Power loss on low fuel?

[AbdulN]

Really conservative tune. You're undershooting targets a little bit, timing is pretty low, car is pulling a little bit of timing, mostly likely from shitty fuel. (93). Looks generally inline from a 93 OTS tune.

Thanks for checking it out, I'm on-stage 2 91 ots, you think it's worth while to go custom ? How much more could I gain ?

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[underdonk]

I think from my research it seems car looses grunt close to quarter tank..

What research?

I'm glad I'm not the only one. Maybe I'll do a couple of dragy runs at 1 or 2 bars of fuel and at a full tank and see what happens. Technically, all things being equal, the full tank should be marginally slower due to the heavier fuel load... though I'm not sure you could pick up that kind of a difference on a dragy.

 

[AbdulN]

What research?

I'm glad I'm not the only one. Maybe I'll do a couple of dragy runs at 1 or 2 bars of fuel and at a full tank and see what happens. Technically, all things being equal, the full tank should be marginally slower due to the heavier fuel load... though I'm not sure you could pick up that kind of a difference on a dragy.

Called a local tuner, was told b58 have this built into the software plus reading on forums and asking the members.

 

[zrk]

Called a local tuner, was told b58 have this built into the software plus reading on forums and asking the members.

This local tuner is full of shit. Every single drag car runs 1-2 gallons over 'fuel reserve' at the most for weight.

 

[zrk]

Thanks for checking it out, I'm on-stage 2 91 ots, you think it's worth while to go custom ? How much more could I gain ?

Yeah, go custom. It's not about more, necessarily, it's about a smooth powerband. But you can squeeze more boost out of that setup.

 

[underdonk]

This local tuner is full of shit. Every single drag car runs 1-2 gallons over 'fuel reserve' at the most for weight.

Yeah I just can't think of a reason for the car to be setup to suppress power when low on fuel. Doesn't make sense for it to purposefully happen.

 

[kanaka]

Yes, it does reduce power on low fuel.

 

[underdonk]

Yes, it does reduce power on low fuel.

Do you have any evidence of this? Again, I just can't think of a reason that BMW would build this into their cars. Especially in a "high performance" model where people are going to be running low fuel on the track, at autocrosses, and on the strip. Just to be clear, I feel like it does this as well, I just want to dig up some evidence of it actually happening.

 

[zrk]

Yes, it does reduce power on low fuel.

No it doesn't. lol. There can be fuel starvation, if it's real low or your doing corner-y things.

 

[razorlab]

Yeah I just can't think of a reason for the car to be setup to suppress power when low on fuel. Doesn't make sense for it to purposefully happen.

Just because you can't think of a reason doesn't mean it's not real. It absolutely does as a fail safe to try and save the engine. It uses rail pressure deviation as a safety check valve.

Having lost an engine on track from fuel starvation (different car) I am very happy the ECU in the Supra has this capability. It becomes even more apparent with more ethanol content (happens sooner).

 

[zrk]

Just because you can't think of a reason doesn't mean it's not real. It absolutely does as a fail safe to try and save the engine.

Having lost an engine on track from fuel starvation (different car) I am very happy the ECU in the Supra has this capability. It becomes even more apparent with more ethanol content (happens sooner).

Then we're talking low low low fuel. Like, fumes. Definitely isn't happening before 'reserve' light which is like 50 miles.

 

[kanaka]

No it doesn't. lol. There can be fuel starvation, if it's real low or your doing corner-y things.

Our BMWs do not explicitly say it compared to the newer models, but it's build into our ECUs
New ones show it. On fuel reserve, it will cut power

 

[razorlab]

Then we're talking low low low fuel. Like, fumes. Definitely isn't happening before 'reserve' light which is like 50 miles.

Sorry, you are wrong. This will and does happen on track with lateral forces under half a tank on right hand corners. With pump gas you can go lower but with higher ethanol content and higher power demands it happens sooner.

Many of the modified track (with corners when you turn the steering wheel) have encountered this.

Fuel surge tank is the fix. You will notice all the competitive track supras have surge tanks because of this very reason.

 

[zrk]

Our BMWs do not explicitly say it compared to the newer models, but it's build into our ECUs
New ones show it. On fuel reserve, it will cut power

That threshold has to be.. like.. a liter or less. I've seen anyone have issue with very low fuel at the track. 2 gallons-ish is most folks are using.

 

[underdonk]

Just because you can't think of a reason doesn't mean it's not real.

Well I know that, ya marmeladinger.

Our BMWs do not explicitly say it compared to the newer models, but it's build into our ECUs
New ones show it. On fuel reserve, it will cut power

Well fuck me sideways. I've never paid attention to the message and I've only ever gotten that low maybe twice. I notice things seem flat above reserve fuel levels too, which I would be very interested in having some evidence to support or not. Again, may just all be in my head.

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