[T3] cool weather idle hunt

Keith Park topnotch at nycap.rr.com
Mon Jan 9 17:14:07 PST 2017

Thinking back over 25 years when mine was last drivin in the winter, I
remember having to tweak the head temp sensor to get the right warmup
mixture, and yes, adjust the AAR, they can be too slow to close and start
too open to keep the idle speed right on warmup, if its a 71 or earlier you
hit the idle cutoff at 1400 rpm or so and it will cut out.

The winter idle needed noodling with to get just right over the summer


Topnotch Restorations
topnotch at nycap.rr.com
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 Daniel Nohejl
Sent: Monday, January 09, 2017 7:49 PM
To: type3 at vwtype3.org
Subject: Re: [T3] cool weather idle hunt

When replying, please consider trimming your message. Thanks! :)

It seems pretty quiet out here on the list, but I thought I’d try breaking
out this old chestnut of my cool weather idle hunt/lope because I have some
new data and experience with it: the colder it gets (18* this morning), the
worse it is. As always, the idle surges very high and then plunges very low
but with greater cold, this cycle is shorter and sharper and much more
irritating. Like I reported a month or so ago, hoses are less than year old,
intake runners and boots are good, etc, etc. 

The only time I didn’t get this hunt/lope was when I decided to clamp the
hose from the AAR to the oil bath. While the motor struggled to stay running
for a block or two in the cold, there was no surging whatsoever and the idle
got up to normal in due time. Could it be that the AAR is too open when
cold? Is that even possible?

I also reported another hunt that seemed to happen at random moments once
the motor was warm. The idle sounds like it drops 300 rpm and does short
little surges almost as if it’s running out of gas. If I take too long to
get back on the throttle, the motor stalls. On the way home tonight in
traffic, the car stalled 5 times and another 4 times while trying to
parallel park. Jim theorized (below in messaged dated Dec 2) that this hunt
was the result of an intermittent connection, but I’ve tried gently wiggling
each connector in the engine bay on several and nothing has made any
difference (hasn’t made the idle rebound or get worse). 

I have noticed, though, that this hunt ALWAYS happens when driving in
traffic with the headlights on: thus it mostly happens at night or on rainy
or snowy days. It SOMETIMES happens under other conditions, but I haven’t
logged enough of them to report back anything of interest. 

I have a little cigarette lighter voltage meter and I’ve plugged it in
during this hunt but haven’t seen any voltage numbers I haven’t seen before.
With the headlights on in traffic, the voltage can drop as low as 11.5 but
it comes back up to about 13.8 or more once I get back on the gas which has
long been the case.

I’ve got a solid state VR, and a recently rebuilt generator. It’s probably
time to get the battery tested at the FLAPS as it’s been a while. 

In any event, I wonder if this new presentation of information rings any
bells for anyone??? It seems to point in the charging system, but perhaps
another issue is making it seem that way. 

>> On Dec 2, 2016, at 1:50 AM, Jim Adney <jadney at vwtype3.org
<mailto:jadney at vwtype3.org>> wrote:
>> To me this sounds more like an intermittent connection than anything 
>> else. One thing I would recommend that you definitely NOT do, would 
>> be to start randomly changing random components. I believe the 
>> problem you were having when you stopped by here last summer was due 
>> to the many times you had disconnected and connected the pressure 
>> sensor connector. Too many connection cycles and those connectors 
>> were loose and no longer making a reliable connection.
>> If possible, find a time when you can examine the engine while it's 
>> parked and running with this problem. Then VERY GENTLEY wiggle each 
>> connector. If you find that you have to push hard somewhere to affect 
>> the symptom, you're not pressing close to the problem. Also keep in 
>> mind that the problem could be one spark plug not firing all the 
>> time.
>> Regarding the spark plugs, check the resistances of each SP 
>> connector. Check the cap for tracks or dirt inside and out. I'm 
>> assuming you have Bosch cap, rotor, and condensor. Those never seem 
>> to give problems.
>> Assuming your 75 rpm drop occurs with the AAR and engine at least 
>> partly warmed up, this does not sound like an AAR problem. The thumb 
>> on the hose should make a big idle difference on a cold engine and a 
>> small one on a warm engine. You should check this both hot and cold; 
>> if you don't get both correct responses, your AAR has seized up 
>> again.
>> On 1 Dec 2016 at 20:02, Daniel Nohejl wrote:
>>> I continue to have a very annoying loping idle that begins about 2
>>> minutes after a cold start in the AM. I´ve tried lowering my idle
>>> speed to around 850 and then to 800 to no avail. I wrote back in
>>> October that I´ve pulled the AAR hose off the air cleaner and put my
>>> thumb over the end and have found that the idle dips about 75 rpm.
>>> ITMve tried spraying around various joints and hoses with carb cleaner
>>> and havenTMt found anything at all.?There was no lope during last
>>> winter, spring, or summer. It started this fall and I havenTMt touched
>>> any h?ses, the intake runner boots, or the intake manifolds which ITMve
>>> confirmed are tight to the head. Yes, I could just accept it, but ITMd
>>> prefer not to, especially b/c we havenTMt had this issue before. Any
>>> ideas? 
>>> And here´s another problem in a similar vein. At the beginning of this
>>> month, I developed a strange idle problem. The engine would idle
>>> normally once warm but sometimes would enter a hunt phase with short
>>> and sharp peaks and valleys. When in traffic, it became problematic
>>> b/c if the hunting went on long enough, the generator light would c?me
>>> on at the low point. Sometimes, the engine would stall if I didnTMt get
>>> my foot on the gas quickly enough after shifting into neutral and
>>> getting the parking brake on, which is hard to do in NYC traffic while
>>> negotiating cabs and crazy drivers.  This would go on for maybe 15 or
>>> 20 mins in traffic. Then, out of nowhere, the idle?would suddenly go
>>> back to normal. After a few days, this issue went away. In the last 2
>>> weeks, it has come back. Tonight, for example, in traffic, the car
>>> stalled 6 times b/c I couldnTMt get on the gas quickly enough after
>>> getting into neutral. Of course out of nowhere, the idle just went
>>> back to normal. The other morning, this ha?pened on a bridge over the
>>> East River. Not fun and potentially dangerous as some overzealous
>>> driver could easily rear-end me! ITMve tried to replicate the problem
>>> by pulling on various wires and connectors to no avail. 
>>> There are maybe 2 things I´ve encountered that sound like this hunt: 
>>> -when we´ve tried a new MPS and had the AFR gauge plugged in and it
>>> was reading very very lean. 
>>> -when the idle speed is around 600 and the motor barely runs > >
>>> Again, anyone have any ideas? 
>> -- 
>> *******************************
>> Jim Adney, jadney at vwtype3.org <mailto:jadney at vwtype3.org>
>> Madison, Wisconsin, USA
>> *******************************
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