Help me... Please

CanadianBak'inSupra · 03-24-2013, 08:35 PM

here is some great info on the cold start injector and i way to test some things good reading:

"I've been having a lot of trouble starting my mk2 lately. As the weather got colder the worse the problem got. Having checked the TSRM, I figured out that the cold start injector was not firing. Ok, so same problem umpteen million other supra owners have had to deal with. However, being low on cash right now, I couldn't just run out to Toyota and buy a new one, and it's too cold to go roaming through the junk yards. So I started looking through the electrical diagrams, trying to figure out another way. Here's my solution.

Now in case you didn't know, the cold start injector is not powered by the ECU. It's actually powered by the starter circuit. When the starter is not cranking the injector does not fire, period. The ECU only decides when to allow the injector to fire, based on coolant temperature. It fires the injector by letting it go to ground. The injectors positive side is always connected so any time the starter cranks the injector has power. The "Switch" is after the injector on the ground side. So we don't actually need it.

By connecting the injector directly to ground it will always fire any time the starter runs. Ok, it's true that once the engine is already warm this will make it go rich when starting, but only for an instant. As soon as the engine kicks and you let off the key, it's back to running on the primary injectors only. Not a real problem. And it seems to work like a dream on my car. Instant starting again, nice.

So, here's the mod. It's easy and only cost about 50 cents.
Disconnect the start injector time switch. When looking into the connector, (that is, the side with the wires), the pin you want is on the right side of the connector when the dimple inside the connector is facing up. You'll see what I mean if you look inside it. You need to run a wire from this pin to ground.

To protect the circuit use a 50k ohm resister in line with this wire to limit the power going though it. That's it.

The quick and easy way to do this is run a wire to the negative terminal on the battery or any convenient bolt on the block or chassis. As long as it's grounded. Cut the wire in half and use the resistor to splice the wires back together. Wire/Resistor/Wire. Connect one end to the battery and the other to the pin of the connector. Use some electrical tape to hold everything together and make sure nothing can get caught in the belt and such. Use your imagination. Instant temporary repair until you can get a new switch.

By the way, although this mod is currently working in my own car...
Use at your own risk. If anything goes wrong, don't blame me"

03-24-2013, 08:35 PM	#11
CanadianBak'inSupra Official hall monitor / search nazi - NO SOUP FOR YOU! Join Date: Oct 2009 Location: Canada, BC Posts: 837	here is some great info on the cold start injector and i way to test some things good reading: "I've been having a lot of trouble starting my mk2 lately. As the weather got colder the worse the problem got. Having checked the TSRM, I figured out that the cold start injector was not firing. Ok, so same problem umpteen million other supra owners have had to deal with. However, being low on cash right now, I couldn't just run out to Toyota and buy a new one, and it's too cold to go roaming through the junk yards. So I started looking through the electrical diagrams, trying to figure out another way. Here's my solution. Now in case you didn't know, the cold start injector is not powered by the ECU. It's actually powered by the starter circuit. When the starter is not cranking the injector does not fire, period. The ECU only decides when to allow the injector to fire, based on coolant temperature. It fires the injector by letting it go to ground. The injectors positive side is always connected so any time the starter cranks the injector has power. The "Switch" is after the injector on the ground side. So we don't actually need it. By connecting the injector directly to ground it will always fire any time the starter runs. Ok, it's true that once the engine is already warm this will make it go rich when starting, but only for an instant. As soon as the engine kicks and you let off the key, it's back to running on the primary injectors only. Not a real problem. And it seems to work like a dream on my car. Instant starting again, nice. So, here's the mod. It's easy and only cost about 50 cents. Disconnect the start injector time switch. When looking into the connector, (that is, the side with the wires), the pin you want is on the right side of the connector when the dimple inside the connector is facing up. You'll see what I mean if you look inside it. You need to run a wire from this pin to ground. To protect the circuit use a 50k ohm resister in line with this wire to limit the power going though it. That's it. The quick and easy way to do this is run a wire to the negative terminal on the battery or any convenient bolt on the block or chassis. As long as it's grounded. Cut the wire in half and use the resistor to splice the wires back together. Wire/Resistor/Wire. Connect one end to the battery and the other to the pin of the connector. Use some electrical tape to hold everything together and make sure nothing can get caught in the belt and such. Use your imagination. Instant temporary repair until you can get a new switch. By the way, although this mod is currently working in my own car... Use at your own risk. If anything goes wrong, don't blame me" __________________ 1984 supra - 1uzfe - w58 - 4.10 - 1 piece aluminum shaft.