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Leaning CTS & IAT with Pot
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pdai11 Offline
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Post: #1
Leaning CTS & IAT with Pot
I have fitted a Dry Cell and works really well. The problem is when the engine is cold and not filled with HHO, the first 10-15 minutes, the fuel economy is quite bad until the engine warms and the Efie set voltage kicks in.
I have purchased 2 potentiometers to control the CTS and the IAT but do not know what prongs to use, it has three prongs, left and center to sensors and what do i do with the other one ?
Also how would i know how many ohms to set at for each sensor ?
Appreciate for your help
07-20-2009 08:22 AM
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bsmart Offline
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Post: #2
RE: Leaning CTS & IAT with Pot
You can just ignore the unused prong, it doesn't have to connect to anything. Or you can short it to the center prong and connect the 2 outer prongs as the sensor replacement.
To know accurately what value to set the pots to, you'll need to know the resistance value of the sensors your are removing from service. They have a predetermined resistance curve which you could find in a repair manual, maybe.
Otherwise, using an ohmeter, measure the resistance of the sensors you are taking out of service. Dial your pots to these respective values as a starting point. Then you can 'tune' from there if the vehicle isn't responding correctly.
07-20-2009 09:26 AM
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colchiro Offline
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RE: Leaning CTS & IAT with Pot
For my toyota, I just paralleled a 10k ohm resistor across each sensor and got the recommended 10 deg F. change found in "Turning for Mileage".

You can't put a pot in parallel with a sensor (or replace a sensor), unless you also add a fixed resistor to the pot. Otherwise you can short out the input to the ecu, which could blow a fuse or throw a code.

The fix? Just solder a small resistor like a 3k in series with the pot (either terminal). Now your minimum will be 3k and the maximum is 3k plus the pot value.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-20-2009 12:38 PM
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pdai11 Offline
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RE: Leaning CTS & IAT with Pot
Thank you both especially colchiro, your information is exactly what i was looking for, thanks a million





(07-20-2009 12:38 PM)colchiro Wrote:  For my toyota, I just paralleled a 10k ohm resistor across each sensor and got the recommended 10 deg F. change found in "Turning for Mileage".

You can't put a pot in parallel with a sensor (or replace a sensor), unless you also add a fixed resistor to the pot. Otherwise you can short out the input to the ecu, which could blow a fuse or throw a code.

The fix? Just solder a small resistor like a 3k in series with the pot (either terminal). Now your minimum will be 3k and the maximum is 3k plus the pot value.
07-20-2009 03:47 PM
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pdai11 Offline
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Post: #5
RE: Leaning CTS & IAT with Pot
I forgot to mention earlier, i have read some members stated that some manufacturers has the IAT sensor built into the MAF Sensor, so how or which 2 wires do i place the resistor parallel to ?




(07-20-2009 03:47 PM)pdai11 Wrote:  Thank you both especially colchiro, your information is exactly what i was looking for, thanks a million





(07-20-2009 12:38 PM)colchiro Wrote:  For my toyota, I just paralleled a 10k ohm resistor across each sensor and got the recommended 10 deg F. change found in "Turning for Mileage".

You can't put a pot in parallel with a sensor (or replace a sensor), unless you also add a fixed resistor to the pot. Otherwise you can short out the input to the ecu, which could blow a fuse or throw a code.

The fix? Just solder a small resistor like a 3k in series with the pot (either terminal). Now your minimum will be 3k and the maximum is 3k plus the pot value.
07-20-2009 06:45 PM
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colchiro Offline
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RE: Leaning CTS & IAT with Pot
You can fill out a "sensor request form" (link on my documents page link, may take a couple days tho)

OR

Go to my Autoshop tutorials link and read up on "thermistors" or "air flow" sensors. They will tell you how they work and often give you wiring diagrams and enough theory where you can probably figure out what wires you have by the voltage.

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-20-2009 06:55 PM
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pdai11 Offline
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Post: #7
RE: Leaning CTS & IAT with Pot
Thanks alot, i have now fitted a 10k resistor in parallel to the CTS. From cold start the first 10 minutes the FE got worse than before, should i let it run for a couple of days for the ECU to set in or is there a problem ? Also when the engine is warmed, the fan ran continously. I had read your link "tuning for mileage" stated to add more resistance, does it mean add or replace with a resistor higher than 10k ?
Many thanks
07-21-2009 02:50 PM
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colchiro Offline
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RE: Leaning CTS & IAT with Pot
The best way to adjust this is with a Scangauge II, Dash Daq or other code reader to read the temp the ecu sees from the sensor.

How are you measuring your mileage?

Higher resistance would give you a smaller change.

If 10k is too much, and I originally picked up a 5 pack of resistors, I'd use 2 in series, to give you 20k. O/W, a 15k would be a popular size.

You're positive you're using a 10k (brown black orange)?

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-21-2009 03:04 PM
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pdai11 Offline
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Post: #9
RE: Leaning CTS & IAT with Pot
I do not have access to a scangauge, too expensive. I use the onboard digital trip computer to check my mileage. Normally i have it shown how many miles i have till the tank needs refill as i use this daily since fitted the HHO but never saw the mileage drop this fast after fitting the resistor. When i bought the resistor, it was brought to me from behind the counter. It is in blue colour with 5 bands, don't know which is first or last, it's brown, red, 2 black and a brown. Are resistors same in every country ?
Many thanks
07-21-2009 03:35 PM
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colchiro Offline
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RE: Leaning CTS & IAT with Pot
Yes, they're all the same.
black = 0
brown = 1
red = 2
orange = 3

So brown, black, orange (then maybe gold or silver, which denotes the precision, 5 or 10% I think), would give you:
1 0 000 or 10,000 ohms.

(The 3rd color denotes the number of zeros at the end, in this case 3 zeros.)

Rick

Links: Documents / Tuning for Mileage | Toyota Sensors | Autoshop Sensor Tutorials
07-21-2009 07:05 PM
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