still having start up issues. come in and help me out, i need ideas
07-12-2005, 08:00 PM
#1
still having start up issues. come in and help me out, i need ideas ok so here is the deal, and this has gotten a lot better, kinda lol
car is cold, 28* c start up. crank the car, no troubles at all. the idle will hunt around in the first 5-10 seconds the car starts up. the rpms shoot up to 1500 when the car fires and then the go to 500 then 1200 then to 700 and then they steady out around 900 where the idle is set. this will only happen when the car is cold, i just went out there to start the car up, i am guessing its in the 40-60* range, in *C, and the car fires right up with absolutely no hunting. here is list of things i have changed to try to help the problem out.
-start up spark correction, i decreased the multiplier becuase i felt the car needed more timing with the cam, just like it does at idle. this helped out slightly.
-open loop f/a, with the bigger cam the map range is in the 50's and the numbers in this area would have made the car really rich so i leaned it out to where the car has a 10.5:1 commanded a/f ratio in this start up range.
-friction airflow and decay, i was demanding way too much air at start up that my ported/epoxy filled tb could not compensate for the changes so i lowered the airflow to get closer to the max airflow i can get at idle and increased the decay so it will get to the raf numbers faster. again this helped out some but didnt correct the problem.
-the effective area and raf tables are 100% inline after many tunes so i know these arent causing trouble.
i cant remember the other things i have done really but i have tried a lot. o yeah the ect air fuel ratio adder at start up was changed as well. if i zeroed it out the car ran really bad, so i dont think taking fuel away helped, maybe im too lean? the dynamic airflow oscillates but decays at the end of the 10 sec to a steady line. im really lost on what to try. i think tomorrow im going to try adding more fuel to it to see what happens. either that or is the iac just maxed itself out where it cannot compensate enough for the car to run ok when its that cold needing high airflow. its odd cause sometimes the car, well 2 times, she starts up fine when cold. unless the coolant is hotter, hell i dont know. im open for any ideas right now. this is the ONLY issue i really have for idle tuning left, and i want to fix it lol. tb has been opened up and when the car is hot rpms are steady and iac counts are low, i attached 2 screen shots.
i made a small range on the idle log so i can see whats going on better, idle isnt as bad as it looks on the second one lol and ignore the lean readings in the histogram, that was with the o2s still warming up when i was moving the car around, the settle down when the are on for about 5 min
car is cold, 28* c start up. crank the car, no troubles at all. the idle will hunt around in the first 5-10 seconds the car starts up. the rpms shoot up to 1500 when the car fires and then the go to 500 then 1200 then to 700 and then they steady out around 900 where the idle is set. this will only happen when the car is cold, i just went out there to start the car up, i am guessing its in the 40-60* range, in *C, and the car fires right up with absolutely no hunting. here is list of things i have changed to try to help the problem out.
-start up spark correction, i decreased the multiplier becuase i felt the car needed more timing with the cam, just like it does at idle. this helped out slightly.
-open loop f/a, with the bigger cam the map range is in the 50's and the numbers in this area would have made the car really rich so i leaned it out to where the car has a 10.5:1 commanded a/f ratio in this start up range.
-friction airflow and decay, i was demanding way too much air at start up that my ported/epoxy filled tb could not compensate for the changes so i lowered the airflow to get closer to the max airflow i can get at idle and increased the decay so it will get to the raf numbers faster. again this helped out some but didnt correct the problem.
-the effective area and raf tables are 100% inline after many tunes so i know these arent causing trouble.
i cant remember the other things i have done really but i have tried a lot. o yeah the ect air fuel ratio adder at start up was changed as well. if i zeroed it out the car ran really bad, so i dont think taking fuel away helped, maybe im too lean? the dynamic airflow oscillates but decays at the end of the 10 sec to a steady line. im really lost on what to try. i think tomorrow im going to try adding more fuel to it to see what happens. either that or is the iac just maxed itself out where it cannot compensate enough for the car to run ok when its that cold needing high airflow. its odd cause sometimes the car, well 2 times, she starts up fine when cold. unless the coolant is hotter, hell i dont know. im open for any ideas right now. this is the ONLY issue i really have for idle tuning left, and i want to fix it lol. tb has been opened up and when the car is hot rpms are steady and iac counts are low, i attached 2 screen shots.
i made a small range on the idle log so i can see whats going on better, idle isnt as bad as it looks on the second one lol and ignore the lean readings in the histogram, that was with the o2s still warming up when i was moving the car around, the settle down when the are on for about 5 min
