Diagnosing D-Jet Problem...solution & update, All of a sudden...loss of power... Options

[MikeInMunich]

Greetings once again from Munich gentlemen! (IMG:style_emoticons/default/bye1.gif)

It started with a thought and no wood to knock on, seriously! (IMG:style_emoticons/default/mad.gif)

I was driving around Munich about 6 weeks ago and thought to myself, this car is running perfectly and needs nothing. What could go wrong? Then literally, less than a few minutes after that, it started. A light hesitation in the lower RPM range. Seemed like the car was choking a bit, or missing on once cylinder.

I was at a D-Jet workshop last year with Dr. D-Jet. See https://oldtimer.tips/de/

Volker is a great guy and knows as much about this system as anybody. He tested the vacuum on my MPS last year and informed me that it was "borderline". So that was the main culprit. I took it out, sent it to him and this year it was indeed worse and thus the main culprit. Volker disassembled it and replaced the copper diaphram. Now it's tight like new. Some may be surprised that this is possible and / or where he got a new diaphram from. He had them manufactured or perhaps, I'm not sure, manufactured them himself. PM me if you want / need one and I'll send you his email address.

So, with my restored MPS I hooked it up and, low and behold, the problem was quite the same, only about 10x worse! (IMG:style_emoticons/default/hissyfit.gif)

Now, with the car immobile and Volker hundreds of km away, I'm practically on my own, with his and your advice, to try to track down the real problem.

Volker thinks that because the MPS was operating sub-optimally previous to my purchase of the car that the mechanic or the P.O. had compensated elsewhere to get the car to run properly and that now that the MPS is sending a different signal to the CPU, things are off.

More info:

Just before the problem started my milage was really bad
The CPU is the correct one for my MPS and working according to specs. Volker tested it.
Engine has about 5,000 miles on it. Was rebuilt and running GREAT.
Fuel pressure was set at 29 psi only about a year ago. I reckon it could have hardly changed on its own since then. (IMG:style_emoticons/default/idea.gif)
The engine was originally a 1,7 but is now 2liters with a “proper FI performance Webcam” (as stated by the mech ic who rebuilt the engine)

No adjustments were made to the FI to get it to run properly. It was running excellentwith a virtually perfect idle when warm and just slightly rough for the first 3 Miles or so.

TPS plate and air temp sensor are new.

What do y'all reckon could be the culprit? What should I be testing?

I'm taking it to a place to tell them what to test, including:

Fuel Pressure
Plugs
Compression
CO value
TPS setting
Timing & dwell
search for Vacuum leaks
grounds
Valve adjustment
Fuel filter
Relais
Injectors...

What else should I have them look for?

Thanks for your input!

With best regards from what was just ranked The Most Livable City in the World by Monocle Magazine,

Mike in Munich