Fuel starvation, who else?
 

I put this in the DDM thread, but in case you aren't following,

So, on the fuel starvation issue. I experienced the same thing today on my car at Road Atlanta during the BMW Oktoberfest lapping days, turns 1 and 7 (right handers). Oil temp was approaching 260 and I thought and was focusing on that. Took a couple cool down laps, then went at it again going into the back half of the track, but for me, coming out of turn 7, the car totally died.

It wouldn't restart and fuel gauge showed empty. Wound up getting towed in, then filled it up and it only took under 14 gallons to fill it completely.

Now that I know what it was, I think that if I had ever completely shut the car off and then restarted it would have worked, but I never did that since I thought it was out of gas (even though it was half full when I started, after 3 previous sessions), and the car thought it was out, so it shut down the gauge and fuel pump?

Regardless, its very embarrassing to get towed off the track, especially at a national BMW event for running out of gas. Other than that, the car is feeling pretty good.

Haven't been on the track yet, But i think it will happen to me and anyone who's going to track their car. It's been awhile since the problem have cored on the surface, and no solution yet!

I haven't been in a situation with fuel starvation. So this is new to me. So far what i know is there is two solution. Either replace the tank with a better designed one, Or a fuel surge tank (witch i think will be an ideal solution for most of us),

I've been doing my own research and I only came across this item from SPL website Sard fuel surge tanks

http://www.splparts.com/main4/parts/...lSurgeTank.jpg

Sard website

Scott at Fontana nissan said they are working on developing a surge tank kit also.

when my engine was cutting out at the track, i thought it was related to limp mode, but looks like it *might* be fuel starvation. when it happened to me i was at about 1/3 tank and it was most noticable going up the hill (top of 2nd gear, shifting into 3rd) just before the last two turns before the front straight at sow. the thing that makes me think it's fuel starvation is that if i am hard on the gas, it would cut out (engine almost shutting off, but not quite). it happens at around 5-6k rpm. but if i very slowly rolled on the throttle, it would rev all the way up to redline. and when it happened, my oil temps were only about 240-250.

i thought that hitting limp mode in the previous session somehow caused the ecu to not let the engine rev up again in subsequent sesssions, even though oil temps have gone down.

so at this point, im thinking it was probably fuel starvation, but am still not certain that it was not some form of limp mode....

does anyone know if it is required to reset the ecu after limp mode gets activated? or do you just have to let temps go back down and the car will behave normally again? answering this will allow us to rule out fuel starvation or limp mode.

I ran into the same scenario last weekend. I thought the car was in limp mode but when I hit the long straights, the engine was reaching max RPM's. Oil temps were reaching 270-280. I also thought it might have been the VDC kicking in on exit through the tighter corners. I didn't consider fuel starvation. I will pay closer attention next time out. I should have any oil cooler by then.

I've had both happen on several occassions... when it is limp mode you will know it for sure because the motor / throttle will abruptly cut-out at a very specific RPM, but under that RPM it will work just fine

Whereas fuel starvation you lose all throttle regardless of RPM. It can be for just a moment, or it can be so severe that it last a few seconds... if it last a few seconds, you have a very good chance that the motor will turn off all together, which has also happened to me on the track

Got a stumble on the track today at 3/4 full. Filling up every session now.

yup. and those 'stumbles' are no biggie if you're just out for a DE, but in time trial can cost you a second or two and in a race could cost you a position... it's pretty frustrating... we need a vendor to offer up some packages to fix

hmm.... i'm not sure now. from what you're describing, it now sounds more like limp mode, since it only does it above about 5k rpm. but the weird thing is that my temps are only around 220 (cooled back down from about 280+ in a previous session). and it only does it if i'm "pushing" the car hard. (will not cut out if i gently roll on the throttle - in which case i can rev it all the way up to redline).

fuel starvation

boosted, its still probably starvation, especially if you are getting it after right hand turns.

In my case, I think I have gone from having it happen around 1/2 tank to 3/4 now because I switched from used R888s to Goodrich R1s. The grip is awesome, and the new brembos really rock.

spl parts sells a surge tank kit, but I don't know if I have the patience to install something that complex, or if I want to pay someone else to do it for me.

Damn - starvation at 3/4 of a tank with tires is pretty out of control. I"m not there yet, but I'm still on stock tires.

Strangely, the surge tank may be one of the best weight single saving devices around. If they can allow you to run 10 fewer gallons of fuel, that's 62 lbs. I assume they weigh in under 5 lbs for the kit. Anyway, that's 30-55 lbs. less fuel weight you're carrying around just to avoid starvation.

Good point !

We ran into this problem as well. Anything less than a topped off tank would lead to starvation. We haven't made the jump to R-comp's but i'm sure it would be a nightmare.

+1 on the weight saving nothing having to run a full tank.

Were in the process of putting together a swirl pot and small pump for our car.

Here's a simular set-up I had in my GTR, something like this (smaller scale) would be perfect.
http://i10.photobucket.com/albums/a109/Paul2x/gtr-2.jpg

glad to hear AE will be stepping up to build/offer a swirl pot... I think there will be a healthy market for this product... there are at least 3 options I can think of

1 swirl pot
2 gut and replace the fuel system... fuel cell, lines, regulator, pump etc
3 custom in-tank 'can', as discussed on my build journal

#3 would involve building a 4-6" diameter cylinder with baffling that can be put in around the fuel pump and would act as a staging area for fuel and resist the flow away from the pump in right hand g's... just a theory at this point, but the guy posting the idea on my journal designed and built one that went into production on an unnamed GM car... I like it b/c it would cheap - avoiding the cost of the extra pump for a swirl pot