Help me diagnose my '11 5.0L's launch

[Five Oh Brian]

My '11 5.0L has a horrible problem at launch that I can't figure out, so I'm hoping that someone here can help make sense of it for me and point me in the right direction. I've owned many stick shift cars over the years and have been drag racing successfully for 30 years, yet I'm perplexed with this issue.

My '11 5.0L has 3.73 gears, an SCT canned 91 octane tune, K&N panel filter in the stock airbox, FRPP GT500 axlebacks, adjustable rear LCA's, and M&H 28" tall drag radials. I always turn off the traction control and AdvanceTrac completely. I heat the tires lightly (starting in the water box then rolling out to clean/dry off the tires). I get plenty of traction and no bog.

When I try to launch at anything other than idle, the car nose dives (feels like the traction control has totally kicked in and taken out all the power) and after a half-second to a second the power comes back on and the front lifts up high. It only does this in 1st gear. All subsequent gears pull hard. I've tried every launch rpm and tried slipping the clutch while feeding more gas to keep the revs up without bogging, but the power still turns off. 60' times are in the 2.30's to 2.50's when this happens.

Conversely, if I launch at idle I get 60' times in the 1.90's with zero loss of power (and much better timeslips, accordingly).

Can anyone guess what might be pulling timing/fuel/power/etc. from my car at launch to make it nose over like what I've described? I've reloaded the SCT tune several times to see if that changes anything - it doesn't.

 

[konablue11gt]

Maybe you may want to look at a custom remote tune or a dyno... Try data logging with your SCT to see what it's doing

 

[Steedman07]

Ya, that sounds like a tune issue man..

 

[stkjock]

U have any vids of the launch?

How much fuel r u raceing with?

Certainly sounds like it could be the tune.

 

[Unreal]

Are you just bogging it? Launch higher or slip the clutch some more.

 

[cgibs89]

I would flash to the factory tune and see what it does. I went to the drag strip last night with the first couple runs on my MT ET Street IIs and I've got the Ford factory tune and factory sealed engine, including filter. I was launching at around 5000 and dropping the clutch and giving it hell.

1.96x 60'


1.800 60'


Nothing else. No LCAs, UCA, any brackets of any kind, nothing. Just tires.

 

[Five Oh Brian]

Thanks for the responses. I'm definitely not bogging, the power is just lost for a second. I had my car on a dyno a couple months ago and we specifically looked for this issue, but it did not happen on the dyno. I'm going to run the factory tune next trip to the track. If it runs fine then I'll be ordering up a tune from one of the well known tuners out there. At this point, I'm 99% certain it's a tuning issue. I'm trapping 115-117 mph, so there's an 11.90 (or better) timeslip waiting to happen once I get the launch figured out.

 

[Seer]

How much fuel in the tank? Usually I've found if any less than a 1/4 you may have sloshed the fuel away from the sender.

 

[Five Oh Brian]

How much fuel in the tank? Usually I've found if any less than a 1/4 you may have sloshed the fuel away from the sender.

I started with a 1/2 tank, and after 23 passes, was down to 1/8 tank. Plenty of gas in the car for many of the passes with the power drop.

 

[cgibs89]

I've gone to the track with 1/4 tank every time and haven't had a problem with fuel starvation even after it got to 1/8 tank.

 

[REDS197]

What process are you using to turn off the traction control? It sounds like it isnt totally disaled.

 

[Five Oh Brian]

What process are you using to turn off the traction control? It sounds like it isnt totally disaled.

Foot on the brake with the car at a complete stop, hold t/c button for 5-6 seconds until it says "AdvanceTrac Off". I turn off my t/c every time I drive the car and can drift and do long smoky burnouts so I know it's fully off.

That said, when I launch with any rpm's it feels like t/c is engaging and pulling out all the power. So, I think my tune is messed up. I'm racing in two days and will be running the factory tune to compare launches.

 

[stang1971]

i found that on my m6 2011 that if i heated them GOOD, i could launch about 5500 rpm's with very little spin and get low 1.7's...maybe try a higher launch to keep the power up on the launch.

 

[Five Oh Brian]

So, I went to the track tonight with the stock tune back in the car. Best run was launching off idle for a 12.95 @ 110+ (85 degrees). However, my launch problem was still there on the runs with any revs at launch. The car just lays down in 1st gear for about a second, then the power magically comes on full blast. Our SVT Director for our store thinks some sort of 'torque management' is pulling power in despite the traction control and advancetrac being totally turned off.

To make matters worse, I tried to reload my SCT 91 octane tune at the track and it wouldn't load. Said that my battery voltage was too high and I could not start the car. Tried several times to reload that tune with no success and my car wouldn't start until I loaded the stock tune back in. I was worried that I'd be calling a tow truck! Any ideas? High battery voltage from running to redline on the track? If so, I'm not liking this SCT tuner. I had a DiabloSport Predator tuner for my '07 GT and never had any glitches.

 

[Five Oh Brian]

Spent an hour on the phone with SCT today. My tuner was frozen essentially. They connected to my laptop remotely and I had the tuner plugged into my laptop so they could access it. Ended up having to completely format the tuner! Completely reinstalled the latest software and firmware revisions for me (took another hour after I got off the phone with them. Loaded the new 91 octane tune in the car successfully and the car is good and strong again! Seems to launch very hard with no power being pulled now, but I'll have to confirm if my launch issue is really 'cured' next time at the track.

 

[HEMI LOL]

interesting findings Brian.

 

[Five Oh Brian]

interesting findings Brian.

I hope things go smoother for you and Caleb when you tune your 5.0L's! You gotta come out to the track with us sometime soon.

 

[808muscle]

I hope you have figured out your gremlin's. Nice to see your back to racing the new FiveOh. I am sure it was hard to not race it after you purchased it.

 

[Five Oh Brian]

I hope you have figured out your gremlin's. Nice to see your back to racing the new FiveOh. I am sure it was hard to not race it after you purchased it.

I hope they're figured out, as well. Next track day is 3 weeks away. It was tough to sit out last season with a brand new car, but the wait was worth it as the new 5.0L is faster than my supercharged '07 (barely). Looks like your Roushcharged 3V is coming along nicely!

Sure wish I could have tried out that TCI shifter in my '07 before it went to you. I kinda miss having an automatic (shifting and launching has been my biggest issue at the track with the 5.0L).

 

[808muscle]

Yeah I love the shifter. Shifting a manual at the track is fun but for my bracket racing I had to get a auto. Brenspeed is writing me two new tunes. One will have less timing so I can compete in my 12.9 bracket.
Sucks you have to wait 3 weeks but I know the feeling as we race only once a month here.