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Major surging at idle and low rpms 21 3500 with a Asin

I

Issaslow

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I’ve been dealing with this issue longer that I’ve wanted to it’s bone stock other then a delete
Recently replaced rail pressure sensor,front 4 injectors(truck would stop surging with the first 3 unplugged no change after install)(4th injector had a broken bolt)no change in idle,changed the fuel rail pressure sensor no luck I don’t have any codes that are fuel related could this be caused by a bad FPR ? I check the commended rail pressure and it’s fluctuating in sync with the rpm so is the actual rail pressure any feed back is greatly appreciated.

Pressure rail idle mid 4500psi jumping up and down between 4300-4700
 
Issaslow said:
I’ve been dealing with this issue longer that I’ve wanted to it’s bone stock other then a delete
Recently replaced rail pressure sensor,front 4 injectors(truck would stop surging with the first 3 unplugged no change after install)(4th injector had a broken bolt)no change in idle,changed the fuel rail pressure sensor no luck I don’t have any codes that are fuel related could this be caused by a bad FPR ? I check the commended rail pressure and it’s fluctuating in sync with the rpm so is the actual rail pressure any feed back is greatly appreciated.

Pressure rail idle mid 4500psi jumping up and down between 4300-4700
Click to expand...
Its clearly the tune for the delete if the commanded is changing that much
 
Issaslow said:
Went and got the program re installed and still nothing took it to another shop and they told me is not tune related
Click to expand...
Going to be impossible to rule that out without going back to stock.
 
Maybe surging, but I can’t think of any reason why it would make the commanded rail pressure change.
 
Issaslow said:
Went and got the program re installed and still nothing took it to another shop and they told me is not tune related
Click to expand...
The tune controls the commanded pressure so if its not the tune its the ECM or something electronic causing it, has anyone monitored throttle position with a scanner?
 
What is the rpm fluctuation with the surge?
 
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