1/8th tank factory power reduction

[SoonerStingerGT]

A little while back I was looking at some Lap 3 stuff and was intrigued with their back end tune for the various piggybacks out there. (Jb4 here)
Their literature says this tune will nullify the built in power/torque reduction with less than 1/8th of a tank of fuel.
I searched every forum but i never have found crap doing that.
Anyway, can anyone verify that we actually do lose power with low fuel, and how much it is stymied? I have not been able to tell in my car by draggy times or by butt dyno.

 

[SafetyPilotCal]

I know some cars do that, but I've never heard of it with the Stinger, nor have I seen it documented anywhere.

 

[SoonerStingerGT]

I know some cars do that, but I've never heard of it with the Stinger, nor have I seen it documented anywhere.

I have an email from either a distributor or possibly the manufacturer.
I said Lap3 but now I'm not sure. I.cant remember which tuner company it was.
I will dig for the email and post what they said.
I really hope he wasn't trying to sell me something by lying about the benefits. I really am interested in the back end tune.

 

[SoonerStingerGT]

My apologies to Lap3... here is the email.

 

[SoonerStingerGT]

Tork not Lap3

 

[Stock_stinger]

Last I read it was 1/4 or less you get iffy

 

[SafetyPilotCal]

I mean I guess John would know if there are tables or a flag in the ECU for this function since he has tuned them.. but I dug through the service manual and everything else I have and I can't find anything referencing this. You'd think Kia would put it in a troubleshooting table somewhere so a tech would be aware of it.

 

[Stock_stinger]

Maybe it's so the gas doesn't stay slammed in the back of the tank and starve the engine. Makes sense

 

[SoonerStingerGT]

Last I read it was 1/4 or less you get iffy

1/4 tank is still a lot of fuel to be limiting power. If true, I would love to know exactly what happens and where it happens in regards to remaining fuel. What a stupid thing to do. Gasoline is not a lightweight material. 10 gallons vs 1 gallon could be the difference in running 12.1 and running 11.8 or so.

 

[Stock_stinger]

Message tork motorsports. I've also seen several see the reduction in logs when doing 1/4 mile runs

 

[Aarvix]

I drive on 1/4 to 1/8 a lot and haven't noticed anything. Maybe it doesn't reduce power until the low fuel light comes on?

 

[ephone]

I've had my G70 on a track 4 day last month. I start each day with a full tank and after 4 20 minutes sessions, I was between 1/8 and 1/4 tank. I didn't notice any power reduction - and on a track, you would easily notice. This function likely doesn't kick in until 1/8 or lower.

 

[Travis Wills]

I have plenty of digs with a dragy where the tank was showing empty and it never shows any reduction in performance. I don’t believe the car’s performance is affected by how much gas is in the tank.

 

[oddball]

I remember Tork talking about this whenever that was - over a year ago? - but don't know any details myself.
The general concern is when fuel runs low, fuel supply could suddenly drop, resulting in a drop in fuel pressure at the injector. If it's not noticed quickly enough then the engine can suddenly run lean. When at full thunder, this can cause damage.
This is a really big deal on cars running nitrous. A lean spike on nitrous will melt piston tops, break ring lands, melt spark plugs, etc etc - immediately and every time. On moderate turbo cars like ours? It's not good, but not guaranteed to break anything.

So with that in mind, I wouldn't be surprised if the ECU is a little conservative, especially since fuel flow appears to be the current limit on the drivetrain. (seems fuel starts to drop off shortly before stock turbos start to flutter - go to big turbos and you quickly hit fuel limit)

Also remember that Tork is playing around in the deep dark woods of the ECU. He may be addressing a part of the logic that is very rarely accessed, or only hits in specific situations. e.g., 9/10 drag runs with almost no gas are fine, but then that 1/10, for whatever extra reason, the failsafe triggers.

Given Tork's work here, I fully expect that failsafe is there and does what he says it does. The follow up question - "Does it matter?" - is way more complicated.

 

[friss]

In my experience after a few track days that left the car at gas light on and "do you want the nav to search for gas stations" the car definitely felt more sluggish. I had always attributed this to be me being accustomed to track speeds but it would make sense that it was the car in an almost limp mode.

While on the track there were no issues but only after turning the car back on with a low tank. That may be the difference some people are seeing (driving to empty doesn't enable it but starting at empty does)

 

[CKeeler]

Never noticed it.

 

[Stock_stinger]

ok so i have the clarification now that im not overtired. there isnt a torque pull/power reduction.

tork talks about adding a power/torque reduction for safety.

this is to avoid fuel starvation. no fuel = big problems when tuned high

 

[Jayphil]

ok so i have the clarification now that im not overtired. there isnt a torque pull/power reduction.

tork talks about adding a power/torque reduction for safety.

this is to avoid fuel starvation. no fuel = big problems when tuned high

That make more sens now similar to when JB4 auto change to stock map when a problem is found it could also put stock power if tank is close to empty vs just wait for an event in the logs to happen to put back to stock.

Also JB4 does something similar for METH map if the flow is not to 100% or bottle become empty.

 

[SoonerStingerGT]

ok so i have the clarification now that im not overtired. there isnt a torque pull/power reduction.

tork talks about adding a power/torque reduction for safety.

this is to avoid fuel starvation. no fuel = big problems when tuned high

That is not what they said in the email to me at all...i posted a screenshot above

 

[Stock_stinger]

if the car already has the torque limiting if below a fuel level, i dont see why they need to also add one