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Roger Priddle
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Joined: November 01, 2017
Posts: 1
Location: Penetang, ON, CA
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 Posted: Wed Nov 01, 2017 11:24 am Post subject: Fuel Exhaust relay module |
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... for an '82. (P/N 071 906 069)
Apparently these are hard to come by... I'm in Ontario, Canada.
My local (extremely competent, and very helpful) repair guy says I need one, but we're having trouble finding it. Apparently, the alternative is to revert to a Carb.
Anyone got any good ideas? |
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djkeev
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Joined: September 30, 2007
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Location: Reading Pennsylvania
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Vanagon Nut
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Joined: February 08, 2008
Posts: 10379
Location: Sunshine Coast B.C.
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| Posted: Wed Nov 01, 2017 12:23 pm Post subject: Re: Fuel Exhaust relay module |
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I was curious so googled a bit.
That part number took me to a thread here
https://www.thesamba.com/vw/forum/viewtopic.php?p=7944968
containing the image below.
I have to wonder if your relay has any fractured solder joints. If the start fault for sure lies at that relay, and it's considered broken, it doesn't take much work to reheat any fractured joints with a soldering iron. (lower Wattage type)
Neil.
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1988 West DIY 50º ABA
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T3 Pilot
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Location: Deep South of the Great White North
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Abscate
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Location: NYC/Upstate/ROW
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| Posted: Wed Nov 01, 2017 12:56 pm Post subject: Re: Fuel Exhaust relay module |
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Is it really 126 USD for two relays and wiring ?
Sounds like a project to build a workaround with two 8 buck relays would pay off
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djkeev
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Location: Reading Pennsylvania
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djkeev
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T3 Pilot
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Posts: 1507
Location: Deep South of the Great White North
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| Posted: Wed Nov 01, 2017 1:32 pm Post subject: Re: Fuel Exhaust relay module |
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http://www.busdepot.com/0332514121
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1988 Vanagon
The most important part in every vehicle is the nut behind the wheel...... |
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djkeev
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djkeev
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Joined: September 30, 2007
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Location: Reading Pennsylvania
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| Posted: Wed Nov 01, 2017 2:10 pm Post subject: Re: Fuel Exhaust relay module |
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Looking at the wiring diagram, the relay seems simple enough.
It has four white wires.
They are identified by numbers....
#2 goes to terminal #15 on the coil (hot with key on)
#6 goes to ground
#8 goes to the throttle valve switch. The throttle valve switch gets the injector power (typically 5v) from the ECU terminal #3. (The injectors pulse by the ECU making and breaking ground)
#4 goes to the injectors
My relay thought goes like this......
Turn on the key, coil terminal #15 gets +12v, this 12v activates the relay by utilizing the ground path through wire #6.
The relay when energized completes the fuel injector voltage feed from the throttle valve switch to the injectors.
Why do they make a simple relay so very complex?
I'm sure there are reasons just as there are for utilizing solid state turn signal flashers, but I don't know their logic.
If it were my vehicle, I would so pick up a common relay and wire it in to see if it works.
Dave
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http://www.thesamba.com/vw/forum/viewtopic.php?t=392473
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http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537
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https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert |
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djkeev
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monstersteve
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Joined: June 14, 2006
Posts: 24
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| Posted: Tue Mar 27, 2018 1:40 pm Post subject: Re: Fuel Exhaust relay module |
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That might not work. But there is another simpler hotwire that would work.
The reason jacking in a basic relay might not work is this gizmo (speed limit switch, fuel enrichment module, OXS relay) is not just a simple relay. It may be responsible for reducing voltage to the 5v needed by the injectors Alternatively, it may involve regulating when the relay functions based upon engine rpm. That is at least, according to SlowLane in this post : https://www.thesamba.com/vw/forum/viewtopic.php?t=...y+3000+rpm
That is what all that fancy circuitry may be about. In other words, the rpm aspect prevents the WOT switch from bypassing the ECU to dump fuel into the TB when you floor the pedal unless your motor is running 3000 rpms or better. This is supposedly set up to prevent the damage to your Catalytic Converter that may occur if a flood of gas gushes in there without the motor running fast enough to burn it efficiently.
Frankly, I cannot remember a situation where I have driven my '83 CA van where I have floored the car at less than 3000 rpm. First of all, that maneuver would not result in the desired response. It would be much more effective to drop the thing into a lower gear and use the better torque to zip around the slow moving truck or whatever. Granted I drive a stick shift and have a webcam and a number of other modifications that allow me to take the rpms past manufacturer recommended shift points. Even so, I question whether this gizmo offers any real value to someone that is properly driving a Vanagon.
So, if it fails, if you have no CAT or if you just plain don't want some weird obnoxious, unnecessary piece of electronics in your engine to complicate your diagnostic zen, here is what you can do instead of searching for an NLA, impossible to find part. Eliminate it. That's right, just bypass that sucker. There are 4 wires. One of the wires goes to the WOT switch (my guess is it brings 5v from the ECU through the WOT switch to the relay when the ECU gets 3000+ rpm). One wire goes to the coil (either power or to get the rpms or both?). Another goes to the injectors. Another goes to supply ground.
So get your meter out and isolate the power wire and figure out which side the WOT switch supplies 5v volts (it's either coming from the ECU or from the coil, right?) and do some splicing. If you get 5v at the WOT switch coming from the ECU when you rev the engine to 3000 rpm (what I suspect), then you need to remove the wire between the WOT switch and the ECU and get a resistor and wire to replace it and supply constant +5v to the WOT switch. Then splice the wire on the other side of the WOT switch to the wire going to the injectors. Otherwise (what I don't suspect is the case - if your 5v is produced inside the OXS relay), you will want to unplug the wire from the coil to the OXS sensor and put your resistor on that wire from the coil (to reduce the +12v to +5v), pull the wire running between the WOT switch and OXS sensor and splice it to your coil wire to supply constant 5v through the WOT switch and then (when you floor it) through the ECU and on to the injectors.
One way or the other, depending on where your 5v is coming from, you should be able by some simple re-wiring be able to bypass this gizmo out of the equation and your WOT switch will function unimpeded by any rpm regulator. Your CAT will be fine so long as you don't lug the engine like by jumping on the throttle when going 40 in fourth, which you are not going to do anyway because if you do that instead of dropping into third the van is just going to do the mechanical equivalent of "uhg" instead of giving you the zoom you want.
Okay, I have not run my little test and have not tried it (yet), but this seems like a simple way to work around this part.
Happy trails ! |
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Wasted youth
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Joined: July 06, 2012
Posts: 5134
Location: California's Hot and Smoggy Central Valley
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| Posted: Fri Dec 03, 2021 1:20 pm Post subject: Re: Fuel Exhaust relay module |
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What should happen if this relay is removed when the engine is idling?
https://www.thesamba.com/vw/forum/viewtopic.php?p=7946409#7946409
FCP Euro shows this part as the same:
This is the module on the California emissions 1981 Vanagon. It is not a relay:
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