SAI Pump diagnostics with Durametric,Bentley and Multimeter - FAILED !

[Smallblock454]

Reminds me on something Mercedes related. I know Porsche is different, but have you checked the relay contacts and the tray contacts of the relay. There is a lot of currency running when these SAI air pumps starts. So often the contacts in the relay melt which leads to misfunction.

Concerning Mercedes the SAI relays are located in a module called RCM module. The relays are mounted on a circuit board and the solder joints brake. But this is Mercedes specific.

Regards, Markus

[Gelbster]

Thank you Marcus !
I am hoping to have more diagnosis and tracking done this evening.I suspect a break in continuity deep in the wiring harness.

[Gelbster]

A few more hints for those who follow.
HOW TO FIX A NOISY SAI PUMP.
To test an SAI Pump you need to run it for 2 minutes continuously. In normal operation it runs for 60 -90 seconds. Chuck's pump was quiet for 2 minutes after I tweaked it .Mine was not.I had only tested mine for 10 seconds and presumed that was enough.
After you do the Krazy K rebuild of the pump it may run perfectly for 30 + seconds . Then it may start screeching. STOP ! If you are quick, you can save it.
Remove the discs and run just the motor.If it still screeches, you need to replace the bearings - as described in previous links.
If the motor is quiet ,it must be the discs rubbing. The prime suspect is the last disk to fit.The center lip in the middle of the disc rubs against the fixed disc in the final part of the housing. Look carefully and you should see the rub marks. Note the raised lip in the center ? Use a Dremel tool to grind away part of that lip. Make it perfectly smooth. add a little grease to the suspect area, try again.Yes, it is dentistry. RInse and repeat as necessary until the pump runs quietly. Test for 2 minutes.
Feel the blind end of the motor - is it hot or just warm? Hot = need new bearing.
Feel the volume of air being blown .It should be powerful and the air should be not much above ambient. If the flow is weak, check the air filter.in the end cap. Be very careful removing the tiny push nuts. I used a set of picks from HF. More dentistry ! If you loose one of the push nuts - they spring out wildly - you may be able to substitute an internally serrated washer of the right/tight i.d.
I mention this noise issue because I suspect a noisy pump is often condemned as having defective bearings when actually ir was the center of the last disc rubbing. I hope this helps others.