AEM F/IC writeup
- Thread starter Ricktalife
- Start date
So my car was down for a while thanks to the incompetence of Pep Boys, long story.
In the meantime I did change the O2 to an intercept on the Analog A In/Out. This appears to work much better than the tap configuration, but I haven't had time to really test the ECU's reaction to the modified O2 other than for a few minutes in the garage.
I also went back to a straight to PCM, non-intercepted MAF signal. The AEM doesn't really need the MAF, and it was more headaches than it was worth. My perfect MAF map was no longer perfect as soon as I reset the ECU since it's nearly impossible to go through the entire RPM range and adjust out all the trims.
In the meantime I did change the O2 to an intercept on the Analog A In/Out. This appears to work much better than the tap configuration, but I haven't had time to really test the ECU's reaction to the modified O2 other than for a few minutes in the garage.
I also went back to a straight to PCM, non-intercepted MAF signal. The AEM doesn't really need the MAF, and it was more headaches than it was worth. My perfect MAF map was no longer perfect as soon as I reset the ECU since it's nearly impossible to go through the entire RPM range and adjust out all the trims.
Ricktalife
Member
- :
- 2012 Subaru WRX
Well I was questioning the life of my turbo a week or 2 ago, but now I'm pretty confident it's about to s*** the bed. It's making some very unhealthy sounding noises under boost and is probably the cause of the bucking.
Ricktalife
Member
- :
- 2012 Subaru WRX
Well I spent a little time fooling with the 02 map and watching one of the AEM instructional videos over and over. I'm still not sure how they got a single AFR value in each cell to create a table with. Is it just my wideband, or does the AFR bounce back and forth between ~14.7-14.4 at idle? It says to hold the throttle at 2000 RPM's, but still the AFR bounces back and forth and I can't just get a single value. Jdwk, how did you set your table up?
The only thing that worked ever with the O2 being tapped by the AEM's O2, was setting everything to -50% above atmospheric, 14 aPSI MAP, on the O2 map.
This gave me my nice smooth injector duty cycle and AFR, but even this was finicky and simply didn't work sometimes.
I did follow the instructional video but it didn't really work either. I tried using the offset mode as it instructs, and I could see a lower voltage on the OBDII scanner, but the lowest it would bring the AFR down to on the wideband was about 13.0, but never steady, it would bounce between 13 and 14. So to answer your question, yes, in closed loop mode the AFR will oscillate around 14.7. I usually see between 14.4 and 15.1 stock, and about a 1 second cycle between the two.
A narrowband O2 usually outputs .1V at 15:1 AFR and 1.1 at 14:1 AFR. The PCM is trying to maintain 14.7 in closed loop mode, which is actually around .445 V. The theory is if you want to lower the closed loop AFR you can offset the O2 voltage so the PCM thinks it's running leaner than it really is and adds fuel. The problem with our cars is that it isn't measuring the voltage, it's just testing to see if it's lean or rich.
So if you offset a 0-1V signal by .5V for instance, it will now oscillate between -.5V and +.5V. But -.5V is simply seen as 0V, and +.5V is still seen as rich since it's over .445V. This is why the behavior is finicky. As soon as the PCM sees a rich signal, it will start pulling fuel, and will continue to do so until the next cycle. So even with the -50% O2 table, it still was able to see a rich voltage and start pulling fuel, and reach super lean 16:1 AFRs under boost before the 4200rpm closed to open transition.
Due to completely unrelated mechanical issues I haven't had time to play around with the map since I switched it over to the Analog A IN/OUT. I think my goal will be to output a steady voltage that the PCM sees as stoich which should be around .445V, when in boost. This way the trims will be zero, and I won't have to worry about resetting the PCM and losing stored LTFT's. The PCM will just be going off the stock fuel maps, and I'll be able to alter them without the PCM trying to trim any of the extra fuel.
The only thing I am worried about then is that the PCM may not like seeing a static signal on the O2 line, but it would only be in boost and as soon as I let off the throttle it should go right back to closed loop and be fine. With all the playing around I've done so far I haven't seen a CEL for the O2 yet, so I don't think it's that sensitive.
This is one long journey. I just hope to get most of my task list done before it gets super hot again.
This gave me my nice smooth injector duty cycle and AFR, but even this was finicky and simply didn't work sometimes.
I did follow the instructional video but it didn't really work either. I tried using the offset mode as it instructs, and I could see a lower voltage on the OBDII scanner, but the lowest it would bring the AFR down to on the wideband was about 13.0, but never steady, it would bounce between 13 and 14. So to answer your question, yes, in closed loop mode the AFR will oscillate around 14.7. I usually see between 14.4 and 15.1 stock, and about a 1 second cycle between the two.
A narrowband O2 usually outputs .1V at 15:1 AFR and 1.1 at 14:1 AFR. The PCM is trying to maintain 14.7 in closed loop mode, which is actually around .445 V. The theory is if you want to lower the closed loop AFR you can offset the O2 voltage so the PCM thinks it's running leaner than it really is and adds fuel. The problem with our cars is that it isn't measuring the voltage, it's just testing to see if it's lean or rich.
So if you offset a 0-1V signal by .5V for instance, it will now oscillate between -.5V and +.5V. But -.5V is simply seen as 0V, and +.5V is still seen as rich since it's over .445V. This is why the behavior is finicky. As soon as the PCM sees a rich signal, it will start pulling fuel, and will continue to do so until the next cycle. So even with the -50% O2 table, it still was able to see a rich voltage and start pulling fuel, and reach super lean 16:1 AFRs under boost before the 4200rpm closed to open transition.
