HELP: 1st gear + clutch + brake = stalling out

Brent · 04-25-2009, 04:18 AM

To add a few things to what has been said above:

Vacuum on a street port is generally a little lower than on a stock engine. When you check compression, the Mazda compression tolerances are based off engine RPM's being 250.

If compression checks out, I would look into your throttle body and components. As for your symptom where it stalls when you pull in the clutch while in 1st gear, check out your dash pot on your throttle body. They are known to go bad and cause this problem. Do you run a PFC? If you do, I can give you some pointers to help with this problem. As for your idle being high, I would also ensure everything is set correctly on your throttle body, not just your idle adjustment screw. Street ports tend to need to idle a little higher to smooth out opposed to a stock engine though, so that might be normal.

muibubbles · 04-25-2009, 10:03 AM

compression- yeah my friends told me i should vacuum lower with a street port but it seems like everyone over looked that detail

as per throttle body idler screw some people mentioned, i prefer not to mess with that as it has never been touched and it was running well before with the current setting

what exactly am i looking for on the dash pot?

i am running a pfc, last time rich tweaked it at DGRR, and im back in nj now.. idk if the altitude makes a difference?

when my car was running perfect i would idle around 850-900 rpms.. i believe its idling higher as i had to add tension to the throttle cable in order to drive the car home from dgrr

thanks for the input, my friend should be bringing over a compression tester today
-benny

04-25-2009, 04:18 AM	#1
Brent Sua Sponte Join Date: Feb 2008 Location: Killeen, TX Posts: 839 Rep Power: 18	To add a few things to what has been said above: Vacuum on a street port is generally a little lower than on a stock engine. When you check compression, the Mazda compression tolerances are based off engine RPM's being 250. If compression checks out, I would look into your throttle body and components. As for your symptom where it stalls when you pull in the clutch while in 1st gear, check out your dash pot on your throttle body. They are known to go bad and cause this problem. Do you run a PFC? If you do, I can give you some pointers to help with this problem. As for your idle being high, I would also ensure everything is set correctly on your throttle body, not just your idle adjustment screw. Street ports tend to need to idle a little higher to smooth out opposed to a stock engine though, so that might be normal. __________________ Road Atlanta August 2011 NASA TT 1:33 http://www.youtube.com/watch?v=IFY00PAK_Ps Traqmate's video of my car from the 2011 UTCC at VIR http://www.youtube.com/watch?v=2Zcn6...layer_embedded Video of Yellow LS1 FD at NASA TT at VIR http://www.youtube.com/watch?v=e6k0lJkcwrM

04-25-2009, 10:03 AM	#2
muibubbles Bubble Tech Join Date: Oct 2008 Posts: 161 Rep Power: 18	compression- yeah my friends told me i should vacuum lower with a street port but it seems like everyone over looked that detail as per throttle body idler screw some people mentioned, i prefer not to mess with that as it has never been touched and it was running well before with the current setting what exactly am i looking for on the dash pot? i am running a pfc, last time rich tweaked it at DGRR, and im back in nj now.. idk if the altitude makes a difference? when my car was running perfect i would idle around 850-900 rpms.. i believe its idling higher as i had to add tension to the throttle cable in order to drive the car home from dgrr thanks for the input, my friend should be bringing over a compression tester today -benny