hard start some times not every start.

[mychevyisntheavy]

2003 gmc seirra 1500, i swap in the lm7 4l80e ptc 3800 stall truck has many mods, to many to count, truck was a stock dbc 4.3 with a 4l60e. i swap the motor, pcm and harness, dbc out of a 2002. everything is fine other than on some start up from cold it might crank 30 to 40 times then starts and idles fine, then there is times hit the key to start and one crank starts and idles fine. truck runs amazing. like im asking what can i do to get it to start like it should. and it does just not every time. i have hp tuners mpvi3 and no im not a tuner. im new to this ls stuff. i old timer, just trying to grab some old times with this new stuff..lol

[abc]

Start with list of mods. Be specific when it comes to the fuel system and injectors.

Then attach the .HPT and .HPL during a crank and short idle.

[mychevyisntheavy]

im going be replacing the starter with new one, battery is hot 12.2 volts, charging @ 14.2 volts. key switch is new, all grounds are clean and tight, just had it retuned. a rolling tune we spent like 3 hours driving as he tuned it. oil psi is like 40 psi @ idle raises up to 60 to 80 psi under power, temp 186* trans temps 140* , shift amazing drives amazing runs amazing, just at cold starts and not everytime just at cold first start it might crank a bunch of times before it starts up

[2xLS1]

You know when you describe your cam only by the lift numbers it tells nothing about the cam. And that second post of yours really helps.

[blindsquirrel]

The CMP sensor 1 X signal is used by the PCM to determine if the cylinder at top dead center (TDC) is on the firing stroke or the exhaust stroke. The PCM can determine TDC for all cylinders by using the crankshaft position (CKP) sensor 24 X signal alone. The engine will start without a CMP signal as long as the PCM receives the CKP sensor 24 X signal. A slightly longer cranking time may be a symptom of this condition. The system attempts synchronization and looks for an increase in engine speed indicating that the engine started. If the PCM does not detect an increase in engine speed, the PCM assumes that the PCM incorrectly synchronized to the exhaust stroke and re-syncs to the opposite cam position.

[mychevyisntheavy]

tuner said that the injectors looked great in the tune from what he saw, they are stock decapped flow tested and flow matched bye eric derr out of bowl green, 80lbs, fuel pump is a in tank walboro 255lpg, after market fuel rails, tbss intake, after market feul pressure regulator. with in cab fuel psi gauge that reads a constant 58lbs. no drop at all. i have a gauge on the rail also no drop. stock coils

[mychevyisntheavy]

trick flow 585/585/ 224/228 lsa 114 i think i dont have the cam card right at the moment

[2xLS1]

Without the tune file and a data log of it not starting you are just wasting your time here. Unless you just like doing that.

[mychevyisntheavy]

ive replace the cam and crank sensors numerous times. i can see them hitting on the live data in the scanner on my hp tuners

[mychevyisntheavy]

let me try to log in here im new to this stuff

[mychevyisntheavy]

Black Silverado load NA2.0.hptrunetime740pm11.20.24.hpl here is my tune and data log on my truck after i had it tuned

[blindsquirrel]

Flow rate is the least important injector spec, it's all the other stuff that changes after being attacked with an angle grinder that will forever be unknown. Offset, Short Pulse Adder. Decaps are fine if it's a dyno queen or drag-only and doesn't need to do anything other than idle and then run WOT. If you want it driveable and tuneable without a bunch of frustration get different injectors, ones that come with ALL THE DATA and in GM format. No modified injectors, no redrilled injectors. Make sure the data is available before you buy.

Most guys here will not even offer tuning advice if it's got decaps.

[mychevyisntheavy]

i didnt just decap and throw them in. i sent them to eric derr he cleans and flow matches them and send them back with the data. i know better than to just hrew them in

[blindsquirrel]

Yeah you got the flow rate. Great. Please explain why that's important (it isn't, not nearly as much as the other data). What you don't have is updated data for the Offset vs Volts vs VAC table, or the Short Pulse Adder table. You do not know what you don't know.

[mychevyisntheavy]

sorry guys im new to this stuff but i am learning. like i said this truck runs very good and starts up 90% of the time great. just a cold first start and not every time. just mybe one a day

[mychevyisntheavy]

a man i dont know what you want . the tune is what my tuner did, and the data log is the most newest one

[mychevyisntheavy]

its not the injectors even tuner says its not the injectors. now it could be what the pc is tell the injectors. truck runs to good to have a injector bad and i have two sets and both sets do the same thing to the truck so i know its not the injectors. and yes i sent all 16 to eric and had him flow them and give me the data. i just dont have here in the house its in the garage

[blindsquirrel]

If you are happy with the way it runs, best of luck to you.

https://forum.hptuners.com/showthrea...l=1#post809250

[mychevyisntheavy]

i posted the tune a data log in the post of mineAttachment 154755Attachment 154756 does this help you man

[mychevyisntheavy]

a bud i didnt ask for your help .