Couple of questions on coolant temp sensors for a 308 2V Injected

See page 76 in your 216/81 OM -- it talks about how the EGR system uses the engine coolant temperature as a control input (ergo -- coolant temp sensor required).

 

That's funny....Dave's trying to disconnect the very Cold-Start 'feature' I'm trying to get working in my car. No, Dave, we're not switching cars....

 

Hi Dave,

The sensor under the coolant reservoir tank is the temperature sensor for the K-Jetronic FI only; this does not input to the dash gauge. Temp sender for the dash (on my 328) is in the crossover coolant manifold between the two cylinder heads (under the plenum). 328 does not have a sender on the thermostat housing; this may be analagous location for 308 model.

The FI temp sender, as I recall, reads continuity until the coolant warms to pre-set temperature then "opens" to infinite resistance. You can check this by allowing car to warm up then disconnecting either one (or both) input wires (effectively causing infinite resistance). If no change in engine speed, this is "warm/hot" endpoint. Bridging with paperclip will revert to "cold" and correspondingly increase your idle speed. Or if you prefer could always pull out the multimeter and take readings. Interestingly, this part is ferrari-specific (not Bosch) but fortunately not expensive. I purchased one from Algar for about $25 earlier this year.

If you wanted to bypass this function I suppose you could externally bridge terminals or connect an inconspicuous jumper between terminals when installed. Not certain if this would affect CSI though (think this is limited to TTS control & not ECU).

Carl

 

Hi Carl
I have the same issue with my 1980 Ferrari 308 Gtsi and wanted to know the name or part number your purchased from Alagar and is it something
i can install myself?? I did the test of pulling one of the wires and the car immediately stopped the high idol.
Please let me know a part number or name really appreciate your Help.
Herman Lemos

 

That's very unusual, because they inverted the logic of how that thermoswitch works on a US 1980 308i versus a US 328 (they are different part number thermoswitches).

1980-1982 US 308i
Thermoswitch Ferrari PN 115477
Cold = open
Warm = closed
(so unplugging it does not simulate the warm condition)

1985-1989 US 328
Thermoswitch Ferrari PN 121777
Cold = closed
Warm = open
(so unplugging it simulates the warm condition even if it has failed in the always closed state)

Some questions:

1. Is your car a 1980 US version 308i or a 1980 euro version 308i that has been "converted" to be emission legal in some other country?

2. Do you have the yellow "cold-running" warning light in your dash? If so (with the thermoswitch plugged in), is it correctly "on" during cold-running and then wrongly stays "on" when warm-running but at the wrong high idle?

 

Hello
First want to Thank You for your response i have the US version 1980 308gtsi And my Dash lights were not working but i checked the fuse and was blown .
Now that i replaced the fuse the yellow warm up light on the dash lights up. So now the issue i have is the car starts cold warms up to high idle but never drops down to normal idle and i have radiator fluid coming out from the over flow. I also replaced the radiator cap to the upgraded 1.1 version but that did not resolve anything was told yesterday by a mechanic that if i disconnect the 2 cables from the sensor near the reservoir tank that i would run normal i disconnected just one of those cables and immediately noticed the car idles lower. So just trying to figure out what that sensor is called?? and were i can buy it. The issue i have
with most Ferrari mechanics is none of them want to do small jobs they give me excuses that they are booked for next 6 months and i want to drive the car i dont want to wait for 6 months when was to do an oil change couldn't get anyone to do it and since i have a lift ended up doing it myself.
Appreciate your help and thanks for taking the time.
Herman

 

Sounds like you have some serious sorting to do (and, unfortunately, a lot of the emission systems on a 1980-82 US 308i get mucked with). Does the yellow light go "off" when the car is warm or stay "on" when the car is warm? If it does go "off" when the car is warm = your coolant thermoswitch is probably OK (and the problem is elsewhere). You can also (unplug one wire from the thermoswitch) and measure the resistance between the two terminals of the thermoswitch when cold (should be infinite Ohms) and when warm (should be near 0 Ohms or just a few Ohms maximum) to directly confirm if it is working correctly or not.

 

Hello Steve
Yeah the yellow light stays on does not go off even when the car is warm.

 

Now that's a fairly clear sign that you do need another 115477 thermoswitch, but I'd still suggest that you measure its resistance both cold and warm to really confirm that it's bad. The yellow light system is also tied into the air injection system (IIRC), and depending on if/how that's been removed, it could affect what the yellow light does, or doesn't, do correctly.

 

No - I don't do offline phone conversations.

 

ok