Ignition Problem Using SAFC

[SeeYaAWD]

I've been chasing this problem for a month and am hoping for some good advice on here:

A little over a month ago, my SAFC somehow cleared itself. No idea how it happened. It was not disconnected, the battery was not disconnected - I have absolutely NO idea how this happened. Because I lost the paper that had all of my dyno-tuned fuel trims on it, I needed to go to the dyno again to re-tune it. After getting the car all strapped down and started up, and doing a slow pull, we discovered it was missing occasionally and had to quit. I knew it was missing, but attributed it to bad fuel trims.

I sent the injectors in to be tested and cleaned - the worst one was only reading 3% low, so that was not the problem, but they were cleaned and re-installed anyway. Then I changed the coil pack, thinking it may be going bad. No change. Ignition module swapped - no change. I am baffled by this. I really don't think it is the fuel filter or regulator (because of the symptoms I will list below), but am at the point that I don't know what else it could be.

Symptoms:

1. My SAFC is set at 0 across the board (as in profile, I'm running 550 injectors). If I TOUCH the fuel trims - even adjust them to -2% - the car will start sputtering and giving me grief.

2. If I am cruising along, even with the cruise on, and the slightest acceleration is applied (like less than +2% according to TPS reported on SAFC), some of the time (roughly 7-10%), the ignition seems to stop completely - across all cylinders - like I am coasting along with no power, then all of a sudden it will fire again and continue running like normal.

Notes:

It doesn't seem to me like it would be a fuel filter/regulator because a) the change in throttle is so slight that I don't think it would make a difference, and b) it runs fine (most of the time) if I give it a decent amount of throttle.

My SAFC readings do not change AT ALL when the ignition stops - throttle position, RPM, Karman Hz all read exactly the same (correction stays @ 0 because that is where it is set)

I am very critical of the SAFC since all of this seemed to occur when it was somehow cleared, but do not know why the ignition issue would seem so random if it was the SAFC - I really have no reliable way of reproducing the problem. My best method is to apply roughly 25% throttle and slowly accelerate from a higher gear.

Again, I am baffled. Any insight or even a fresh point of view would be greatly appreciated!!!

 

[Ceddy]

Have you compared your SAFC TPS reading with a logger reading?

The SAFC gets its TPS scaling from the highest and lowest value its sees.
So your actual TPS could be at 50%, while the SAFC thinks its is 100%

Also did you reset your ecu? Need to when ever major changes are made with the SAFC.

You should be running black soot rich with 550s and the safc zeroed out.

May be you are bogging out from to much fuel when the ecu switches from closed loop to open loop operation.

 

[GVR4592]

It sounds like it's either way to rich from the settings being messed up or you have a boost leak, or it's both. If you have a stock maf sensor, and stock fuel pressure settings. Set the SAFC to -15 across the board and see if it runs better, check for boost leaks as well.

 

[spyderturbo007]

Also did you reset your ecu? Need to when ever major changes are made with the SAFC.

I don't know where you came up with this, but it's not true at all. There is no reason to reset the ECU after making alterations to the SAFC's settings.

 

[Ceddy]

I don't know where you came up with this, but it's not true at all. There is no reason to reset the ECU after making alterations to the SAFC's settings.

I said you need to reset after major changes. The ecu needs to relearn fuel trims and octane. Read any of the guides on setting up the SAFC and it will tell you to do this.

 

[1bad92awd]

I would try leaning it out a bunch first. -15 is where I started when I was running 550's with a walbro 190 and stock FPR with a T28 on my old talon. Then try making some adjustments from there and see if that helps at all or even if anything feels different. Becaue even with 18psi on the T28, I never had my settings anywhere near 0's all the way across.

 

[spyderturbo007]

I said you need to reset after major changes. The ecu needs to relearn fuel trims and octane. Read any of the guides on setting up the SAFC and it will tell you to do this.

Here is one of the most respected SAFC tuning write-up's and there is no mention of resetting the ECU.

How does changing the Lo Throttle maps on the SAFC impact octane value? There is no reason to reset the ECU after making changes to the SAFC.

 

[steve]

There is no reason to reset the ECU after making changes to the SAFC.

Resetting the ECU clears the fuel trims and that's one reason why you want to reset it.

You want any corrections you make to the low settings to be against the base defaults. The "zeroed" out long term trims.
If your tuning the high settings for knock you want to make sure that the ECU isn't interpolating between the main and "octane" timing maps so resetting the ECU clears that "octane" or long term knock variable too.

Resetting the ECU speeds the process of getting the right SAFC settings if you far off. Otherwise the ECU has to unlearn the current trims which can take some time.