I just installed some FIC 1250cc BlueMax injectors. I copied the scaling number and latencies from mrfred. i saw someone else use the same scaling number too...i know its higher than the typical rule of thumb, but it was said that these scale higher than normal....
91 Oct
Scale: 1271
4.7v - 4.8
7.0v - 2.4
9.4v - 1.896
11.7v - 1.368
14.1v - 0.96
16.4v - .744
18.7v - .456

LTFT Low = 4
LTFT Mid = 3

The car is hard to start when it is cold or warm. I have to crank it for about 3 seconds and then it slowly catches and gets up to rpm. If I shut it off and then start again after a few seconds, it starts pretty quick, but has alot of trouble the rest of the time. I cant tell if it is getting too much fuel or not enough...is there some way to figure that out?

I added the cold start enrichment tables to my rom and added some fuel, but didnt seem to change anything. maybe i didnt add enough... or maybe its getting somewhat flooded...

when i crank it over, i logged the voltage, it drops to 10.5 volts. is it possible that if i change the latency at 9.4v it could help this???

thanks for the help!

 

Scaling seems pretty high for 1250s. 125# (FIC 1250) would actually be 1312 and then a rule of thumb that seems to work well is 85% of that for scaling (1115) and decrease the latency until the trims are back in check.

my 2 cents anyway.

 

thanks for your input, i got those numbers from mrfred... and another guy had the scaling number the same. they said these scale higher than normal...

did you look at my fuel trims? are those acceptable?

 

I used 1170 for me
4.8
2.4
1.896
1.368
0.96
0.744
0.456
I played with all the latencies up and down. These were the closes for me. WHen I used that injector scaling(1271) It was giving me trims that were not close to 0.

 

thanks, ill try that out, but i doubt that will fix my hard start issue... right? or were you having the starting issue when you scaled to 1271...?

 

For starting I did this(found this after much searching MrFred post):

If you are running pump gas then use this formula as a baseline for startup IPW values:

new startup IPW value = (old startup IPW value)*513/(current injector scaling)

If you are running E85 (can't remember) then use:

new startup IPW value = 1.3*(old startup IPW value)*513/(current injector scaling)

 

If you have driven your car enough your trims seem "ok". However you must edit the injector startup IPW tables. You need to divide all the numbers in the table by (new injector size in cc/old injector size in cc) or roughly 1250/560=2.232 in your case. That will give you a good staring point that at least you won't flood the motor when trying to crank.

 

Also note that your trims are pretty decent. I read that +/- 5 is good. razorlab said +/- 3 is really good. Trying to get any closer is diminishing returns - Johnbradley.

 

Edit: dan and bambooi are saying the same thing, just a little different way. If you are installing substantially larger injectors, then any starting IPW numbers must be decresed.

To the OP, a quick way to test if your injector scaling is correct is to run your car in open loop. Does it idle and cruise at around 14.7? If so, then your scaling is correct. If not, adjust until it does. Then, when you run in closed loop again, use your latencies to adjust the trims.

 

AWESOME!!! That worked
Thanks bambooi and dan_l. I searched but could not find anything about this. Thanks so much! That formula makes complete sense.

 

I want to try this. In order to get into open loop i go into ECUflash and change the values in the 'open loop throttle' tables and the 'open loop load' tables to zero??

 

Just do load. 0 - 1000 rpm. Throttle wouldn't make sense because you want to be idling (0 throttle input). For cruising you would modifiy higher rpms

 

Turns out I am still having issues. after I divided all of the cold start IPW values by the 2.23 scaler it seemed to be great that night. It starts up alot better when it is totally cold, but I am having issues when it has been sitting for several hours and i go to start it. i think it may have something to do with hotter outside ambient temps... but i dont know. i have played with it. i have increased the scaler to 3, then 4, then 5... still behaves the same...
any suggestions?

 

Check out the thread in Alternative fuel forums about hot starts. It may help.

 

Now you have to mess with ISC steps... Do what MLSpilot suggest. There is a thread refering to warm/hot starts.