Another cold start injector question

The cold start injector should only function when the starter is cranking and when the thermo-time switch is closed. Look to the thermo-time switch and relays that control it. There's a circuit diagram in the owner's manual.

 

It shouldn't do this so i guess it's faulty. It acts now like an acceleration pump found on carburetors I unplugged mine also because the engine doesn't need it.

 

Here it is:
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Hi Eric, the Ferrari part # is 121778, Bosch part# is 0 280 130 217. It's item #10 in the first image below. The switch screws into the top of the engine under the plenum and it's a bit challenging to get to. It can be replaced without removing the plenum but you have to remove the oil filter and move a vacuum hose and coolant hose out of the way to get a wrench in there. The second image gives you a peak at what it looks like in the engine. The third image shows a close up of what it looks like out of the engine. Hope this helps.
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

It's may be the thermo time switch.

1985 TSB 10-13 states:
Bosch k- jet with lambda

Additional fuel under acceleration with cold engine

With the engine block still cold ( temp below 45c), the cold start injector gives additional fuel under the control of the thermo time switch (providing ground) and the differential pressure switch (providing a positive). The latter, via a vacuum hose, is connected to the intake manifold, and closes momentarily when vacuum decreases quickly.

 

To test the thermo-time switch, unplug the cold start injector and measure the resistance from the RV (red-green) wire in the (now unplugged) harness connector to the bare engine block with the key "off" (this is identical to measuring from terminal W of the thermo-time switch to the body of the thermo-time switch):

cold (i.e., after sitting overnight and before running the engine) = should be 0 Ohms

warm (i.e., after getting the coolant temp up to normal and shutting the engine off) = should be 100~160 Ohms

If your warm measurement is still 0 Ohms = bad thermo-time switch

If both measurements are OK, your problem is elsewhere.

PS You can do all of the resistance tests shown on page D35 in the Mondial 8/QV WSM at the unplugged CSI connector by knowing that:

1. the RV (red-green) wire in the CSI connector is connected to the W terminal of the thermo-time switch;

2. the BN (white-black) wire in the CSI connector is connected to the G terminal of the thermo-time switch; and

3. the engine block is connected to the body (ground) of the thermo-time switch.

 

Nope....

 

No...but I'd bet some one has tried to wire it that way!

Your 328 has a Lambda sensor that adjusts the mixture continuously based on O2 measured in the cat, and it's often the cause of fuel delivery issues. You may be dealing with two problems and the cold start issue is masking something else.

 

Happily, the O2 sensor is fairly easy and cost effective to replace.

 

It varies depending on the F model/CIS injection system type and the operating conditions:

K-Jet without Lambda (1980-82 US 308i-2V & 1983 US 308QV) = CSI only used during starter motor cranking (see description page 68 260/83 OM); throttle blip enrichment provided by WUR (that senses intake manifold pressure) by reducing the control pressure. CSI not used after starting event.

K-Jet with Lambda (1984-85 US 308QV & US 328) = CSI used during starter cranking and to provide enrichment during very-cold-running throttle blip (see descriptions on page 68 307/84 OM and page 66 396/85 OM). These models use a different WUR that only senses atmospheric pressure. On the late US 308QV, the differential pressure switch detects the intake manifold vacuum drop and fires the CSI during very-cold-running throttle blip. On the US 328, the MicroPlex ignition ECU detects the intake manifold pressure drop and fires the CSI during very-cold-running throttle blip. CSI not used on either model during cold-running nor warm-running.

KE-Jet with Lambda (US TR) = CSI used during starter cranking and to provide enrichment during very-cold-running and cold-running throttle blip. The differential pressure switch detects the intake manifold vacuum drop and fires the CSI during very-cold-running and cold-running throttle blip. CSI not used during warm-running.

For these descriptions:

"very-cold-running": coolant thermoswitch in cold state and thermo-time switch = closed (after recooling after starter motor cranking)
"cold-running": coolant thermoswitch in cold state and thermo-time switch open
"warm-running": coolant thermoswitch in warm state and thermo-time switch open

 

Even in the best tuned car, O2 sensors don't last forever.