resistance in the spring. This is why I decided to test all the nodes to see if anything was off. This was only at first. After waiting a while and starting the van again, the AFM wiper worked well in all its range of motion. I do have another AFM with me. This one previously showed high resistance but was cleaned at a Bosch center and they got it back within the Bentley specs for resistance.
Amskeptic wrote: adjust the spark plug gaps to .024".
I've always had them at 0.028". Is 0.024" only for this problem or should they always be at this gap?

I was thinking maybe with the timing/mixture I had the engine run rich and was flooded. It reminded me of when I had a bad temp2 sensor and got stuck in Mexico. I was unable to start the van right away but after letting it sit a while, it was able to start again.


Thank you for bearing with me. It's really the first time I have to deal with changing elevation and adjusting the timing.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

ohmydarlingcharlie
I'm New!
Contact:
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Sun Sep 11, 2016 11:52 am

Hello VW Team,

Just wanted to give you an update on my Ecuador/ South America situation.
I was able to take the van to a VW mechanic who resides in Quito (3000m) and therefore familiar with working with VW's at elevation. I'm not fully sure why the van broke down upon entering the city but he mentioned that it had to do with pressure and the compression and after letting it sit for a while it was able to restart.

He checked my timing and he said it was fine at 36 *BTDC (@ 3400) which happened to be 22*BTDC at idle.

When I went to check the hose going to the intake manifold to see if it was running rich as per Colin's instructions, I broke the hose and also noticed that the hose was also broken. So I had a vacuum leak. Installed a new hose. (The broken hose was completely out of sight, and the hose was so brittle)

With timing at 36*BTDC I was able to get to 4000m (13 000ft) . From 3700-4000m the van would want to shut off when idling. I would press the gas and keep going. When I enter Peru, should I just go with 36*BTDC for up to 4000m and advance it some more for 4000+m? (I think some passes or over 15 000ft)

I am back at the coast at the moment. I set the timing to 28*BTDC (@3400 RPM). The van idles a bit fast at this timing (1200-1300RPM). I adjusted the mixture screw and checked the intake manifold hose to see if I was running rich. Right now, when I remove the intake manifold hose the idle does not change.

*CURRENT ISSUE*
The current issue that I am having is that when FIRST starting the van for the day, it runs terribly. The idle surges and drops from 2000RPM to 1000RPM and back up. I let it warm up, it hesitates for the first 5 minutes of driving and then runs fine for the rest of the day. I can leave it for hours, return to the van and it runs fine (but has a high idle).

Throughout all my timing adjustments I never touched the idle bypass screw. I just moved the mixture screw and the distributor.

My current home on the beach:
DSC_0070.JPG
Santa Marianita, Ecuador
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Sat Sep 17, 2016 8:34 pm

ohmydarlingcharlie wrote:back at the coast timing 28*BTDC @3400 RPM.
idles a bit fast at this timing (1200-1300RPM).

current issue runs terriblyfrom 2000RPM to 1000RPM and back up.
You need to drop the idle speed down to 1,000 rpm.
Back at the coast, the engine has redeveloped compression/power.
Your distributor advance is taking off on you at 1,200-1,300 rpm. If you have an idle stabilizer, then the ECu is chasing its tail.

Turn in the idle speed screw clockwise to lower rpms to 1,000 rpm. Do this slowly so ypu can catch the moment that the centrifugal timing drops out.
I never thought highly of the nomenclature from the factory.
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

ohmydarlingcharlie
I'm New!
Contact:
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Tue Nov 29, 2016 6:00 pm

Amskeptic wrote:
ohmydarlingcharlie wrote:back at the coast timing 28*BTDC @3400 RPM.
idles a bit fast at this timing (1200-1300RPM).

current issue runs terriblyfrom 2000RPM to 1000RPM and back up.
You need to drop the idle speed down to 1,000 rpm.
Back at the coast, the engine has redeveloped compression/power.
Your distributor advance is taking off on you at 1,200-1,300 rpm. If you have an idle stabilizer, then the ECu is chasing its tail.

Turn in the idle speed screw clockwise to lower rpms to 1,000 rpm. Do this slowly so ypu can catch the moment that the centrifugal timing drops out.
I never thought highly of the nomenclature from the factory.
Colin
I was able to adjust the idle using your instructions but this did not solve the bucking.

I ended up changing the rotor and this solved the problem.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

ohmydarlingcharlie
I'm New!
Contact:
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Tue Nov 29, 2016 6:24 pm

For the past two months I have been traveling through Peru and some of the its Andes.
DSC04102.JPG
Huayhuash, Peru


When I got to 8000ft I adjusted the timing to 36*BTDC (hose off 3400RPM) and turned the mixture screw 1.5 turns ccw. This worked for a while (total turns 6.75 ccw). I also moved my idle screw 1/2 turn ccw.

