Post injections on big tune?

NC-smokinlmm

NC-smokinlmm

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Hey guys, Is it common practice to keep the post and pilot injections on your big competion tune? I have been dropping rail pressure in my big tune and I think I know why now. My PW at WOT is 3250 and my rail falls all the way down to 21,000 then slowly climbs back to 22,500 or 23,000. Couldn't my RP be falling bc the post injection is following the piston down at 3250 with useless fuel...
 
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S Phinney

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Aug 15, 2008
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On my tunes I usually keep it operative. If it is tuned out then you get a noisier engine. I haven't seen it hurting any truck that I have tuned. That shouldn't be your problem. I have yet to see a stock truck hold perfect rail with a tune that size. They are normally down 4000 psi or more.


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THEFERMANATOR

THEFERMANATOR

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I shut off post injection for every tune I do, but I keep the pilot injection in there. Sounds like you need to rescale your desired flow VS current table some to get it to where the regulator is giving you the needed fuel instead of it having to use the correction tables to get rail pressure back up.
 
chevyburnout1

chevyburnout1

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Doesn't pilot injection shut off above about 2700rpms anyhow? So full throttle runs I wouldn't see pilot effecting it anyhow. I could be wrong though.
 
THEFERMANATOR

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chevyburnout1 said:
Doesn't pilot injection shut off above about 2700rpms anyhow? So full throttle runs I wouldn't see pilot effecting it anyhow. I could be wrong though.
Click to expand...

LB7 yes, LMM and LBZ can keep pilot on all the time. I shut it off on big tunes above 2500 or so just because I don't want to work the injectors any harder than they have to.
 
NC-smokinlmm

NC-smokinlmm

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THEFERMANATOR said:
LB7 yes, LMM and LBZ can keep pilot on all the time. I shut it off on big tunes above 2500 or so just because I don't want to work the injectors any harder than they have to.
Click to expand...

That's kind of what I was thinking, maybe it is contributing to my RP issue. I might try shutting them off after 2500 to se if my rail holds better...
 
THEFERMANATOR

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NC-smokinlmm said:
That's kind of what I was thinking, maybe it is contributing to my RP issue. I might try shutting them off after 2500 to se if my rail holds better...
Click to expand...


Your description of how it drops and then comes back up is the rail valve current table needing adjusting. Shutting it down may help, but not very much as the pre and post injections are VERY small.
 
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jwrkansas

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You could post up a screen shot of your regulator current table. FWIW my pre and post events are shut off after 2500. Im also running a 3250 tune and hold perfect rail press
 
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THEFERMANATOR

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In the B1021 table set it to 2 instead of 5, and if you want to kill it up top you can set it to 1 at 2400 on up. In the B1015 table start at 11390 and start dropping it down a little to make it maintain rail pressure better on the big tune. 12000 and down is your normal daily driving portions, and around 12000+ is where you enter power enrichment portions. At WOT it should be in the 30000-42000 range for flow. These numbers are what I have found from logging my LB7, but LMM I would imagine is fairly close.
 
TheBac

TheBac

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THEFERMANATOR said:
Your description of how it drops and then comes back up is the rail valve current table needing adjusting. Shutting it down may help, but not very much as the pre and post injections are VERY small.
Click to expand...

Thank you for that information.
 
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duratothemax said:
post injection is also for emissions control, not just for DPF regen stuff.
Click to expand...

Regens is part of the emissions control(just giving you a hard time). I know it can be active during just above cruise RPM's for NOX reduction as I understand it, but it rarely kicked in when I logged one to see. Also I know BULLYDOG activates post injection to make them smoke at WOT to make people think they're stronger than they actually are(since we all know smoke = power). Had an 06 LLY I tuned and that thing with the 65HP triple dog on it would lay some coal, but not really go anywhere. Log it and you can see the post injection was very active, with 1450+ EGT's. Tuned it with my tune and no more smoke at all, but ALOT more power with a 1350 MAX EGT.
 
duratothemax

duratothemax

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THEFERMANATOR said:
Regens is part of the emissions control(just giving you a hard time). I know it can be active during just above cruise RPM's for NOX reduction as I understand it, but it rarely kicked in when I logged one to see. Also I know BULLYDOG activates post injection to make them smoke at WOT to make people think they're stronger than they actually are(since we all know smoke = power). Had an 06 LLY I tuned and that thing with the 65HP triple dog on it would lay some coal, but not really go anywhere. Log it and you can see the post injection was very active, with 1450+ EGT's. Tuned it with my tune and no more smoke at all, but ALOT more power with a 1350 MAX EGT.
Click to expand...

hahaha!!! Now that is hilarious. :rofl:
 
NC-smokinlmm

NC-smokinlmm

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Mine dosen't even haze at wot, but my EGT's are toasty, do yall think this will get them down a little as well as help kept RP up?

I need to get to working on this. Thanks for the input fellas, I am learning a lot...:)
 
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