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914World.com _ 914World Garage _ D-Jet Cold Start Valve?

Posted by: Angelface01 May 27 2005, 03:15 PM

So I have this 1.7 engine that I'm trying to start for the first time in 10+ years. I have spark and all four injectors work but the cold start valve isn't shootong fuel. The engine was converted to carbs in it's past lifetime and now is being converted back to fuel injection. The right side head is not tapped for a temp sensor. Will the cold start valve work if there is no temp sensor in the head to tell it that the engine is cold? Please Help me!!

Posted by: Headrage May 27 2005, 03:17 PM

I thought the cold start valve didn't even work unless the temp was 40 degrees or so.

Posted by: Air_Cooled_Nut May 27 2005, 03:39 PM

You need the cold start temp. switch and that is different from the head temp. sensor. The cold start injector gets its power from the starter (terminal #50) and it's the temp. switch that completes the circuit when it grounds (below 50ºF).

Also, you need to have wire #18 from the ECU connect to the same terminal on the starter (#50). This will help start-ups even when the cold start injector is not enabled. BTDT

Posted by: brant May 27 2005, 03:55 PM

I was surprised at how cold the temp had to be to get the cold start valve activated...

I think its much closer to 30 degrees F, than 40.
basically unless its freezing out the cold start will have no effect. And since its summer, I doubt this is your problem.

brant

Posted by: Bleyseng May 27 2005, 04:05 PM

not having a CHT will cause you problems

Posted by: type47 May 27 2005, 04:56 PM

re: the missing CHT sensor. i believe it is needed to basically run, not just run right. maybe you could fool the ECU by hooking up an external resistor to the CHT terminal and adjust as the engine warms up. sounds like the engine is in the car? major PIA to drop engine, change head (find head, rebuild head, install CHT, install head, bolt everything back together, put engine back in car). if i remember, CHT is in the 0-2000 ohm range. maybe that would at least get it running.

Posted by: Air_Cooled_Nut May 27 2005, 05:12 PM

QUOTE (brant @ May 27 2005, 01:55 PM)
...I think its much closer to 30 degrees F, than 40.
basically unless its freezing out the cold start will have no effect. And since its summer, I doubt this is your problem.

Depends upon the type of temp. switch used.
Early models: 5ºF (-15ºC) or colder
Late models: Between 50ºF - 32ºF (10ºC - 0ºC) or colder
So for late models the switching temp. will be somewhere between the given values. At that temp. or colder the switch will ground. For my Type 3 VW the switching temp. is 45ºF.