[T3] Car Runs Great, but Why?

[J. Jonik]

Re/ the "Endless Fuel Problem" issue w/ 72 FI Std T-3

Follow-up, after a couple weeks of testing, on the unplugged Temp Sensor topic....

After some bad gas flooding into the engine, and irregular idling and acceleration, a friendly VW mechanic, knowing the things I've been through already, and having seen the car once, advised me to change to another Congrol Box...with the proper numbers and all. I have a few on hand.   He said testing the control box would be too much of a job...for me anyway...so just change it.  I did.   (Without a tow truck following, it was too risky to drive 13 miles to his shop.)

.Bingo!  All performance problems disappeared!...EXCEPT that it was still somewhat tricky to set the idle to make acceleration smooth.   To see what negative changes there would be, I unplugged the Temp Sensor at the Air
 Distributor.

Then, double Bingo!... The car now feels like new.  It idles regularly, accelerates without any hesitation (no need to rev a little), and it now starts right up on the first key turn.   With the Cold Start Switch unplugged and un-hosed, it needed at least a few key turns to prime up the fuel lines. But not now.  Don't understand that.   I've finally, bravely, gone out on the interstates and...well...it's just fine.  No troubling fuel smells, or fuel leaking from heater box clamps etc. And, the oil level is staying right at its level...no fuel getting into it.

I asked about unplugging that Temp Sensor not too long ago and was told that doing that makes the Control Box think the engine is cold, and that this would lead to higher fuel consumption.   Can't check that because I don't know previous MPG anyhow.

So, what explains this?  Why would sensor plugged in make car perform
 worse?  This must be a clue to something.    I tried two other sensors...but they made it a little worse idling and hesitating etc than the original one.

No...I haven't yet tested sensors in hot oil to check ohms.

Related, or not?  Should the unplugged Cold Start Switch have the fuel intake nozzle plugged...say, with a short piece of hose with a bolt in it?    Can that un-covered  Cold Start nozzle be a vacuum leak or anything?




      
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