During a head gasket project, the Cold Start Injector Switch was broken, and we all know the cost of a new one!
After many searches and great advice, it appears that the CSI only gets power (8 volts) during cranking. Then, only when the computer thinks (!) the engine is cold, via the temp sensor and the CSIS (and possibly other inputs). The computer completes the circuit by grounding the CSI and- the CSI sprays fuel into the plenum to provide an extra shot of fuel to start the cold engine. When the engine starts and the key is released from the cranking position the CSI no longer gets voltage and consequently stops injecting fuel.
During prolonged cranking (no or slow starting) the CSIS will interrupt the CSI after a few seconds to prevent flooding.
All this gets me to my broken CSIS, and a possible way to avoid buying a new one.
If the CSI is provided a direct ground via a switch on the dash, then it should inject fuel anytime the engine is cranking and the switch is ON.
So, to start a cold engine, Hold the switch In to complete the ground circuit- and Crank the engine. The CSI should have voltage and a ground, and inject fuel. When the engine starts, release the key and the CSI switch, and all is normal.
When the engine is at operating temperature, simply start as usual.
Care should be taken in poor starting situations that this procedure does not cause flooding.
Seems to be working good for cold morning starts.
Any comments or technical advice concerning this suggestion would be appreciated.

 

You've added a choke switch to your truck lol. You should add a fuel pump bulb next

Cool fix!

 

Or just take a trip to the junkyard and get one for way cheap. I have a 91 3vz-e engine and my CSIS had been broken the whole time I had the truck (2 years) and didn't know it. Some blockhead snapped the thing in two and just shoved it back in. I took one off a 92 4Runner that had the same specs (measured with ohmmeter) and put it in. Cost $7.50 an the junkyard compared to $200 at the stealer. As far as I can tell, it works just fine.

 

Just because the CSIS is broken or disconnected does not mean the injector is not working. There were situations when mine worked without the CSIS being connected.
Apparently, the Temp Sensor or the Air Temp sensor (and possibly other sensors) also plays a role in the operation of the CSI. But on really cold starts (35 or lower), the CSI only worked with the injector being grounded (whether by me or the CSIS).

 

Do we? That sort of information IS what I look for here. I get $140.80: http://www.toyotapartszone.com/oem/t...462-20040.html Did you get a different price?

LOL! And don't forget the manual "spark advance"!

If you can get a junk part ($7.50!), you really can't justify a Frankenstein approach. If you "flood" the engine you're pumping liquid gasoline into the exhaust system. Then when it starts, you'll get a fireball out the back that could certainly blow your exhaust system (including the oh-so inexpensive cat converter) apart. If $140 (or $7.50) is beyond your budget, I'd just leave it out. And only drive on warm days.

Go ahead and fix it.

 

Instead of replacing the sensor, here is what I do. Wire in a push button (like a horn) to the cold start injector. All you have to do is push the button once and you will hear the injector click and then the engine will start. You can hide the button if you want and it works as a theft deterrent.

 

Works I suppose. You can't just cut the connector and solder the wires to the remaining switch though?

 

Nice mod. I'd replace the toggle switch with a pushbutton switch so you don't accidentally leave the switch on. My old Tercel wagon had lots of custom switches. One turned the radiator fan on after the fan's temperature switch died. Two more turned on the accessory and ignition power, and a hidden pushbutton started the car. It was cheaper and more fun to add switches than it would have been to buy a new ignition switch after I broke the old one by taking it apart.

My pickup is having severe cold start issues, but it's too cold outside to go and dig around to find the problem. Ironic, isn't it? I've been using starting fluid as a semipermanent temporary measure.

 

I would not consider this a mod, but as a alternative fix without spending a lot of money for the proper part. I know it's pricey, but as stated above junk yard $7.50. IMHO it just seems kinda like a mickey repair, but if it works for you, then that's all that matters.

 

Sorry,guys, but I remember when $7.50 would buy 1/2 tank of gas, dinner for you and your favorite girl at the local drive-in, and a good movie.
Hard to break old habits!
Thanks for the responses!

 

FYI, I do this for anti-theft. Along with the typical fuel pump switch most others do. I have a few switches in a row as dummy switches. It works great, unless you know which switches to flip the pump wont work. The engine still won't start unless you know to push the cold start button.

 

I appreciate it purely because you did some interesting electrical work. Sure it's just a switch, but it's still neat. Too many people are scared of electrical work on cars

 

Hmmm, I thought I was addressing an issue regarding a broken CSIS and the cost of replacement, not a anti theft issue.

 

Providing that car thieves are only active in the dead of winter... How many days a year do you actually need a csi in MS anyway? I was getting chewed by gnats in February on my only visit! Not to mention, as the OP said, that your ecu can trigger the csi without the switch anyway. Definitely not a reliable anti-theft by any means.

 

Yeah, I just disconnected the csi plug on my 90 after it was sitting for a week. 30 degrees outside and it sputtered a few times and was running in <5 seconds. Downgrade that from unreliable for anti-theft to useless, no offense. Maybe your truck has another issue going on.