Engine clunks hard on shutdown; idle RPMs too high

[howardc64]

What brand MAF did you put in there? This all sounds like a MAF problem. Using anything other than Bosch or Volvo means you will STILL have a MAF problem...

+1, tried 2 aftermarket no brand cheap MAFs from ebay awhile back. Both just changed from one problem to another. Only Bosch/Volvo on this car.

[pbierre]

Are you certain there IS an idle air control valve? Haven't seen one of those since my 1985 Volvo 245 GLT with a B-21FT that had K-jetronic injection.

On this engine, the idle air bypass path is built onto the Throttle Body, an appendage called the Idle Air Controller.

[pbierre]

What brand MAF did you put in there? This all sounds like a MAF problem. Using anything other than Bosch or Volvo means you will STILL have a MAF problem...

I replaced it with a Bosch MAF Sensor, exact same part number that was built into this car.

[OslosisJones]

Definitely get some MAF cleaner and spray it down if you haven't yet. If you have the old MAF, you could clean it up and swap it in (could have just been dirty in the first place), or try running the car without the MAF plugged in. ECU should revert to 'safe tables' with conservative air/fuel and timing.

Then pull the throttle body and give it a cleaning. Make sure all the intake hoses are well secured when re-assembling.

I'm not convinced that this is an intake problem given the lean air/fuel mixture. I don't know about that gurgling sound in the tank but it could be related.

How much and what quality gas to you have in there right now?

[pbierre]

The Volvo dealer figured this one out:

It was a multi-component failure in the EVAP system (sucks up fuel fumes from the fuel tank, so they don't pollute the atmosphere.)

These two solenoid valves were both failing to actuate:

30670448 Turbo Boost Pressure valve

8653908 EVAP Vapor Canister Purge Valve

When I got the car back, all the reported problems seem to be fixed. There engine shutoff "kick" is gone, and the idle RPMS is steady at 650-700.

They used the individual solenoid valve testing feature in VIDA to figure this out, where you actuate one valve at a time, and listen for the audible click.

[Rabid Koala]

Thank you for the follow up!