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

Sun Dec 10 17:53:51 PST 2017

 Jim :

 I haven't checked the ECU yet I will.

 When I got this car it had a MAP Bosch number 0280 100 106  Vw # 311 906 
051E . The 72 had a Bosch 0280 100 101 / VW 311 906 051 D and what it has 
now is only Bosch 0280 100 116  no VW #.

 Back in 91 since the one that came on this car looked old and was screwed 
together yet all 3 have the same nose and black cap and ground tab on the 
MAP not knowing I put the 051D on it , it was riveted together and looked 
new . I had it tied to the 016 so I could drive to Vegas and just swap the 
plug and hose and it ran the same which is not to say it was right . I had 
the 051D on it since 91 until 2015 . I tried to pass smog with the 106 and 
tried to adjust it and marked it any adjustment just didn't help with 
passing smog. When I rebuilt the 72 engine and installed it in 97 I still 
had the 051D on it and at that time they had a dyno at the ford dealer where 
I worked and it passed smog. All I knew back then is they all looked the 
same all had the black tamper cap and ground . It was just under the wire of 
being rich at idle.

 It did run great . I'm not saying I shouldn't have matched parts .

 I only know the ECU has a black tag and it is an E unit. If it does not 
have a Bosch number on it I'm not sure what that might mean. Now days trying 
to locate one would be quite a task with the proper Bosch number that you 
provided. Then if I do whether it's any good is another issue besides the 
cost.

 97 is a long time ago and fuel has changed so much since perhaps they ran 
fine on that fuel yet not so much any longer. In 91 I could still get leaded 
fuel by 97 it was just lead free.

 Russ years ago had a chart and it was only VW numbers by then I wasn't sure 
what mine was yet it was the 051D.
----- Original Message ----- 
From: "William J" <catnine09 at dslextreme.com>
To: <type3 at vwtype3.org>
Sent: Sunday, December 10, 2017 4:14 PM
Subject: Re: [T3] On a 73 T-3 SB fuel injected auto trans pinging

