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RE: [T3] idle problems

I believe the 1200-1500 range is a little high for the idle.  The idle, when the engine is warm, should be 850-900 rpm.

Also, that very slight vacuum from the AAR you mentioned earlier can cause the hunting you described.  What happens to the idle when you disconnect the AAR from the intake distributor and plug the hole with you finger?  If the hunting disappears, you need to look at the 

>From the "Hunting at idle at all temperatures" section of my d-jetronic troubleshooting web site @ http://www.geocities.com/MotorCity/Shop/4123:

	A. Leakage in intake manifold 
	        Pull auxiliary air regulator hose off at intake elbow and close it with the thumb 
	        If idle is steady, go to B. 
	        If engine continues to hunt: 
	            Pull intake elbow off throttle valve support 
	            Close off by-pass drilling with thumb and listen for sucking noises (put picture here) 
	           Possible causes for leaks: 
	                - Hoses between intake manifolds and intake air distributor 
	                - Intake manifold gaskets 
	                - Rubber mountings for injectors 
	                - Vacuum hoses 
	            Eliminate all leaks found 
	
	B. Auxiliary air regulator not closing 
	        Type 3 (automatic) and Type 4: 
	            Run engine and check if there is voltage at the connection on auxiliary air regulator 
	            If voltage present, replace regulator 
	            If no voltage, check wire to terminal 87 on pump relay and repair. 
	        Type 3 (manual) Replace mechanical regulator 

Good luck
Jay
'72 411
'79 Type 1 convertible	


> ----------
> From: 	Seldom[SMTP:seldomss@yahoo.com]
> Sent: 	Wednesday, March 08, 2000 8:41 PM
> To: 	type3@vwtype3.org
> Subject: 	Re: [T3] idle problems
> 
> This afternoon I had time to look at the Fuel
> Injection on my '70 Fasty again.  I went over all
> manifold connections etc. with a propane torch looking
> for vacuum leaks... nothing.  I found the specs. for
> resistance between the two outer and two inner pins on
> the pressure sensor connector and verified they were
> good.  I also found that by cracking the hose
> connection running from the manifold to the pressure
> sensor just right, the idle smoothes out and jumps
> back up to the 1200-1500 rpm range. does this say
> something about the condition of the diaphragm?  (I
> interpreted it as meaning it's good).  Unbelievably,
> the thermostat is there and functioning.  I also took
> it out on the highway, hoping to burn off some of the
> carbon crud built up from having a faulty voltage
> regulator.  Sure is sweet to drive.  
> 
> And, following many suggestions, I ordered the Bentley
> manual :-) Thanks!  It should be in on Friday.  I
> suppose once I receive it I can do a more systematic
> check of things but if anyone has any suggestions what
> to look at next, I'm all ears.
> 
> -Damian
> 
> Almost forgot, here's a more complete description of
> the cars behavior than in my last post:
> 
> From a cold start the car has a high smooth idle ~
> guessing 1200-1500 rpm.  After 2-3 minutes, the idle
> drops to ~ 1000 rpm and starts hunting.  Within
> another 2-4 minutes, the hunting is severe enough that
> it'll stall out.  
> 
> 
> Thanks,
> -Damian  
> 
> --- Jim Adney <jadney@vwtype3.org> wrote:
> > On 5 Mar 00, at 21:05, Seldom wrote:
> > 
> > > The vehicle:
> > > 70 Fastback 85K original miles, AT, F/I
> > 
> > > The status:
> > > Replacing the voltage regulator made a huge
> > difference
> > > with the richness problem so now the car runs well
> > > under load, but the hunting remains.
> > 
> > > The details:
> > > - Fuel pressure is at 30 PSI
> > > - I've adjusted the throttle valve, and it seems
> > to be
> > > functioning properly 
> > > - resistance for temperature sensor I & II seem to
> > be
> > > within specs, both when warm and cold
> > > - auxiliary air regulator seems to be working OK> 
> > > although there is a very slight vacuum, even when
> > the
> > > car is fully warmed up. 
> > 
> > These all sound perfectly normal.
> > 
> > > - The idle adjustment screw has no apparent affect
> > > (vacuum leak I thought!) but
> > > - Hoses seem to be in OK shape - I'll replace them
> > > next.  In any case, I haven't been able to find
> > any
> > > obvious vacuum leaks.
> > 
> > Places to check: intake manifold gaskets, pressure
> > sensor 
> > diaphram. One way to check is with a propane torch
> > (unlit); when 
> > the engine sucks in propane instead of air, the
> > richness changes 
> > and you can note the change in the engine.
> > 
> > Having changed the VR you should also change the oil
> > now, and 
> > just getting it running and warm will often have
> > good effects. Make 
> > sure that the thermostat is connected and operating
> > correctly. If 
> > the engine can't warm up, it can't burn off all the
> > carbon that has 
> > accumulated.
> >  
> > -
> > Jim Adney
> > jadney@vwtype3.org
> > Madison, WI 53711-3054
> > 
> >
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> > 
> > 
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