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Discussion Starter · #1 ·
I have an 05 taco, URD maf cal, LC-1/XD-16 combo, Volant intake, and flowmaster exhaust. My question: is there a way around closed loop? ie some sort of voltage clamp for the coolant temp? If the ECU thinks the engine is cold all the time it will run open loop and could be adjusted via the piggyback right? I installed my volant tonight (btw a total piece of crap, nothing fit, should have got the urd tcai) and noticed that my AFR went from a near perfect 12.5 to around 11 at WOT, and the fuel trims were also way rich. While retuning I thought that it would be cool to write a complete map across all rpm's myself, and wondered if this was possible. Also is the reason the AFR's went rich because the volant flows LESS air than stock?
 

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I have an 05 taco, URD maf cal, LC-1/XD-16 combo, Volant intake, and flowmaster exhaust. My question: is there a way around closed loop? ie some sort of voltage clamp for the coolant temp? If the ECU thinks the engine is cold all the time it will run open loop and could be adjusted via the piggyback right? I installed my volant tonight (btw a total piece of crap, nothing fit, should have got the urd tcai) and noticed that my AFR went from a near perfect 12.5 to around 11 at WOT, and the fuel trims were also way rich. While retuning I thought that it would be cool to write a complete map across all rpm's myself, and wondered if this was possible. Also is the reason the AFR's went rich because the volant flows LESS air than stock?
Well, temp is usually a measure of resistance. So if you took a stock engine, measured the resistance after it reaches operating temp and then pulled the sensor cable and put a resistor in the terminals that matches your previous ohm reading, you should be able to fool the computer at all times. You probably could even put a switch in this system so you could run it open or closed loop depending on what the weather was like or whatever else.
 

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Well, temp is usually a measure of resistance. So if you took a stock engine, measured the resistance after it reaches operating temp and then pulled the sensor cable and put a resistor in the terminals that matches your previous ohm reading, you should be able to fool the computer at all times. You probably could even put a switch in this system so you could run it open or closed loop depending on what the weather was like or whatever else.
maybe. the ECM may complain if it never sees a cold condition (typical of a cold start, etc). you can try it and see what happens. the diagram shows a logical pic of a thermistor type sensor (http://haroldmiller.net/FSM/05+/data/ileaf/06toyewd/06toypdf/ewd/2006/tacoma/h/em01d3.pdf), so it should be fairly easy to rig a dash mounted potentiometer for manual control, etc. but having a ODBII/CAN scan tool will help you see what the ecm "sees", etc.



"(1) Engine coolant temp. signal circuit
The engine coolant temp. sensor detects the engine coolant temp. and has a built–in thermistor with a resistance which
varies according to the engine coolant temp. The engine coolant temp. is input into TERMINAL THW of the engine
control module as a control signal."
 

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maybe. the ECM may complain if it never sees a cold condition (typical of a cold start, etc).
I would think it would be ok since you sometimes start your truck after it's only been off for a few minutes. Sometimes even from a pulled battery while it's still warm. It should just consider itself warm at all times. I wouldn't imagine it is programmed to monitor this over time, but I could be wrong.
 

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I would think it would be ok since you sometimes start your truck after it's only been off for a few minutes. Sometimes even from a pulled battery while it's still warm. It should just consider itself warm at all times. I wouldn't imagine it is programmed to monitor this over time, but I could be wrong.

i dont mean cold as in "starting". i mean "cold" literally. the ecm is smart these days. being "warm" all the time is not normal. i am assuming you would want to make it so that the ecm thinks the water temp is at operational temp, which is around the 180-210°F mark. there are other sensors by which the ecm could use as metrics to determine operational problems, etc.

try it and just see what it does. no cel the great, if you trip a cel then you'll need to figure out some other way, etc.
 

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shouldnt the MAF calibrator do OPEN loop anyway...
if you wanted to tune the CLOSED loop get an AFR calibrator..
 

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maybe. the ECM may complain if it never sees a cold condition (typical of a cold start, etc). you can try it and see what happens. the diagram shows a logical pic of a thermistor type sensor (http://haroldmiller.net/FSM/05+/data/ileaf/06toyewd/06toypdf/ewd/2006/tacoma/h/em01d3.pdf), so it should be fairly easy to rig a dash mounted potentiometer for manual control, etc. but having a ODBII/CAN scan tool will help you see what the ecm "sees", etc.
it seems that you would have to constantly adjust for temperature.. i doubt that would work.
 

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I have the MAF cal myself did you need an OBD II to set the maps for it or did you just run it out of the box? Sorry to hijack your thread
 

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Discussion Starter · #10 ·
I have the MAF cal myself did you need an OBD II to set the maps for it or did you just run it out of the box? Sorry to hijack your thread
I ran it out of the box with the URD map, but to be safe I have a wideband to monitor AFR's too. It's not needed really, the URD map is pretty safe for a stock rig. If you have intake/exhaust mods it needs tuned.
 

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I have the MAF cal myself did you need an OBD II to set the maps for it or did you just run it out of the box? Sorry to hijack your thread
if you are supercharged and have fuel upgrades it is necessary to have a wideband sensor and OBD scanner
without it you have no clue what is going on in your motor
 

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still new to EFI so I am trying not to get flammed I appreciate your patience what type of wide band did you use and how did you set the fuel maps did you run both the R4 and the wideband off of a PC to tune it all i have is the cai and the exhaust on a 3.4
 

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I read that a few times when I found it searching but it didnt look like any of it had to do with non S/C engines?
 

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I read that a few times when I found it searching but it didnt look like any of it had to do with non S/C engines?
i cant really help ya there.. im supercharged with an AIC and AFR controller with the urd 7th injector
 

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it seems that you would have to constantly adjust for temperature.. i doubt that would work.
why? the OP could dial it to what he wanted, and if need be make changes. perhaps i dont understand what you mean by "would have to constantly adjust for temperature..", its kinda a set-it and forget-it method, etc.
 

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yeah all my deployment money went into buying a house, but next time I go over that is one of the first mods to the new truck
 

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why? the OP could dial it to what he wanted, and if need be make changes. perhaps i dont understand what you mean by "would have to constantly adjust for temperature..", its kinda a set-it and forget-it method, etc.
the same reason you have to tweak the fuel map when it gets warmer or colder...
it will end up doing the same thing those little ebay 20hp resistors do..
 

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Discussion Starter · #19 ·
Well after about a half a tank of gas I think I'm finally tuned. That Volant pos is a pita to tune. I had to pull out a lot of fuel. At WOT above 3000 rpms it hangs right at 4.2V and to get into the 12's AFR wise I had to write 8.5 into the "sweet spot" column which for me is the 4.2V column. That seems like a hell of a lot, no? I started with Urd's baseline map that came preloaded, selected all, then took out -5%, and that only put me into the low 11's. Don't buy a volant if you don't have a MAF calibrator! Better yet don't buy one period.
 
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