slivel

I tried to look back through this thread but at 32 pages and counting, gave up on trying to find what you are using for engine control - stand alone or Porsche ECU with chip or piggyback. All commenters are looking at boost management and this may be the root cause since boost spikes are seen in your data. Could there be a secondary problem such as the ECU going into protection mode (limp mode) from a spike? This could be caused by the knock sensor reporting valid or invalid detonations. The stock ECU/KLR would go into limp mode when certain conditions were met such as over boost and detonation but would reset on an ignition off/on cycle but may not require an ignition cycle with your setup. Maybe look at this as well.

Since the problem is intermittent and not reliably repeatable, it makes for a difficult and frustrating search. Another idea might be to run a tankful of racing fuel and see if the problem reoccurs.

Frank@Work

I started post 470 Link with the setup. AugTronic ECU.
Indeed! The intermittent part makes it very frustrating. I hoped to have tested tonight if the wiring was the problem, but did not get to it.
To be sure I have ordered some double shielded wire. I did hook up the old wiring for the EBC, but could not put the ECU back into the foot well. As soon as I have the new Breakout Box I will also replace the EBC wiring with the double shielded wire.

Friday I will have time to get back to it.

Frank@Work

@951Dream: Thank you for point me in the right direction!

The Electronic Boost Controller is controlled by the AugTronic ECU. There are two wires going from the ECU printboard to the boost controller (see red arrow).



Previously I made a short cable with a connector. Connecting the wires on the AugTronic ECU board and hooking the connector to the cable which ran to the electronic boost controller. That way I can pull out the ECU without having to cut the wire going to the EBC. There was a kink in that cable. That might have been the issue. The connector might also have been the issue.

I replaced the wire from the ECU board to the EBC with a double shielded wire without any connectors. The EBC is directly connected to the ECU board. During a testdrive I did not have any issues. Strong, solid boost up to way past 6000 rpm.

Closed loop Boost frequency is set to 30hz.
Boost solenoid duty is now set to 44%
TiAL 38 Sport wastgate has a 0.4 bar / 5.8 psi spring

951dream

frank can you link me to a photo album of your re-assembly? it's been so long since i took the turbo car apart i forgot the order for a few things

Frank@Work

I'm working on it.

951dream

thank you Frank!

Frank@Work

Here are all the pictures:

Porsche 944 turbo 1987 restoration

951dream

thank you so much Frank! i owe you one!

951dream

frank, the heat shield by the brake booster.. iirc it's 951-355-123-01 for the original, but yours looks like it's a newer/different revision? mine was re-plated but it's already failing after zero miles in the garage

yeah, it's been so long i have nfc where all the hoses go lol

Frank@Work

I love the color!!! :-)

My shield has the code 951.355.123. I've removed the turbo waterpump bracket. Not sure if there is a difference.