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Car cuts off when reaching Normal Op Temps

Hittman

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Sep 11, 2009
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472
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Northern VA
1990 JDM Galant VR4

After installing the Plazmaman IC setup, once my car reached operating temps it would randomly shutoff /ubbthreads/images/graemlins/confused.gif

I did some research and saw that possibly a failing TSTAT could cause this issue, so I replaced it today, and still am having the same issue...

Any ideas on what else it could be?
 

raptorWagon

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May 17, 2007
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Oak Harbor, WA
That sounds more like a failing ECU temp sensor (2 prong one) problem than the Tstat causing the issue. If the signal from the temp sensor is non-existent, it will trigger the ECU to shut the engine off as a fail safe when it reaches operating temp. So check your wiring for breaks in the wires at the connector. The wiring in that area gets brittle over time and tends to break apart.



Also, how do you like the Plasmaman IC kit? I had been eyeing that for a while, but was unsure.
 

Hittman

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Sep 11, 2009
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So the 2 prong sensor on the bottom of the thermo housing?

The kits quality looks nice, but the fitment was far from OEM, between working with plazmaman and doing some research here on the forum, I got it to fit, definitely NOT worth the money I paid IMO, but I couldn’t find any full lightly used or “new” ETS kits at the time.
 
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GSTwithPSI

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The ECU doesn't have any fail safe features built into it. The ECU (especially in stock form) will run the car bone cold or until the engine seizes from overheating. The only thing the ECU will do to save the engine is pull timing when overly hot or after sensing knock. If the ECU is killing the car, it's because it's failing.

Is the car shutting down, or dying? Shutting down meaning the entire thing goes dead (dash, engine, fuel pump, etc), or dying meaning the engine dies/ceases to run until restarted? Depending on the condition, it could be anything from a failed component to a tune issue caused by a simple vacuum leak. If you could describe the symptoms better, we could possibly help better.
 

raptorWagon

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It most definitely will shut off the engine, if the ECU is getting no signal from the ECU coolant temp sensor.
 

GSTwithPSI

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No, it won't.

If there's no signal from the CTS, the ECU may over-fuel during a warm start because it thinks the car is cold, which will lead to a no start condition. But the ECU won't simply kill the engine if there's no signal from the CTS.

Go start your car, and unplug the sensor...I guarantee you the car stays running no problem.

Again, there's no kill or fail safe features built into the DSM/Galant ECU aside from the timing adjustments I mentioned above. If you've read or understood otherwise, it was misinformation.
 

Hittman

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Northern VA
Exact symptoms are as follows:

Start car normally, idles great, drives fine, no issue.

Once the needle on the temp gauge reaches the halfway point, while driving, only when switching gears or when the idle goes lower than 1500RPM, it INTERMITTENTLY cuts the car off, all lights are on, radio, all electronics are still on, and even if I engage in gear (while still rolling) it will cut the car back on. (I had a similar issue with the IAC on my first Galant, as well as my Evo, but the only difference was I had come to a complete stop when the cars would cut)

I played with the wiring to said temp/ecu sensor today and lo and behold had no issue at all. So if it is indeed this area that is the culprit, I suspect that the actual wiring to the sensor may be in need of replacement.
 

thomcasey

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Indianapolis, IN
Stock ECU? BOV recirculated or vented?
 

gvr4bnr

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Jul 23, 2019
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rochester michigan
So usually when something goes wrong, it's the last thing you touched. A boost leak test could reveal the issue.

I will throw out there, that the coolant temp sensor might not be that far off as the answer. The ECU will switch over to closed-loop at about 130* during warmup, which would be right where you said the issue starts to happen. If you could somehow lock the ECU in open-loop, it would be interesting to see if the issue goes away.
 

Hittman

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Northern VA
Haven’t boost leak tested yet, but will this weekend if it’s not solved.

Stock ECU, with an Evo 8 BOV, recirc.

I think it this is boost related, I may have found the issue, but I’m not sure the best way to fix it yet.

The line that ran from the boost solenoid/actuator and T’d off to the LICP on the stock setup...there wasn’t any spot on the new setup to plug it in, so I just cut it and didn’t think much of it. If this is the issue should I just plug it, or tap into the LICP like the stock setup?



 
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