tech tips how to verify 355 Exhaust valve

Hello
Im one of the users of this forum who has learned a lot reading all of the tech threads.

Although I've often felt that I can not add information missing on this forum (because everyone seems to know so much already), I can do something for 355 EURO and USA owners who have Motronic 2.7 systems!

So if you want to verify your Exhaust valve :

First, test the vacuum system:
---unplug the little hose coming from head of engine while car is runing, you must hear pchit pchit,

---unplug the hose on the vacuum tank you must hear a pchhhhhhhhhit (different from pchit pchit !)


Next, test the exhaust valve:
When car is not too hot you can manually move the exhaust valve open/closed to see if it is not damaged (it must move easily).

Also, as you test the valve above and remove the hose going to it and block the opening, the valve must not close on its own. It must close only when you manually open it...


Shunt the solenoid to see the valve working.

Use paper/tape on the valve system and drive the car, if the valve works properly the paper will be damaged by the opening/closing.
Photo shown on a bmw exhaust (easier to see)



Electric test

*Remove the solenoid clamp. On the solenoid plug you must have a full 12v between the + terminal and the engine mass/ground/earth. The ECU gives the ground (signal) to open the valve when needed.

You can test the solenoid by putting +12v directly onto the solenoid terminals (it will open and you'll hear a "clac").

Now if the exhaust valve is still not working, look at the ECU defaults codes.

On EURO 355's the diagnostic system exists even though in the manual they say no!

Use a short wire to shunt the red and black wires together on the diagnostic plug (SD1 on 2.7) for 10 seconds. It will give you a flashing check engine light (CEL)....I have done a video about it , posted in technical questions and answer.

Thanks for all tifosi help and good luck to anyone having any future problems!
Thanks to Eric and to No Doubt for help !!

nico
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Thanks ! Im realy happy to be helpfull !
nico

 

Hello ! now you know everything I know about it, tell us what you found !
me I had lot of error in the ecu and that was the reason why it did not work (temp sensor error) so maybe it is same...
I was wondering about locking the valve open but it is too noisy as I hav no cat and a tubi exhaust...