Could I run with this issue?

Markmo said:

If I look voltage between pins 92 and 83 on the ecu (right now I am not sure if that was the numbers, but first is the sensor grounding and second one is the sensor input). I can see a 0.9v 30min after engine was stop from hot. I start the engine and voltage drops slowly until 0.630v (warming up decreases sensor resistance) but fans won't start. If I press the gas pedal, voltage goes up to 0.680v that is not normal cause fans are stoped and sensor must be decreasing all time until fans runs.

Click to expand...

I followed your last post describing your problems, the great on-point suggestions from @paul93VR4, and the results you posted in response to a few of his recommendations. Like other members posted, I do not see a clear logical explanation linking the slow wipers, dim dash lights, and cooling fan questions together. First the cooling fans......I have owned 4 of these cars personally, buying my first one new 31 years ago,and have worked on many others. I have always been amazed how rarely my radiator fans turn on living in Southeastern USA, where daily temps are 80-100*F from May-October. My condenser fan runs on low always, because the AC is running. Your concern is "radiator fans are not working when water is hot". You never say that your temp gauge rises past the midway point at any time or that you have actual signs of overheating.... boiling water in overflow, steam, hard expanded radiator hoses, etc. I will post some images from this car's related service and tech manuals to prove my belief that you likely do not have any fan/ cooling problems. You have both fans properly running on high when your ECT is unplugged, and you have cond fan on low with AC....PERFECT. Restarting the warm car began at 0.9V = ~160*F engine block. Radiator would be significantly lower...cools down much quicker than the engine block. Look carefully at the coolant system flow diagram I provided. The thermostat is actually 2 gatekeeper valves in one....it totally blocks the output of the 160* to the rad and blocks any cool rad water from from returning into the system. EXPLANATION: You started car=>water circulates around block/heads only mixing water from hot/cold spots together as they flow past the ECT=>T's and V's jumping up/dn briefly ...then T rises causing V to fall=>at 170* thermostat begins to open and is fully open at 194*. The entering cool rad water mixes with hot and quickly drops T and V rises and the thermostat starts to close =>the water quickly heats, thermostat reverses again=>the back and forth stops when the thermostat remains near to or at fully open and a temperature equilibrium in the system is reached....you saw that happen with ECT showing 0.630V - 0.680V. Look at my posted table...probably is about mid 180's. Now, look at the tables showing the ECU programmed temperatures required to turn on the fans. Lowest is 203*F. YOUR FANS SHOULD NOT BE RUNNING !!!!! You could reassure yourself by unplugging the installed ECT connector and attach it to your old ECT. Boil water~212*, quickly take it to the car, turn the key to ON/RUN, lower connected old sensor into water...Does the fan turn on? ? measure voltage quickly.

Hi @mothsmoths thanks for that awesome answer.
I'm pretty sure that car is overheating. I have not put a temperature meter to the water, but I have few signs that is happening:
Since I have this problems, I never seen my fans working.
-Not arriving to my parking spot like always before.
-In traffic jam I can see my oil gauge going down and I have seen one time the oil light flickering (new oil installed). Oil at 2 ticks. With big fan working oil is on the big lower oil gauge line at idle. (I know that stock gauges are shit, but there is a big difference. Now if I try to brake the car and release the clutch to stall it, oil light don't comes on at 4-500rpm (less than this the engine dies).
Water reservoir was going up to much.
-If I start the engine and idle it, fans never run. But after 10min I can see that revs start to die and the ecu fights to maintain the base idle while the oil pressure drops with time. Of course I can't touch anything on the engine bay cause is so so hot.
I am sure like I am a man that fans are not working properly.
All engine is restored with OEM parts (Thermostat, water pump, oil pump, cooling and oil sensors... I think that everything in it is new).

Then with that chart that you have put, I can see that sending unit is not working properly. Then the questions:
-Is there more than one genuine temp sensor for ecu? (Could be a bad generation sensor installed).
-Could be the wire to the sensor that have so much resistance? (Wire in bad shape).
-Could be a bad ecu instead a bad wire to the sensor? How to know?
Disconnecting the 83 pin on the ecu connector (input sensor) and look resistance between the wire and body? How to diagnose if is the sensor wiring or ecu internal damage?
Were I must to check that voltage chart? Is same pins that I have been looking? (83-92).
Really thanks for that post. So clarifying.

Markmo said:

Hi @mothsmoths thanks for that awesome answer.
I'm pretty sure that car is overheating. I have not put a temperature meter to the water, but I have few signs that is happening:
Since I have this problems, I never seen my fans working.
-Not arriving to my parking spot like always before.
-In traffic jam I can see my oil gauge going down and I have seen one time the oil light flickering (new oil installed). Oil at 2 ticks. With big fan working oil is on the big lower oil gauge line at idle. (I know that stock gauges are shit, but there is a big difference. Now if I try to brake the car and release the clutch to stall it, oil light don't comes on at 4-500rpm (less than this the engine dies).
Water reservoir was going up to much.
-If I start the engine and idle it, fans never run. But after 10min I can see that revs start to die and the ecu fights to maintain the base idle while the oil pressure drops with time. Of course I can't touch anything on the engine bay cause is so so hot.
I am sure like I am a man that fans are not working properly.
All engine is restored with OEM parts (Thermostat, water pump, oil pump, cooling and oil sensors... I think that everything in it is new).

Then with that chart that you have put, I can see that sending unit is not working properly. Then the questions:
-Is there more than one genuine temp sensor for ecu? (Could be a bad generation sensor installed).
-Could be the wire to the sensor that have so much resistance? (Wire in bad shape).
-Could be a bad ecu instead a bad wire to the sensor? How to know?
Disconnecting the 83 pin on the ecu connector (input sensor) and look resistance between the wire and body? How to diagnose if is the sensor wiring or ecu internal damage?
Were I must to check that voltage chart? Is same pins that I have been looking? (83-92).
Really thanks for that post. So clarifying.

Click to expand...

You wrote, "I'm pretty sure that car is overheating. ..I have not put a temperature meter to the water". You put 2 water temp sensors to it. The ECT sensor voltage proves your NOT OVERHEATING and your gauge never goes past 1/2 way up. You saw `0.63-0.68 volts ...the table I posted puts those voltages @ 180ish F. Your condenser fan is on low already since you have the AC on. The rad fan SHOULD NOT COME ON until 203*F. You wrote "that chart that you have put, I can see that sending unit is not working properly". WRONG-look again. I will post the actual voltage to temp table below that is programmed in YOUR ECU and mine from the factory. Shows same temps very very accurately....0.63-0.68 V is 178-182*F. Thermostat is only 1/3 open....fully open is at 194*F.

You can back probe voltage at ECT connector then immediately at ECU pins...if very close proves wires are good.

As the coolant gets hotter, it expands and pressure increases. Overflow cap opens to release/maintain coolant ~13psi, so coolant flows into bottle... level increases......THAT'S NORMAL...NOT OVERHEATING symptom. The coolant gets sucked back into the system from the bottle as the engine cools down.

Your oil pressure gauge sounds like all of our cars using OEM pressure sender. Oil temp rises->oil is thinner-> pressure reading drops-> no valve noise, goes up as RPM's go up-> NO PROBLEM.

You can buy an infrared laser temp gun... ~$15 U.S....? Euros en ESPANA. Point it at water manifold at base of ECT and upper rad hose.....inexpensive/easy/quick/ so can let go non-problem and sleep. DON

Hard to read with size and colors, but that's what's in the ECU, I can't change that. You can hold cursor over table, right click, choose open in new window/tab, then just click on the tab to open, with cursor over table click on +.