help with stumble please

[Otto J]

i have my car pretty well tuned, but the only thing i found is that if you are sitting still and just punch it it bogs right down and almost stalls if you roll into it it is fine or if you are moving and you floor it it is fine but from a dead stop it just bogs down
what should i adjust for this
i have a speed-pro b2b wb setup
thanks Otto

 

[RickWI]

Data log it to see what way the fueling is going. I suspect it is lean. Either way I would go into the demo file and copy/compare the AE fueling 2d windows for both tps and map. This should get you into the ballpark. Before changing though do the data log to make sure the demo files get you going in the right direction. If lean I would say you will have to richen up the MAP AE screen(s) to start with. The reason I say this is I suspect you can sit there in park and jab the gas and the motor is responsive. If not then you need to richen up the AE TPS curve as well. Either add more PW or raise the curve up in the AE Vs TPS position screen toward the center/right side. If the Data log screen shows it going dead rich you need to do the opposite.

 

[Spooled]

Another thing you might try is this. Go into the "AE fuel vs. TPS position". Find out what TPS value your car idles at. Then at this point on the X axis, raise the value on the graph a little. It sounds like you have the AE right at all other TPS levels so if you just go into the AE MAP or TPS graphs, you may screw up other your transition fueling at higher TPS levels. Sounds like you just need to richen it up at low TPS levels. So do this and keep raising it until the stumble is gone. Sometimes you have to raise it quite a bit. Good luck

 

[Otto J]

tried what rick said and it worked,thanks to both of you, but on the way to work my convertor started whining bad so trans is coming out, i had to sent it out ro be loosened anyway
Otto

 

[RickWI]

Solve one problem start on another. Well at least you can switch forums (tranny) and find the fix there

 

[quickstrike]

Exact same problem last few nights at the track! Car runs great once past a couple thousand RPMs but stumbles(in gear only) at low rpm. I will try this in the morning with AE vs MAP. Weird thing is it didnt used to do this, and I cant remember messing with anything.

Thanks for the help.

Randy

 

[RickWI]

You just may want to make sure the fuel pressure is OK at idle. I was chasing a glitch last week "in the programming" and it was an external problem. Clogged fuel filter.

 

[quickstrike]

Actually that is exactly what I was thinking. I havent changed the 2 filters at the pump since I installed the fuel system last year(probably only 2000 miles tho). I looked at the fuel pressure at idle and under heavy load, and looks fine. Wouldnt car lean out pretty bad at top end if this was the case? Need to change them regardless. at 350 HP I never did anything but drive it, now at 550 it seems I am always working on something! At this rate when I get 700 HP I will spend 90% time working on it and 10% racing it!

Oh well Gotta love it

Randy

 

[RickWI]

Yea trust me on this one, if your filters are plugged it will major lean out on the top end.