6 replies to this topic

[mininerd]

Hello,

I need your help. My 1992 SPI runs rich. I changed CTS, O2 Sensor, Vacuum Pipes, Injector, Catalytic. I failed the emission test after all this.

Just changed the thermostat for a new one. Coolant in rad gets up to temp but sensor still reads low when driving.

So either sensor, wires going to it, or the ossageway is partially blocked.

I used a 88 deg thermostat. Will pull the sensor, check the hoses and intake tubing, and re-check the wires from sensor to ECU.

And swap out for a 195 deg thermostat.

by the way gage still doesn't move. So car is still seeing engine as cold. Yet logs show it sees 70C or better until you start driving.

I'm pulling that coolant temp sensor to test in a pot of hot water again.

Going to run a bottle brush through the manifold piping and make sure it is clean and clear And re-check that wiring run for the coolant temp sensor.

What do you think ? Thanks

 

[cal844]

Clean the coolant circuits

[minifreek1]

As above, the inlet manifold will most likely be blocked with corrosion.... had the same problem on mine :)

[Nu2mini]

Double check the thermostat is located in top of the sandwich plate. NOT in the head. 88 Degree thermostat is correct for SPI.

[FlyingScot]

Remove inlet manifold and descale after checking the wiring. The fact that the gauge isn't at the "white pip" means that the MEMS ECU sees cold motor. Use kettle descaler or citric acid solution.

FS

[mininerd]

My inlet manifold is clean. 

[Alpenflitzer]

First of all hav be a look on the sparks. Are the black? sooty? - the the engines runs to fat and your instrument shows real values.

 

Check the gasoline trap (little black box) from where a vac hose goes to the ECU and the second goes to the inlet manifold. If this little box is defect, gasoline penetrates the ECU and causes wrong commands to the injection. The gas trap is cheep and sometimes you cannot see if it is defect.

If this is the case you should take the ECU and put it in a warm environment sticking a woolen fiber in the nipples to get gas out through evaporation. 

 

 

The coolant temp sensor is the black sensor located in the inlet manifold.  (taken from a contribution)

It can be found underneath at the right side of the manifold as you stand at the front of the car.

The coolant temperature sensor works on the same principle as the air temperature sensor, where by as the temperature falls the resistance rises or vica versa. Problems arise when this sensor reads out again for the same reasons as the air sensor. This has a more dramatic effect on the fueling of the engine. If its so far out the ECU may never leave the cold start and warm up programs wich are open loop control where the signal from the oxygen sensor is almost ignored. Again this sensor will usualy read out low. A permenantly rich condition will result. This sensor is connected directly to the ECU and then the ECU provides a signal to the Temp gauge on the dash. The gauge should read not quite mid way, just a little below the white line when the engine is warm. If it reads any different then there is a problem with the engine controlling the temperature. Or the sensor is faulty. On that note it is worth while checking the plug connectors as these can suffer contact corossion. This sensor can only be acurately checked with the diagnostic and a calibrated thermometer. If there is any doubt and you are unable to have a diagnostic done then I would advise replacement but thats only if you are suffering a rich condition and the temp gauge reads below and never anywhere near the mid white line, not above as this would probibly be a cooling system fault.

Again if this sensor is faulty and causes an over rich mixture for long periods, the Oxygen sensor will usualy fail too, as discused above in the air sensor section.
It also may be worth noting that if the thermostatic control is not working correctly on the cooling system that both a hot and cold condition can result so it is in your best interest to fault find this first. For instance if the cooling system fault causes cooler engine temperatures then the ECU will see this as if the engine is still warming up and stay in cold start.