My experience with the AEM FIC
 

This is my experience with the AEM FIC 1913. This is not meant to be a professional guide and is based only on my personal observations. I installed this device on my 1996 Jeep Cherokee XJ with a custom extension harness which I would recommend for a clean look.
The FIC allows for timing retard, bigger injectors, o2 scewing dual tune map, on the fly tune changes and two 0-5 volt analog signals. The 1913 is designed to work with the high impedance injectors in the Cherokee to avoid a CEL. It retards timing my intercepting the crank signal to the ECU so it can be used on the OBD2 distributor or 00-01 spark rail.

The FIC is a piggyback and as such the hardest part of tuning is getting the stock ECU stable/No longer making large changes. The JTEC seems to rank manifold pressure as the highest priority for WOT conditions, more on that later.

This was my first experience with a supercharger, piggyback tuning a JTEC and second time tuning with an FIC. It was and still kind of is a PITA. I can see why people move away from it in frustration. A megasquirt would be, in the end, the easiest most reliable option. Unfortunately it cannot pass obd2 plug in emissions unless it itself is piggybacked and changed back to the stock ECU and injectors for testing...which are buried under a supercharger now.

A third option is a rescaled and tuned JTEC that can read positive pressure, retard timing, pass emissions and look clean. Sounds perfect right? well, there are some limitations. Once you get your tune locked in that's it, that is now your set up. If you change anything that will introduce more air or fuel you will need a revision to make it work. That will add up to be a fairly expensive tuning option. I also have not personally talked with anyone who will tune more than 14.5psi of boost with a JTEC tune.

Once you have the FIC connected and linked to a laptop open the system setting menu. On the left side of the menu near the top is the load display. I like kpa because when you hit 101 you are in boost. It just makes it easier for me to read. If you choose psi just keep in mind it is PSI absolute (PSIA) so 14.5psi would be 0 on a boost gauge and 14.5 psig is what you would see on an in-cabin boost gauge.

Next section down is the injector response time. When you buy injectors who ever is selling them should be able to tell you the IRT at 12,13,14 volts. I typically use the 13v IRT seems to work out. If the sellers of these injectors cannot tell you the IRT that is not a good sign don't buy them. Injectors are rated at lbs/min@43.5psi so if you run 36lbs injectors on a Cherokee at a fuel rail pressure of 49psi those are now 38.2lbs injectors. I have used rebuilt injectors from eBay and have been lucky. Not all eBay sellers are good not all are bad. Use at your own risk.

Under that is the MAF configuration. Change the load input to MAP and mode to voltage. Then it asks for a max voltage clamp. The way I was told to set this was using an obd2 scanner with live data turn on the ignition with the engine off. Read the map sensor voltage and put that into the voltage clamp. Well that method caused my computer to hold closed loop all the time in boost. increasing the value from 4.61 to 4.9volts allowed the JTEC to jump to open loop every time without a CEL.

Skip analog A and B.

On the right side of the set up menu starting at the top there is the o2 configuration. Set load input to MAP, mode to offset period to 1000mS, delay to 10sec. bank 1 hi .85 and low to .1
What I have observed with then JTEC is as soon as open loop is triggered represented on the OBD2 scan gauge as "fuel system 1 open" the o2 sensor values are ignored and short term fuel trims will read 0 ( no changes) that is what we want. BUT long term fuel trims may still show a value. That is because the very last o2 reading before flipping to open loop seems to affect all load cells up the rpm scale in the JTEC fuel table. This is one reason people get pissed at the FIC as it cannot log fuel trims from the host ECU. If it did an autotune program would already be on the market. Think DSM link. The key is to get open loop LTFT to read +/- 5 all the time in boost. A friend to drive or tune is incredibly helpful. Last thing on the O2 configuration is the mystery high level drive box. I still don't have a 100% accurate answer on this but it is primarily used for cars with wideband 02 sensor that are non-responsive to an offset voltage. I leave it unchecked but maybe will use it in the future.

