My coolant sensor is EVIL... please help me kill it!
#1
My coolant sensor is EVIL... please help me kill it!
I'm running a Hydra and FMII on a 99 1.8L. It has the single coolant sensor for the ecu and gauge with the triangle connector at the back of the motor.
Issue: Coolant temp shows accurate in the Hydra when the key is in the on position, and for 1-2 minutes after I start the car. Then it starts getting erratic with some crazy temp swings, then it goes to a whopping 3.2 degrees F so the car runs like crap. Gahh!!! I have a brand new temp sensor so I put that in. Nope, does the same exact thing. The factory temp gauge appears to be working fine which makes it even weirder.
The only thing that has changed on the car since this issue started is me ******* with the grounds on the front of the motor. I didn't move any of them, but I did chop the factory brass wire crimp there and put the four wires on a ring thinking it would clean it up a little.
Could that really be what caused this? I didn't think it was possible to create a ground loop issue by taking wires using the same ground and simply putting them together. I attached a pic so you guys can see what I'm talking about.
Does anyone have a pic of the grounds at the front of a 99 1.8L? I can't find a pic showing the ground wires so I can put it back to stock.
Issue: Coolant temp shows accurate in the Hydra when the key is in the on position, and for 1-2 minutes after I start the car. Then it starts getting erratic with some crazy temp swings, then it goes to a whopping 3.2 degrees F so the car runs like crap. Gahh!!! I have a brand new temp sensor so I put that in. Nope, does the same exact thing. The factory temp gauge appears to be working fine which makes it even weirder.
The only thing that has changed on the car since this issue started is me ******* with the grounds on the front of the motor. I didn't move any of them, but I did chop the factory brass wire crimp there and put the four wires on a ring thinking it would clean it up a little.
Could that really be what caused this? I didn't think it was possible to create a ground loop issue by taking wires using the same ground and simply putting them together. I attached a pic so you guys can see what I'm talking about.
Does anyone have a pic of the grounds at the front of a 99 1.8L? I can't find a pic showing the ground wires so I can put it back to stock.
#9
The coolant sensor gets voltage on one wire and outputs a different voltage depending on the temperature it senses. It simply changes resistance which changes the voltage.
Since you said the factory gauge appears to be working fine the issue could be with the ECU. To test this, measure voltage on the coolant temperature input at the ECU.
Since you said the factory gauge appears to be working fine the issue could be with the ECU. To test this, measure voltage on the coolant temperature input at the ECU.
#12
Found an old thread on m.net where the guy had the same exact issue and replaced his fuel injector harness to fix it. I don't think the grounds are the issue since the car was running fine with them essentially the same way they are now. It makes sense if it is the injector harness, it carries all three of the coolant sensor wires to the connectors on both sides. I found one used for about $40. I'll give it a shot and report back.
#14
Correct, car was running. Did it a few times just to confirm with both of my coolant sensors, one being brand new.
Found an old thread on m.net where the guy had the same exact issue and replaced his fuel injector harness to fix it. I don't think the grounds are the issue since the car was running fine with them essentially the same way they are now. It makes sense if it is the injector harness, it carries all three of the coolant sensor wires to the connectors on both sides. I found one used for about $40. I'll give it a shot and report back.
Found an old thread on m.net where the guy had the same exact issue and replaced his fuel injector harness to fix it. I don't think the grounds are the issue since the car was running fine with them essentially the same way they are now. It makes sense if it is the injector harness, it carries all three of the coolant sensor wires to the connectors on both sides. I found one used for about $40. I'll give it a shot and report back.
#15
Just saw your advice on checking it. Good stuff and I need to pull a Hydra wiring diagram to figure what wire to measure voltage at.