Tune Changing

DEIVIONCRX · Post by **DEIVIONCRX** » Sat May 22, 2010 1:55 pm

I know Temperature and Humidity and the like will effect the tune somewhat, but i was under the impression that the ECU would accommodate for that, based on the ECT and IAT and BARO sensors plus others. It seems like every time i start and run my car the tune is changing. One day it will idle 14.7, the next 13.0, the next 15.3. Is there some compensation I'm missing that can account for this. I'm still running Open Loop, does closed with the narrow band input really account for this much? I'm still breaking in the engine so I'm only tuning to 4500rpms for now. But id like to get a good Idle - 4500 so i can get out on the road and finish up the 1000 mile break in without worry.

Vtec6000 · Post by **Vtec6000** » Sat May 22, 2010 8:19 pm

I have the same problem with IAT correction causing big swings in my AFR's I didn't alter the table values but is something I am going to adjust in the future. Basically I tuned idle with car fully warmed up and my IAT at it's highest Reading which worked out that even when IAT were lower I was getting a richer idle rather than going lean.

DSMR · Post by **DSMR** » Sun May 23, 2010 12:41 am

Also make sure that you tune out your injector battery offsets as this can cause a similar issue.

David974 · Post by **David974** » Sun May 23, 2010 1:55 am

+1 also check you battery compensation table, start each morning with laptop hooked on, wacth the table in parameter , you should see if each day it's different and you will adjust

Post by **Bugermass** » Mon May 24, 2010 10:29 pm

These ECUs are 10 years old.. They don't have the advanced abilities to hold super duper consistant fueling all the time. Thats why they invented closed loop. If your tune sways alot, first be sure all the correct compensations have been tuned, then turn closed loop back on.

antoni · Post by **antoni** » Sun Dec 18, 2011 5:56 pm

DSMR wrote:Also make sure that you tune out your injector battery offsets as this can cause a similar issue.

Where can you find the injector battery offsets?

joppez · Post by **joppez** » Mon Dec 19, 2011 10:16 am

92 ecu is soon 20 years old

Post by **Gaskleppie** » Fri Dec 23, 2011 5:24 pm

Changing AF's are often caused by changing outside air pressure. If you tune the last 2 columns at the same values it will be a lot more constant. Try it. I also thought it was because changing air temps but it turned out that the air pressure changed it a lot more.

Bindegal · Post by **Bindegal** » Fri Dec 23, 2011 6:07 pm

I usually find that ever changing AFRÂ´s are caused by old crappy ground wires or other electrical issues. And yes, in case of bigger injectors, battery comp tables play a big part... /Allan