Mattman928

I've been having idle issues, and have done all the standard troubleshooting. I did notice that when I disconnected the large hose that goes to the ISV at the Y connector on the driver side manifold the engine ran great. As a matter of fact I don't think the engine ever felt more lively. Is this something I can leave this way?

worf928

You're feeding unfiltered air into the engine.

And this air bypasses the MAS; it is "false" air. You're 928 should be idling at ~2k rpm with that hose disconnected.

The only way a 928 would run better in this configuration is if there are at least two other things wrong with it.

You can leave it disconnected as an emergency measure to get home from wherever you are now.

GlenL

Yes but it's a bad idea. (as above)

Fixed or replace the ISV. I think you've shown that's your problem.

Mattman928

Thanks. I tried the wd40 with a thin hose to get it to the valve, and the idle has stabilized, but it still doesn't feel as responsive as with the hose disconnected.

I'm going to try borrow MAF also to try and see if that makes a difference.

worf928

You can check operation of the ISV at the LH ECU pins. And you should check the operation of your idle switch. (If you don't know how, directions for both are in my PPI guide linked in my signature below.)

Jadz928

You're doing this. Don't do that.

GregBBRD

Over almost 50 years of working on cars, I've learned to never dismiss or ignore what a client thinks or feels.....people are usually much better "in tune" with their own cars than I can ever be, in a test drive.

If your performance is really better with the ISV sucking additional unmetered air, you need to figure out why your engine is running so rich....because that is the only possible variable.