>
> ----- Original Message ----- 
> From: "Jim Adney" <jadney at vwtype3.org>
> To: <type3 at vwtype3.org>
> Sent: Sunday, December 10, 2017 1:29 PM
> Subject: Re: [T3] On a 73 T-3 SB fuel injected auto trans pinging
>
>
>>I was concerned that I was mixing up different IAD front covers when I 
>>said
>> there was a tiny hole at the PCV outlet. I just went down and looked at a
>> '72-3 IAD and, you're right, it does not have a tiny outlet hole. The 
>> tiny outlet
>> hole is only on the '68-9 IAD with the optional cold start valve. As a 
>> double
>> check, I also blew thru the '72-3 pipe to make sure there wasn't some
>> internal restriction in there and there isn't.
>
> Jim ; did you notice on your 73 IAD if the MPS port has a 3 mm ID 
> restrictor inside it . it's right near the end and flush can't miss it . I 
> thought perhaps it was placed there to maybe compensate for the size of 
> the PCV port of the IAD cover.
>
>
>>
>> Nevertheless, I don't see that system causing a problem. It's possible,
>> however, that the PCV valve in the breather box has dirt in it, which 
>> makes it
>> stick open or closed at times. That might explain your idle variation. 
>> Try
>> removing and cleaning it.
>
> There is a bit of dirt in the breather . It's not bad and since it has a 
> sort of wall betwen the two cap sides although they are open at the top 
> the PCV itself does not look bad just a bit of dried oil film on the valve 
> itself it wouldn't hurt to clean it.
>>
>> I understand that you've already got the valves and timing done 
>> correctly.
>>
>> Here are some other things to try/check/consider:
>>
>> '72 & '73 MAP sensors and brains have the same VW part #, but they have
>> different Bosch numbers. I've always suspected this was because VW/Bosch
>> felt that the later part numbers would be backwards compatable, but this
>> does not insure forward compatability. You need to make sure you have the
>> '73 version of each
>>
>> The '73 brain has a Bosch part # ending in 048. (The '72 brain is 024.)
>>
>> The '73 MAP sensor has a Bosch part # ending in 116. (The '72 MAP sensor
>> is 106.)
>
> I never looked to see if the ECU has a Bosch # it has the proper VW number 
> . I would need to look . The one from the 72 has no # all I see is the 
> clean area wwhere the # tag was. At the time in 97 when I was trying to 
> pas smog here in Calif were are now exempt up to 74 models . I didn't have 
> internet and not knowing I removed the VW E  ECU and installed the one for 
> the 72 and got the same reading's based on emissions Both were just a bit 
> rich on idle yet the same and both just made it at the higher RPM 
> something like 2500 if I recall. Both have the ground on the ECU case as 
> well as the thermal unit used for the EGR . I don't know if the 72 was a 
> sold in Calif car didn't have the EGR.
>
> The MAP has only a Bosch number which ends in 116
>>
>> I believe you're already using the correct AH distributor.
>>
>> These parts were all developed to make the vacuum advance/retard
>> distributor used in '72 unnecessary. They work together, as a team.
>>
>> Regarding your ping. My first recommendation would be to take the car for 
>> a
>> nice long drive. If that fixes it, great, if it does not, stop halfway 
>> thru your
>> drive and top up your tank with the highest octane gas you can find. If 
>> this
>> fixes or severly reduces the ping, you know that what you have is actual
>> ping, caused by compression pre-ignition.
>>
>> If high octane gas does not change the ping, this is not real ping, but
>> something else.
>>
>> (If you're already using premium gas, try regular. If going to regular 
>> doesn't
>> make the ping get a lot worse, then this isn't ping.)
>
> The Ping is gone . I did add 4 gallons of 89 octane before I put the AH 
> dist in . It did strike me odd that the ping was so sudden and the first 
> thing I thought was fuel since we now have the winter blend and for it not 
> to ping at all then all of a sudden . Normally distibutors don't suddenly 
> stick or have weights hang up . Yes if a spring breaks or maybe a fiber 
> washer under one  weight cracked and fell out. This didn't happen . Over 
> all since I cleaned and lubed the AH and changed the shaft shims that were 
> worn, it's better since now it takes a second to return to 5 BTDC rather 
> than 2 minutes. Also the ping the sound I heard was quite a bit louder 
> than a normal ping . It sounded like a ping , I'm familar with that sound 
> , this sounded like it was timed at far more advanced than 5 BTDC . At the 
> same time and I only allowed it to ping for a few seconds , I didn't feel 
> any power loss . It just caught me by surprise , didn't know if it was my 
> car or another car near me and as son as I backed off it was gone . The 
> very next stop it didn't do it and I knew it was my car . This is what 
> made me think it was the Dist .
>>
>> Regarding the cyl head temp sensor, just leave it alone. There's more
>> resistance in series with that sensor inside the brain. (In the one 
>> schematic
>> that I've been able to find on the web, there's a 300 Ohm resistor that 
>> gets
>> connected in series, only at idle.) It's always possible that something 
>> has
>> gone wrong with the circuit inside the brain, but the brains have been
>> extremely reliable over the years.
>
> So far as the ECU has worked as far as the fuel pump relay times out and 
> it starts once I prime it a bit , Starts right up once it's been started . 
> Yet there are resistors and caps and transistors in them as well as solder 
> joints and anything over all these years can go out of spec especially 
> caps . I've built tube powered guitar amps they don't have transitors and 
> by design produce far more heat from the tubes and resistors do go out of 
> spec and even new ones do not all read the same yet close enough. The caps 
> in an amp are electolytic , this type is used only to filter out ripple 
> converting A/C to D/C  and resisters used are high temp between these caps 
> what they do is drop voltage since each tube from pre amp to power 
> requires less voltage . The other caps are used in tone circuits and most 
> often they stay within spec and are not electrolytic . When the power 
> section filter caps get old you get noise or they leak or dry out and can 
> short and kill the power transformer. Now on transister guitar amps caps 
> last a long time .
>
> I imagine these ECU's can have out of spec resistors and mostly the caps . 
> Yet here we have low voltage 14.5 at best and the caps are more than 
> likely rated @ 25 to 50 volt yet over years if the leak or dry out then 
> you will have issues As you know they really only store a charge or may be 
> used as filters in these ECU's . I can't imagine changing all these ECU 
> parts . At least they don't use IC's
>>
>> BTW, I believe all the VW/Bosch cyl head temp senors are the same, except
>> for details like the length of the wire, the insulation, and, possibly, 
>> the style
>> of connector.
>
> Yes they seemed to replace then all with one part number long ago ending 
> in 041A if I recall.
>
> The one thing I'm still trying to understand . That's how all the issues I 
> have just vanish once I unplug the air temp sensor . The miss is gone , 
> the idle is stable and I no longer have that 1500 RPM when engine cold 
> with AAR open . I set it @ 950 hot idle in park and it stays there . Once 
> the AAR closes and it does just takes longer than it should , the idle in 
> drive is 850 nad always drops to 850 put it in park it's 950 . Before it 
> was all over the map . This tells me it's lean if the 10% across the board 
> rule applies , with what I see it seems to , I don't know the precise % 
> yet what ever it is it works.
>>
>> -- 
>> *******************************
>> Jim Adney, jadney at vwtype3.org
>> Madison, Wisconsin, USA
>> *******************************
>>
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