308 GTSi Cold start not working

The difficulty with your idea is two-fold:

1. The cold start injector should only be active during cranking when the engine is fairly cold (i.e., themo-time switch closed) -- with that mod it would also open on every warm restart, and

2. The thermo-time switch limits the "on" time of the cold start injector during cranking to a couple~few seconds maximum. If something else went wrong and you needed to run the starter for a long time that would dump a lot of fuel into the engine.

(I need to recheck this, but) if you unplug the thermo-time switch you should measure +12V on both of the wires (relative to the chassis ground -- not relative to each other), but only during actual starter cranking (you'll get nothing with the key just "on" even if the engine is running) -- have you tried this?

And what about the resistance checks on the thermo-time switch itself that Malcolm posted in the other thread? When (unplugged and) cold do you measure near 0 ohms resistance between the W terminal of the thermo-time switch and the chassis ground? (Doesn't need to be absolute zero ohms, but shouldn't be more than a few ohms maximum.)

Also, have you verified the control pressure from the warm-up regulator is generally doing the right thing vs temperature?

 

Cooly0 -- I had a peek at the 308i OM schematic so have a couple of suggestions:

1. You most definitely should get +12V on the white/black wires that go to the "G" terminal of the thermo-time switch and the white/black wire that goes to the cold start injector when the starter motor is cranking. The path is very direct: battery -to- ignition switch terminal 50 (when in "start" position) -to- fuse 8A for start injector -to- terminal G -to- cold start injector. If the white/black wires on those devices don't go +12V during starter cranking then you've got to look at each of those upstream nodes for the presence of +12V during cranking until you find where it is missing.

2. You have another thermoswitch in series with the the cold start injector and the thermo-time switch (labeled item 106 on your schematic as "Cold start thermoswitch"). It has two terminals, and each terminal has 1 Red/Green wire.

As a first test:

(Ignition key "off" and engine "cold")
A. Unplug the cold start injector
B. Measure the resistance from the red/green wire of the connector for the cold start injector to the chassis ground.

-- if low (like a few ohms maximum), then both the cold start thermoswitch and the thermo-time switch are OK;

-- if high, go to this test:

(Ignition key "off" and engine "cold")
A. Unplug the cold start injector
B. Unplug the thermo-time switch
C. Measure the resistance from the red/green wire of the connector for the cold start injector to the red/green wire of the connector for the thermo-time switch.

-- if low (like a few ohms maximum), then the cold start thermoswitch is OK and the thermo-time switch must be bad (but you can double-check that by making a direct resistance measurement between terminal W of the thermo-time switch and chassis ground);

-- if high, the cold start thermoswitch is bad (or it's connections).

HTH -- give a shout if you find something interesting...