| Author |
Message |
TurkisMafia
Samba Member
Joined: August 21, 2019
Posts: 186
Location: Sarasota, FL
|
 Posted: Tue Oct 15, 2019 9:31 am Post subject: High idle in park - 78 Automatic EFI |
 |
|
Hi All,
Recently, I’ve had an odd little issue with my bus. After I drive it around for a few miles, if I put it in neutral or park, I get an extremely high idle. If I shut the bus off and start it again, it idles normal. It’s an EFI with an automatic. Anyone have any direction on this?
I think this thread may touch on some solutions but I’m having trouble fully wrapping my head around it:
https://www.thesamba.com/vw/forum/viewtopic.php?t=385580
Thanks!
_________________
1961 Turkis Sedan, 1641cc
1963 Turkis Ragtop, 1200cc
1963 Turkis Vert, 1200cc
1963 Turkis Single Cab, 1600cc
1964 Turkis Standard Walk-Thru, 1641cc
1978 Westfalia 2.0L EFI Automatic
Turkis Mafia
Turkis Mafia Facebook Group
Sunny Sarasota, Florida |
|
| Back to top |
|
 |
udidwht
Samba Member
Joined: March 06, 2005
Posts: 3779
Location: Seattle, WA./ HB, Ca./ Shizuoka, Japan
|
| Posted: Tue Oct 15, 2019 9:34 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
Vacuum leak.
_________________
1972 Westy Hardtop/Type-4 2056cc
96mm Biral AA P/C's~7.8:1CR
Headflow Masters New AMC 42x36mm heads w/Porsche swivel adjusters
71mm Stroke
73 Web Cam w/Web solids
Dual 40mm IDF Webers - LM-2 - 47.5 idles/125 mains/190 air corr./F11 tubes/28mm Vents - Float height 10.45mm/Drop 32mm
Bosch SVDA w/Pertronix module (7.5 initial 28 total @ 3400rpm)
Bosch W8CC plugs
Pertronix Flamethrower 40K coil
S&S 4-1 w/Walker QP 17862
3 rib 002 Trans
185R14 Hankook tires |
|
| Back to top |
|
|
sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5995
Location: Brooklyn
|
| Posted: Tue Oct 15, 2019 9:34 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
Make sure your ignition timing is set properly and also fix any vacuum leaks you have.
_________________
1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
|
| Back to top |
|
|
TurkisMafia
Samba Member
Joined: August 21, 2019
Posts: 186
Location: Sarasota, FL
|
| Posted: Tue Oct 15, 2019 9:41 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
Just last week I had it in an air cooled shop who went thru the whole bus (I just purchased it). I had a restored svda distributor installed. It only started after i picked it up. They checked and fixed all vacuum leaks, or so I was ensured, maybe they set the timing wrong? What’s weird to me is that it’s just if I cycle the bus off then immediately back on... it runs perfect. to me that would eliminate timing or vacuum leaks? I figured it was something with the FI. I am new to VW’s tho, I know little to nothing about anything 
_________________
1961 Turkis Sedan, 1641cc
1963 Turkis Ragtop, 1200cc
1963 Turkis Vert, 1200cc
1963 Turkis Single Cab, 1600cc
1964 Turkis Standard Walk-Thru, 1641cc
1978 Westfalia 2.0L EFI Automatic
Turkis Mafia
Turkis Mafia Facebook Group
Sunny Sarasota, Florida |
|
| Back to top |
|
|
SGKent 
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
|
| Posted: Tue Oct 15, 2019 9:52 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
best guess is the idle is too high so the distributor advance is kicking in. That or sticking,
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
|
| Back to top |
|
|
sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5995
Location: Brooklyn
|
| Posted: Tue Oct 15, 2019 10:44 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
| Danam404 wrote: |
| Just last week I had it in an air cooled shop who went thru the whole bus (I just purchased it). |
that don't mean shit, to be quite frank. Seen plenty of crap/incompetent work on this forum by air-cooled shops.
| Quote: |
| I had a restored svda distributor installed. It only started after i picked it up. |
Hmm let's hear more about this distributor. Quite possible it's wrong for your Bus. See if you can recover the original one.
| Quote: |
| They checked and fixed all vacuum leaks, or so I was ensured, maybe they set the timing wrong? What’s weird to me is that it’s just if I cycle the bus off then immediately back on... it runs perfect. to me that would eliminate timing or vacuum leaks? |
No.
| Quote: |
I figured it was something with the FI. I am new to VW’s tho, I know little to nothing about anything |
The FI has no knowledge of or control over the idle speed. The idle speed is controlled completely mechanically by a bypass air passage around the throttle plate and the size of that passage can be adjusted by a screw, thus restricting the amount of air that can flow around the throttle plate.
Ask the shop if they fucked with this screw.
