coolant temp sensor acting up

[joe_dejesus]

My MS3/MS3x has been running great for over a year now.. lately my coolant temp reading has been acting up, it reads correctly then drops to 0, then a few seconds later reads correctly.

Thought it was connector or sensor, replaced sensor with a new one and still doing the same.
checked connections and they seem fine... the only change was firmware upgrade to 1.3.1 , Car has not changed.

its intermittent so it works fine for a while then acts up..


could it be my ms3?

[billr]

Take the sensor out and inspect, that is usually a trivial job. OEM Saturn (and maybe other GM, other makes) ECT sensors all through the '90s had plastic tips out in the coolant that routinely cracked, letting coolant get to the RTD element and even corrode the connector pins/sockets.

[joe_dejesus]

I put a new sensor and acts the same way

[billr]

Well, then, you probably have to investigate the wring. Do you have both an ECT sensor and IAT sensor, are they similar calibration so that you can swap the ECT over to the IAT input back at the MS DB37? That could quickly tell you if the problem is inside the MS or outside.

[racingmini_mtl]

Did you assemble the ECU yourself? Do you have a stim on which you can test the ECU?

Jean

[joe_dejesus]

yes I assembled it myself over a year ago. Its been in the car ever since, daily driven with no issues.

I see it mainly acting up when car is started and cold/warm. I don't think while hot and restarted it acts up.


yes I have stim... Havent tried that since I haven't figured out a pattern yet.


Joe

[joe_dejesus]

Fellas, As I monitor the gauges in tunerstudios I see BOTH coolant sensor and Air Intake sensor reading correctly then go to 0 then back to reading. Each acts up differently , meaning I have not seen them BOTH go to 0 at same time.


I checked my documentation and my coolant sensor and air intake sensor go into MS3 connection pin 20 (air) and connection 21 (water)

[joe_dejesus]

OK guys I connected the stim and I can see air temp and collant temp act weird... so I oresume car wiring/sensors are not the cause.

How can I go about trouble shotting my MS3 to fix it???????????????


I attached a log of stim, I rorate each air temp and coolant temp on stim, sometimes reading gets stuck .. my stim and ms3 when build never did this before.

Here is a stim log

[joe_dejesus]

her is another stim log

[DaveEFI]

The ATS and CTS inputs both use Vref - so I'd first check you have 5v relative to ground on both sides of L2. If that is OK check for 5v at both R4&7.

[joe_dejesus]

The ATS and CTS inputs both use Vref - so I'd first check you have 5v relative to ground on both sides of L2. If that is OK check for 5v at both R4&7.

I have 5.03 volts on both sides of L2

resistor leg side facing L2 of R4 R7 I get 5.03 on both R4 & R7


on the other side for both R4 & R7 I read between .002 to 4.01 volts depending on what stan pot is set to.. what I see that might help:

While unit is powered back on and on-line- I measure voltage on R4 coolant resistor and the voltage sweeps smooth when moving stim but at 2.924v
tunerstudio reading drops to 0 but voltage on R4 reads fine.
Same with Air temp and R7, voltage measures fine but tunerstudios drops to 0.


in tunerstudio I found 2 spots each air/coolant that temp reading DROPS to 0 moving stan pot (coolant) between 142-144 & 163-165 will read 0 in tunerstudio
air temp between 162-165 & 182-185 makes tunerstudio read 0 temp

hope this helps

[joe_dejesus]

in tunerstudio I found 2 spots each air/coolant that temp reading DROPS to 0 moving stan pot (coolant) between 142-144 & 163-165 will read 0 in tunerstudio
air temp between 162-165 & 182-185 makes tunerstudio read 0 temp

these temp spots are what I see while car is running. when temps land within these windows reading drops to 0 and car goes rich, when temp passes the window it reads correctly.


air temp window rarely seen exept when air temp sees hot air from restarting hot parked car and heat soaked, usually goes away fast.


the collant temp being in Miami florida, only felt when car is cold, after car finished warm up enrichment its always past 175 water temp

[joe_dejesus]

anyone know how to fix this ms3??????????

[Matt Cramer]

Can you try reloading the firmware and loading an MSQ from before the problem happened?

[joe_dejesus]

Can you try reloading the firmware and loading an MSQ from before the problem happened?

I do not recall when the issue started, might have been a few months back. I know for sure I did not have issue prior to 1.3.1 upgrade. I need to look for saved files to try that. Or should I stay on 1.3.1???

[joe_dejesus]

Can you try reloading the firmware and loading an MSQ from before the problem happened?

Tried reloading firmware - same issue

Went back to older 1.2.4 firmware - same issue

1.2.4 firmware with a NEW project from scratch - same issue

Loaded back 1.3.1 with my tune - same issue on STIM...

[joe_dejesus]

what do you think could be bad?

[jsmcortina]

Possibly a dodgy connection to pin 1 on the MS3 card?

James

[joe_dejesus]

Possibly a dodgy connection to pin 1 on the MS3 card?

James

pin 1 where??? what do you suggest I do???????

[jsmcortina]

Possibly a dodgy connection to pin 1 on the MS3 card?

James

pin 1 where???

On the MS3 card.

what do you suggest I do???????

Check it.

James