FSCM tuning ss 1le vs zl1

[Sjd6795]

As far as I am aware the FSCM in the 2014 ss 1le is the exact same minus some adjustments in the tables considering I have the same pump. I noticed it has an injector flow rate table. The image on the right that goes to 768 KPA is from a zl1 however on the left is mine from my 1le that only goes to 640 KPA. It claims to be an exact copy of the ECM table but my ECM table goes all the way to 768 KPA? I am having fuel pressure drop into the 48 psi range under boost so I am trying to adjust the FSCM to hopefully solve for that, but it just has me confused as both FSCM read 6991 and tables read 12307.

FSCMdifference.JPG

[blindsquirrel]

Does the fuel pressure really drop or are you just basing that on the Fuel Pressure Sensor PID?

[Sjd6795]

Does the fuel pressure really drop or are you just basing that on the Fuel Pressure Sensor PID?

I don't have a fuel pressure gauge in car but in the data logs it shows it dropping to 48 psi. I noticed the SS FSCM decreases fuel pressure as the flow rate increases whereas the ZL1 holds a static 450kpa. I've set mine to 400kpa across the flow rate and will go out and data log that. I just don't get why two tables that share the same ID from the same car ECM/FSCM have different injector values. It appears the hard cap is 63.5 on the FSCM flow rate compared to 127 on the ECM flow rate.

[blindsquirrel]

Does the Fuel Pressure Sensor voltage fall off too, corresponding with the calculated pressure it's showing?

This is a common thing, btw. The sensor pressure will lie to you while the actual pressure and sensor voltage stays where it should be.

[Sjd6795]

Does the Fuel Pressure Sensor voltage fall off too, corresponding with the calculated pressure it's showing?

This is a common thing, btw. The sensor pressure will lie to you while the actual pressure and sensor voltage stays where it should be.

Interesting.. I don't think I have the voltage logged. I'll go over the config and find it and add it for my next data log.

[blindsquirrel]

As to the difference in axis scaling between the two modules, you will never ever get into a situation where it is using those cells over at the far right (or the far left either, for that matter) of either table. Do some math to figure what manifold pressure & fuel pressure would be in those cells. Not realistic conditions. Not here on planet earth, anyway. No I don't know why the factory made tables that extend that far off into fantasy-land.

[hjtrbo]

Blindsquirell was discussing this with me just the other day. Sensor lies.

https://forum.hptuners.com/showthrea...-sensor-doubts

[Sjd6795]

As to the difference in axis scaling between the two modules, you will never ever get into a situation where it is using those cells over at the far right (or the far left either, for that matter) of either table. Do some math to figure what manifold pressure & fuel pressure would be in those cells. Not realistic conditions. Not here on planet earth, anyway. No I don't know why the factory made tables that extend that far off into fantasy-land.

So where my sensor is saying 43.9 PSI at 6,460 RPM 100% throttle my control module voltage is 14-14.4

The WOT portion is near the very end of the log. I had some light cruise on my way to Mcdonalds in the first half.
vvvvvvvdd.hpl

[blindsquirrel]

Sensor voltage. There should be a PID for it. It's a 0-5 volt sensor.

[blindsquirrel]

Blindsquirell was discussing this with me just the other day. Sensor lies.

https://forum.hptuners.com/showthrea...-sensor-doubts

Yes... but... if there is a question, it should still be verified with a real gauge like you did. Just because it lies doesn't mean it can't tell the truth sometimes. The problem with a liar is you never really know.

[Sjd6795]

Sensor voltage. There should be a PID for it. It's a 0-5 volt sensor.

I'll take another look for that. To late to go back out and get another log tonight though .

[Sjd6795]

Sensor voltage. There should be a PID for it. It's a 0-5 volt sensor.

The only other sensor that I found was fuel pressure sensor so that's probably it, wish I would've just selected all of them the first time. I'll log it tomorrow on my way to work, I'm going to get a mechanical gauge that I can route and just tape in front of my windshield to confirm while driving, having that threaded pressure relief on the fuel rail will make it easy to install.

[blindsquirrel]

Well if you don't have a running-lean issue, and the sensor voltage stays nice and flat while the sensor pressure is falling off, you don't have a problem.

[Sjd6795]

Well if you don't have a running-lean issue, and the sensor voltage stays nice and flat while the sensor pressure is falling off, you don't have a problem.

AFR gauge stays exactly at 11.3 all the way until it cuts me off from redlining. Still frustrating that the data logs show super low pressure lol. ZL1 pump is only a 250lph and back in my 4g63 days a walbro 255 was needed for anything over 450whp. But completely different engines though.

[Kittyboy]

I was curious about the same issue a while back. The other poster is correct, the table has areas you will never need. GM cobbled what was available at the time and made it work. I have an LSX376-B15 and have set all my pressure settings to 3 bar (43.5psi) using DW300c pumps, and ID1050x injectors, never any problems! I would determine when it is your injector duty cycle goes past 60% and then go into the FPCM open loop table DC and increase the fuel pump operation percentage to 100% for those areas, basically the 13.5v-15v range is all that is needed. The higher pressures programmed for stock are used with smaller pumps and injectors. With upgraded pumps and injectors, more flow, less pressure is required. This setup should get you to 800hp without additional fuel mods.