Is this normal cooling behavior?
#41
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So I started having an issue over the last couple weeks where my boost controller would intermittently toggle on and off during a pull. Ended up finding today that my CLT reading in TS was violently oscillating within a 40*F window at full throttle, sometimes dropping below my 175*F minimum CLT requirement for boost control to enable.
I cleaned the ground on my valve cover and added another ground between the valve cover and firewall and the CLT reading shows no noise or abnormal fluctuation anymore.
Shoutout for bringing this to light. Even before it started affecting my boost control, the CLT fluctuations were probably messing with my fueling. Did you ever end up messing with or adding grounds?
I cleaned the ground on my valve cover and added another ground between the valve cover and firewall and the CLT reading shows no noise or abnormal fluctuation anymore.
Shoutout for bringing this to light. Even before it started affecting my boost control, the CLT fluctuations were probably messing with my fueling. Did you ever end up messing with or adding grounds?
#42
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Kind of, but not really? I tried adding a ground wire from the IM to some sensors I had grounded to the chassis in the cabin, but that didn't seem to make much of a difference to anything.
I basically changed the filtering value in tuner studio to make the coolant sensor less responsive. IIRC the recommended value is 180 out of 240. I had changed it a few times, but never ran it that high. That caused the values to look a lot more like what I'd expect.
Having said that, I did drain my coolant recently and saw more aggressive temp spikes at autocross today. I thought I bled the system well, but I think I need to give it another pass.
I basically changed the filtering value in tuner studio to make the coolant sensor less responsive. IIRC the recommended value is 180 out of 240. I had changed it a few times, but never ran it that high. That caused the values to look a lot more like what I'd expect.
Having said that, I did drain my coolant recently and saw more aggressive temp spikes at autocross today. I thought I bled the system well, but I think I need to give it another pass.
#44
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I should also note that while I had my ducting in place the factory belly pan/undertray was off the car. I removed it when replacing the turbo and bushings and did not get it back on the car before autocross. That was likely a large contributor to the cooling behavior this past weekend as well.
The course was also quite punishing from a cooling perspective. Two sections where I was on limiter for a couple seconds but shifting didn't make sense. Everywhere else was pretty much part throttle at mid/high RPM.
The course was also quite punishing from a cooling perspective. Two sections where I was on limiter for a couple seconds but shifting didn't make sense. Everywhere else was pretty much part throttle at mid/high RPM.
Last edited by SimBa; 06-17-2024 at 11:53 AM.
#46
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Funny you’d mention that. I started out running the stated RX7 calibration after making a thread about CLT sensor calibrations, which I believe you answered. One of my first posts on this site lol. Ran it no problem but ended up tweaking the values a bit after seeing coolant temps in TS reading almost 20* lower than my standalone gauge at higher temperatures only. I’m running an Autozone CLT sensor, though, so it’s very possible the resistance values from my sensor are just hella off. It’s stayed consistent for two years, though. I’ll check IAT vs CLT next time I go to cold start the car.
//Threadjack// Sorry.
//Threadjack// Sorry.
#47
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Late to the conversation here.
When you turned off the filtering the CLT trace showed really significant digitization noise. The filtering hides that, but does not change it. So your sensor analog output signal is very poorly matched to the A to D converter (ADC) in the ECU. This can cause errors in the quality of calibration, and increased sensitivity to ground noise.
Do you have any way to change the gain on the analog input of the sensor, or to change the input signal to digitization range on the ADC? For example, selecting a 1 V per 1024 bit range instead of a 5 V per 1024 bit range.
It probably does not explain your problem, but better quality digitization, (more bits per analog signal range) could reduce sensitivity to ground noise.
When you turned off the filtering the CLT trace showed really significant digitization noise. The filtering hides that, but does not change it. So your sensor analog output signal is very poorly matched to the A to D converter (ADC) in the ECU. This can cause errors in the quality of calibration, and increased sensitivity to ground noise.
Do you have any way to change the gain on the analog input of the sensor, or to change the input signal to digitization range on the ADC? For example, selecting a 1 V per 1024 bit range instead of a 5 V per 1024 bit range.
It probably does not explain your problem, but better quality digitization, (more bits per analog signal range) could reduce sensitivity to ground noise.
#48
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@Icedawg I agree, the filtering is just a Band-Aid, but doesn't address the issue.
I personally don't have a way (or know how to) adjust the gain of the input. For the time being I'm just going to crank the filtering and move on to other projects around the car. It's an annoyance but I feel like I understand the behavior well enough to write it off as "accepted behavior" for now. At some point I think I'll move on to a different ECU, and I'll be interested to see if this behavior lingers or disappears.
I personally don't have a way (or know how to) adjust the gain of the input. For the time being I'm just going to crank the filtering and move on to other projects around the car. It's an annoyance but I feel like I understand the behavior well enough to write it off as "accepted behavior" for now. At some point I think I'll move on to a different ECU, and I'll be interested to see if this behavior lingers or disappears.
#54
Cpt. Slow
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Try disconnecting the factory black/green ground eyelet by the back of the manifold, and take another log. There’s two eyelets, if the car doesn’t start, you disconnected the wrong eyelet.
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