Revving on its own.
 

With a ton of help from the_pipefather my MS is up and running. There is one problem we couldn't figure out. Sometimes I will start the car and it will rev from 1k-2k up and down up and down. Other times it will go about a 1/2 mile and start doing it. When it does that it drives normal and everything, it just revs up and down. So far there is no pattern it is just random. When it does it I can just turn off the car and restart and it is fine.

I did some research and found it could be a vacuum leak or a faulty TPS. I have double checked that it is not a vacuum leak, and if it was I think it would always happen. I'm still on the 5 speed on/off TPS. I will be putting in a VTPS as soon as I can get one.

This happens maybe 1 out of 5 starts, so it is pretty annoying. My IAT sensor is right before the throttle body, is that poor placement? Any ideas?

Run HR code.

It IS running HR10g code. it can't be either of those because i'm running a different TPS and a different IAT, yet the same thing happens to my car.

Hmm.. interesting. Well tell me if you figure it out because actually mine does it to but it didnt on hr code. Now that i am back to low res, it does it.

Mine did that when I had the Recovery Speeds in Idle Control Continued set too quick.

Mine does it too when cold and sometimes when warm too, with it set to steady no less. Though mine has some other issues, including a nb manifold/idle valve and fairly lumpy cams...

I had this problem too. It turned out to be the IAT sensor heat-soaking. Paul adjusted some settings for me and its been running perfect since.

Pretty sure thats not the case with mine, it is still N/A and IAT sensor is only in a bit of pvc pipe:)

What are the intake temps when it does this? Do you have a WBO2? Have you noticed that when it does it, its going really lean?

My car is NA right now too... until Tim finishes the AbsurdFlow manifold. :)

gotta be an idle valve thing.

OR TPS...my Link was doing the same thing and it turned out to be the TPS...tried cleaning, waiting to see how it works now...might need new one.

is it possible for you to log this when it happens so we can change the recovery settings to match the rpm oscillations?

These are the settings we are using right now:

Deadband : 50 rpm

Upper limit: 280 rpm

Lower limit: 100 rpm

Fast recovery: 15

Slow Recovery: 100

Closure Speed: 2

Startup Delay: 2

Not sure of intake temps, but AFR is normal for whatever rpm the engine is at(I have an LC1).

I can try getting my laptop to link up. It happened last night on my way home. The injector settings are working, it started right back up.

I should try to adjust the recovery speed, I think thats what causeing mine.

Mine does the same idle-bouncing with MS as it did with the stock ECU. If messing with the idle recovery doesn't help, I can bet you it's the IAC going bad as it eventually does on almost every Miata.

Head over to m.net and search "idle droop" in the NA/NB forums. There's an easy way to clean the passages and test the voltages to see how healthy the unit is. A new one is like $350 or you can get one off a parts car for cheap... or you can just deal with it. Mine's done it for 30k miles and I don't even notice it anymore.

Additionally, how would one go about adjusting the IDLE RECOVERY settings. What does each one of those settings do?

maybe one of your screws on your butterfly valve is missing.... :rofl: oh god i fail.