Idle surge with bigger injectors

[flybynite]

I tried both 34.5 and 37.5 injector flow rate and it didnt do anything  :icon_mad: :icon_frown: Not sure what to do now  :icon_cry:

It made no difference. A change that major should have done something. What was the Afr at idle before the changes and after? What ecu(xdf for tunerpro) are you using?

Adam maybe he is having the same problem we had last friday where the idle fuel is based on EGR position?  I had no EGR so we had to change it to run off of the injector flow rate.  Before Adam did this we made huge changes to the injector flow rate with no response......and I was 10.5 to 1 at idle.  If your egr is deleted this could be your problem.

My egr is deleted. Care to explain a little more ? What did you do to fix it ? I bought a megasquirt but I'm still not sure I want to use it  :icon_lol:

Ok The TGP code uses the BPC vs DESIRED EGR for fuel calculations at cruise and idle. As the injectors get larger, You run out of room for adjustment to the AFR at idle. There is a flag that is called   Calculate BPW at idle as a function of airflow. This flag is set by the factory and with larger injectors you will need to un-check it so that the ECM will use the injector constant for fuel calculations at idle and not the BPC vs DESIRED EGR. Now the BPC vs DESIRED egr will still be used for fuel calculations but now the ecm is looking at the injector constant at idle. This will allow the ecm to lean things out much better at idle and you will have better control of the fuel at idle. Doing this will also put everything out of wack. So you will need to re tune the idle,  part throttle, cruise and wot stuff. WOW I got pretty bent last night. So I hope this helps because it made my brain hurt.... :laugh:

[TurboGTU]

DOnt forget when your tunning and your plugs are compleately black, swap them out because it will screw with your tune. Onece wet with gas, plugs worn't work the same or missfire.

[TurboGTU]

Just wanted to bring something old to this topic about the injector constant. When I was tunning for the gtp 35lb'ers , I found out that the hex in this table is backwards. 178= 22lb thats a given, but 1= 44 lbs and 291= 8lbs.  Largest injector supported in the code is 44lbs.

http://www.tgpforums.com/index.php?topic=2725.15