foxbat

As I'm trying to calibrate a set of RC1600cc injectors, the fuel trims don't seem to be functioning at all, stuck at 0 all the time. I removed the battery cable for 30 seconds, went on cruise for 20 minutes followed by another 20 idling.
The car is an Evo 7 & I'm using a stock JDM rom 98650015. E7s don't have a rear o2 sensor, I'm wondering why the fuel trim seem disabled?

EvilEvolution8

Seems you running in open loop?

foxbat

I'm not sure why would I be in OL, I'm using an unaltered stock rom to calibrate the injectors. I thought to get the injectors calibrated on a stock rom first before converting to a Tephra rom.
Would an electrical issue cause the car to run full OL?

Raceghost

iTrader: (4)

If they are stuck at Zero all the time, that implies a few things.
First, is the stock ROM your using have the stock scaling and latencies?
I assume you have the estimated scaling and settings in their.
I have seen this happen when the guessed settings are out of spec more than what the injector can respond to. The car would run pretty crappy, possibly rich, but usually lean. Try scaling at about 1360 or the next size up, this is scaled at 15% reduction. From there, most people don't agree, but try the recommended manufacturer latencies. Several latencies are posted on here somewhere, to get you started.
As to the Tephra Rom, you can tune injectors on a tephra rom too. There are totally stock roms modded with tephra mods, deactivated, which makes them like a stock rom.

Good luck.

foxbat

Yes, I did change the latencies & scaling prior to resting the ECU. The car idled perfectly fine at approx. 14.5 AFR and even cruised fine, so I thought that my numbers are perhaps not that far from an accurate scaling. But then I couldn't get any trim readings to improve my numbers!

Raceghost

iTrader: (4)

How are you resetting the ECU? Are you pulling the 20 amp fuse? Are you pulling the ECU in the same fuse box? or are you pulling the battery cable? All three will reset the ECU Trims. I am wondering on the 20 amp fuse, if it is blown, will the car still run, but no trims...? Check that fuse.

Asmodeus6

iTrader: (7)

Log your front o2 and make sure it is still breathing. If it's super sluggish (dying) or not connected, dead, etc. You get open loop fueling.

#2 is coolant temp sensor. That little 1 wire connector by the thermostat housing. If it can't see the car as warmed up, it won't set trims.

You can log to see OL/CL state. That answers the million $ question to whether you are or aren't.


***I haven't done this stuff in a while, so there's your disclaimer***

I know I saw in the rom options something for open loop / closed loop when I was looking the other day. I think there is an option to lock the car into open loop. I may be losing my mind, but I think one of the newer modded roms has an option related to that? Maybe someone who is more familiar can fact check me on that. But I swear I saw it.


Disconnecting the battery should 0 your trims. Let the car come up to 92-95* C and idle for about 5m and you should see the LTFT's move. Log coolant temp all the LTFT's and STFT's and state. Log NB fr 02. Check for life.

Report back.

ETA: Does that rom support a rear 02 input? In the mod options there should be an option to disable it if it does. That could be an issue if the carpet doesn't match the drapes.

wreckleford

iTrader: (2)

If the ROM is for a car with a rear 02 and it is disabled in the periphery it will also disable the long term trims.

Raceghost

iTrader: (4)

I have never seen this to be the case. All the different roms for my car have the rear 02 disabled, and they call for the rear 02. My trims still work.

wreckleford

iTrader: (2)

Likely you are using the rear 02 patch and not disabling it from the periphery (periphery bit 1).

It depends on the ROM you are using. The OP is using an Evo 7 Rom however. All Evo 7s I have seen have no rear 02 so this bit is disabled from the factory and fuel trims still work. Do the same with an 8 ROM and it will kill the long term trims.

foxbat

Which parameter in evoscan would show fueling mode (CL\OL)? Again, I have no reason to suspect that the car is in full OL mode. I'm using a stock E7 rom, so no rear o2 sensor. I logged other parameter such as coolant temp & o2 sensor voltage & they seem fine, o2 constantly changing voltage.
I might stop attempting to fine tune the injectors & move to the second step tuning fuel & ignition using a v7 sd based rom & keep an eye on CL AFR.

lancerrally45

iTrader: (22)

02 Feedback
Oxygen Feedback Trim (STFT)

wreckleford

iTrader: (2)

As lancerrally alluded to, are you getting short term fuel trims? If the 02 value is cycling back and forth and you are showing STFT then you are in closed loop.

For the hell of it try enabling FAA bit 1 and see if you start getting LTFT.

foxbat

I did log Oxygen Feedback Trim (STFT) & all I got is zero as the rest of the fuel trims. I'll try a different rom version or to a tephra rom & see how it goes.

Raceghost

iTrader: (4)

Just an observation I had today. I reflashed my ECU and pulled the fuse to reset the trims. I idled for 20 minutes, no LTFT, I drove for 20 min, no ltft stopped at lights, idled again for 20, no ltft. SHut the car off for about an hour. Fired it up, no ltft after 5 minutes, drove another 20, no ltft, shut car off again for about 30 minutes, started up, no ltft, drove for about ten, idled again for about 5, and finally there was ltft. The whole time I had STFT and LTFT MID, no low. Fluke situation, but it happened when I reflashed the ecu, it was the same rom/maps I was already running, and have flashed several times in the last month, first time LTFT low has done this. So all I am saying is try to reflash again, and idle, try it several times. If it still doesn't read, you might have an ecu issue.