You should NOT fuck with this screw until you are sure that a) the engine is fully warmed up and b) you have eliminated any vacuum leaks.
Vacuum leaks allow extra air in past the throttle plate and can therefore cause rpm to increase. If there is enough of a leak it can even keep the idle speed adjusting screw from having any effect on the idle speed at all, even if screwed in all the way.
_________________
1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
|
| Back to top |
|
|
WhirledTraveller
Samba Member
Joined: January 09, 2008
Posts: 1399
Location: Cambridge, MA
|
| Posted: Tue Oct 15, 2019 1:10 pm Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
| Danam404 wrote: |
| Just last week I had it in an air cooled shop who went thru the whole bus (I just purchased it). I had a restored svda distributor installed. It only started after i picked it up. They checked and fixed all vacuum leaks, or so I was ensured, maybe they set the timing wrong? What’s weird to me is that it’s just if I cycle the bus off then immediately back on... it runs perfect. to me that would eliminate timing or vacuum leaks? I figured it was something with the FI. I am new to VW’s tho, I know little to nothing about anything |
Can be caused by mechanical advance sticking on the "restored" distributor.
However regular old vacuum leaks/high idle can also cause similar symptoms. What can happen is that you get into a bit of a feedback loop. When you start it, idle is normal and advance is normal. You rev it, and the mechanical advance - advances. Then when you let off the gas, the advance is still advanced and it doesn't *quite* go back to where it should be because the revs are just enough to keep it advanced and the advanced timing causes higher revs, a catch 22. In order for everything to work correctly everything has to be correct... idle air screw, idle mixture, distributor timing and advance curve, etc etc.
Also don't overlook a sticky accelerator pedal. Try pulling UP on the pedal next time it does it.
_________________
1977 Westy, Automatic. Big Valve heads, CS Cam. |
|
| Back to top |
|
|
Wildthings
Samba Member
Joined: March 13, 2005
Posts: 50338
|
| Posted: Wed Oct 16, 2019 9:18 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
I will go so far as to say you may have a weak primary spring in your distributor. There are two springs in the distributor one (the primary) that works over the entire rpm range and one that only has effect at higher rpms. If the primary spring is weak it will allow the timing to advance too quickly at idle and/or not return as others mentioned. It is very likely that your distributor went years or even decades without having any oil applied to the felt that sits under the rotor. This felt is supposed to provide lube for the mechanical advance mechanism, but can't do so if it is not lubed occasionally.
The taps onto which the springs are hooked have little plastic pieces on them that can crack and fall off over the decades, once gone the springs will effectively be too long to work correctly |
|
| Back to top |
|
|
airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12721
Location: on a bike ride somewhere
|
| Posted: Wed Oct 16, 2019 9:36 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
Later automatic buses used an electronic decel valve that was actuated during deceleration but also at idle to act as an idle speed control valve, (to boost the idle airflow when a gear is selected to combat torque converter loss.)
Sorry I have to run and I can't expand on this sooner, but the throttle body MUST return and close the circuit on the throttle body switch to trigger the valve to open. If the ECU is not communicating with the valve properly, you could be getting excess airflow through the auto decel valve. If you have a picture through the upper hatch of your engine, we can start diagnosing that with you.
Robbie
_________________
Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
|
| Back to top |
|
|
TurkisMafia
Samba Member
Joined: August 21, 2019
Posts: 186
Location: Sarasota, FL
|
| Posted: Wed Oct 16, 2019 9:46 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
The distributor was just restored by Bill Fowler/wcfvw69, so for now I think it’s safe to rule out a malfunction there. When I return to the bus on Sunday I will definitely snap some photos and see if we can’t go from there. I will also check for vacuum leaks. Thank you for all the input everyone!
_________________
1961 Turkis Sedan, 1641cc
1963 Turkis Ragtop, 1200cc
1963 Turkis Vert, 1200cc
1963 Turkis Single Cab, 1600cc
1964 Turkis Standard Walk-Thru, 1641cc
1978 Westfalia 2.0L EFI Automatic
Turkis Mafia
Turkis Mafia Facebook Group
Sunny Sarasota, Florida |
|
| Back to top |
|
|
sjbartnik
Samba Member
Joined: September 01, 2011
Posts: 5995
Location: Brooklyn
|
| Posted: Wed Oct 16, 2019 11:36 am Post subject: Re: High idle in park - 78 Automatic EFI |
|
|
| Danam404 wrote: |
| The distributor was just restored by Bill Fowler/wcfvw69, so for now I think it’s safe to rule out a malfunction there. When I return to the bus on Sunday I will definitely snap some photos and see if we can’t go from there. I will also check for vacuum leaks. Thank you for all the input everyone! |
Good deal, yes I would not worry about his work. I was concerned maybe you had some autozone Cardone special in there.
_________________
1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
|
| Back to top |
|
|
|