Figuring out what negative values to use in the o2 offset map are explained here:


While we are on the oxygen sensor subject let's talk about that 1000ohm 1/4 watt resistor that the directions say to put inline before the FIC taps into the signal wire. To be clear it does not make the vehicle run rich or even change the voltage of the sensor out put. In does make the signal "volume" weaker though. The FIC needs this so it can hear the signal and then YELL the offset voltage over the oxygen sensor voltage to the ECU. The high level drive box is more like a YELL louder box. I run 8000ohms of resistance on my o2 signal line. 10k ohms triggered an o2 sensor code. My answer to how much resistance to put into the signal wire is: As much as it takes to make the ECU responsive to 02 changes without throwing a code.

Some helpful hint with the FIC is after install with stock Injectors in place plug in the bypass harness and see if everything runs correctly. This is the first step to see if you wired it in correctly. The next step is to put the FIC in with a zero'd fuel, o2 and ignition map to see if it runs correctly. If it does not run correctly there are probably some mixed up inputs and outputs. Note: injector outputs goes TO Injectors but the map output goes TO the ECU.

The AEM FIC comes with a helpful but not necessary base fuel and ignition map. Right click on the map while it's open to find them and input the values to automatically populate the table. Timing is extremely conservative. As of now I am pulling .25 degrees of timing per psi with methanol. When I would pull a full degree per psi on long grades holding 10psig I would experience some high coolant temps. A visual knock gauge was a very helpful warning to get out of the throttle fast.

This is an on going project and I will add to it as I can.

IIRC the AEM fuel table doesn't let you actually set the injector on time. It take whatever value the ecu is spitting out and can then add or subtract a % of the signal. So you don't really know what the actual injector on time really is. That was confusing to me and put me off using it.

Max boost of 14.5 is because of only using a 2 bar MAP sensor. I don't know for sure but there are only so many divisions of the MAP value, maybe 8 IIRC. So when N/A the MAP range is divided into 8 ranges. When you scale it for boost, you still have only 8 divisions, 4 for N/A and 4 for boost to 14.5psi. For more boost, like 3 bar MAP sensor, you still only have 8 divisions and divided now up across N/A and 28psi.

We have been looking at Syked ECU tuning software. Might be something you might want to look at.

Injector pulse is controlled by increasing or decreasing the factory pulse signal. An incorrect IRT value or firmware will cause fueling issues.

The onboard map sensor is 41psia. A and B analogs can be scaled for a 3,4,5 bar. It all gets scaled to a 0-5v range.

The MAP map isn't really used but say you wanted more resolution in the boost section of ANY map you can shift the resolution in the n/a part of the map by decreasing the Y axis map values under 100kpa. Each map in total is 21x17 load cells. Allocate them as you wish.

Kevin will only tune a JTEC for 2bar BTW.

This is for the AEM, right?

'Kevin will only tune a JTEC for 2bar BTW'.

Do you know any other details about tuning the JTEC?

The info I have is specifically for the AEM FIC 30-1913, the box for the 03-05 dodge neon SRT4.

I contacted syked over 2 years ago and things may have changed since then. Best I can tell you is that the JTEC only has so many MAP load cells to work with. If half are rescaled for boost then only half remain for vac. Your resolution is cut in half.

On my set up the factory ecu has all its resolution below 100kpa or 0psig of boost. My FIC has 4 of 17 MAP rows devoted to vac scale down for the larger injectors and 13 of 17 rows for 100-196kpa or 14psig of boost. The FIC will calculate in between cell values if there is a difference between them. So if I am pulling -40% fuel at 26kpa, -40% at 36kpa and -40% at 46kpa then the 36kpa row is not needed because the scale is not changing between load cells.

If anyone has more updated info as to what any of the JTEC tuners can do please post what you know and how much it costs.

I forgot I had made this ...but some minor updates that I have done is drop the o2 sensor resistance to 3k 1/4watt. The 8k and even 6k caused a strange throttling effect at very light cruise. I can't say this was the fix for sure but it seems gone with the 3k in. Also there is an AFR tool that was made public. I haven't got a chance to use it but here it is.
http://www.chippernut.com/uploads/2/..._mappingv2.xls

Not mine in anyway but I did get a chance to talk with the creator of it. Again if the FIC had provisions to input STFT and LTFT this would have been helpful.