[T3] On a 73 T-3 SB fuel injected aut trans pinging .
catnine09 at dslextreme.com
Fri Dec 8 15:13:50 PST 2017
Let me ask if I have this correct.
The idea of the AAR is to allow air to bypass the throttle plate being
closed on cold start. This extra air causes the MPS to riched the mixture =
more fuel along with the Head temp sensor . Once the engine is warmed up the
AAR should close and the head temp sensor resistance has dropped it
basically is out of the picture. These are mainly warm up devices.
At this point the MPS is the main control of the fuel to air ratio and the
5 pin TPS is what controls the full load and the 20 clicks is what add's
fuel as you advance speed which is form of enrichment .
Any vacuum leak other than the AAR for cold start enrichment is going to
cause a rich mixture . Since the MPS is reading vacuum which is based on
load is it less vacuum in the IAD that is less vacuum to the MPS= more fuel
taking the TPS out of the picture?
I ask simply because my unplugging the air temp sensor richens the mix by
10% across the board and the engine erratic miss stops tells me it's running
lean . Since from what I understand vacuum leaks cause rich mix is this
across the board ?
What am I missing here? Also what is confusing is why the idle does not
drop to set idle speed right away when I let off the gas? I know it used to.
Is this also caused by a vaccum leak?
I've read no vacuum leaks are allowed . Does this include the PCV system
this 73 has , meaning as far as I can tell the PCV closes at idle if I watch
it with the small cap off the crank case vent can then as I open the
throttle I see it open a bit.
----- Original Message -----
From: "William J" <catnine09 at dslextreme.com>
To: <type3 at vwtype3.org>
Sent: Wednesday, December 06, 2017 4:28 PM
Subject: Re: [T3] On a 73 T-3 SB fuel injected aut trans pinging .
>I installed the AH dist I rebuilt today . connected the light , set the
>dist right where the old one was and it started right up . I let it warm up
>and checked the timing without resetting the idle speed and set it to 5
>BTDC. Opened the throttle and it did return to 5 , not in an instant yet
>within a second . Then I dropped the idle to 850 and it was a hair below 5
>BTDC and returned the same . I set the idle to 900 .
> An hour later I drove it and the idle was at 800 and in 1st gear I stepped
> on it and heard a slight ping . The next stop then idle was back to 900
> and I heard no ping . I tried several times in 1st and second it seemed
> The issue is if it sits when I stopped at a store for about 30 minutes the
> idle was back to 850 I stepped on it in 1st not ping yet I thought i head
> a ping for an instant when I started it without being in drive.
> Also it has this 50 to 100 RPM up and down you could say hunt that's been
> there for some time in park and even though I dropped the idle speed even
> before the Dist deal . Sometimes it's steady most times it's not.
> I couldn't drive it far because all the traffic this time of day. It's
> better yet not right yet.
> I have no idea why the idle speed changes or how it can be set at 900 then
> drop to 800 and or 850 then return to 900. I could see when I had the idle
> set to 900 and watched the timing marks it was right on 5 BTDC then a tiny
> bit below and followed the RPM rise and fall . The only tach I have is
> mounted on the speaker grill top of dash .
> All the idle fluctuation goes away once I unplug the Air intake temp
> sensor . 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 .
> I just don't know where to look next , don't know if it's rich or lean .
> It always ran fine before 2009 and at that time I checked every thing . I
> cleaned the FI grounds and it was better then it started acting up with
> that erratic no load miss again. Then the ping deal wondered in weeks
> ----- Original Message -----
> From: "William J" <catnine09 at dslextreme.com>
> To: <type3 at vwtype3.org>
> Sent: Wednesday, December 06, 2017 12:40 AM
> Subject: Re: [T3] On a 73 T-3 SB fuel injected aut trans pinging .
>> ----- Original Message -----
>> From: "Jim Adney" <jadney at vwtype3.org>
>> To: <type3 at vwtype3.org>
>> Sent: Tuesday, December 05, 2017 9:58 PM
>> Subject: Re: [T3] On a 73 T-3 SB fuel injected aut trans pinging .
