RX8 idling issues
 

Alright. I didn't want to post this question because it seems to be very similar to other questions asked, but it isn't. My RX-8 will not idle, unless it cause the idle itself. What do I mean? Well when I rev the car and let the revs drop, it won't idle. However, when it warms itself up and slowly drops it's own engine speed, it will idle until I interfere and rev it of course. DON'T TELL ME IT'S LOW COMPRESSION. I just finished swapping my engine out for a rebuilt one and trust me, I know low compression when I see it.

However, with the old, low compression engine installed, WHEN I got the car started (after squirting oil into the leading spark plug holes) the car would do the same thing, wouldn't hold an idle. This is weird because there doesn't seem to be a vacuum problem (I hooked a vacuum gauge up to the nipple on the top of the intake manifold where the brake booster would connect and it has a steady rate of in/hg). Most of the ignition components are new (plugs, wires, coils, etc.) And when the car is above 800rpm, it's great! Runs for as long as it doesn't idle and starts right up as well.

Now, the car did sit for quite a while (God knows how long before I bought it and for about 4 months after I bought it while I was swapping the engine) and in that time, the throttle pedal got pretty sticky (it's quite difficult to feather the throttle). So i popped the throttle assembly open and greased it up which helped but it's still a bit difficult to move the pedal in small increments as if you were trying to change the rpm by like 200rpm with your foot. So anyway, could the throttle pedal be a problem or what do you guys think because this is quite bizarre to me and I REALLY want to drive the car after all my time spent swapping the engine. Thanks!

Let me tell you the specs as well.
- K&N CAI
- Greddy cat back that exits right out the middle (I hate it)
- BHR resonated midpipe (Love it, but its still new so we'll see)
- ACT Prolite Lightweight Flywheel (Haven't driven with it yet)
And that's about it plus it's a 2004 with 81k and 0 miles on the rebuild.

Also it has the upgraded 13 tooth starter and like I said, all new ignition components, new MAF, new ESP, and both new Oxygen sensors.

We have a drive-by-wire throttle system so there's no direct connection between the pedal and the throttle. If the pedal feels funny, that's where you should start.

Log the throttle position and accelerator pedal position (and commanded throttle actuator control, if you can).

The Idle air Control circuit is built into the throttle body. It uses small increments of throttle opening to adjust the idle

If your throttle body isn't working it will not be able to make those fine adjustments

I would try and find a throttle body to swap in...even as a test

Keeping the Engine at an Idle
• Ignition Coils
• Spark Plugs
• Spark Plug Wires
• Engine Compression
• E-Shaft Sensor (ESS)
• Mass Air Flow Sensor (MAF)
• Front O2 sensor
• Catalytic Converter (Cat)
• Intake Vaccum

I've seen this get posted before and I can tell you that everything is new/good on this list except for the vacuum which seems to be good but I guess it wasn't? Here's what i mean.

There was a throttle body spacer sitting behind the throttle body not for any particular reason but to hear an air whooshing sound when stepping on the throttle. Anyways, I took that of a while ago and broke the gasket, but fixed it with gasket maker as i couldn't really get a new gasket for the spacer. So since the spacer wasn't necessary in my eyes, I took it off. And voila, the car will hold an idle now! Strange, but maybe there was a small yet but enough leak around the spacer. However, we sprayed it with carb cleaner and there was no difference in idle speed so not very sure yet the problem is fixed.

It still doesn't make much sense though. Throttle body spacers aren't a new thing, they've been around for a while. So why this one would mess the readings up so much I'll never know. It could also be the fact that not only were the readings with the spacer just a tad off, but the apex seals are brand new so the engine is getting used to that well. Maybe one day I'll put the spacer back on, I want to sound like I'm BOOSTED!