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Launch issue using 2step
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DRR Trophy
Picture of jacedeering
posted
Hoping someone can help me out here. Having issues that started this year when launching off the 2step (never had this issue in the past leaving this low on the 2step). The car will launch and have a slight consistent hesitation at 4,000 rpm when I launch and then it will stall to what the converter should.

I've changed coil, plugs, wires, cap, rotor, cleaned carb, changed low side chip. Going to try replacing the MSD 2step module next.

Link to videos attached:

2 step launch - https://www.youtube.com/shorts/7KHm_qZvnX8


I'm a no-boxer and have always left low on the chip

This message has been edited. Last edited by: jacedeering,
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR S/Pro
Picture of BP758
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Are you on the mat 2 step vs at 2500 foot brake? Could be float adj or it might want some fuel.

Mine wanted more fuel when we two stepped it. It’s about .02 quicker and consistent.


Raceless in California!
 
Posts: 4267 | Location: Vacaville  | Registered: January 07, 2004Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
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Im matted when on the 2step. Float adjustment is set to where i bump the car to have fuel come out.
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
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When you say "more fuel" are you talking squirter size or something else???
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR S/Pro
Picture of BP758
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Very well could use some squirter but on the mat there’s no more squirt so I’m thinking lean jet. Been a while , can’t remember if I fattened it but I will look at my records.


Raceless in California!
 
Posts: 4267 | Location: Vacaville  | Registered: January 07, 2004Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
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Still having the same issues...This is a list of everything I've changed:

Carb
7al-2
2 step chip
High Side chip removed
2 step module
Unplugged the Tach
Cap
Rotor
Plugs
Wires
Coil
Verified all ground wires are good

Talked to Coan Engineering to verify the converter is spragless, which it is. He insist its not the converter but I'm almost out of things to check.

Thinking about changing the converter tonight?
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR Pro
Picture of CURTIS REED
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Maybe you have a fuel supply issue when leaving harder on the brake. Or it could be using up fuel on the brake that it doesn't when footbraking, then runs low because of G-force and it catches up after the hesitation. Just a thought. Any fuel pressure data?



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2017 and 2018 Osage Casinos Tulsa Raceway Park No-Box Champion

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Posts: 2361 | Location: KIEFER, OK. | Registered: August 17, 2007Reply With QuoteReport This Post



DRR S/Pro
Picture of Mike Rietow
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Have you checked the transmission line pressure and converter pressure?

I'd check the line pressure at the servo cover for starters , idle and above 2000 rpm's. There should be like a 25-30 psi split max there. If there's more that would be a weak pump.

If that checks good I'd check converter pressure at the out cooler line - T a 200 psi gauge in there, check pressure on the T-brake w/ no rev limiter around 5000 rpm's.


https://youtu.be/FZ6zwnyDwUg

http://ottm.store

https://youtu.be/I8QWEaqeFRw

1996, 1998, 2001, 2003, 2005, 2006, 2008 Super Pro Champion Sunshine Dragstrip, Clearwater Florida
 
Posts: 8821 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR Sportsman
Picture of TD3550
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quote:
Originally posted by jacedeering:
Im matted when on the 2step. Float adjustment is set to where i bump the car to have fuel come out.


Where is the fuel pressure? That above statement is confusing on how you have it worded. 5-6 Lbs is normal. Too high a pressure or level too high,the boosters will bleed over
 
Posts: 1369 | Location: Under a Truck | Registered: August 23, 2013Reply With QuoteReport This Post
DRR S/Pro
Picture of Mike Rietow
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If you do check converter pressure, check with and without the cooler.

Swap the lines on the cooler, and check both ways too.


https://youtu.be/FZ6zwnyDwUg

http://ottm.store

https://youtu.be/I8QWEaqeFRw

1996, 1998, 2001, 2003, 2005, 2006, 2008 Super Pro Champion Sunshine Dragstrip, Clearwater Florida
 
Posts: 8821 | Location: Madeira Beach Fl. | Registered: June 12, 2018Reply With QuoteReport This Post
DRR S/Pro
Picture of BP758
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Raise the float 1-2 flats and try it. It sounds like it’s low too fast.


Raceless in California!
 
Posts: 4267 | Location: Vacaville  | Registered: January 07, 2004Reply With QuoteReport This Post
DRR Sportsman
Picture of novaX522
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Hey Jace, It may be fuel sloshing out of the vent tubes. Try running a piece of rubber hose from the front carb vent tube to the rear one. Make sure to cut a hole in the tube so the vents still work.


Rob Livingston
 
Posts: 176 | Location: Waterloo, Iowa | Registered: July 03, 2005Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
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quote:
Originally posted by novaX522:
Hey Jace, It may be fuel sloshing out of the vent tubes. Try running a piece of rubber hose from the front carb vent tube to the rear one. Make sure to cut a hole in the tube so the vents still work.


Hey Rob! I currently have a vent tube on it. No Help
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
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quote:
Originally posted by BP758:
Raise the float 1-2 flats and try it. It sounds like it’s low too fast.


I'll give it a try.
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post



DRR Pro
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I had a similar problem off my sle this year.I got rid of it using the mixture screws.I was 1.5 turns out and i kept backing them out a 1/4 turn at a time.I think i am at 2/3/4 turns out now and hesitation is gone.No clue if this will help
 
Posts: 1404 | Location: united states | Registered: January 16, 2006Reply With QuoteReport This Post
DRR Sportsman
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Like jenavet said you might be able to work it out by making sure your mixture screws are set right.make sure your base idle is not so high that the mixture screws have no affect,seen it before. Also do you have jet extensions? If not you need some. Good luck getting it lined out.
 
Posts: 320 | Location: observing the mayhem | Registered: December 22, 2014Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
posted Hide Post
quote:
Originally posted by BP758:
Very well could use some squirter but on the mat there’s no more squirt so I’m thinking lean jet. Been a while , can’t remember if I fattened it but I will look at my records.


I tried to fatten the jets up and it didnt help. I also tried to lean it out and it didnt help either. also tried adjusting floats up and down, that also didnt help
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR Trophy
Picture of jacedeering
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quote:
Originally posted by TD3550:
quote:
Originally posted by jacedeering:
Im matted when on the 2step. Float adjustment is set to where i bump the car to have fuel come out.


Where is the fuel pressure? That above statement is confusing on how you have it worded. 5-6 Lbs is normal. Too high a pressure or level too high,the boosters will bleed over


I have a belt driven blp pump. It shows 5lbs at idle, i dont have a fuel pressure gauge in the car so thats my next step is to install one. The pressure is set the same as last year when i had no issue, not saying that it could be different, so i will try the gauge.
 
Posts: 13 | Location: clinton | Registered: July 27, 2016Reply With QuoteReport This Post
DRR S/Pro
Picture of BP758
posted Hide Post
quote:
Originally posted by jacedeering:
quote:
Originally posted by BP758:
Very well could use some squirter but on the mat there’s no more squirt so I’m thinking lean jet. Been a while , can’t remember if I fattened it but I will look at my records.


I tried to fatten the jets up and it didnt help. I also tried to lean it out and it didnt help either. also tried adjusting floats up and down, that also didnt help


Well that sucks!

Sending you a pm , call me when you have time.


Raceless in California!
 
Posts: 4267 | Location: Vacaville  | Registered: January 07, 2004Reply With QuoteReport This Post
DRR Trophy
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Jet extensions on the rear jets?
 
Posts: 330 | Location: Pride, La | Registered: April 18, 2006Reply With QuoteReport This Post
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