STC wrote:Then Scope trace of SAI Pump Current, Valve Solenoid Current and both pre cat O2's from cold with 2 minutes across the screen ?
I think I can figure out how to hook up the scope!
Actually was going to do Voltage for Pump and Solenoid originally, but changed my mind to amps for pump (based on the Diagnostic Module Tank Leakage (DMTL) fuel system test, while the SAI does not monitor current, I thought what the heck, I can, and it's diagnostically no more work ...) Current has already been checked at the relay, with circa 40amps inrush and 14amps running, which is about normal, having tested 30 or more over the last 10years. High but within norms.
Sticking to voltage for solenoid, which is operating a vacuum control valve on the exhaust manifold. Mechanically have checked the system works, both valves (2 - 1 for each 4cyl bank) open and close cleanly, air flows (monitored at tailpipe) and ceases on command. ECU can drive both pump relay and solenoid, and vacuum system has integrity. So only an intermittent fault or Lambda as possible causes.
Client reports the MIL lights during driving not starting - hard to pin down if the "driving" was within 2 minutes of starting, but it's a client, so everything is pinch of salt and read into things as widely as possible if needed !
So, except lambda issues, which from live data I doubt, but will check on scope and post up here, the only stuff left is to tap gently the solenoid, just in case it's shorting internally, or the Pump relay ... which was showing some hot marks, but 70amp relay pins often do, anyway swapped it out, as too hard to confirm a relay intermittent faults verse the price of the component, so it got a new one.
Fault codes, sadly they got deleted in error before printing them, only 1 present. There are only 4 possible codes relating to SAI, but don't have them to hand, as out and about today. Might be on someone's phone, just waiting to check ...
It's the dry sump 4200 engine version of this Maserati, for those who might have glanced through the document Kim shared.
Will try and get the capture taken and uploaded today/tonight.
STC, your headlight thing has arrived and you'll need 3 AAA batteries Also we've ordered our own Diesel Compression tester with the VAG fittings, so will not need yours, but thanks for the loan.