[T3] Question about D jet idle issues 73 T3

William J catnine09 at dslextreme.com
Wed Jan 27 14:21:58 PST 2016


Jim:

 I didn't even know whe the vacuum advance unit failed . I only noticed it 
in 2009 and then plugged the line so I would not have a vacuum leak during 
high vacuum conditions which would be at idle or decell or steady speed load 
dependant. It's possible that vacuum can vacuum leak allowed the engine to 
run a bit more rich at idle no load. It's not a large hose yet a vacuum leak 
no less.

 With that said a few questions.

 1) You set the timing with the vacuum line off/plugged so it will not 
affect the base timing. Once it's connected and at idle throttle closed it 
will advance the timing to a point because at that point the vacuum is high 
, at least I think so it depends on which side of the throttle plate the 
vacuum advance port is I would need to look at the 73 IAD I have , can't 
recall . Yet thinking about it say it's on the oil bath side and at idle 
throttle closed due to the air bypass there is still vacuum on that port. 
I'm pretty sure it's on the oil bath side of the throttle plate. Yet it 
didn't seem to have this issue at idle that I noticed. Trust me I really 
never noticed this issue at idle until march 2015. It's not like I go 
looking for things . Would you say the increase in timing from the advance 
at idle above the base 5 BTDC may make it a bit leaner or perhaps since the 
points and advance are tied to the same shaft as the trigger points if 
advanced at idle a bit above 5 BTDC you would have spark sooner say a split 
second before the trigger sends the signal to the ECU , would this affect 
the lean/rich?

 2)  The trigger points I got are Bosch were in a Bocsh box got them because 
the two other sets I had were bent as if at some point someone screwed with 
them . I had to hand them over to this place if I recall because I don't 
have them and I would not toss them. I think he gave me a break on the price 
if I gave him the old ones .

 I know this is not an accurate way to check the trigger points yet when I 
had the AH dist apart and an ohm meter connected to the trigger ground and 
one side I marked the rotor right at the point where that set opened so just 
about when the trigger cam lifts , did the same with the other side and the 
rotor was 180 degrees from the first mark . I always grease the cam lobe. I 
did turn the rotor in the direction so the mech advance would not move .
 I was able to drive today about 12 miles but only at traffic speed 30 MPH 
had the IAD sensor unplugged. Acted just like it did with the old 101 MAP .

 3) What about the HTS dropping to 90 OHM once it's run just warm not hot . 
It does read at temp what the charts I have found suggest or the Bentley 
suggests only cold not to be open which it wouldn't run or above 2500 ohms 
temp dependant which really tells you nothing . Would adding 250 ohm 
resister possibly bring it more rich?

 4) On the injector plugs . The 2&4 are brown not gray like the Bentley 
suggests . 3 had no boot and 1 has the shank that is black . I did check 
from the ECU connector yet can't recall if I actually checked each pin from 
the ECU to each injector plug . I always put them where they always were and 
never had this issue , the cables have a set to them . That was 2009 at this 
point I just can't recall . I read if they are switched this could cause an 
unstable idle or poor speed transition would this possibly if switched be 
somewhat compensated for by unplugging the IAD temp sensor or act up at all 
times.

 I need to drive it with that temp sensor plugged in . The only thing is it 
never pings and I don't drive highway speeds yet if I stomp on it I don't 
hear a ping. In the past when the Vacuum advance did work up a hill even at 
low speed I would hear it I know what it sounds like. The only thing that 
makes a change is that temp sensor at this point . I had a vacuum gauge T'd 
into the line from IAD port to MAP port and what I found with the sensor 
plugged in and engine warm it would fluctuate up and down , once I pulled 
the temp sender it was steady so this fluctuation has to be screwing with 
the MAP big time. I found this true even if I raised the RPM and it didn't 
steady out until 2000 RPM no load. If I had access to a sniffer I could tell 
what it's doing yet I don't . I say this only because with everything 
connected and driven I have no idea what the AF mix is. Yet popping out the 
exhaust by letting off the throttle quick going about 30 MPH seems to me or 
at least I'm told this is unburnt fuel burnt in the exhaust caused by an 
exhaust leak . I do have a bit of a leak on the right HE to the crappy EMPI 
header that I sealed better . The stock muffler was fine yet when I removed 
it to swap the engine the muffler pipes to the HE pipe was paper thin and at 
that time I didn't have $450 to spare and no internet or sites like this or 
Samba all I had was the Bentley and Haynes and my own long term experience 
working on Fords mostly as a tech then a assistant service manager /shop 
foreman/quility control manager / tech trainer and all around heated up 
customer complaint person. When I bought this car in 85 I got it from the 
used car lot and opened the lid and thought what is this , all these pipes 
and wires. Wish I was 36 now , be a lot easier to bend over that rear bumper 
to work on it. Back in 85 we still had leaded fuel and my car was only 12 
years old. VW dealers still had many new parts wish I had stocked up.

 Finally , since I don't foresee a time I can get by for 10 days without 
this car what would the 505 cost if you will sell me one. And if I send a 
dist do you set the mech advance to what it would be spec wise.
  I'm sorry for the long posts I just felt it needed to cover all I could 
and offer all info I can , perhaps it will help others here. Next posts I 
will keep it short all I know I have expressed.
William


----- Original Message ----- 
From: "Jim Adney" <jadney at VWType3.org>
To: <type3 at vwtype3.org>
Sent: Wednesday, January 27, 2016 11:57 AM
Subject: Re: [T3] Question about D jet idle issues 73 T3


>I have 505 vac cans, but that's only an fuel economy part and would
> not cause your symptoms.
>
> Your best eventual distributor solution would be to send both
> distributors to me sometime when you could do without the car for 10
> days. I could swap everything over to the '73 dist, including the
> Pertronix, and install a correct 505 vac can.
>
> When I was working on figuring out how to adjust the FI trigger
> points, several people on this list were good enough to send me some
> NOS and very new trigger points for comparison. The NOS set was
> non-Bosch, the only such set I've ever seen, and it was totally out
> of whack. (That's the technical term.) It would never have worked at
> all, until I adjusted it.
>
> I'm not a fan of NOS. I'm afraid lots of people see NOS as the holy
> grail and are willing to spend big bucks on such things, when good
> used (and tested/proven) parts are cheap. About the only parts I will
> routinely replace are exhaust valves. Everything else gets
> tested/inspected and reused or replaced with good parts, new or used.
>
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
>
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