Surging Idle

[stevec]

I get a funky hunting idle after the car is warmed up run hard and turned off and started again.

Cold start is fine fires right up and fast idles with no surging. AF ratio 13.00 and 11.5 in gear. Now when you WOT it come back shut it off and start in again it is showing lean 14.00 to 14.75 which causes the motor to surge as it goes rich/lean. To correct I bump the VE number by 1 and it starts to smooth out.

I have 160 lb injectors so it does not take much tweaking to see a change. I dont have any temp correction in any of the tables.

I wonder what could be causing this?? Maybe the injectors are getting warm and change there flow rate slightly. Also the alt voltage looks stable.

the motor is a Stage 2 off center GN 1 heads 236/236 roller, BGC intake etc. The motor is mech sound > 4 % leakdown.

Maybe a vacuum leak?? I dont run a PVC valve instead I have a vac pump hooked to the intake boost triggered.

I will double check the vac connections

Thanks


Steve

 

[Craig Smith]

It sounds like the motor is getting heat soaked and leaning out when you restart it. Try increasing the after start fueling in the higher temp ranges; this frequently cures this problem.

 

[bobc455]

Steve,

Make sure you don't have too much timing at idle.

-Bob Cunningham
bobc@gnttype.org