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Date:         Sun, 21 Jan 2007 11:07:45 -0800
Reply-To:     Michael Diehr <md03@XOCHI.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Michael Diehr <md03@XOCHI.COM>
Subject:      Re: Ping/Knock/Detonation
Comments: To: Dennis Haynes <dhaynes@OPTONLINE.NET>
In-Reply-To:  <000001c73d75$f1bcaad0$6400a8c0@MASTERPC>
Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed

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?


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