OK Chris
I told you I'd get that info and I really had to dig for it.
I decided to not pm you with it because the other members may get some benefit from this stuff.
Before I start, I wanna say this stuff is from a Tweecer & EEC Tuner perspective.
Three fixed parameters in the pcm fuel tables come into play when talking about startup.
1) Time
2) Load
3) ECT
We are dealing with two fuel tables.
1) fuel_table_base_OL
2) fuel_table_startup_OL
The base table is where you see the commanded ratio and it is used during warm up conditions.
The startup table is where you see values that are subtracted from the base table to give you a fatter ratio and time comes into play here.
You asked about hot start conditions so lets use that as an example.
btw, we're gonna use an unmodified j4j1 file for our little example.
Say you've been driving around and go in the house for a while and decide to go somewhere else. When you start the car for the second time, the ECT is 180*
Most NA h/c/i combos will idle at a load of say about .20 to .30 so we will use that load factor.
Looking at the base table you see the pcm is commanding a ratio of 14.302 at that load value and ECT.
Looking at the startup table in the 180* temp column at 0 to 6 seconds you see the value of 1.716. Notice as the time increases, the value decreases until finally at 40 seconds, the values in the table are no longer used.
Here are the commanded, startup, and final ratio values
00-06 secs cmd 14.302 startup 1.716 final ratio of 12.586
07-10 secs cmd 14.302 startup 1.487 final ratio of 12.815
11-20 secs cmd 14.302 startup 1.259 final ratio of 13.043
21-40 secs cmd 14.302 startup 0.572 final ratio of 13.73
At this point in time, you most likely go from Open Loop to Closed Loop conditions and the O2's are calling the shots to achieve the pcm's goal of 14.7 CL happiness.
The Fix is to go to the 210 & 240 ECT columns in the startup table and zero out those entire columns. If need be, you could always play with the values in the 180* column as well.
This topic of discussion makes me wanna ask you guys this ................
What do ya'll think might happen if you start a pull after a cool down at ...... lets say about 20 seconds after you fire it up?
hummmmmmmmmmmmmmmmmmmm!
That info would be another thread
Grady
I told you I'd get that info and I really had to dig for it.
I decided to not pm you with it because the other members may get some benefit from this stuff.
Before I start, I wanna say this stuff is from a Tweecer & EEC Tuner perspective.
Three fixed parameters in the pcm fuel tables come into play when talking about startup.
1) Time
2) Load
3) ECT
We are dealing with two fuel tables.
1) fuel_table_base_OL
2) fuel_table_startup_OL
The base table is where you see the commanded ratio and it is used during warm up conditions.
The startup table is where you see values that are subtracted from the base table to give you a fatter ratio and time comes into play here.
You asked about hot start conditions so lets use that as an example.
btw, we're gonna use an unmodified j4j1 file for our little example.
Say you've been driving around and go in the house for a while and decide to go somewhere else. When you start the car for the second time, the ECT is 180*
Most NA h/c/i combos will idle at a load of say about .20 to .30 so we will use that load factor.
Looking at the base table you see the pcm is commanding a ratio of 14.302 at that load value and ECT.
Looking at the startup table in the 180* temp column at 0 to 6 seconds you see the value of 1.716. Notice as the time increases, the value decreases until finally at 40 seconds, the values in the table are no longer used.
Here are the commanded, startup, and final ratio values
00-06 secs cmd 14.302 startup 1.716 final ratio of 12.586
07-10 secs cmd 14.302 startup 1.487 final ratio of 12.815
11-20 secs cmd 14.302 startup 1.259 final ratio of 13.043
21-40 secs cmd 14.302 startup 0.572 final ratio of 13.73
At this point in time, you most likely go from Open Loop to Closed Loop conditions and the O2's are calling the shots to achieve the pcm's goal of 14.7 CL happiness.
The Fix is to go to the 210 & 240 ECT columns in the startup table and zero out those entire columns. If need be, you could always play with the values in the 180* column as well.
This topic of discussion makes me wanna ask you guys this ................
What do ya'll think might happen if you start a pull after a cool down at ...... lets say about 20 seconds after you fire it up?
hummmmmmmmmmmmmmmmmmmm!
That info would be another thread
Grady
