Bobbing of idle with larger injectors fix

[dirty830]

The bobbing when i come off throttle and truck is trying to idle is getting worse with the increased temperature outside and when i have my ac on when it revs up it blows quite a bit of smoke out. It stops when i get to a speed less than about 10mph. Question is could i break the vss line momentarily or ground it out to trick the ecm that i stopped and return to a normal idle? 

[Mopar1973Man]

Valve lash. Check this first.

 

As it gets warm or hotter outside the problem get worse to the point it possible to stall.

[dirty830]

valve lash is good. problem stops 100% if i go below ~10mph. seems to be computer related. 

[Me78569]

It is computer related.  The ecm thinks it needs xxx fuel to idle, but since you have big injectors you only need yyy fuel.  The ecm over fuels then under fuels

[dirty830]

i understand that but im looking for a way around it. if i disrupt the vss signal momentarily would that trick the ecu i was stopped and solve the issue?

[Dieselfuture]

Logic would say yes, but I'm not me either

[Me78569]

Is suppose that would fix it.  The ecm doesn't go into idle routine until mph is near zero, like you noticed.  

 

Is it causing a big enough issue to want to fix?

[dirty830]

ya when i have my ac on it causes it to bog down enough it pours out smoke trying to recover and it gets real old as im coasting to a stop im puffing a cloud of smoke out every few seconds or i can kill the ac and its not as exaggerated. im thinking about a momentary disconnect activated by the clutch.

[kzimmer]

I think you should try dropping your pop pressure down to 330 - 340 bar.

Edited March 22, 2018 by kzimmer