LBZ: Help! No one can figure out the issue.

[Chevy1925]

as long as actual rail pressure follows commanded rail under all driving/parked conditions, the pressure is irrelevant. if its too high, you generally get a lope at idle or the truck will lope as you decel coming to a stop. this can all be monitored by the actual vs commanded rail pids. if they follow closely and dont have peaks and valleys all over the place, pressure is fine.

will it hurt to turn it down a few psi? nope, just dont go too low. i wouldnt run under 8psi but its more of a preference than anything. higher the pressure, less chance of cavitation.

 

[stibuilder]

as long as actual rail pressure follows commanded rail under all driving/parked conditions, the pressure is irrelevant. if its too high, you generally get a lope at idle or the truck will lope as you decel coming to a stop. this can all be monitored by the actual vs commanded rail pids. if they follow closely and dont have peaks and valleys all over the place, pressure is fine.

will it hurt to turn it down a few psi? nope, just dont go too low. i wouldnt run under 8psi but its more of a preference than anything. higher the pressure, less chance of cavitation.

Id turn it down by cutting the spring it sounds like. I do remember hearing the commanded vs desired was 500psi difference.

 

[Chevy1925]

Id turn it down by cutting the spring it sounds like. I do remember hearing the commanded vs desired was 500psi difference.

no idea on a fass, i have not played with them. they need to post up a log and i can tell ya then. trying to describe what im talking about is pretty hard to do unless you know exactly what you are looking at. a flat difference isnt what you need to look for, there is more to it.

 

[clrussell]

My lift pump runs at 14psi on a stock regulator and pump FYI.. I don't see a problem with your lift pump pressure. Sounds about normal for a fass

 

[kidturbo]

I helped a friend get his 4500 running again couple weeks back. Hadn't been started in over a year. When it fired up, without the doghouse on, fuel knocked like a mother for about a minute. Then cleared up one injector at a time over next minute. I didn't get concerned, but it was nasty sounding. He had previously experienced a loose injector plug on #8 that we fixed couple years back. So first thought was....

On your setup, glad to hear setting the flow rates is bringing it back in line. My only thought was the hazing lends towards insufficient atomization at idle. When ever going oversize injectors, bumping up fuel pressure about 1k at idle helps clean up mixture. Just my personal experience.. So if your still seeing issues, I'd ask your tuner to make that change and give it a try at least. Personally, I won't run a locked tune, unless the tuner is willing to be locked to the truck also...

:spit:

 

[stibuilder]

I helped a friend get his 4500 running again couple weeks back. Hadn't been started in over a year. When it fired up, without the doghouse on, fuel knocked like a mother for about a minute. Then cleared up one injector at a time over next minute. I didn't get concerned, but it was nasty sounding. He had previously experienced a loose injector plug on #8 that we fixed couple years back. So first thought was....

On your setup, glad to hear setting the flow rates is bringing it back in line. My only thought was the hazing lends towards insufficient atomization at idle. When ever going oversize injectors, bumping up fuel pressure about 1k at idle helps clean up mixture. Just my personal experience.. So if your still seeing issues, I'd ask your tuner to make that change and give it a try at least. Personally, I won't run a locked tune, unless the tuner is willing to be locked to the truck also...

:spit:

That is a good point, ill have to see what this turns into on the tune, having the ability to make fine adjustments would be nice on this truck.

Now my other question is how do others deal with larger than stock injectors and whats the protocol. Do you put stock info in the ECU and then the tune handles the offset?