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Hi All .. Looking to replace the Thermo Time Switch on my '86.
Anyone have a part number or where I might get one?
It screws into a mounting hole right at front of inlet manifold, above water pump, right next to the coolant temp sensor. Purple & tan wiring. Location diagram is at 8A - 201-5.
It apparently controls the activation of the 9th (cold start) injector.(shop manual 8A20-7 has a circuit diagram). Shop manual at 6E3-C2-1 provides an explanation & refers to a Cold Start Fuel Injection Switch, which I think is one and the same thing, from what I can gather. By detecting water temp the switch can open the circuit to the cold start injector at various coolant temperatures.
Thermo Time Switch on left
The attached photo was from a YouTube video ..
P/N 14084318, it is also a timer, the colder the coolant temp the longer it is on. This is a hard find, I see no new cold start switches made or anything close to it.
Corvette parts yard is your best bet.
I can't vouch for these numbers but the third gen chevy and the fiero folks used it.
More Information for ACDELCO 212312{Alternate Inventory Numbers: 14084318, 19244930
Last edited by Vets-Vet; Jun 13, 2024 at 08:49 AM.
Thanks to Vets-Vet with a few leads on the part numbers - I've researched Delco 212312, GM 14084318 & 19244930 and from what I can see the part was discontinued way back in 2010 so I guess the only option is to block the hole. Presume the the cold start injector will be inoperative. I wonder about fault codes.
I am replying here so that others don't waste their time chasing a dead end.
The cold start system is stand alone, you should not have codes.
Is yours damaged ??
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Not damaged any more - - (LOL I blew a head gasket and in doing so softened the alloy heads- thus destroying them).
So I took the opportunity to stroke the engine to 383. Scat crank, Edelbrock Performer RPM heads, very mild Lunati roller cam, roller rockers & valve springs, new piston set of course, Scat larger flex plate (which then requires new 'mini' starter motor), fresh paint, injector clean - basically a full refresh of the engine, verifying all clearances.
So whilst the engine is out I am renewing every accessory nut and bolt (mostly ARP stainless), every sensor, every gasket, and checking the routing of every electrical connection / plug. Have deleted throttle body coolant hoses and blanked off outlet/inlet, smog pump delete, removed AIR control & AIR switching solenoids. I did consider deleting the EGR but decided against it as it certainly would require a re-flash oi the ECM. So the shop manuals and I have become good friends, BUT I need to to work out revised routing of water hoses and vacuum hoses after deleting the aforementioned components. I am no expert, but have time on my side.
Make sure you check the EGR can hold vacuum, most of them by this time have leaky diaphrams. If you decide to reflash, and I am NOT the expert, you can also change your fan on temps and program out the cold start injector. The 89 used the existing injectors to add additional fuel at startup. A specific tune may be available as a new memcal or piggy-back chip.
This is what I have in my 86. I'm not sure if I need one also. I can't find one. I have the motor apart and figure I may as well replace it. My car is running very rich and from what I have read, it sounds like I need this. Anyone know where I can get one?
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""My car is running very rich and from what I have read, it sounds like I need this""
If it were to somehow stay on maybe, but I doubt that is it. Your connector looks bad though. Unplug it and see what happens. Right next to it in the front of the intake manifold is the more likely suspect engine coolant temp sensor. The cold start valve only opens for a maximum of 8 seconds.
From: Liliha Bakery stuffing my face with coco puffs!
Originally Posted by Vets-Vet
Make sure you check the EGR can hold vacuum, most of them by this time have leaky diaphrams. If you decide to reflash, and I am NOT the expert, you can also change your fan on temps and program out the cold start injector. The 89 used the existing injectors to add additional fuel at startup. A specific tune may be available as a new memcal or piggy-back chip.
Idk if you made it clear enough...in 1989, the cold start injector was eliminated so you possibly could remove the CSI and run a '89 tune/PROM. Or yes if you have the means or want to work with a tuner, '85-'88 can be programmed with a richer start up routine where the CSI can be removed.
Originally Posted by Vets-Vet
""My car is running very rich and from what I have read, it sounds like I need this""
If it were to somehow stay on maybe, but I doubt that is it. Your connector looks bad though. Unplug it and see what happens. Right next to it in the front of the intake manifold is the more likely suspect engine coolant temp sensor. The cold start valve only opens for a maximum of 8 seconds.
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Keep in mind that the CSI circuit is ONLY energized during cranking and also take into the account of the temperature limitations <95dF. If I understand that correctly, you can only get the 8 seconds max of enrichment from the CSI if and only if you're hanging on to the ignition in crank for >8 seconds below the temp threshold. Inadvertently on? Highly unlikely but leaking all the time maybe.
I am not sure of the injector end but the sensor switch timer end is a standard injector connector like the other 8. I believe it is a SMP HP3980. https://www.rockauto.com/en/catalog/...connector,2577
. "" If I understand that correctly, you can only get the 8 seconds max"" That's why I said it could only stay on for a max of 8 seconds !!
Thermo Time Switch 1986
