Update for the archives -- I've had the fuel injectors rebuilt, and
so far it seems like the pinging is gone...

On Jan 21, 2007, at 11:48 AM, Bob Donalds wrote:

> Mike
> I have a used dist I could loan, sell you but you need to get out
> the timing
> light and see whats what
> someone has to get a look at the timing marks as the critter is
> misbehaving
> timing lights are cheaper than paying the tech to once again tell
> you he
> does not know
> timing light sears $30
>
> Bob Donalds
>
> ----- Original Message -----
> From: "Michael Diehr" <md03@XOCHI.COM>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Sunday, January 21, 2007 2:07 PM
> Subject: Re: Ping/Knock/Detonation
>
>
>> First, let me say thank you all for your fast & detailed responses.
>> It's such a pleasure reading that it almost makes one want to make up
>> phony vanagon symptoms just to see your minds at work.  :-)
>>
>> After reading these responses, a bell has been rung -- my 1.9 (now
>> 2.1 but still digijet) is pinging, but it also has been plagued by
>> the hunting idle problem.   What's very weird is that both the
>> pinging and hunting idle seem to come & go -- I'll run for a few
>> hours and it'll be fine, and then after a long freeway run I'll pull
>> into a gas station, and maybe once time out of 4 the idle will be up
>> around 1500 & surging.  Usually fine after filling up and restarting
>> the engine.  Drive a few more hours, stop for gas, and the idle will
>> not be high.   Very odd.   The pinging is also intermittent, though
>> with varying road noise, temperature and altitude changes it's hard
>> to say.
>>
>> It almost sounds like I have intermittent weak distributor
>> centrifugal advance springs syndrome?
>>
>>
>> On Jan 21, 2007, at 8:05 AM, Dennis Haynes wrote:
>>
>>> Bob,
>>> The VW fuel pump is roller cell pump, no vanes. For most part wear
>>> is non
>>> existent and it either works or it doesn't. Corrosion on the
>>> rollers or
>>> outer housing can be the pumps demise. Debris can cause intermittent
>>> operation and a bad motor can cause poor pump output. Most pump
>>> failures are
>>> due to running dry, blocked inlets or debris. On the 1.9
>>> distributors I have
>>> seen the diaphragms go bad and weak centrifugal advance springs.
>>> Bad springs
>>> can make real havoc with the idle settings as anything above 900
>>> rpm will
>>> cause the timing to advance, further increasing the idle speed,
>>> then at 1300
>>> rpm the fuel cut out occurs, speeds falls, fuel turns back on but
>>> O2 sensor
>>> is ignored for 30 crank revolutions, so rich mixture, idle speed
>>> creep up,
>>> ignition advances again, more idle speed, 1,300 cut off. Yes, this
>>> is the
>>> famous 1.9 idle surge.  It can also add to engine ping as the
>>> advance is not
>>> where it should be.
>>>
>>> Dennis
>>>
>>> -----Original Message-----
>>> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On
>>> Behalf Of
>>> Bob Donalds
>>> Sent: Saturday, January 20, 2007 10:27 PM
>>> To: vanagon@GERRY.VANAGON.COM
>>> Subject: Re: Ping/Knock/Detonation
>>>
>>>         Its an interseting combinations of events. I guess an
>>> extented road
>>> trip gives you the time to notice variations.
>>> The 1.9 dist has both vac advance, retard plus centrifical advance.
>>> Most
>>> check the timing at idle and asuume the rest
>>> is ok but total advance is even more important to engine life,
>>> power and
>>> ping than where it is at idle. You mentioned that you went with a
>>> rebuilt
>>> dist, rebuilt distributors have a better chance of sticking
>>> centrifical
>>> weights than the old fathful units that came out IMHO. Rebuilts
>>> have been
>>> washed and lubed maybe once so they easly stick from lack of
>>> mantanance.
>>> Mantanace? on a dist ? yes my friend right here in river city with
>>> the rotor
>>> removed on the 1.9 dist you will see a felt pad inside the shaft it
>>> requires
>>> a drop or two of 3 in 1 oil a couple of times a year to keep the
>>> weights
>>> lubed and free just like the world famous 009 bug dist plus very
>>> other dist
>>> installed in a bug from 1971 on.
