Hey all,
First, 2002 Type-S, 169k, basically all stock. Intake and exhaust no Kpro or anything like that.
So last fall, I was participating in an autocross event, when sudden downpour ensued mid-run. By the time I crossed the timing light, the red flags were out and the rest of the night was cancelled. On my way back to the grid to grab some things, I had an up and down hunting idle, very similar to what you'd hear with a large vacuum leak. CEL also popped on, P0505.
Drove her home, and the following day took off the TB and cleaned the IACV. I did NOT remove the sensor that was attached to it....
Upon reinstalling everything, CEL went away, so did the fluctuating idle. Thought all was well! Until I drove the car round a bit... sitting at a red light, my idle dropped so low the car stalled out. Started back up right away, and it hasn't happened since (this was last fall). But I've been dealing with another strange idle issue since, and now that warm weather is coming back I want to get this resolved...
Currently:
No CEL
Poor gas mileage (got 24.4 mpg last tank, didn't even get 300 from full to gas light).
Cold idle is around 2k, warm idle is normal ~7-800.
The issue is that when the car is at normal operating temp and is put in neutral, the idle doesn't drop down to where it should be. At least not right away. It will sit at around 1100, until I'm completely stopped. Even the slightest roll and the RPM's won't drop. If I'm totally stopped and rev the engine, it will come down, sit at 1.1k for a brief second, and then drop down to normal.
When I'm coming to a stop at a red light, same thing, 1k until I'm totally stopped.
Before I start pulling things off again, does this sound like an IACV issue, or a TPS issue? Using a scan tool, TPS shows 10% at idle. I'll get an actual reading on it today leaving work. If I can figure out how to export the data from the app to a file and upload here I will do so...
Odd Idle & Poor Gas Mileage
