Check engine light on Reverant-built MS2
 

I have a Reverant-built MS2 from 2011-2012 group buy. If i understand correctly from Dimitris, the check engine light comes on when the car is at certain temperature. Mine seems to come on at about 200F.

I'd like to find out what the other's experience is. What temperature triggers the CEL? Is it blinking or staying solidly lit? Mine's covered by black tape now but I'd love to bump that temperature up if possible and better understand blinking vs. solid CEL.

I believe blinking was knock
And solid was temps exceeding 216 or something like that.

at least that's what mine did

The group buy I believe that the OP and I are from, does not include any knock functionality with the CEL. I believe in the early versions, it only does CLT temp. Maybe some others, but I'm sure it doesn't do knock.

Mike, hopefully Rev will chime in, but I think mine starts to blink around 214 and stays solid after 220? I'm not too sure about the solid because I've never had my engine up that high before.

EDIT: I'm holding out desperately till Rev comes out with a new version of MS that I just can't pass on.

In the old (non-CAN bus) ECUs, the CEL would start blinking slowly at 105C, then faster at 110C, then it would be solid on at 115C. There's no way to bump these numbers up.

Do you have the DIYPNP-based ECU or the MS3-like ECU?

Dimitris it's Jesse Dillow's MS. Not sure what it's based on. Could you check?

105-115C (221-239F) would be great. But it's not even close. I've confirmed via Tuner Studio that CEL comes on at 200F, which is 94C. Is there a more accurate way to check?

Confirmed, you can't adjust the CEL-on temperature on that ECU. I did have several users who had that issue, but I couldn't reproduce it on my own car. The later units with the CAN-enabled expansion board had adjustable fan settings.

Ummm, that brings up another question. At what point does the fan turn on?

The blinking/lit CEL is really annoying. I'd like to hear from others if it really comes on at 200F or, perhaps, at different temps. If it comes at 200F, specifically, we can possibly look at the circuitry to change that? I mean, there's got to be some way to change it :)

So, can anyone else chime in as to what their CEL is doing on a Rev-built MS2?

Main fan at ~200 CLT
AC fan joins in, CEL at ~212 CLT
I believe my CEL is solid

I'm also troubleshooting a CLT related CEL, FWIW/YMMV/OMFG/WTF/BBQ/???:
https://www.miataturbo.net/megasquir...ff-fast-79539/

Main fan is 206 on my Reverant MS3 basic, I know that I can change those with TS. Don't have have AC so I can't help on that.

But if your temp go past 220-230, you should look at your system. Air pocket can be trapped or it's time for a reroute...

Curious if this type of re-calibration would work:
Dimitris, you've also mentioned this at some point, I believe?

So, any thoughts on this?

I don't remember if your unit has any programmable outputs left on it.

If it does, you may be able to trim the bias resistors to make the CEL come on later on, recalibrate the MS thermistor tables so that the ECU will still read the temperature properly, and move the fan control to the programmable outputs instead of the built-in fan controlllers.

A hack, but its the only solution outside of an upgrade to the CAN bus version of the expander board.

Thanks, Dimitris! How do I find out about the extra outputs?

And what's involved in upgrading to CAN bus board? What are the benefits?

Email me a picture of the internals of the ECU and I'll see if it has the programmable outputs or not.

To upgrade to the CAN bus expander, I'll need the ECU here.

Just a few of the benefits of the upgrade:

1) Sequential ignition
2) Advanced DSP knock control
3) Configurable dual fan control with many parameters and idle-up
4) Configurable CEL control
5) Onboard barometric sensor
6) 2 programmable outputs
7) Oil pressure and temperature inputs, linked to the CEL, programmable
8) Configurable A/C control
9) Configurable P/S idle-up
10) Configurable alternator control and battery light
11) Multiple inputs to allow launch control, switchable tables, A/C, etc.

Thanks again!

I'm pretty sure I will not be taking the ECU out of the race car till the end of the season - already missed one event this year with starting issues (which, oddly, turned out to be coils and bad plugs). We'll probably talk in more detail in the late fall.