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IP Throttle Advance: Mechanical vs. Vacuum Actuated
by
eaders
on 16 Dec, 2017 11:28
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Hello,
I did an honest and thorough search and could not find what I needed...
I am currently doing an AAZ rebuild. I have two IPs; 1) from a 1.9B/1.6H hybrid in a Vanagon custom project by the PO; and 2) another from a stock 93 Passat. I will be using the IP from the Vanagon as it has an LDA/BP and I was told that the Passat pump is an ECO model.
The Vanagon pump (286) has a mechanical spring loaded lever for the Throttle Advance. The Passat pump (323) has a vacuum actuated Throttle Advance. My understanding is that this vacuum actuator was tied into the EGR system (with the valves for vacuum being controlled electronically from the glow plug relay). However, I am not installing an EGR system on my new rebuilt motor.
So, what I want to know is, would it be beneficial to transfer the Vacuum Actuator from the 323 pump to the 286 pump for Throttle Advance? It will fit externally but can it be done without opening the pump up (i.e. changing internal parts)? Or would it be better to just leave the 286 pump as a mechanically controlled TA?
Also, could someone please confirm my understanding that the Throttle Advance is used in situations of high load to allow for proper fuelling? If so, I would want to tie the Vacuum Actuator lever into something that pulls high vacuum under load? Are there any other situations you would want Throttle Advance?
Thanks for the help friends!
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#1
by
burn_your_money
on 17 Dec, 2017 20:45
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It's only used on cold starts to increase the idle to decrease warm up time and make the engine run smoother. It has nothing to do with anything other than idle settings.
But perhaps a picture or two to confirm we are talking about the same thing would be a good idea.
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#2
by
ORCoaster
on 17 Dec, 2017 22:07
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Yes, are we discussing the mechanical lever on the back of the pump that is tied to the cold start knob inside the cab? And the advance mechanism on the front of the pump that uses vacuum?
If so then those just control timing at start up and then the internal pump pressure takes over once you get about 1200 RPM or there about.
IIRC.
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#3
by
eaders
on 18 Dec, 2017 12:25
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You folks are great! Thank you.
My understanding is the cold start lever is on the back of the pump at the
bottom. They are mechanical on both pumps and they both use the same screw down clamp to hold the cold start cable in place/adjusted.
The one I'm talking about is on the back of the pump at the
top. I found a diagram somewhere that labeled it as the 'Throttle Advance' lever. Here is a link to photos comparing the two:
https://imgur.com/a/Hhuu5If I recall correctly (1.5yrs ago) when I took the Vanagon pump off it didn't even have the throttle advance connected to anything...
Any and all information, knowledge, or resources you can share would be amazing. Thank you!
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#4
by
vanbcguy
on 18 Dec, 2017 12:30
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My 93 Passat Eco pump had a vacuum idle bump, with a separate cold start handle. It increased the idle speed whenever the glow plugs were active (that is active in afterglow, after startup while cold). Helps reduce vibration at idle till the engine is warmed up a bit.
The other style of pump simply links the high idle to the cold start handle. Pull the handle, get high idle. Push the handle, goes back to normal.
I think the "automatic" system was purely used as the Passat was supposed to be a top of market car for VW. The body vibration at idle when cold exceeded what VW would allow for that market segment. Better to take control away from the operator rather than lose a sale!
The manual setup is clean, simple and works just fine. I liked having that in my Jetta, high idle in 2nd gear was exactly the right speed for playground and school zones. ;-)
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#5
by
eaders
on 19 Dec, 2017 11:54
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vanbcguy you are awesome; this information is fantastic!
Confirming what you said, in order for me to get the vacuum actuator to work I would have to get some N-style valves for the glow plug relay to control vacuum to the actuator; then it would activate vacuum during glow plug activity?! Sadly, I don't think I kept them when I stripped the Passat but I can source used ones. The manual setup has both the Cold Start and the Throttle Advance working tandem?
Based on that, will my glow plug relay from my '82 Vanagon be able to control that function like it did in my Passat? Is the '82 Glow Plug Relay System even compatible with a '93 Passat engine (I heard there are fast glow and slow glow plugs)? Is there a benefit to separating the control of the Cold Start and the Throttle Advance, like is done with the ECO pump?
Like you said, it sounds easier to just use the manual setup. After reflecting on it, I am pretty confident that that lever from the photo (for the manual setup) was NOT connected to anything when I removed the pump. At the time I found it odd, but the pump worked just fine before my block failed so I didn't really question it too much. That being said, if I am adjusting the manual setup, how much RPM would I want to increase idle by during cold start/glow plug relay activity?
Thanks again friends!
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#6
by
vanbcguy
on 19 Dec, 2017 12:40
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From what I could figure out the vacuum solenoid was simply connected to the glow plug power supply. I know when my GP fuse failed the idle bump didn't engage either.
I had mine set up for about 1150 RPM at fast idle.
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#7
by
burn_your_money
on 26 Dec, 2017 00:36
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Pretty sure the vacuum controlled ones are from cars with AC.
The B3 and 82 glow plug relays are not the same at all. 83 is a simple on, start engine, off while the B3 is on, start engine, turn on and off to control emissions etc.
Personally if using the vacuum fast idle I would tie it in with the AC switch and also a second toggle switch in the cab so you can control it. You just need a simple 12v vacuum switch.
The rod actuated fast idle had 2 positions. All the way out was fast idle and timing advance and part way out was just timing advance (or maybe it's just fast idle, I forget).
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#8
by
vanbcguy
on 26 Dec, 2017 15:53
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No AC on my car, but yes they definitely did hook it in to the AC on some vehicles.
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