Cold Start System Testing (hard starting)

mrnickleye · 05-17-2006, 06:20 AM

I've actually never had a problem with a cold start injector on Toyotas, other than a little dirty. I have had to replace several 'temp/time' switches.
They made some changes in them within the first couple years. All of them, trucks, too. They changed the resistance values to get better performance.

I would do the 'following' testing before doing what the TSRM says.

NOTE: The current is only supplied during the cranking mode, not after the engine starts.

You can test the injector for resistance. per TSRM. 2-4 ohms
http://www.cygnusx1.net/supra/librar...fi/FI_077.html

The TSRM does not go into testing the switch, but you can check some resistance values thru the terminals to see if they are shorted or open.

(I have the specs, I'll post them later when I dig them out)

Also, the switch is heat/cold controlled. If the temp outside is more than about 65* (maybe 55*) it won't allow the injector to come on, to prevent flooding. Also, even in a snow storm, after 12 seconds of cranking time, the switch will stop supplying current to the injector. (prevent flooding)

So...
On a cold vehicle (and you may have to pack a bag of ice around the switch for 10 min. ahead of time), you can pull the injector and place the tip in a jar. Crank the engine to see if gas is spraying. Yes?? then system is working properly.

No spray right away?? Stop cranking, and wait a few minutes for the switch to get cold again from the ice pack. Then hook your 12 volt meter to the injector connector, then crank again to make sure current is flowing to injector. Yes? then injector has problem. Pull it and perform testing per TSRM. No volts? Stop.

Pull connector to time switch and then test for current to it by cranking engine.

Have current?? then switch is likely bad, but check wiring from switch to the injector.

I do it in this backwards order because the overall system gets tested right away. It is actually a very simply design, and seldom has problems.

The switch is very sturdy, and a 'dealer only' part, and is a bit pricey $$$$.

Now....there are other areas to check for a hard start problem. Any codes come up when you scanned it, or check the light by jumping for codes ???

TPS, AFM, coolant temp switch for the ECU. Fuel pressure drop, usually due to a leaking injector, or check valve at the fuel pump (in the tank, bummer).

Feel free to ad your $0.02. Everyone needs 'some' help, shortcuts, and beer.

05-17-2006, 06:20 AM	#1
mrnickleye 1000whp postwhore Join Date: Jun 2005 Location: Mojave Desert, Calif. Posts: 1,705	Cold Start System Testing (hard starting) I've actually never had a problem with a cold start injector on Toyotas, other than a little dirty. I have had to replace several 'temp/time' switches. They made some changes in them within the first couple years. All of them, trucks, too. They changed the resistance values to get better performance. I would do the 'following' testing before doing what the TSRM says. NOTE: The current is only supplied during the cranking mode, not after the engine starts. You can test the injector for resistance. per TSRM. 2-4 ohms http://www.cygnusx1.net/supra/librar...fi/FI_077.html The TSRM does not go into testing the switch, but you can check some resistance values thru the terminals to see if they are shorted or open. (I have the specs, I'll post them later when I dig them out) Also, the switch is heat/cold controlled. If the temp outside is more than about 65* (maybe 55) it won't allow the injector to come on, to prevent flooding. Also, even in a snow storm, after 12 seconds of cranking time, the switch will stop supplying current to the injector. (prevent flooding) So... On a cold vehicle (and you may have to pack a bag of ice around the switch for 10 min. ahead of time), you can pull the injector and place the tip in a jar. Crank the engine to see if gas is spraying. Yes?? then system is working properly. No spray right away?? Stop cranking, and wait a few minutes for the switch to get cold again from the ice pack. Then hook your 12 volt meter to the injector connector, then crank again to make sure current is flowing to injector. Yes? then injector has problem. Pull it and perform testing per TSRM. No volts? Stop. Pull connector to time switch and then test for current to it by cranking engine. Have current?? then switch is likely bad, but check wiring from switch to the injector. I do it in this backwards order because the overall system gets tested right away. It is actually a very simply design, and seldom has problems. The switch is very sturdy, and a 'dealer only' part, and is a bit pricey $$$$. Now....there are other areas to check for a hard start problem. Any codes come up when you scanned it, or check the light by jumping for codes ??? TPS, AFM, coolant temp switch for the ECU. Fuel pressure drop, usually due to a leaking injector, or check valve at the fuel pump (in the tank, bummer). Feel free to ad your $0.02. Everyone needs 'some' help, shortcuts, and beer. __________________ Had a Red 1989 N/A. Automatic. Sports Pkg. w/wing. TEMS, and some nice MODS. Sold to a friend 10/08/08. Last edited by mrnickleye; 02-07-2007 at 03:27 AM.*