Information Overload - Troubleshooting random CLT noise

[luftvagon]

I went on a 45 mile drive today in hopes of catching random misses I was having. The data recorder was running!

About 200s into the drive, I started experiencing issues, which are evident in Megalogviewer.

All of a sudden, CLT would experience bunch of noise.

It would go from 160F to 66F within next data point (50 points/s). Coincidentally, Batt V would drop down to 11.1v in the next data point.
MAT, MAP, AFR. and IGN are not changing. AFR changes after the event.

Lost Sync Count: 0
Lost Sync Reason: 0

Bad ground? If it was bad ground, I'd expect AFR, and MAP to go haywire.

Through the entire drive, voltage was going between 13.1v-11.1v. Normal? At times voltage would drop, but it would not affect CLT.

CLT just going bad?

RPM Averaging: 100
MAP Averaging: 100
CLT/IAT/BAT Averaging: 100

I can post the log file, if anyone is interested.

[luftvagon]

In this picture, you can see that CLT went down all the way to -10F

[luftvagon]

The log file is about 40MB.

[Clonebug]

Did you check all your connections to the Relay board or wherever you have them connected???

Ground is the signal for most of the sensors so you might be having power issues instead since it kind of follows your voltage
fluctuation.

Unhook your fan belt and see if your voltage steadies up while idling in the shop.

First check if the oscillations are there at idle with the belt on.

It could be the alternator is sending a dirty voltage signal.

Make sure the alternator is grounded well with the little screw in the body running to the battery ground.

[luftvagon]

Hello, thanks for the quick reply. Yes - I wiggled and jiggled the entire wiring harness. No change. All microsquirt grounds are grounded at the same place.
None of the other sensors showed noise. Oscillations are there at idle too.

[luftvagon]

I've always had some noise coming in from IAT sensor. That's not ground noise either. That's just a bad Ford IAT sensor.
Take a look at the green line. That's the CLT. Look how normal, and smooth it looks, until it doesn't.

Maybe the heat bothers it. Maybe it's too hot for it. I got it connected to Type4 TempII probe location.

I think this is a case of sensor going bad, and battery fluctuation is just a red-herring.

[luftvagon]

Guess the ultimate question is, has anyone seen a CLT start to fail like this?

[panel]

Where is the Type4 TempII probe location actually ?

[luftvagon]

#3 Cyl, on the head by the intake

[panel]

Can you do a test like this?

https://www.diyautotune.com/support/tec ... s-iat-clt/

[luftvagon]

So back in the day when I wired the system I wired TPS wire into the ground directly as suggested by someone. After clipping it off, the noise on air temperature subsided.. and I have not had any issues with CLT. However, the BattV is still very jumpy.

However, this evening I had sync loss issues (#2); but I dont think its related to me cutting the TPS wire off. Now I am starting to wonder if the Hall Sensor had issues. Going to check that out tomorrow with the tooth logger.

I am powering IGN-4 coil from the same switched source as microsquirt, and I believe hall sensor is powered by the same switched source. Should I change any of this? Should I ground TPS wire?

[Clonebug]

All sensor grounds are supposed to be grounded to the ECU or to a common ground shared with the ECU.

All my sensors go to the relay board which in turn go into the ECU.
TPS is three wires and they all go into the relay board.

[luftvagon]

I'm 99.99% confident wiring is good at this point. I split the harness the other day. All my sensors wires terminate to the common ground that goes to pin #20 on microsquirt. I clipped the TPS, and now soldering back on. There was no change in behavior. I'm still having random dips on the CLT to the point where it will kill the engine....

Back to my original thought... if the temperature is "dropping" that means the resistance is increasing somewhere. Which could probably be the thermo probe going out, a bad cable, or something inside of the microsquirt.

[Jadewombat]

Are the ignition wires shielded (or twisted pairs)?

[luftvagon]

Ignition is by the way of IGN4, and QuadSpark. I do not believe parts of this harness are shielded.