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Stuartzickefoose
Samba Post Whore
Joined: February 07, 2008
Posts: 10350
Location: SoCal for now...
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 Posted: Tue Jan 20, 2015 2:09 am Post subject: |
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Vacuum leak?
What year is the bus?
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Stuart Zickefoose
2011 Jetta Sportwagen TDi 6 speed manual
206-841-7324
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borninabus
Samba R&D Dept.
Joined: May 18, 2006
Posts: 4536
Location: Arizona Highways
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| Posted: Wed Jul 20, 2016 10:51 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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hello FI folks 
here's a strange one:
82 fed Vanagon w/ stock LJet that is giving me a weird symptom.
main issue is intermittent missing when warm and no hot start when symptoms arise.
in tracing electricals (fuel pressure good) I've noticed that when i put a test light on the coil neg, it flashes normally but starts to kill the engine.
it will choke and die if you leave the test light connected.
so i am in process of cleaning FI and main engine grounds right now.
oh! it does the same thing with 2 different coils and changing out the pertronix for points did not help either.
any insights appreciated.
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88 Van WBX, A/T - 13 JSW TDI 6M/T - 2012 Touareg TDI Sport |
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airschooled
Air-Schooled
Joined: April 04, 2012
Posts: 12721
Location: on a bike ride somewhere
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| Posted: Wed Jul 20, 2016 11:01 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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I think the test light acts as a temporary ground for the #1 terminal and shorts the engine. We used to play a prank on my high school music teacher by switching his reverse light spade from #15 to #1 on the coil so it would die every time he would put the car in reverse. Same theory!
Robbie
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Tcash
Samba Member
Joined: July 20, 2011
Posts: 12844
Location: San Jose, California, USA
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| Posted: Wed Jul 20, 2016 11:02 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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Test for a High tension leak
Ignition High Tension Leaks |
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borninabus
Samba R&D Dept.
Joined: May 18, 2006
Posts: 4536
Location: Arizona Highways
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| Posted: Wed Jul 20, 2016 11:30 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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you're right, robbie.
you can only do the "test light flash" method while cranking, not while the engine is running.
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88 Van WBX, A/T - 13 JSW TDI 6M/T - 2012 Touareg TDI Sport |
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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 Jul 20, 2016 11:48 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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| oh! it does the same thing with 2 different coils and changing out the pertronix for points did not help either |
If grounds don't get it then it might point to a too rich or too lean condition.
TS II being loose, corroded or bad can cause a too rich. That might seem like a stumble when hot and a failure to start when hot.
Have you tried a cylinder balance test by pulling each plug wire at the cap to see if one cylinder is weak? I'd try that and make sure the TSII is not loose or corroded. RAtwell has the resistance measurements.
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borninabus
Samba R&D Dept.
Joined: May 18, 2006
Posts: 4536
Location: Arizona Highways
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| Posted: Thu Jul 21, 2016 10:18 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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well, after many trials and tribulations this one ended up being ignition related.
even though the rotor, wires & cap all tested ok, i replaced them anyway and the problem went away.
just a friendy reminder that many FI issues are not FI issues at all 
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88 Van WBX, A/T - 13 JSW TDI 6M/T - 2012 Touareg TDI Sport |
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SGKent
Samba Member
Joined: October 30, 2007
Posts: 41031
Location: Citrus Heights CA (Near Sacramento)
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| Posted: Thu Jul 21, 2016 11:18 am Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic |
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| borninabus wrote: |
well, after many trials and tribulations this one ended up being ignition related.
even though the rotor, wires & cap all tested ok, i replaced them anyway and the problem went away.
just a friendy reminder that many FI issues are not FI issues at all |
as the plugs wear the gap widens. The gap is what sets the firing voltage. Narrow gap lower voltage than wider gap. Wires and caps, rotors can carbon track. Since wide plug gaps require higher voltage to fire that can stress an ignition system that is on the edge. A warm engine his higher compression than a cold one usually. Higher compression raises firing voltages too. That higher firing voltage again pushes the system over the edge. It is always a long shot when an engine with plug wires is misbehaving.
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martyrg
Samba Member
Joined: February 29, 2004
Posts: 452
Location: South Lyon, MI. 48178
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| Posted: Sun Sep 24, 2023 3:17 pm Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic FAQ |
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Hi Everyone,
Veteran type 1 guy here, however I'm new to buses, type IV's and Bosch L-jettronic FI.
My 1978 bus with stock FI is having a problem. With the engine fully warmed up and in gear (any gear) it will run OK until I push the gas pedal past a certain point, then the engine acts like it is running out of gas-slows way down, no power, etc. It happens around 3000 rpm. If I push the pedal to the floor it continues to act like it is running out of gas. After 4 - 5 seconds the engine starts to speed up, but then slows down like it is running out of gas. If I back off the pedal to idle, the engine will eventually catch up and run OK.
If this were a carbureted engine I'd think the acelerator pumps were bad.
The bus does have a new fuel filter and a fresh tank of gas.
What should I be checking / testing / replacing? |
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busdaddy
Samba Member
Joined: February 12, 2004
Posts: 51130
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sun Sep 24, 2023 3:28 pm Post subject: Re: I Need Help with L-Jet / AFC Fuel Injection Topic FAQ |
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Start with the simple stuff, ground the wire leading to the TS2 (temp sensor in #3 head) to the case when the engine is warmed up and go for a drive, any different?
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