Hey everyone! Normally I don't post in the troubleshooting forum since googling and searching always does the job but I'm completely stranded right now with my current issue. I've read all the posts and literature on the topic and I just can't seem to solve the issue.

This Issue

I had reset the battery about a week ago. Immediately upon turning the car on (it was warm) the car would stall at idle. Over the course of the whole week I'e been manually idling the car myself while driving but after about 15 drive cycles and 100 total miles, the car still stalls at idle. It will idle on cold starts but it's extremely unstable and once the car nears operating temp, it will keep lowering to around 600 until it eventually can't continue and stalls.

Heres the symptoms:

- P0506 is the ONLY CEL being triggered

-Stalls at idle, ECU doesn't even attempt to correct the rapid rpm drop.

And some side notes:

-I removed and sprayed the MAF, no results.

-I visually inspected the intake and hoses, there was oil in the accordion tube and I cleaned that out. Perhaps oil residue has built up around the SSV or throttle body?

-I've tried the 20 brake stomp procedure many times.

-I've attempted to manually hold the idle so that it eventually stabilize itself, no results. I've also tried the auto PCM memory procedure, no results.

-On cold starts it will start up and hesitates at first but then it will idle. However, as the car gets warmer, over the course of 10 minutes, the rpms will slowly drop until they reach approx 600 before the ecu simply struggles to keep the engine alive and then it stalls.

-The car was compression tested 6 months ago. 8.5 front rotor and 7.5 rear.

-All these issues began after the battery was reset at the mechanic while they installed a lightweight flywheel and new clutch. The problem did occur after bringing it to the shop and resetting the battery but I was able to get it to idle once again and fixed the issue. This was all about a month ago. The car ran fine for 3 weeks or so. Last week I personally reset the battery but this time I can't fix the stalling issue.

-The car runs just as it always has besides for the idle. It pulls well, never misfires, and easily gets to redline.

-Fuel mileage is still great, the car sees almost all highway miles so I average around 20-22 mpg

As of right now my suspicions are with a possible SSV oil clog or throttle body issue but after driving about 100 miles, no CEL has been triggered for these components . Any input?


Hopefully I can get this sorted out! I've had my rx8 for 4 years now and it's been great but this is the first issue that has come up that I can't seem to fix or even diagnose..

 

I couldn't find P0506 in my Work Shop Manual but P0505 looks to be close.
Might give you a place to start.

 

Here's some more ideas: P0506 Idle Air Control System RPM Lower Than Expected - DTC Code

 

So here's an update for some closure on the topic. Essentially the problem is now fixed. However, I'm still not sure what exactly caused it to happen in the first place LOL.

So over the course of the past few nights that I wasn't busy I:

- Pulled and cleaned the SSV (It was filthy..)
- Repaired the faulty actuator arm on the SSV
- Cleaned the MAF again
- Replaced my old corroded battery terminal
- Reset and cleaned the ESS sensor
- Decarbed the throttle body, UIM, and around the SSV chamber
- Installed new ignition coils


Upon starting it back up, everything was perfect! The car immediately idled once again and was absolutely perfect. And as a bonus, after cleaning and replacing all those items, the 8 runs great now! Since i replaced all these parts in one go, its hard to say what exactly caused it but I'm just happy to not have to deal with any of it anymore

Thanks for the help everyone.

 

I'd guess coils....likely a trailing coil wasn't firing properly...that will cause poor idle as the trailings fire first at idle

 

+1
I just encountered something similar.
Started fine and idled OK until the engine warmed up and the RPM attempted to settle, that's when the motor began to struggle and would eventually stall. Of course once it stalled, the motor was flooded and I had to fight past that. I chased it around for awhile and eventually found out I was losing spark.
But changing the coils and plug wires got my car running again!
Just happy it wasn't a lack of compression since the motor was just rebuilt by RR!

 

Thanks for the update.

Cheers everyone