MS2 + A/C = Broken Miata
 

I've got a 2001 miata rev built MS2 and vvtuner. The car ran great.

Thursday I went to the beach with my girlfriend. Whole way (about 3.5hours) with the A/C on. No issues, car was flawless.

Sunday were coming back. A/C varied from fully on to off for a little while. Then were about to cross a bridge, sitting in traffic and the car goes f*cking nuts. Afr's at like 11:1 and idle hunting all over the place.

So I turn it off then on. Problem is gone. Little while later we turn the A/C on again. A few minutes later my cel is flashing and with each flash the car stumbles. Turn it off, the flashing continues for a few moments then stops and its running fine. We try the A/C again, same thing, on any fan speed setting.

So we stop at a rest stop. I check a bunch of electrical connections. Nothing. We let the car cool for a few minutes then get back on the road. We try the A/C no issues, for about 5miles. Then it starts again. Weirdly for the last 30-45minutes I put it on fan speed 1. No issues.

Today I have to go to class. Crank the A/C to max and a few miles later its acting up. Again on any fan speed.

I will try it on fan speed 1 on the way home, as that's the only setting it was on when we drove to the beach. Ill also try to take a datalog. Any suggestions would be awesome.

-Patrick

P.S. I don't think the car was overheating, as I've never had any issues with it before and I drove to the beach last year in 100+ degree weather and sat in traffic for an hour or so with no issues, except then my A/C wasn't functional.

Normally flashing cel means temp readings are above 220 or something.
At least thats what it was one mine.
And if he set up non-linear mat correction (like I had on mine) it'd make sense for it to go rich if its reading skyrocketing temps, because with normal corrections it would go super lean.

just a guess

what's the voltage look like?

Yeah I know the temp thing. Ive never seen it go above 190 though. I havent datalogged anything yet but will.

Datalogging confirms that it's "overheating". I thought the CEL was supposed to start flashing at ~213 degrees Fahrenheit though. When I hit 202-203 degrees it kicks on and suck mode engages. Switching off I run anywhere from 179-195degrees. Shouldn't it be able to cope with the A/C on though? I've never run any sort of ducting or under tray.

Is the A/C fan actually coming on? I had a relay go out that drove the A/C fan and never knew it until it overheated because the 'light' on the A/C came on and it still blew cold air.

The cooling system needs more Qout.

Put the stock under tray back on the car. Is the coolant system still stock? What radiator do you have? Do you have a reroute?

Coolant system is super stock. I've been turbo'd for almost 3 years never had the undertray on since the conversion.

I guess I've never really run the A/C because it shuts off when coming to a stop. Also I only found out I had a bad solenoid last year so, this is my first summer with A/C that actually blows cold.

Go out to your garage and find the stock under tray now. Put it back on, cut it as minimally as possible to fit IC piping with it.

Okey dokey. I've been wanting to do a small splitter/under tray anyway.
Thanks

My Rev built MS2 starts slow-flashing at ~205, fast flashing at ~212, and goes solid at ~218.
A/C being on makes all the difference. With mine, as long as I had the A/C off I had no problems with stock everything & 115+ degree temps.
It took an aftermarket radiator, Flyin Miata fan kit, sealing up every hole possible around the radiator, and M-Tuned coolant re-route to keep it from overheating under any conditions with the A/C on when it's 115+.