[T3] On a 73 T-3 SB fuel injected aut trans pinging .

William J catnine09 at dslextreme.com
Wed Dec 6 21:20:30 PST 2017

----- Original Message ----- 
From: "Jim Adney" <jadney at vwtype3.org>
To: <type3 at vwtype3.org>
Sent: Wednesday, December 06, 2017 7:22 PM
Subject: Re: [T3] On a 73 T-3 SB fuel injected aut trans pinging .

> On 6 Dec 2017 at 16:28, William J wrote:
>> Perhaps I have either a vacuum leak that comes and goes or a head temp
>> sensor that is erratic. Also as you said Jim when I open the throttle and
>> let it close it takes a second to drop to idle speed. At least the timing
>> returns to normal much faster yet why it did ping once bugs me . I did 
>> get
>> some where changing the dist .
> It sounds like you were right about the other dist having a sticky advance
> mechanism, and it sounds like you've fixed that.
> An erratic vacuum leak is certainly a possibility. I would check to see if 
> you
> have the right FI air runner to head gaskets. (Have we been down this road
> before?) The correct gaskets are hard to find and don't come in any gasket
> set.

 The gaskets are the proper ones , the one place that used to sell and stock 
them near me the owner passed away and now they don't sell much at all 
mainly bug parts and bus parts . The ones on there have been on it since 97 
as well as the runner sleeves. .
> Also check to make sure the nuts are tight on those gaskets and that the
> (front) cover bolts on the IAD are tight. The sleeves on the air runners 
> can
> also leak if the parts have been installed skewed.

 Last time in 97 when I had the IAD off I cleaned the entire unit and made 
sure the back cover was tight and used sealer on the original gasket. I 
haven't checked the nuts to see it they are still tight on the intakes.
> See if you can find something to plug the inlet to the AAR, just to take 
> it out
> of the picture. If the idle then settles down, maybe there's something 
> erratic
> about the AAR.

 That thing the AAR you know today it closed fully while running it to check 
the timing . It seems to work half the time.
> I don't have any idea why you would have ping, unless this engine had been
> running extremely rich for a long time and had built up a bunch of carbon 
> in
> the heads that could glow and cause pre-ignition. I believe you said this 
> was
> an X engine, which should have the dished pistons giving and even lower
> compression ratio, which should make ping extremely unlikely.

  I used a late U engine that I pulled from the 72 . It was also a FI auto 
trans engine . The X engine developed a rather loud internal rattle and even 
though it ran fine I drove it like that while I rebuilt the 72 . When I did 
I used flat top pistons and all new German bearings I did this in 97 . Both 
engines did have dished pistons yet no one sold them any more that I could 

 As far as running rich the only thing I can offer is I've brought up this 
erratic miss before. If I unplug the air temp sensor which as far as I know 
makes it run richer that erratic miss completely goes away as soon as I 
unplug it. The best I can describe this is to say once I start the car it 
runs fine , if I unplug this sensor cold engine  it idles worse with in a 
few minutes I can feel and hear this erratic miss . I say erratic because 
it's not steady like one cylinder it's like all the cylinders are affected 
and the odd part is it does not always do this . How ever most of the time 
it does . A few weeks back I cleaned all the FI case grounds and tightend 
them , one was two grounds in one of those plastic connectors used all over 
these cars . I tried to pull it apart and one ground snapped and it was 2 
strands of wire so I removed it and spliced the grounds soldered and heat 
shrink. Point being I started it up and was surprised that 90 % of that miss 
was gone . Then a few days later I pulled the TPS plug and used 2 VW male 
connectors to test out the TPS and it checked out fine. THen thinking well 
maybe since the ign switch is original perhaps since most of the time it 
lives in the run position it might have a voltage drop so I checked for 
voltage drop starting at the battery cables then from the neg cable to all 
the engine grounds all I found was a 1 volt drop at the coil positive. I got 
the same reading using the positive battery post to the coil engine running 
so I had all the draw there.

 You may recall the horn issue I was looking at , felt well I'll pull the 
wheel and fix that and replace the ign switch.

 Then last friday out of the blue this pinging showed up . In between all of 
this the erratic miss came back before the ping . I went out there just a 
bit ago to see if I could see any plug wire arcing since it's dark . Nothing 
. I started it and while looking for an arc within the exact amount of time 
here comes the erratic miss so I unplugged that sensor it went away right 
now and then left it off and since the RPM rose to 1250 I lowered it to 900 
in park just to see how it drives with more fuel .

 I do realize and may have said I don't drive it much maybe 400 miles a year 
and none since 2006 has been freeway it's all max 45 MPH in stop and go 
traffic which could cause carbon build up . I leave it in 2nd gear so the 
RPMs are up yet this is not like 65 MPH . I only drove it once back in 2015 
on the freeway and it ran well yet even then half the time I was sitting on 
the freeway or going 25MPH.

 Yet carbon build up is something that I always noticed well before pinging 
came about not to say it's not possible. Correct me if I'm wrong here, say 
you have carbon built up and even though this is FI and say the carbon is 
red and there is still some fuel pressure in the ring wouldn't it run on 
like cars with carbs used to do ?  It just seems odd to me that it came on 
out of the blue.  I thought perhaps I got some bad fuel since we now have 
winter blend and I put in 4 gallons to what was in the tank from the last 
fill up Aug 1st it was under 1/2 tank . When the ping came I added 3 gallons 
of 89 octane . It's hard to judge MPG when all I do is stop and go driving , 
my best guess is 100 miles per tank. I never see black smoke out the exhaust 
as one would see with low voltage and really can't say if 10% ethonal would 
produce any smoke seems like it would .

 I'm really sorry about this very long post . I also really do appreciate 
you taking the time to offer advice.  It's just so frustrating . In my mind 
most of this seems fuel related as if it's to lean I say this because the 
air temp sensor makes it idle smooth and not only that . With it plugged in 
if I sit in the car in park and bring up the RPM from 900 it struggles until 
it reaches about 2200 RPM and if I hold the pedal steady in between these 
figures the RPM's hunt . I pull that sensor and all of this just ends like 
turning off a light switch. I'm at the point where I'm beginning to wonder 
if the 19 year old Pertronix is the fault . I called them and asked if they 
can cause missing and was told yes and also no start and erratic operation. 
I did install a new magnetic ring I had for the AH and the unit has a good 
ground thing is this clears with the sensor unplugged . I'm going to go , my 
mind races and intermittent running issues drive me nuts. I fix one thing 
and something else crops up and it's probably some wire or ground or crazy 
vacuum leak. Think I fixed it and it comes back.
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
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