[T3] cool weather idle hunt

[Daniel Nohejl]

We dropped the car off for an alignment today and b/c of scheduling issues, we won’t have it back until next weekend. 

As for the cold idle hunt, I tried spraying around the engine compartment with carb cleaner again to see if I could get the idle to smooth out but no dice at any of the joints. The only thing that calmed the idle down when hunting was to pull the AAR hose off of the air cleaner and put my thumb over it. When cold, the idle drops hugely and stabilizes. I also checked again when warm and with my thumb on the hose the idle actually drops about 150 rpm. Could it be that the AAR is too open during cold start and/or that it intermittently closes beyond an expected point which causes my periodic warm idle lope/hunt and stalling issue? Since posting, the warm idle issue hasn’t cropped up so I couldn’t wiggle connections to see what’s up.

Daniel


> On Dec 2, 2016, at 1:50 AM, Jim Adney <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
> Madison, Wisconsin, USA
> *******************************
> 
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