>>> On 5 Dec 2017 at 18:44, William J wrote:
>>>> The Bently state to set the timing to have the lines off and plugged
>>>> only states the engine RPM at 850 idle . Is this correct? And if so
>>>> when you
>>>> raise it back to 950 plus or - 50 RPM this may advance the timing a
>>>> bit. for an
>>>> auto matic car. What is the best way?
>>> It's always a problem if the distributor is already started up the
>>> advance curve at idle. This leads to the vicious cycle I mentioned
>>> earlier. You might want to try lowering the idle speed slowly while
>>> watching the timing to see where the advance starts. For the AT AH,
>>> it should start somewhere above 1000 rpm. So timing at 950 should be
>>> fine. Note that since there's no advance between 850 and 950 for the
>>> AT AH distributor, either speed should give you the same correct
>>> But, if you find that your advance is starting below 1000 rpm, you
>>> might try swapping the springs, just in case they got swapped before.
>>> If that doesn't fix it, you're looking for someone with a distributor
>> I had the AH in the car before and used points and it worked fine .
>> Before I took the springs off I took photo's of which spring went on each
>> adjustment post . I also checked and compared it to the AF and they were
>> the same . If you look at the upper shaft / advance shaft where the
>> springs hook to the adjustment posts one side has a larger hole with a
>> number stamped near it think it was 980 . This is where the lighter
>> spring goes . I checked even though I saw no evidence either one was ever
>> taken apart . At some point someone sprayed red grease all inside the AH
>> , you couldn't see it until I removed the points plate most of it was
>> slung all over and that plate the late type has larger openings plenty of
>> room for a spray nozzle to move around. I know the AF Dist was never
>> touched and it did work fine yet it had rust on the springs and weights
>> and on the inside walls of the body which is aluminum so it looks like
>> rust that was flung there and comes off faily easy . Point is the springs
>> are on proper from my photo's and comparing the two .
>>> As for the springs, one will be snug when stationary and that one
>>> will hold the advance to zero until its preload is met, then it
>>> controls the early, low rpm, advance.
>>> The other spring has an elongated loop so it doesn't come into play
>>> until some higher rpm, then it stops the advance until the
>>> centrifugal force also overcomes that spring's preload; that gives
>>> the flat section of the advance curve.
>>> Once the second spring's preload is met, the advance continues, but
>>> now the advance curve is less steep, because the centrifugal force is
>>> working against the combined strength of both springs.
>>> One other thing to check is to look at the 2 arms that got adjusted
>>> at the factory to set the advance curve. Look for any signs of
>>> damage, because sometimes someone loses the screw that holds the
>>> little plate that holds the points connector to the outside of the
>>> distributor. If they replace that screw with something longer, it can
>>> reach in and bend those arms when the distributor turns. That
>>> completely destroys the advance curve calibration.
>> I looked at them and they are not bent also all the screws were the stock
>> ones on both Distributors . I should have checked the AF from the 72 long
>> ago. That car sat for years at a U-haul across the street from the Ford
>> dealer I worked I bought the 73 I have from that Ford dealer , it was
>> sitting in their small used car lot. The 72 I bought for parts the fuel
>> tank was all rust inside and I'm sure moisture got in the Dist too.
>> Course all the oil caked on the engine saved a lot of it . It has to much
>> up and down play so I know the fiber shaft spacers are shot yet I don't
>> feel any side to side play in the main shaft or the upper section . I
>> think I can save it.
>> I still may go back to points if I can find well made ones . The
>> Pertronix is 19 years years old . I'd rather change points on the side of
>> the road than deal with removing the pertronix then install points. They
>> worked fine . I only changed over because I was told they hold timing and
>> seemed like every set of points I had no matter how careful I aligned the
>> contacts they always ended up touching on one edge then it would miss .
>> One day one of the Ford tune up techs told me I should try the electronic
>> so I did. I had to fiddle to get mine to line up better than out of the
>> box . Now that I don't drive all that much points would be fine .
>>> Hint: Any time you've done distributor work, always spin the
>>> distributor shaft by hand before reinstalling it. If there's an
>>> interference problem, it's MUCH better to discover it by hand, before
>>> you let the engine force it around.
>> I did that as well just to make certain nothing was hitting anything.
>>> Jim Adney, jadney at vwtype3.org
>>> Madison, Wisconsin, USA
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