That wasn't so much fun; AEM firmware change = bad

Talyn

NAXJA Forum User
Several people have told me that they are running the Z104 firmware on their AEM FICs. On first install I had the Z110 file flashed on but it didn't run well with that so I dropped down to Z107. Friday evening I decided to change over to Z104 as others are running that. I flashed the FIC, then updated the calibration zero'd out then updated again to the calibration I am using. Start it up friday evening and its running fine. Drive to work Saturday morning fine. On the way back from work I needed to run by the grocery store, so it was a little longer drive. Thats when it starts to not idle, no power, general nastyness.

I get back home and I'm looking around the engine bay to see if there was a fuel injector plug lose, plug wire lose or some sensor lose. Didn't see anything abnormal, but after going into closed loop it starts to misfire and run like general crap. Then I get under it to see if there is an exhaust leak. That is when I see the cat converter glowing (probably from the rich AFR in 4-5). Shut it down and pull the codes. P0171 (Bank 1 fuel system too lean) and P1075 (Bank 2 fuel system too rich).

Start it back up and log from the FIC. Shows that O2 sensor #1 is showing lean and O2 sensor #2 is showing rich. I run it just long enough for the O2s to come on line. I have the FIC reflash in the back of my mind at this time, but its late and my tools are at the machine shop from earlier. I do some research on these codes and everything from an intake manifold or exhaust leak, vacuum leak, burnt valve, burnt piston, etc come up. MAF sensor on fords with both codes present.

Go to the machine shop this morning (drives fine until it starts reading the O2 sensors in closed loop) and after I finish the vehicle I was working on yesterday I start on mine. Test fuel pressure, test compression (~160 psi on all), see if every injector is firing, make sure that the O2 sensors are connected to the correct harness plugs, check for spark, etc. I check the plugs as well and 1-3 were clean and 4-6 were black with carbon, which went along with the codes. Everything checks out so I bypass the FIC. It clears up and runs fine. I reflash the FIC to the Z107 that I was running, reset the PCM to clear it of the garbage fuel trims it learned and its back on the road. Its just hard to imagine what the FIC was telling the PCM to make it do this.

I don't understand why the Z104 didn't work for me, but glad it was only that and not an engine problem. I think the engine is fine as there was nor much load and it wasn't driven long like that. However, I don't know if the cat converter is still good or not. I do plan on doing a back pressure test later.

BTW, the descriptions of the FIC flashes:
Firmware Hex Files:

Z files (Handle fueling and firmware):
- Z104.hex: Used on older vehicles where multiple injector pulses are not present
- Z107.hex: Updated version of Z104.hex, used for Scion TC
- Z110.hex: Used for newer vehicles that have multiple injector pulses. Faster response time than other hex files.

X files (Handle the calibration and PC software):
- X131.hex: Version 1.31 firmware
- X300.hex: Version 3.00 firmware
- X3.81.hex: Version 3.81 firmware updates include: ability to use TPS as a load option in the Fuel map, acceleration enrichment pump, and maximum RPM raised from 12,000 to 17,000 RPM
 
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Only the x300.hex would work for me the other day, when before the x3.81.hex worked. I've never played with the Z files. Yesterday I removed the 1.1Kohm resistor completely from the post-cat o2 connection and swapped the 1.1Kohm from the pre-cat o2 connection to a 4.7Kohm. Today I removed a noisy water pump and yanked the intake manifold and header off to put on a new combo gasket with the permatex copper spray. The exhaust was leaking somewhere on it. Anyhow, when it's all together tomorrow, I'll see if the PCM continues to interfere with the o2 offsetting. I'll be auto-xing her in the PM on Sat down at Blue Crab Stadium, so at least want to get some WOT tuning done beforehand. A few weeks ago, I had a nightmare updating the firmware on the Innovate LM-2. It locked up and I couldn't even use the older firmware. I ended up having to use my friend's older laptop to update it.
 
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I haven't tried the other x files. I am using x300 now. I have been wanting to try the x381 just to play with the accel enrichment, but from the forum it is still in beta and may have a few problems. After Saturday's experience I am not sure I want to try messing with the firmware at all. The cat doesn't rattle but I still need to do a back pressure test. I don't know if the matrix got melted or not.
 
The PCM doesn't interfere with the 4.7K, though at -.6V offset(max -), the target range is like 13.7@idle and 14.0@3K in Neutral at 6PSIA(though the LM-2 shows it to be 2._PSIA). I'm gonna try a 10K tomorrow and hopefully get it to drop.
 
Did a back pressure test on the cat yesterday and from that test it seems fine. Very little back pressure and it didn't climb past 1 psi. Looks like the cat survived, but a visual inspection would be best. However, I don't feel like cutting it then rewelding it.
 
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