CEL Check Engine Light cruising with A/C and occasionally under hard boost MS2e
 

Howdy folks,

Searched around and didn't find an answer to my problem or even really anybody talking about it, except that apparently Rev sometimes uses the CEL as a warning.

I noticed when driving on the freeway with the A/C on sometimes the CEL would flash. Motor sounded happy and all other gauges showed fine. If I turned the A/C off it might flash for a couple more seconds but then it would go off. Didn't think all too much of it.

Was blasting up a steep mountain road the other day and noticed that, again, the CEL would blink, sometimes under accel, but it seemed to blink more when I was running it a little harder.

At first I dismissed it all thinking it wasn't relevant to MS but hey, who knows.

Any idea why this would happen? Is it something I should worry about? Car runs strong and steady for the most part (sometimes feel some hesitation under full boost... working on learning some more about this thing).

Thanks for the help.

Yes. Your coolant temp triggers that when it exceeds threshold.

Wow... so cruising at 70 mph with a/c on it was overheating in 65* weather?

Apparently the coolant gauge just never moves above center? Cuz I was watching that. I had heard it wasn't super accurate but thought it would at least move a little. It sat right where it always sits.

I know it never got way super hot because it never boiled over or ran strangely or anything... know what the threshold is where it lights up?

thanks for the help. sure doesnt seem like I should be having coolant temp problems. I know it's a stock rad but I'm not putting that much load on it on the highway with a/C on that it should be overheating, it seems to me. Maybe I'll go ahead and spring for an alum radiator........

I didn't say overheating. But definitely getting hotter than normal and tripping that warning. I've had that happen before with an air pocket in the system way way long ago.

I was a fool to replace the original rad with another OEM rad. Shoulda just gone with a dual core like I have now in my 01.

The stock water temp gauge is about as useful as the stock oil press gauge: they're both just idiot gauges. It will skyrocket to H once the car is actually starting to overheat. Before that will probably do next to nothing.

Also is the car still being driven without the undertray and bumper air guide? If so, PUT ON BOTH ASAP!!!!!!

Hook up your laptop to the computer and watch the coolant temps when the CEL comes on. I do not know what Rev sets the CEL at, but I bet it is between 215-225 degrees.

On that version of the ECU, the CEL is generally programmed to come around 217*F. On some setups, it does come on a little earlier (like 212*F) or so, so you may want to check it out.

Thanks for the info guys, you rock. Vlad, I will get that stuff put on. I do remember reading somewhere that its important. Rev, I really appreciate your info!

I put the under tray on. Went to the dealer and ordered it the next day after you suggested it. I didn't realize the bumper air guide was a separate piece (if I had read your post more carefully I would have gathered that...). So it now has the under tray but no bumper air guide. I did put some zip ties under the front of it to the intercooler to help route the air through into the rad. It seemed to help but the cell still came on during my long uphill driving road.

Crazily enough, it looks like the car is sold. On its way to Texas next Thursday. I'm sad about it for sure, but could use the cash since the damn Volvo popped its motor. Next Miata must be more comfortable or cheaper, one or the other. We will see what I end up with. But I love car shopping so it's not so bad !