Idle droop and stall
 

My 2001 has recently started giving me a problem. The idle will droop and sometimes stall. It will do this almost every time with ac on. Decelerating then pushing in the clutch makes it more pronounced. This seemed to start happening when I installed the Flyin Miata fan kit, which has 2 Spal fans. I'm guessing it's the electrical load causing it. I believe modifying my closed loop idle will fix it. The problem is I'm not sure what to do. I did some searching and one answer is to make my MAT density 100, across the board. I'll try that today. I'll also take a datalog and composite log, which I'll post this afternoon with my current tune. In the meantime I've got posted here my ac idle, idle control and closed loop windows. If anybody can give any insight on what to change I'll have a starting point. Thanks for your input.

Have you done he idle output test mode? Your minimum idle duty cycle seems a bit low.

Not being able to figure out how to do an idle output test I started playing with the duty cycles. I have it at 30% now and I'm getting some droop but not stalling. It still will stall though if I have an extended boost period and come to a stop.

How is your initial duty table looks like?
Bump your ac idle up delay to 500 and then you can reduce your duty precentage.

I had left the toggle on use last value. I did change it to this duty table. My friend gave me his initial duty table, which I copied, as you see here. Please let me know what you think of it. He doesn't claim to be that knowledgeable in idle issues. It's just what he came up with in his car. He does have a bit of MS experience though. I'll change my ac idle up to 500 and see how that works today.

Comparably to my 99 your idle duty values seem a bit low. I have my IAC duty cycle min set to about 30%, and my initial duty table looks to be 33-36 range.

Also here is a screenshot of where the idle test mode is. Basically get the car up and idling up to temp. Then go in there and you can adjust the IAC valve duty cycle. I like setting my min duty cycle to be about 750rpms, but that is a personal preference.
Attachment 229992

Shows you how dim I am. I though Can-Bus was for Canadian cars. Never even looked in there.

why would you even touch any of the idle settings at all until you've done the idle test?

that's like tuning timing without sync'ing the timing offset on the ms.

do it before anything else.

you're trying to wipe before you poop

ROFL! Canadian cars.

Yeah the test outputs menu is a bit annoying to find under it, especially if you don't know what you are looking for.

CAN-Bus stands for Controller Area Network. It is the modern communication system that all newer ECU's use. MS has it, but I believe it is a little different then the standard CAN talking pattern.

Similar physical protocol, different data.

I did change to initial values. When I pushed the idle test I got a high flucuating idle. 2-3 k rpms. Value was at 90 percent. I turned it down to 30. It still idles like shit at 2k. Really need to find out how to use the idle test.

What were your AFRs doing during the test? If the VE table for the various cells around idle aren't dialed you could get fluctuations.

I'm not sure, but someone will set me straight, does the Idle Test disable any automatic corrections such as Idle Timing and EGO? Or should they be disabled before starting tests? If they are active they could be messing up your test as well, especially if they're over compensating for poorly tuned tables.

Maybe start a log, then do the idle test, examine the log to see whats going on and if you can't spot the issue post the log here.

I am having a similar problem, also on a 2001. I am interested to see what you figure out.