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the fact of the matter is my car never gets leaner than I have tuned it for it ALWAYS gets richer. even though It is tuned for 12:1 in 5th gear it still touches down into the 10s and when it is heat soaked, in the 10s. so if I tuned it in the 10s where would it be in 5th gear?.... breaking up!
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In the SCT software you have a WOT fuel target table lets say you put in 12.1 (SCT uses lamda) as stated above and have your MTF set corectly there would be NO WAY for the target fuel to change and go RICHER by 2+ full AF points , The harder you run an engine the more heat it sets up the MORE fuel that is needed to keep the engine safe and in WOT the ECU does not use the o2 sensors for fueling so there is nothing to add more fuel to the point of 2+ AF points , and this comes from a tuner at topspeedperformance

Misinfrmation is the worst thing for Foci builders because some people read this stuff and dont know

Tom
 

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well my guess is this particular tuner hasnt spent enough time with the MTF... if any at all

I'm gonna agree with what I recall blivit (Mike) has said several times: Set the base table to what you want, move the MTF around using your wideband to match the base table, then get the timing right. this way your tune will be the same or almost the same for nearly all temperature/altitude situations.
 

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I find it interesting that the tuning shop/tuner that listed all this has sence deleted what he said about his AF , Maybe he now has a better understanding of what it should be and will correct it , kind of makes them look foolish to post misinformation then delete it , guess he knows he was wrong now

Tom
 

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O2 sensors are basically for idle to around 2k RPM correct. That is where all the sensors like TPS, RPM, MAF and fuel maps come in, if I am not mistaking.
 

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O2 sensors are basically for idle to around 2k RPM correct. That is where all the sensors like TPS, RPM, MAF and fuel maps come in, if I am not mistaking.

No, not exactly. O2 sensors are used in closed loop operation which a vehicle will exit on any number of factors. The most common is load vs. throttle position; ie once you are past a certain load at a certain throttle position it will switch to open loop. Go below that load and throttle position and you are back to closed loop.

There can sometimes be several factors that go into determining closed loop or open loop depending on the vehicle.
 

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Blivit is correct , the o2 sensor is used at idle , part throttle and could be as high as 5000 rpm if you havent met the requirements to going into open loop

You can lower or raise the TPS to make open loop come in sooner with boost the load part isnt much of a factor its ready about all the time

Tom
 

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No, not exactly. O2 sensors are used in closed loop operation which a vehicle will exit on any number of factors. The most common is load vs. throttle position; ie once you are past a certain load at a certain throttle position it will switch to open loop. Go below that load and throttle position and you are back to closed loop.

There can sometimes be several factors that go into determining closed loop or open loop depending on the vehicle.
Sweet... Now I will sound like a car genius next time the guys come over for a beer and parts install night!![woot]
 

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Blivit is correct , the o2 sensor is used at idle , part throttle and could be as high as 5000 rpm if you havent met the requirements to going into open loop

You can lower or raise the TPS to make open loop come in sooner with boost the load part isnt much of a factor its ready about all the time

Tom
For example... I have my tune setup to go into open loop fueling VERY early (around 250 TPS counts) I did this because I live in a very hilly area (also very rural) and there were times that I would see 10psi OR MORE (part throttle driving) and would still be at a 14.6 afr. Personally I didnt like the thought of it running that lean and it was a multiple times a day event... so just for personal satisfaction (and knowing I wouldnt be cooking the pistons everytime I went up a hill) I set my fuel tables up to gradually go rich depending on TPS counts.
 

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For example... I have my tune setup to go into open loop fueling VERY early (around 250 TPS counts) I did this because I live in a very hilly area (also very rural) and there were times that I would see 10psi OR MORE (part throttle driving) and would still be at a 14.6 afr. Personally I didnt like the thought of it running that lean and it was a multiple times a day event... so just for personal satisfaction (and knowing I wouldnt be cooking the pistons everytime I went up a hill) I set my fuel tables up to gradually go rich depending on TPS counts.
hey i was just wondering if you lived say in a very flat area with not a lot of hills and such and say you know you are going to be driving around an area with a lot of hills and rural areas.. should you change you tune prior to prevent any possible damage?
 

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as long as you have a good tune to start with there should be no reason to change the tune depending on the terrain you drive on. when you are on a highway in high gear and load the car, you will be loading it just like you would on a hill. there should be no reason to change your tune.
 

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that is why you tune with the mass transfer function that way altitude changes are taken into consideration by the load calculation.

but to be safe maybe just advance your open loop transition a couple hundred counts.
 

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that is why you tune with the mass transfer function that way altitude changes are taken into consideration by the load calculation.

but to be safe maybe just advance your open loop transition a couple hundred counts.
Tried doing it all with the MAF transfer.. but it still was staying lean so I did open up the tables a "couple of hundred counts early"

EDIT: to clarify what I did.. when I went past 270 counts on the TPS I set up the open loops tables to shoot for 13.5:1... just rich enough to support the short stents of boost from going up the hills around here... then I set rest of the tables to go progressively rich until I hit 11.2afr... it really works out good for me and I have set up a couple of other cars to do the same... they seem to like it as well.
 

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well yeah it will run lean in closed loop, changing the MTF wont really do much to help you in that situation because it will just shoot for 14.7 with fuel trims anyway
 

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FWIW.. I think it "feels better" running off of the open loop tables than it does in closed loop.
 
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