AFR issues with Atomic EFI 408 LS
Thread Starter
Staging Lane
Joined: Oct 2014
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AFR issues with Atomic EFI 408 LS 
Hey everyone,
So first startup of new LS stroker, having some issues with AFR. The gauge inside the car (an Innovative AFR) shows 10.8 to 11 on startup but my atomic dash is showing 20:1.
Attached are pictures of the dash. Let me know if anyone has some feedback.
Perhaps an exhaust leak or a bad sensor??
No way this thing would run at 20:1 AFR or higher. I think the sensor is pooched. It isles nicely at 800 ish RPM.
Thanks everyone.
John
Thread Starter
Staging Lane
Joined: Oct 2014
Posts: 54
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Yes that is my first step. I wish there was a real way to bench test these.
Setup is an MSD Atomic EFI LQ4 stroker to a 408 with LS3 injectors, ls3 intake, a large comp cam, and CNC GMPP LS3 heads and longtubes.
Setup is an MSD Atomic EFI LQ4 stroker to a 408 with LS3 injectors, ls3 intake, a large comp cam, and CNC GMPP LS3 heads and longtubes.
Does it just do this after startup or all the time. Some widebands will show full lean while heating up. I haven't used that particular controller, did they have you do a free air calibration?
You'll know pretty quick if the sensor is bad because the ECU is going to throw all the fuel it can to try and kick the 02 rich and the car will start running badly. It will stay at 20:1 and your other wideband will tank rich.
You'll know pretty quick if the sensor is bad because the ECU is going to throw all the fuel it can to try and kick the 02 rich and the car will start running badly. It will stay at 20:1 and your other wideband will tank rich.
Thread Starter
Staging Lane
Joined: Oct 2014
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Thanks for the reply. Haven’t driven the car yet as was concerned about the super lean AFR. Just at idle does this. No calibration was done per instructions. Also yes other sense reads 11:1 for AFR at idle so very rich. Other thoughts?
Where is the that 02 sensor at in relation to the other WB02?
Do you have full exhaust or open exhaust.
Which Innovate WBO2 setup do you have? Is it hard wired in or just temp? What's the ground offset?
When is the last time you did a free air cal on the Innovate?
Sorry to ask so many questions but there are a lot of things that could be the root cause or problem, if there is one.
An exhaust leak in front of the WB02 will show it lean. A misfire on that side will also will "show lean"
A cam with a lot of overlap and a plastic intake can show split fuel trims at idle/low speeds.
A vacuum leak, bad/leaky injector will also cause the problem.
I would swap the WB02 from side to side and see what it does.
That will give you a better idea of its something mechanical, a sensor problem, or something else.
Do you have full exhaust or open exhaust.
Which Innovate WBO2 setup do you have? Is it hard wired in or just temp? What's the ground offset?
When is the last time you did a free air cal on the Innovate?
Sorry to ask so many questions but there are a lot of things that could be the root cause or problem, if there is one.
An exhaust leak in front of the WB02 will show it lean. A misfire on that side will also will "show lean"
A cam with a lot of overlap and a plastic intake can show split fuel trims at idle/low speeds.
A vacuum leak, bad/leaky injector will also cause the problem.
I would swap the WB02 from side to side and see what it does.
That will give you a better idea of its something mechanical, a sensor problem, or something else.
Thread Starter
Staging Lane
Joined: Oct 2014
Posts: 54
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So the one sensor reading lean is on the driver header, the innovative is on the passenger. Did a calibration on it about a month before we started the car. It is permanently wired in, it is a kit from them that has the sensor and then an brain box that converts it so my gauge can read it. I think LC-2 is the model.
I have full exhaust.
I havent checked for a vacuum leak yet, but everything is new and all ports not used are plugged, so I don’t think this is it, especially as one side is good and the other is not.
The cam is a Comp 227/243 with a 113 LSA.
I will swap sides with the sensors and see where that takes me as well.
Thanks
I have full exhaust.
I havent checked for a vacuum leak yet, but everything is new and all ports not used are plugged, so I don’t think this is it, especially as one side is good and the other is not.
