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Location:
New Zealand
Registered:
May 2002
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2TGEU -> THW Operation
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Sat, 15 June 2002 23:37
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I've traced the THW wire to a plug which currently isn't plugged into anything.
I understand the THW wire is for the temperature sensor.
I can run the cold start injector as a manual choke easily.
The thermostat housing doesn't have provision for this plug.
Does the circuit close when the car is up to temperature? or does it vary by resistance?
I just want to set it up so that the computer thinks it is warm all the time.
Thanks
Karl
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Registered:
May 2002
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 Re: 2TGEU -> THW Operation
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Sun, 16 June 2002 02:34
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Karl,
sounds like you have the earlier model 2TG head, head #220 without the yamaha writting on the front(??) or maybe its the yamaha head but without the yamaha head water thermostat housing. Anyways, you'll need one of these housings with the extra EFI connection if you want to run the EFI properly. I've got one you could have for $40+postage if you need it, but sounds like you could run it with the cold start injector.
what your looking for is here-
http://toyoefi.freeyellow.com/EFI13.jpg
or goto-
http://toyoefi.freeyellow.com/
and click on the water and air thermo sensors link to get an enlarged pic.
This log graph shows that when the engine is running around 80degrees C the resistance from the sensor is around 0.4kOhms, so if you just whack a resister between the connections then you can emulate the warm engine temperature.
I was reading your celica mailist message how you hooked 12V and a potentiometer to the cold start, how wells does this work? mines not hooked up at the moment.
rob
YOTA22
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Location:
New Zealand
Registered:
May 2002
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Re: 2TGEU -> THW Operation
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Sun, 16 June 2002 02:57
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cheers for the link, it's awesome.
I have a 2TGEU motor, just with a modified 2TG therm housing to accept a radiator cap. This allows the radiator to be lower then thermostat. I didn't do this, owner before me did.
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Okay, I obviously wasn't clear there.
I hadn't actually hooked that up, but was thinking I could use a pot to adjust how much fuel it flows.
But......... it's a time thing, ie: requires voltage to open, and duty cycle determines how much fuel it squirts.
So.... using a pot wouldn't work.
Some sort of circuit to control the duty cycle would have to be created and be changeable by some sort of pot.
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So........... I was thinking I could just power the cold start for 5 seconds or so when i crank the car.
I presume that running the engine in "warm" mode won't be too bad when it is cold.
I don't have the oxygen sensor plugged in either.
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Brainwave #2:
If i just put a potentiometer with a scale similar to that graph, I can just adjust what the computer thinks is the temperature, and in turn the mixture 
I'll get a pot tomorrow.
Karl
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Registered:
May 2002
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Re: 2TGEU -> THW Operation
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Sun, 16 June 2002 05:22
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ok, but sounds a lot of work, i know i'm getting sick of switching my thermo fan on when my temp. gets to 180, imagine tuning the pot every 5mins to the approx temp of your engine.. not the best way to do it but i guess it would work.
another option would be to get one of these thermo sensors, screw a hole into your existing water housing and bolt the sensor into it.
i was reading something about this the other day from club 4ag i think, they were talking about putting a variable resistor in series with the existing thermo sensor, so when the engines warm you can adjust this dial to add more resistor, fool the computer into thinking the engine's still cold, it adds extra fuel, makes the engine run rich, and bingo instant power(in theory)! I'm going to give it a try sometime so that i could run my 2TG lean to conserve fuel, then when i feel the need whack the 'enrichment' switch and hey presto! kinda like NOS but with less kick! 
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Location:
New Zealand
Registered:
May 2002
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Re: 2TGEU -> THW Operation
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Sun, 16 June 2002 05:31
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true... automatic is always nice.
But I might hook it up now and perhaps one day later I'll get another thermostat housing.
Always possible to have it working with a switch/button. so when the engine is cold, flick the switch . When warm.. turn it off.
Also of course, turn it on for extra fuel.
Karl
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