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keithferraro Samba Member
Joined: September 17, 2006 Posts: 10
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Posted: Tue May 22, 2018 7:07 pm Post subject: Cold Bus Requires Revving to Warm |
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The Bus- 79 Fuel Injected
Assumptions, Mechanically sound ignition, FI, Timing, etc.
Before mentioning that I should have found this topic in an old thread, I honestly tried hard and couldn't find it anywhere. A little CSV talk,etc. but not this specifically....
Bus starts very well (indicating working cold start valve), then tries to stall around the 5-8 second mark, you rev to revive, 5-8 seconds, repeat. At the 1-2 minute mark (right after you finish rolling your cigarette, per Muir) the bus idle will drop but not quite stall and it will idle fine permanently from there. The bus runs fine once warm. It's trivial, I don't mind revving but I'd like for it run as it were mechanically intended. I don't believe that it's the cold start valve, nor the thermo-time switch as it fires up well when cranking. |
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Tcash Samba Member
Joined: July 20, 2011 Posts: 12844 Location: San Jose, California, USA
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Posted: Tue May 22, 2018 7:26 pm Post subject: Re: Cold Bus Requires Revving to Warm |
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Auxiliary Air Regulator (AAR) |
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keithferraro Samba Member
Joined: September 17, 2006 Posts: 10
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Posted: Tue May 22, 2018 8:12 pm Post subject: Re: Cold Bus Requires Revving to Warm |
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Thanks Tcash. Not sure how I missed that. subsequent reading has me agreeing with you. I've got some testing to do, and probably some searching at the junkyard. Thanks! |
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Tcash Samba Member
Joined: July 20, 2011 Posts: 12844 Location: San Jose, California, USA
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aeromech Samba Member
Joined: January 24, 2006 Posts: 16922 Location: San Diego, California
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Posted: Tue May 22, 2018 8:39 pm Post subject: Re: Cold Bus Requires Revving to Warm |
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Pull the AAR and place on the bench. Look down the throat. You should see an open window. Apply 12 volts to the two pins and watch the window close down. Let it cool and watch the window open back up. Pretty simple to test _________________ Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
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Capable of leaping tall buildings in a single bound |
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airschooled Air-Schooled
Joined: April 04, 2012 Posts: 12687 Location: on a bike ride somewhere
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Posted: Tue May 22, 2018 10:46 pm Post subject: Re: Cold Bus Requires Revving to Warm |
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The AAR is VERY similar to cracking the throttle open, so good advice there. A multimeter test of the TS2 cold and warm would be wise too. You should have 250-400 ohms fully warmed up, 2000-3000 ohms on a summer morning before your first start, and above 5000 ohms when below freezing. It should be snug in the mount, but not corroded, and the wire connection should be clean and free of broken wire strands.
Robbie _________________ Learn how your vintage VW works. And why it doesn't!
One-on-one tech help for your Volkswagen:
www.airschooled.com |
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jtauxe Samba Member
Joined: September 30, 2004 Posts: 5778 Location: Los Alamos, New Mexico
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Posted: Wed May 23, 2018 6:18 am Post subject: Re: Cold Bus Requires Revving to Warm |
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keithferraro wrote: |
Bus starts very well (indicating working cold start valve), then tries to stall around the 5-8 second mark, you rev to revive, 5-8 seconds, repeat. At the 1-2 minute mark (right after you finish rolling your cigarette, per Muir) the bus idle will drop but not quite stall and it will idle fine permanently from there. |
This is one notable piece of advice that has been debunked. If you look in your VW owner's manual, it says that you should not rev it to warm up (as this is when the engine is cold and experiences the most wear), but rather that you should get it started and drive off right away. That will warm it even faster, reducing the time of running in a cold state. _________________ John
"Travelling in a fried-out Kombi, on a hippie trail, head full of zombie..." - Colin Hay and Ron Strykert
http://vw.tauxe.net
1969 Transporter, 1971 Westfalia, 1976, 1977, 1976, 1977, 1971, 1973, 1977 Westfalias,
1979 Champagne Sunroof, 1974 Westfalia Automatic, 1979 Transporter, 1972 Sportsmobile, 1973 Transporter Wild Westerner, 1974 Westfalia parts bus, 1975 Mexican single cab *FOR SALE*, 1978 Irish 4-door double cab RHD
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Wed May 23, 2018 7:17 am Post subject: Re: Cold Bus Requires Revving to Warm |
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the bus was designed to get in and drive away (as John said see owner's manual). If it fails to do that then do a full tune up and check for vacuum leaks. Don't believe everything Muir wrote. It is dated and more toward the days of the split or early bug. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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Tcash Samba Member
Joined: July 20, 2011 Posts: 12844 Location: San Jose, California, USA
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Posted: Wed May 23, 2018 7:42 am Post subject: Re: Cold Bus Requires Revving to Warm |
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Sometimes u can clean them. Do a search there is a good thread. |
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