AEM: Cold Start's.....
 

Hey guys as we all know AEM dont put that much thought into cold start's when they made there units for evo 8 reason being there in cali it doesnt get that cold over there. Vs Motec and Autotronic which they really took there time in makeing sure the car will start in cold weather 2-4 turnovers's vs AEM 4-12 depending on what setting's you set it at. I recall last winter where it took me 20 mins one time trying to start my car i called the tuner and he changed a few settings around it got a lil better not all that great.

My Point

Now that winter is almost here ( damn chicago) I would like to see if Martin would take some time out of his crazy and booked days when tuning cars if he can also start to work on mastering the cold start's on the AEM setup's. I would love to see what advances he can come up with and once again prove that he is the 1# tuner in the nation. No one has ever brought this topic to the table but it still is a problem.

+1

It's a pretty simple process to ge the car to start quicker. I don't have it perfect, but it's pretty close.

Assuming the crank injector time table is flat and the car starts fine when the engine is warm, while cranking depress the throttle about 30%-50%. If the engine starts quicker, remove a couple percent from the warmup enrichment table. Do this in small increments until you notice an improvement. If it doesn't start any quicker with the throttle depessed, add a couple percent to the warmup enrichment table, again in small increments until you notice an improvement.
You'll be able to find a middle point after some tweaking.

You'll usually only be able to get 2-3 starts before the engine is too warm to play with cold start. It's usually best to make the adjustments after the engine has had time to cool off over night.


That's the first step in setting up cold start. After that there are tweaks you can make with some of the advanced tables and ignition timing, but just playing with the warmup enrichment should get it pretty close.

My car use to have autronics. It was a PITA in the winter. Coldstart never ever was right. Ive herd the autronics isharder to tune then the aem for coldstart

This is what i followed to get mine tuned. this was a word document made by JasonB (member of the aem forum) originally, hope this helps :) .

Tables used for Crank Fuel:


Crank Injector Time table

Initial Crank Pulse table

Start Extra vs. Temp table

Start Extra Decay table

Warm Up Enrichment table

Ign vs Start Time table



Basic Tuning of Crank Fuel:



-Set Crank Inject All to ON

-If you are running with O2 feedback, set the coolant temp minimum there to 140.



Before you start tuning, get the engine to start and warm up the motor so it is running semi-decently. You may have to crack the throttle and play with fuel a bit to get it to run. You want the motor to have some temp in it before you settle on a Crank Inj Time vs. Throttle value.


Warm Starting:

Tune warm starts first in the Crank Inj Time vs. Throttle table-
-Make a line sloping from left to right from 0% throttle and 255 raw time to 100% throttle and 0 raw time.


FIG A
https://img151.imageshack.us/img151/1448/figanm6.png


-Log and monitor the following so you can see where the engine fires.

https://img207.imageshack.us/img207/...mage003fq4.png


-Start the engine with full throttle and once STAT SYNC goes to ON, decreasing till it fires.

-Take the raw time value that corresponds with the throttle % that the engine fired and stretch it across from 0 to 90 percent or so, then 0 it after for the remaining 10 percent.



EXAMPLE: If car started at 42% Throttle then Time was 140. Setup table like this


FIG B
https://img151.imageshack.us/img151/2964/figbdh2.jpg

*You can also take the raw time value that corresponds with the throttle % that the engine fires and set it to that value at 0 % throttle and stretch the line down to 100 % throttle at 0 raw time so that it is a slope from upper left to lower right. Either is acceptable.



Notes:

-If the Crank Injector Time is too low it will have to crank a long time before enough fuel puddles up for it to fire.

-If the Crank Injector Time is too high it will usually sputter and then die, and will start when pumping the throttle (which leans it out).

-If it starts and is too rich at idle, tune the main fuel table not here.



Low Temperature Starting:


Once it becomes cold outside you can begin to tune lower temp starts.


You will want to tune the Warm Up Enrichment table-


For tuning this area you will use the same method of logging and tuning as before only paying more attention to coolant temp as that what trims fuel during starting and warmup.



-Set this table to about 35% at -40F and then 0% at 158 with a straight line between those points and fine-tune it from there when it is cold.



Fig C
https://img151.imageshack.us/img151/5979/figcig8.png

-Again make a line sloping from left to right from 0% throttle and 255 raw time to 100% throttle and 0 raw time in Crank Inj Time vs. Throttle table as it was in FIG A.

-Starting at full throttle and slowly letting out until the car fires, log the same as you did for warm starting, paying attention to coolant temp and pulse width. This will give you an idea of how much enrichment you need to get the car to fire quickly at cooler temps.

-Making a spreadsheet as you go up in coolant temps and noting pulse width when it starts each time is a good idea. You will want to try and fire the car around each breakpoint and you can calculate in between.

-When you have finished set the Crank Inj Time vs. Throttle table back to your default (warm conditions) (FIG B) settings then use the temperature based trims to get the pulse width perfect at all temps using all of your data.



As a generic rule, you can adjust the AFR:

12:1 for 20 degrees F and below,

12.5:1 for 35 degrees F,

13:1 for 50 degrees F and

13.5:1 for 65 degrees F and above

When full warm you should be idling around 14.7:1 although some cars tend to idle richer.


Start Extra and Start Decay work as a pair and are used for a rapid decaying enrichment right after startup. View your logs while cranking to see if these need adjusted.


Notes:
-Coolant Temp is what trims fuel during starting and warmup.

-Warmup Enrichment stays in longer then Start Extra and Start Decay and should decay to zero when fully warmed up.

-Typically you need to raise the amount in the Warm Up Enrichment table if it starts and then stalls.

-You may have to adjust Idle vs. Rpm Offset table (make it stay higher longer)

Great info SYLVESTER31 but im not that great went it comes to tuning a ecu i rather leave it to the pro's.


Im really not asking how to do it. My ? is if Martin could work on this problem i guess my main point i would like to get out of this is to see if Martin can be the first tuner to make the AEM start like a stock ecu on 1 turn over.

From what I understand, this will be impossible until AEM actually changes the way the Crank sensor and Cam sensor sync. That is where the real problem is, not in actual tuning. My car starts up as soon as Stat Sync is on, it's just waiting for that to happen.

That is correct, Its not a cold start issue but rather the way it picks up those two signals. There really isnt anything you can do about it.

If you are having some cold start issues just call the shop and make an appnt to get it all dialed in.

Eric