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Discussion Starter #1
hi.i have a strange problem with my v6 gen siii
i have been reset my ecu a couple weeks ago with discon the negative battery and turn ign on and push brake pedal because of install a k&n air filter.its run perfect after i reset the ecu(before reset i have stalling and hesitation and lose of power with k&n filter not stock one) but its good just before i stop and turn off engine.no matter i drive for 100 kilometer or 50 kilometer its run fine after ecu reset and before an engine turn off.to clearify i mean its run really good beetwen an ecu reset and an engine turning off.sorry for bad english.i test my stock air filter and its have a little defrence.i exp bad mpg and really bad accel in my 2nd run after ecu reset.icant fine any thing about this.can anyone help?
 

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i exp bad mpg and really bad accel in my 2nd run after ecu reset.icant fine any thing about this.can anyone help?
Did you remove the MAF sensor while fitting the K&N? Could you perhaps have refitted the MAF sensor the wrong way round? There should be an arrow pointing towards the throttle body.

Have you checked the MAF power supply and ground? Connect a voltmeter across the two outer terminals of the MAF connector and make sure you have 12V.

Do you have a scan tool to check the MAF sensor data and fuel trims? Checked for trouble codes?
 

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first thank for reply.i put maf in right way and check it supply and then check for its respond to tp.i have to error code and check this with obd2 apps.i will also check my maf data but what it should be in gs?fuel trims is also will be checked after i take my car back from service.i will be thankful again if you check my topic for forther information and help me
 

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Discussion Starter #4
but my question is if there is some bad thing or wrong why engine runs really good after ecu reset and just in first run?
 

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Sounds like you reset the ECU, that loads the factory tables back in and clears the learned values. It then runs good but starts to run badly as the ECU starts to replace the factory values with new real time values?
 

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i will also check my maf data but what it should be in gs?
If my arithmetic is correct the data should show approx 3~4 g/s at idle rising to approx 8~10 g/s at 2000RPM.

but my question is if there is some bad thing or wrong why engine runs really good after ecu reset and just in first run?
My guess is when you reset the ECU you are resetting the fuel trims so the engine runs normally again until the trims readjust. If I've understood your original post, you have tried refitting the original factory air filter and the same thing still happens??
 

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Discussion Starter #7
Sounds like you reset the ECU, that loads the factory tables back in and clears the learned values. It then runs good but starts to run badly as the ECU starts to replace the factory values with new real time values?
yes i think its what heppend for me and i am confuse now
 

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If my arithmetic is correct the data should show approx 3~4 g/s at idle rising to approx 8~10 g/s at 2000RPM.


My guess is when you reset the ECU you are resetting the fuel trims so the engine runs normally again until the trims readjust. If I've understood your original post, you have tried refitting the original factory air filter and the same thing still happens??
i think its happen again with stock filter beacuse i can see bad mpg and lose of power even with stock filter but not bad as that k&n one.i am confuse and want to solve this
 

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i think its happen again with stock filter beacuse i can see bad mpg and lose of power even with stock filter but not bad as that k&n one.i am confuse and want to solve this
Drive the car until it starts to run bad again. Don't reset the ECU or you will loose any adaption data stored in it's memory. Use a scan tool to check for trouble codes and look at the fuel trim data. That should give you a clue as to what the problem might be.
 

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Discussion Starter #10
Drive the car until it starts to run bad again. Don't reset the ECU or you will loose any adaption data stored in it's memory. Use a scan tool to check for trouble codes and look at the fuel trim data. That should give you a clue as to what the problem might be.
ok i will do this soon and update topic.thank you
 

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Discussion Starter #11 (Edited)
today i have been reseted again the ecu and put k&n filter.one thing i want to mention is that i have erased my catalytic converter materials because i have cel with p0420 and p0430 error code.i was go for a test tonight and there is no mpg drop or poor performance problem but i use an obd2 app to see the values.first in the emissions teset i have catalytic incomplete and also o2 sensors and its heater incomplete.one more thing is my my 2nd o2 sensors of both banks are behave unormally.i mean their voltages are not variable and most of the times stays at low about .15 or somthing like that.also have a p0156 code and i have been clear that code(P0156 O2 Sensor Circuit Malfunction B2S2).i will test my car again but wanted to update the information for any noticeable thing to help.
 
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daniyalkza
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