Due to completely unrelated mechanical issues I haven't had time to play around with the map since I switched it over to the Analog A IN/OUT. I think my goal will be to output a steady voltage that the PCM sees as stoich which should be around .445V, when in boost. This way the trims will be zero, and I won't have to worry about resetting the PCM and losing stored LTFT's. The PCM will just be going off the stock fuel maps, and I'll be able to alter them without the PCM trying to trim any of the extra fuel.
The only thing I am worried about then is that the PCM may not like seeing a static signal on the O2 line, but it would only be in boost and as soon as I let off the throttle it should go right back to closed loop and be fine. With all the playing around I've done so far I haven't seen a CEL for the O2 yet, so I don't think it's that sensitive.
This is one long journey. I just hope to get most of my task list done before it gets super hot again.
RunAroundNekid
Member
Great writeup.
I'm still torn between using this F/IC I already have, using my Unichip, or manning up to a Haltech unit...
I'm still torn between using this F/IC I already have, using my Unichip, or manning up to a Haltech unit...
I don't have any experience with a full stand alone, and I am sure it comes with its fair share of headaches, but at least there are no limitations. Cost was definitely a factor, but since this is my daily driver, the AEM allowed me to do a more incremental install, and a quick fall back to stock. In hindsight, with all this reistance non-sense, it probably wouldn't have been any more difficult to go with a halltech.
I decided against the unichip because I am a DIY'er. I am a firm believer in "if you want something done right." I might buy some dyno time, but since I work 9-5 every day, it's not convenient to take my car to a shop anytime I need a tweak to the tune. I don't really like dyno's either. If you want to know if your car is faster there are drag strips. Tuning a car in only 4th gear from 3 or 4 k on up at WOT is not a complete tune. That is a very small percentage of the driving range.
Until I have a good O2 manipulation for perfect closed loop operation, I can't recommend the AEM FIC, but if you already have an FIC, then I strongly suggest skipping the MAF manipulation completely and intercepting the O2 with one of the analog I/Os.
I decided against the unichip because I am a DIY'er. I am a firm believer in "if you want something done right." I might buy some dyno time, but since I work 9-5 every day, it's not convenient to take my car to a shop anytime I need a tweak to the tune. I don't really like dyno's either. If you want to know if your car is faster there are drag strips. Tuning a car in only 4th gear from 3 or 4 k on up at WOT is not a complete tune. That is a very small percentage of the driving range.
Until I have a good O2 manipulation for perfect closed loop operation, I can't recommend the AEM FIC, but if you already have an FIC, then I strongly suggest skipping the MAF manipulation completely and intercepting the O2 with one of the analog I/Os.
Ricktalife
Member
- :
- 2012 Subaru WRX
I need to consult a local tuner about this thing. I know of a shop nearby that is supposedly AEM certified so maybe they can shed some light on this mess.
If I had the software and cable to tune the Unichip myself, I definitely would have got it. Haltech is very good from what I hear, but I wasn't looking for a standalone and wanted to keep it simple without any inspection issues.
If I had the software and cable to tune the Unichip myself, I definitely would have got it. Haltech is very good from what I hear, but I wasn't looking for a standalone and wanted to keep it simple without any inspection issues.
RunAroundNekid
Member
Having an used an F/IC on my old fully built, GT3071R powered Tiburon, I'm already familiar with the F/IC. Its a brilliant device once worked with properly. The biggest draw to this Unichip I have is just that... I can't do anything with it.
Having experience with Hydra standalones, a complete standalone EMS is the best option if you have the money and patience to work with.
I'l probably end up using the f/ic, as I also have an aem uego wideband which can wire to the f/ic and provide some nice logging aids
I'm not searching for an assload of power, I'm still on stock motor. So 8psi is all I'll tune for. Keeping a very conservative tune thats more on the safe side.
Having experience with Hydra standalones, a complete standalone EMS is the best option if you have the money and patience to work with.
I'l probably end up using the f/ic, as I also have an aem uego wideband which can wire to the f/ic and provide some nice logging aids
I'm not searching for an assload of power, I'm still on stock motor. So 8psi is all I'll tune for. Keeping a very conservative tune thats more on the safe side.
Ricktalife
Member
- :
- 2012 Subaru WRX
Yea same here, except I may push it to 9 psi. I was running that for a bit with my SSAFC but it wasn't a spectacular tune so I turned it back down. Once I get professional help, I will bump it back up and it shouldn't be risky since I'll have timing control now. I also may invest in a J&S safeguard.
If I had the software and cable to tune the Unichip myself, I definitely would have got it. Haltech is very good from what I hear, but I wasn't looking for a standalone and wanted to keep it simple without any inspection issues.
Funny thing . There is a Unichip in the FS section with the software and cable so you can tune by yourself
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Funny thing . There is a Unichip in the FS section with the software and cable so you can tune by yourself
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Ricktalife
Member
- :
- 2012 Subaru WRX
Yea I saw that, but I already went through the hassle of installing this thing and I don't think my harness would survive another patch job.
Ricktalife
Member
- :
- 2012 Subaru WRX
I haven't had time to swing by a shop yet. I will try to do so this weekend. Unfortunately, the one that I know is AEM certified is closed on weekends. So I guess I will have to go to another local shop that says they have experience with AEM units.
Ricktalife
Member
- :
- 2012 Subaru WRX
Please post the wiring pinout so I can update the first post. Or just PM me. Feel free to put up the base map as well so everyone has an idea of what to work with.
RunAroundNekid
Member
Can somene e-mail me their map? Whether it be a base map or complete tune. I'm doing my install either this weekend or next, and will need something to get the car running so I can drive it up onto my shops dyno.