At 10 000 ft, the idle would drop and shut off so I adjusted the timing to 40*BTDC (hose off, 3400RMP) and turned the mixture strew +0.5 turns ccw. (total turns 7.25 ccw. )

When I traveled to 13 000-14 000ft the idle would drop and want to shut off but I kept the van running by pressing the gas. I slept at 14 000ft and was able to restart the van in the morning. On a different day, the van turned off while going over a speed bump at 14 000ft and I needed to push start the van to get it going.

I will be returning to elevation shortly. My question is:
1. When at 13 000ft+(I may reach 16 000ft) should I adjust the timing above 40BTDC?
2. Is there a maximum timing that should never be passed?
3. I was thinking I should continue advancing the timing because it seems to compensate for the altitude but past 40BTDC is there another RPM figure I can use other 3400 because I am beyond the marks on my scale?
4. Does octane rating make a difference to run better at elevation? I am currently using 90 octane but 84, 90, 95 are available in Peru.

Cheers and thank you itinerant air cooled team.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Tue Nov 29, 2016 7:16 pm

ohmydarlingcharlie wrote:For the past two months I have been traveling through Peru and some of the its Andes.

DSC04102.JPG

When I got to 8000ft I adjusted the timing to 36*BTDC (hose off 3400RPM) and turned the mixture screw 1.5 turns ccw. This worked for a while (total turns 6.75 ccw). I also moved my idle screw 1/2 turn ccw.

At 10 000 ft, the idle would drop and shut off so I adjusted the timing to 40*BTDC (hose off, 3400RMP) and turned the mixture strew +0.5 turns ccw. (total turns 7.25 ccw. )

When I traveled to 13 000-14 000ft the idle would drop and want to shut off but I kept the van running by pressing the gas. I slept at 14 000ft and was able to restart the van in the morning. On a different day, the van turned off while going over a speed bump at 14 000ft and I needed to push start the van to get it going.

I will be returning to elevation shortly. My question is:
1. When at 13 000ft+(I may reach 16 000ft) should I adjust the timing above 40BTDC?
2. Is there a maximum timing that should never be passed?
3. I was thinking I should continue advancing the timing because it seems to compensate for the altitude but past 40BTDC is there another RPM figure I can use other 3400 because I am beyond the marks on my scale?
4. Does octane rating make a difference to run better at elevation? I am currently using 90 octane but 84, 90, 95 are available in Peru.

Cheers and thank you itinerant air cooled team.
40* is it, if you do not want to damage the engine.

Be very very sure to retard the timing as your elevations drop.

At this rarified elevation, you have pretty much left factory parameters. Use your mind. Do not go into a drunk-logic stupor like, "if 40* idling timing helped it at 10,000 ft, then 80* has GOT to help it at 20,000 ft."

All you can do now, is to try to cram as much air into the engine as it will take, and make the fuel mixture sufficiently volatile, which lower octanes can do just fine. You want a correctly lean mixture.
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

ohmydarlingcharlie
I'm New!
Contact:
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by ohmydarlingcharlie » Tue Nov 29, 2016 9:11 pm

Amskeptic wrote:
40* is it, if you do not want to damage the engine.

All you can do now, is to try to cram as much air into the engine as it will take, and make the fuel mixture sufficiently volatile, which lower octanes can do just fine. You want a correctly lean mixture.
This is exactly what I wanted to know. 40* is the maximum and I will stick with that.

Since 40* is it, should I just continue to lean out the mixture screw in combination to using 84 octane?

Can I use the idle bypass screw? I have enough power at elevation. My only real issue right now is that the engine dies when it is left to idle.
1982 Aircooled Vanagon Westfalia, FI, Federal
Canada to South America. Currently in Colombia.
Follow along @ohmydarlingcharlie on Facebook and Instagram

User avatar
Amskeptic
IAC "Help Desk"
IAC "Help Desk"
Status: Offline

Re: 82 Vanagon idle drop at elevation in the Andes

Post by Amskeptic » Wed Nov 30, 2016 3:28 pm

ohmydarlingcharlie wrote:
Amskeptic wrote:
40* is it, if you do not want to damage the engine.

All you can do now, is to try to cram as much air into the engine as it will take, and make the fuel mixture sufficiently volatile, which lower octanes can do just fine. You want a correctly lean mixture.
This is exactly what I wanted to know. 40* is the maximum and I will stick with that.

Since 40* is it, should I just continue to lean out the mixture screw in combination to using 84 octane?

Can I use the idle bypass screw? I have enough power at elevation. My only real issue right now is that the engine dies when it is left to idle.
Yes, you want to overcome the lack of burnable oxygen up there by cramming more air through the engine at idle. However, you don't want to crank the screw out so far that it falls out or begins to allow air leaks.
ColinWayDownAt440ft
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

Post Reply