>>> To little advance can be just a leaking vac hose they do rot out
>>> and or fall
>>> off. That reminds me that my 84 with a 2.1 thas a tee fitting that
>>> goes to
>>> both the fuel pressure reg and the vac canister from the plentum.
>>> If it was
>>> not 20 F and dark I might go check that on my own van.
>>> The other possiblity that comes to mind is the fuel pump just
>>> like the
>>> timing its most often checked at idle and pronounced healthy. The
>>> vaines in
>>> the pump can wear over time 20 years in some cases and idle
>>> pressure is not
>>> an indication of that the pump is doing under load with the
>>> injectors wide
>>> open so to speak. Old weak pumps might only have 20 pds at 3K under
>>> load and
>>> would show some loss just by reving the engine. lower fuel pressure
>>> sure
>>> would cause a leaner mixture and ping.
>>> I also seem to recall that when I first installed my 2.1 engine it
>>> ran very
>>> lean untill I checked the continuity of the ground wire on the left
>>> head
>>> from the coolant temp sensor the wire and connector looked just
>>> fine but
>>> zero continuity.
>>> As for timing the 2.1 engine I found 2 things 10 hp more power on a
>>> dyno
>>> once you get to 3 or 4 BTDC. Number 2 problem you run into a higher
>>> idle
>>> than desirable made worse by the fact that the engine speed screw
>>> will
>>> bottom out long before the ilde comes down to a resonable 950 or so.
>>>
>>> My conclusions
>>> 1) Check timing both at an idle and at 3K is best.  When reved it
>>> should
>>> total about 54 deg
>>> 2) TDC is a good place to set the timing on a 2.1 with the digijet
>>> system
>>> 3) Never trust a dyno reading to tell you where to set the timing
>>> (this from
>>> the school of hard knocks)
>>> 4) check the fuel pump pressure at idle and at 2k
>>> 5) checking the exhaust gas with a 4 gas anilizer again at and
>>> above idle
>>> can tell you lots about the injection system.
>>>    Another option would be a fuel air ratio meter with the wide
>>> band 02
>>> sensor $300   ( how many hours labor is $300 at your local repair
>>> shop )
>>> 6) very few repair shops do the pin testing needed to see what the
>>> computer
>>> is getting from the sensors threw the wiring harness AND blame
>>> the dam
>>> rebuilder for a sh--ty job "must be the cam is in wrong send it
>>> back"
>>> 7) Ranting seeping in it is past the cocktail hour
>>> 8) my spell check does not work
>>> 9) Always carry a trash bag in your van and only you can prevent
>>> forest
>>> fires
>>>
>>>  going faster miles an hour with the radio on
>>>
>>> I remain
>>> Bob Donalds
>>> Boston Engine
>>>
>>> all rights reserved
>>>
>>> ----- Original Message -----
>>> From: "Michael Diehr" <md03@XOCHI.COM>
>>> To: <vanagon@GERRY.VANAGON.COM>
>>> Sent: Saturday, January 20, 2007 1:02 PM
>>> Subject: Ping/Knock/Detonation
>>>
>>>
>>>> I'm finishing up a long (3K miles) road trip and the van has been
>>>> running like a champ (for the first time ever, wahoo!).   However,
>>>> I've noticed a problem with pinging (aka knock aka detonation).
>>>> It's very particular -- it only happens at 1/2 throttle or
>>>> higher at
>>>> 3200 thru 3500 rpm, even on 91 or 92 octane gas.   Happens most of
>>>> the time -- only exception seems to be at temperatures of 30F and
>>>> lower at 3000F altitude or higher, which seems very consistent with
>>>> it being ping (heat & pressure related).
>>>>
>>>> As far as I know, the timing of the engine is good at idle, but I
>>>> doubt that the advance has ever been tested.
>>>>
>>>> This is a 85 westy automatic with a newly rebuilt 2.1L block
>>>> installed (about 5k miles post rebuild).  It has the stock 1.9FI
>>>> system, including a rebuilt computer & distributor & afm.
>>>>
>>>> It seems weird to me that the RPM range is so specific -- it really
>>>> only does it at that particular RPM range.  Any ideas?   Bad
>>>> distributor advance?   Flat spot in the AFM?   1.9L FI system not
>>>> well matched to a 2.1L block?