Fuel Injection wiring? Options

[mike_the_man]

Hi all,

I have a question regarding my fuel injection wiring harness. I pulled it on the weekend to have a look, and make sure there are no cracker wires, etc. It's off of a 74 2.0L. I'm wondering what all of the hook ups are? There was one wire not connected, and I'm not sure where it goes. The ones that I am sure of are the following:
4 fuel injectors
MPS
CHT
Manifold Temp sensor
Trigger Points
TPS
Cold Start Injector
Grounds
Connection to Relay Board
There is one wire left, and it seems to come out of the same place as the trigger point connection. Anybody know what it shoudl connect to? Anybody that can tell me will have my ever lasting admiration.

Thanks,

[Brad Roberts]

What color is the wire ??

The only thing you didnt list is the thermal time switch....



B

[mike_the_man]

Hi Brad,
The wire is white, but all of the wires in my injection harness are white. Where would I find the thermal time switch, and what does it do? Is that for the cold start injector?

Thanks,

[JeffBowlsby]

Yep that wire is for the TTS. The TTS sits down on the engine case, towards the rear of the car from the dizzy. The TTS switches the CSV on/off when its cold.

[Brad Roberts]

The thermal time switch mounts to one of the legs on the 2.0 intake plenum. Its about 4 inches away from the distributor.

B

[Brad Roberts]

Jeff,

can you send me the full size pic of that race car ??


B

[JeffBowlsby]

This is the biggest one I have Brad:

[JeffBowlsby]

Take 2

[mike_the_man]

So, if the wire that runs to the thermal time switch was disconnected, and grounding out on the tin, could that cause the cold start injector to be squirting all the time? Probably not, becuase doesn't it only squirt when the started is engaged? Hmm, I guess thats probably not the problem. What colored wire powers the AAR, I don't have that hooked up either?

Thanks guys,

[Brad Roberts]

The AAR is powered from the same harness that goes to the dizzy/coil. The connector for it should have a plastic shield around it. Jeff will know.. but I'm pretty sure the wire is WHITE also. Its the only wite wire in that loom.

B

[mike_the_man]

Yikes, too many white wires, but I think I may be able to get this all sorted now. I just love playing with automotive wiring. If I get it all figured out, I think it will be time for a few (IMG:style_emoticons/default/beer3.gif)

Thanks everbody, you guys are great!

[JeffBowlsby]

All 1.7, 1.8 and 2.0 FI wiring harnesses have ONLY white wires in them. (The 912E and 914/6 are different, they do have colored wires.)


From Brad Anders page on the TTS:

Function: Senses cold starting condition and provides additional fuel during starting to richen the mixture.
Normal Value(s): Bosch says the cold start valve coil resistance should be 4.2 ohms. Measurements I've taken on a NOS 0 280 170 015 valve I have are R = 4.24 ohms. Coil inductance was 4.51 mH.
Failure Modes Open control wire from the thermo/thermo-time switch: Prevents valve from operating. Poor cold start operation. Check by inspection.
Shorted control wire from thermo/thermo-time switch: Causes valve to stay open. Very rich mixture across all operating conditions. Check by inspection.
Open or shorted thermo/thermo-time switch: Prevents valve from operating (open) or causes valve to stay open (shorted). Poor cold start operation (open) or rich mixture (shorted). Check by removing the switch, placing it in your freezer for a full 10 minutes (see notes section below), and checking for continuity from the terminal to the case. If there is no continuity, the switch is open and bad. Allow the switch to warm up to room temperature (70 deg. F) and check for continuity. If there is continuity, the switch is shorted and bad. Note that if you have a 75-76 2.0L, you have a thermo-time switch which has an internal heater that limits the time the switch is active. This switch also has two leads instead of the single lead on the thermo switch. I don't have a pin-out on the thermo-time switch and don't know which terminal is the switch and which terminal is the heater lead (+12V).
Open or shorted thermo-time switch heater: The 75-76 2.0L thermo-time switch has a heater element which limits the time the switch is active. If this lead is open and the heater is inoperative, you could experience flooding or fouled plugs during repeated attempts to start the car. If the lead is shorted, you will likely blow a fuse (unknown which one) when you start the car, which may disable other systems. I don't have the pin-out for the thermo-time switch and don't know which terminal is the switch and which terminal is the heater lead (+12V).
Open power lead from the relay plate to the valve: Prevents valve from operating. Poor cold start operation. Check by inspection.
Valve Stuck Open: Very rich mixture across all operating conditions. See URL in the Injection Valve section above for a test method.
Valve Stuck Closed: Poor cold start operation. See URL in the Injection Valve section above for a test method.
Valve Leaking. Rich mixture across all operating conditions, poor fuel economy. See URL in the Injection Valve section above for a test method.
Mismatched thermo/thermo-time switch: Provides wrong temperature set point for operation, poor cold start performance. Check part number against the table above.

Notes: The cold start valve provides a fine mist of fuel in the intake manifold to richen the mixture during cold starts. For most of us living in the continental US, the valve doesn't turn on except in the coldest months of the year. The valve is controlled by the thermo- or thermo-time switch and operates independently of the ECU. The valve is active only when the key is in the "start" position and the temperature is below the set point of the thermo-time switch. Actual measurements of the switching temperature of a sample thermo switch (311 906 161 C) indicate a lower temperature than quoted by the FWM, somewhere closer to 0 deg. C / 32 deg. F.Jeff Bowlsby found a reference (VWTG) that has a table of actuating temperatures for the early and later thermo switches, but not the thermo-time switch (note there is an error in the units conversion of the entry in the VWTG for first sensor listed below that has been corrected here): 311 906 161 : -12 to -18 deg. C / 10 to 0 deg. F
311 906 161 A : 0 to -10 deg. C / 32 to 14 deg. F
311 906 161 B : -2 to -8 deg. C / 28 to 18 deg. F
311 906 161 C : -6 to -14 deg. C / 21 to 7 deg. F