The cam is a Comp 227/243 with a 113 LSA.
I will swap sides with the sensors and see where that takes me as well.
Thanks
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So the one sensor reading lean is on the driver header, the innovative is on the passenger. Did a calibration on it about a month before we started the car. It is permanently wired in, it is a kit from them that has the sensor and then an brain box that converts it so my gauge can read it. I think LC-2 is the model.
I have full exhaust.
I havent checked for a vacuum leak yet, but everything is new and all ports not used are plugged, so I don’t think this is it, especially as one side is good and the other is not.
The cam is a Comp 227/243 with a 113 LSA.
I will swap sides with the sensors and see where that takes me as well.
Thanks
I have full exhaust.
I havent checked for a vacuum leak yet, but everything is new and all ports not used are plugged, so I don’t think this is it, especially as one side is good and the other is not.
The cam is a Comp 227/243 with a 113 LSA.
I will swap sides with the sensors and see where that takes me as well.
Thanks
Definitely keep us updated. I'm interested in seeing where this goes. I haven't used the Atomic for PCM control, only for TCM stuff.
Last edited by LilJayV10; Jun 4, 2018 at 12:10 PM.
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Staging Lane
Joined: Oct 2014
Posts: 54
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So update here, I have swapped sensor sides and getting the mirror image results on both sides. MSD reads super lean and other side reads very rich.... very frustrating... gonna phone MSD tomorrow.
Any thoughts?
Any thoughts?
Launching!
Joined: Jan 2018
Posts: 283
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its an NA engine. you'll really struggler to hurt is it with too little fuel. just run very conservative timing until your fuel is sorted. ping is the only thing that will kill your motor.
super rich idle isn't good. it will wash the bores with fuel, causing excessive ring wear and can result in oil burn. however your engine with that bigger exhaust duration on 113LSA would not physically idle at 800rpm with 20:1 AFR.
likely your camshaft overlap is causing only partially burnt fuel straight into the exhaust at idle causing what I call "false rich" data.
don't be scared with an NA engine go drive it and get some off idle light cruise AFR data. get that close to your target and then work back to idle.
so if your fuel table numbers at cruise, medium throttle and off idle points are giving your desired AFR then the fuel table values at idle aren't going to be 30-40% different.use cruise data to interpolate back to idle values in fuel table.
same process is generally used in a car with massive solid roller cam. fuel table values for idle and low rpm with large amounts of overlap are interpolated or calculates based on the cruise and higher RPM light load areas.
false rich can be several things. altering EOIT at idle or idle timing can also help. but don't be fooled into thinking your 11:1 idle AFR is correct.
go cruise it and gather some data. don't be sacered with an N/A engine. just don't let is ping. running 14:1 to 18:1 AFR on cruise or light load for the short period it will take you to data log and edit your file to target AFR wont damage anything.
super rich idle isn't good. it will wash the bores with fuel, causing excessive ring wear and can result in oil burn. however your engine with that bigger exhaust duration on 113LSA would not physically idle at 800rpm with 20:1 AFR.
likely your camshaft overlap is causing only partially burnt fuel straight into the exhaust at idle causing what I call "false rich" data.
don't be scared with an NA engine go drive it and get some off idle light cruise AFR data. get that close to your target and then work back to idle.
so if your fuel table numbers at cruise, medium throttle and off idle points are giving your desired AFR then the fuel table values at idle aren't going to be 30-40% different.use cruise data to interpolate back to idle values in fuel table.
same process is generally used in a car with massive solid roller cam. fuel table values for idle and low rpm with large amounts of overlap are interpolated or calculates based on the cruise and higher RPM light load areas.
false rich can be several things. altering EOIT at idle or idle timing can also help. but don't be fooled into thinking your 11:1 idle AFR is correct.
go cruise it and gather some data. don't be sacered with an N/A engine. just don't let is ping. running 14:1 to 18:1 AFR on cruise or light load for the short period it will take you to data log and edit your file to target AFR wont damage anything.
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