[T3] cool weather idle hunt

[Keith Park]

BTW Jim, have you had a chance yet to crank up the idle speed on your
73 and see if that idle cutoff is indeed removed on the late cars?
Im pretty sure it has been, and its important to using the E system
on the T4 motor when that goes back in the car someday

Keith


Topnotch Restorations
topnotch at nycap.rr.com
http://www.a383ina68.addr.com/radiorest/main.htm
71 Squareback  "Hothe"
65 Notchback  "El Baja Rojo"
93 RX7  "Redstur"
87 Golf  "Winterat" RIP
01 Sentra SE "Boremobile"
 
-----Original Message-----
From: type3-vwtype3.org [mailto:type3-vwtype3.org-bounces at lists.vwtype3.org]
On Behalf Of Jim Adney
Sent: Thursday, January 12, 2017 3:18 PM
To: type3 at vwtype3.org
Subject: Re: [T3] cool weather idle hunt

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On 12 Jan 2017 at 8:10, Daniel Nohejl wrote:

> I feel like the words hunt and lope are getting a little
> confused.....at least in my head. In my head, a 'hunt' is what I've
> been describing at warm-up idle, where the speed surges very high then
> dips down until going away and a 'lope' is the weak/stalling idle I've
> been describing. Is that the correct application of the terms?

Yeah, the definitions are fuzzy and probably vary depending on who 
you talk to.

I use "lope" to describe the situation where the idle goes so high 
that it hits the FI closed throttle rpm threshold ~1400 rpm. That 
shuts the FI off until the rpms drop to something like 900. Then it 
repeats. It sounds much like there's someone on the gas pedal who's 
blipping the throttle every few seconds.  

To me "hunt" means more like a random wandering of the idle speed. 
Could be up, could be down, could be fast, could be slow.

There's no real idle stabilization in the D-jet system, so the idle 
on these cars is never rock solid stable. Nevertheless, even though 
it's not clear to me what you're experiencing, it's clear that it's 
something out of the ordinary for your car.

If you didn't have the new electronic VR, I'd suggest that this was a 
sticky VR relay, which happens when they get old. The contacts weld 
and then break free. This causes the generator to go from full on to 
completely off every few seconds. At idle, this causes the engine to 
slow down every time the generator goes full on. This jerkyness in 
the generator causes the generator to jerk on its belt, which rather 
quickly leads to the generator pulley breaking as the belt gets 
wedged down in the pulley groove.

Maybe the new VRs have a similar fault, but a loose wire at the 
generator or the VR could cause the same thing. '69s were the first 
year that got ground wires on everything, but VW didn't bother to 
connect the ground wire nicely to the VR at the factory; they put it 
under the mounting screw, rather than to the less rust prone ground 
screw. Does the new VR have a separate ground screw? Is the ground 
there secure?


-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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