fuel trim issues where to start? closed loop
fuel trim issues where to start? closed loop ok the car is 90 rx7 motor is ls1 from 2000 camaro. swap is a few years old so nothing related to that. new mods are clutch and flywheel everything else been there for months with no problems. yesterday i noticed that when i stopped the car would start to run a little rough then kinda rev and clear up. so i cycled scan guage to bank 1 and bank 2 fuel trims. the ecu would pull fuel on both banks and at about -25 on both would reset to zero clear up and start counting again. went to work and plugged in snap on scanner to verify same thing. runs smooth in open loop but when goes in to closed loop it is pulling fuel. everytime it clears up it leaves closed loop for a sec and returns. dont seem to be running rich but something is causing it to think so
only codes i pulled that were not related to the swap are p0135 b1s1 o2 heater circuit and p0155 b2s1 o2 heater circuit. will the heater circuits cause it to do this. i know how to test this so no big deal. just wondering what else to check.
done so far:
cleaned mass air flow sensor
only codes i pulled that were not related to the swap are p0135 b1s1 o2 heater circuit and p0155 b2s1 o2 heater circuit. will the heater circuits cause it to do this. i know how to test this so no big deal. just wondering what else to check.
done so far:
cleaned mass air flow sensor
did that and fuel trims stabilize but also puts it in open loop and its ok there regardless
gonna check heaters and wiring tomorrow kinda weird for both banks maybe its a power or ground issue on heater circuit
gonna check heaters and wiring tomorrow kinda weird for both banks maybe its a power or ground issue on heater circuit
Last edited by j_tizzle_84; Jan 21, 2011 at 04:42 PM.
ok here the data idling in closed loop while acting up
maf gram/sec 7.98
maf hertz 2600
baro 29.8
map "hg 9.5
inj pw 3.1
o2 b1s1 between 500 and 600
o2 b2s1 between 500 and 600
tps .63v
ft cell 20
maf gram/sec 7.98
maf hertz 2600
baro 29.8
map "hg 9.5
inj pw 3.1
o2 b1s1 between 500 and 600
o2 b2s1 between 500 and 600
tps .63v
ft cell 20
ok i rule out mass air flow tried new gm unit same thing. the o2 heaters are getting 12v and ground and circuits of sensor are 4.5 ohms. definitely getting worse when im driving its pulling so much fuel it feels like im running out of gas. i know this is not a fuel delivery issue because it would be tring to add fuel not subtract. i used my scanner to force it to stay in open loop and it seems fine. what sensor are used in closed loop to determine air fuel. 
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From: CT
intake air leak... CAI air leak... exhaust leak....
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06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS - LS3, 6-speed manual, short-throw performance shifter, NPP dual-mode performance exhaust, 1LE front splitter, ZL1 rockers, Z28 Rear Spoiler, all paint-matched Red Rock Metallic, BMR strut tower brace, Cold Air Inductions cold air intake, Apex Motorsports, Inc. catch-can, Custom DiabLew Tune
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06MonteSS / DiabLew Tune
2014 Camaro 2SS/RS - LS3, 6-speed manual, short-throw performance shifter, NPP dual-mode performance exhaust, 1LE front splitter, ZL1 rockers, Z28 Rear Spoiler, all paint-matched Red Rock Metallic, BMR strut tower brace, Cold Air Inductions cold air intake, Apex Motorsports, Inc. catch-can, Custom DiabLew Tune
www.diablewtune.com -- www.diablocustomtune.com -- www.diablocustomtunegm.com
Fuel trims are a multplier table.
Look at it this way. It is very simple. Fuel Mass vs Air Mass at set Stoich and EQ.
You don't even need to think about the second half.
Simplified: Fuel Trims = Fuel Mass vs Air Mass ERROR
Look at it this way. It is very simple. Fuel Mass vs Air Mass at set Stoich and EQ.
You don't even need to think about the second half.
Simplified: Fuel Trims = Fuel Mass vs Air Mass ERROR
not stuck at 450 but stay in the range of 500 to 650 mv. i know this is not right they should be switching gonna try inducing a lean condition and see if the o2s swing the other way. then ill know if they are stuck because it is legitimately running rich or **** o2s. thanks for helping me i am also ase master tech with L1. but its good to have someone to bounce ideas off sometimes.
ok pulled a vacuum line and induced a lean condition 02s had no response. so i am pretty sure that 02 sensors are the issue. i looked at the wiring and realized when the previous owner put the long tubes on they cut and extended the wires on the harness. so i ordered 2 new denso o2 sensors for a corvette with the longer wires so i could eliminate the extensions.
Hey will you keep us posted and let us know if thats the issue? I have just recently heard about splicing/extension issues, and was looking for a specific instance. I am guessing it was working alright before, and it just started showing symptoms?
the o2s were the problem. got 2 brand new denso sensors (these are what gm now uses) from rock auto for 80 buck. put them in and the fuel trims went right back to normal. didn't get a chance to do anything with the extension wire but i ordered my o2s with longer wire so i could eliminate them.
Launching!
Joined: Oct 2009
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same problem here. finally got my extensions last night and put them and the o2 sensors back in today. goes into closed loop after a few minutes then starts to idle bad and sounds like its gonna die. it then switches back to open loop and rpm's climb and runs fine. is buying new o2 sensors my only option? It's a daily driver and i really dont have $200 to throw at new sensors. everything was perfectly fine until the long tubes went in and ran great in open loop for past 2 weeks right up until i put the o2's back in today. would cleaning them help? will any stock replacements work? or do i need something with a better heater?
if you have the rear ones still put them in the front they are the same sensors and will work fine giving they are not beat also. but for 80 bucks id just buy new ones. the corvette rears fit with no extensions. DO NOT BUY CHEAP O2 SENSOR IE STANDARD get bosch or denso or you will be buying them anyway. prefer denso
