Post Downhill Stall

[KevinRWat]

So I have a new small mystery problem (for me). '89 Multivan auto trans, starts and runs great. Yesterday and couple of days ago my van stalled when I came to a stop after exiting off of a two-mile freeway descent, fairly good grade, mostly coasting. Started right up and runs perfectly afterward. No idea what it could be. Thanks in advance for any thoughts!

[DanHoug]

were you low on fuel? the pickup is in the center of the tank and could have gotten starved if you were low and pointing downhill for a period.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[KevinRWat]

No, in fact I had just filled it the day before and only driven a few miles.

[E1]

You could have unintended air coming in that tricks the computer into thinking it needs gas. Check all vacuum lines and your air intake.

Your oil breather could also be clogged. See if you get any blue smoke when it fires back up.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[KevinRWat]

Thanks, I will definitely check the hoses in the morning and check for blue smoke after it stalls as long as I'm not in an intersection! It has been super rainy here the past few days as well which is when it stalled the first time, but have no idea if that is a problem or not. It's just a weird deal since it runs really well the rest of the time (I'm knocking on my wood desk as I write this).
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'89 Multivan, Auto

[E1]

You'll definitely see the smoke in the passenger mirror if that's happening -- but I lean towards my first theory more.

We had a longtime member here, Tom Powell, with the same issue a year or so ago, but he died.

You might search for that thread.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Howesight]

The cause of the problem could be the throttle position switch. They get intermittent on these old vans, sometimes failing to close.

Here's what happens:

1. The ECU cuts all fuel to the injectors whenever the throttle switch is closed and the engine is turning at greater than (IIRC) 2,000 rpm. The purpose of this feature is to save fuel and reduce exhaust emissions. This scenario only arises when you are engine braking, as in decelerating from highway speed, or going down a grade with no throttle applied.

2. If the throttle position switch is working intermittently, then it might not close the circuit at closed throttle position, as it is intended to do, and then the ECU does not operate the Idle Speed Controller which then does not power the Idle Speed Valve. In an automatic trans Vanagon, this usually results in stalling as the torque converter and pump create a load on the engine.

Bottom line: Remove your throttle body and clean the whole throttle position switch assembly and lube and adjust it. It is not possible to properly clean the assembly on the vehicle and it is much easier to adjust the switch with the throttle body removed.

Here are a couple links to excellent throttle position switch articles here on the Samba:

https://www.thesamba.com/vw/forum/viewtopic.php?p=5309306

https://www.thesamba.com/vw/forum/viewtopic.php?t=455400&highlight=
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'86 Syncro Westy SVX

[KevinRWat]

Howesight: This sounds like the problem exactly, since it seemed to happen when I was coasting or engine braking nearly the entire 2-mile descent. I am definitely coasting at greater than 2000rpm; it's probably more like 3500 rpm. I will give that a try and see if that cures the problem. Thanks!
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'89 Multivan, Auto

[uberaudi]

I was having consistency issues with resetting my tps...it would click at times coming off idle and sometimes it wouldn't. I pulled the tb, and only while it was on my bench realized that the switch itself was loose and moving around a bit. It's glued/taped and pressed onto the lower plate and my adhesion was gone, causing it to move around in and out of it's range. I used some 3m VHB tape on it and pressed it back on. Good to go.

I highly recommend pulling the throttle body and inspecting it thoroughly on your bench...you may find other things that need your attention. It wouldn't hurt to use a multimeter to verify the switch settings as well.

Good luck!

[KevinRWat]

Thanks again. I have not yet pulled the throttle body, but the problem seems to be consistently inconsistent. Also, when the motor does stall, which is only one time after a longer downhill, I just restart it and everything is perfect again. Any thoughts about just putting in a GoWesty throttle body?
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'89 Multivan, Auto

[E1]

I'd do a stock one.
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[?Waldo?]

By 'coasting' I assume you mean shifting the trans into neutral. My understanding is that one should never coast with a Vanagon automatic trans. I've seen a couple sad stories in the archives.

[KevinRWat]

No, I definitely do not shft into neutral with an auto trans! Sorry, coasting was not the right word. Deceleration is probably the correct term. This happens when I come to a stop after driving downhill at hightway speed with just my foot off of the accelerator since the grade is steep enough that I do not need to push on the accelerator pedal.
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'89 Multivan, Auto

[KevinRWat]

Ok so here is another little nugget of info for this little gem of a problem. I looked at the PO's documentation just now and it looks like GoWesty replaced the TPS at its shop in Los Osos in 2010, and the van has only been driven about 16k miles since then (9k of those are mine since last year BTW). The GW invoice for the TPS item shows "NLA" (which I know means no longer available) so I am wondering if GW replaced it with a rebuilt TPS or their proprietary TPS. Let me know what you think!
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'89 Multivan, Auto

[Charlyfarp]

Hello from the future . . . Did you ever find a fix for this? My 85 Manual is doing the same thing, dying after a longer downhill coast.

[Hammy1]