CP3, FPR or tuning?

[TheBac]

Just take a look at this log from my pull and tell me what you think. I think the CP3 is just getting tired. Also, should I be concerned about the FPR commanded/actual discrepancy?
I referenced the tune, and at the note, B1001 shows 170mm3, TBIQ shows 110%, TLIQ isnt even referenced. (I dont know if that info is needed or not, but you guys always talk about it being important). Could be I still need to lower pulse/timing so the CP3 can "catch up" to the 30-overs? If you need any other info, please ask.

This is the same tune I drag race with, and my last logs in 2010 also showed rail psi trending lower. Engine runs strong on this tune, though. Always has.


As usual, I appreciate your input.

 

[IOWA LLY]

Need to log regulator current to see what its doing. Shouldn't have trouble holding rail with that kinda pulse.......

 

[TheBac]

B1010? I dont think I logged that.

 

[IOWA LLY]

Also, timing (S.O.I.) will have no effect on rail pressure.

 

[IOWA LLY]

B1010? I dont think I logged that.

Yes.

 

[TheBac]

Nuts. I'll have to look in my PIDS and see if I can find it and add it to my "race log" list.

 

[S Phinney]

That's a stock pump with 30 over injectors right? It's showing about 19.5k on a 23k desired pressure. If it is a stock pump and 30 overs you are asking a lot out of it to hold pressure with those demands.

 

[TheBac]

That's a stock pump with 30 over injectors right? It's showing about 19.5k on a 23k desired pressure. If it is a stock pump and 30 overs you are asking a lot out of it to hold pressure with those demands.

Yep, thats what it is. Thats why I ask. Think I should bring pulse or timing down to help the pump out?

 

[DAVe3283]

I agree, log the regulator current. Make sure your regulator is not being held partially shut. If it isn't being held shut part way by the tune, than I'd say the CP3 is getting tired.

If the regulator is wide open, then you can try pulling back the pulse and see what happens.

 

[TheBac]

I agree, log the regulator current. Make sure your regulator is not being held partially shut. If it isn't being held shut part way by the tune, than I'd say the CP3 is getting tired.

I searched the PID list and didnt see one. Which PID is it?

 

[DAVe3283]

From the v7 software:
Commanded Fuel Rail Pressure Regulator Current (GM.FRPACOM)
Desired Fuel Rail Pressure Regulator Current (GM.FRPADES)
Fuel Rail Pressure Regulator Commanded % (GM.FRPCOM)

I think the one you really want is Commanded Current (FRPACOM), but the commanded percent might be useful as well.

 

[TheBac]

From the v7 software:
Commanded Fuel Rail Pressure Regulator Current (GM.FRPACOM)
Desired Fuel Rail Pressure Regulator Current (GM.FRPADES)
Fuel Rail Pressure Regulator Commanded % (GM.FRPCOM)

I think the one you really want is Commanded Current (FRPACOM), but the commanded percent might be useful as well.

The FRPCOM % is 0.00 throughout the run. The FRPCOMM (mm3) is 60000 though the run, too. Looking at the B1010 table, those values match what is listed there.
I did not log the other parameters though. Thanks for telling me which ones to look at. They are added to my PID list.

 

[TheBac]

More unfortunate news. Dyno'd the truck yesterday, and she only pulled 506/1033 best. Other 3 runs were totally pathetic. Dyno was like Dunbar's setup.
Turbo showed 21lbs boost on the gauge, mid-18000psi rail on the logs using the same tune as logged above.
Have never had an issue loading the turbo on a dyno before.....maybe its all just me. Damn thing downshifted every stinkin time.

 

[SteveFord]

More unfortunate news. Dyno'd the truck yesterday, and she only pulled 506/1033 best. Other 3 runs were totally pathetic. Dyno was like Dunbar's setup.
Turbo showed 21lbs boost on the gauge, mid-18000psi rail on the logs using the same tune as logged above.
Have never had an issue loading the turbo on a dyno before.....maybe its all just me. Damn thing downshifted every stinkin time.

What about high return rates? That may cause your lower than normal fuel pressure and loss of power.

 

[TheBac]

What about high return rates? That may cause your lower than normal fuel pressure and loss of power.

Could be Steve. Thats a lot of work to test, though.

I think Phinney may be right that the 2700us + 28* timing + 30% injectors = low rail. Have to lower the pulse and/or timing to see. I dont think a 170,000 mile CP3 could take much more punishment and like it.
The lack of boost does trouble me, though. Maybe the old stock turbo is finally giving up the ghost? Have to go do some WOT test runs and go find out.

 

[SteveFord]

Yeah I'd say that cp3 probably doesnt like you anymore lol! I forgot you kept the original stock one during the rebuild. Do you have logs to compare the rail pressure before with the same mods from one of your passes at the track?

 

[TheBac]

Do you mean from 2009 before the rebuild? Yes, I have them all. Thank god they werent on that chip that got stolen.

 

[TheBac]

Yes, I reused my old parts. Here's the log of my 12.34 run in 2009 on essentially the same tune (pre-rebuild). Stock everything internally, including injectors. IIRC, the tune had 3100us, 31* timing. I still run this same base tune, with the lower pulse and timing. You can see it would hold 22000+ back then.
The more I think about it, Ive just pushed the turbo and CP3 too hard for too long. But dang, she ran good back then.

 

[SteveFord]

Got any with the bigger injectors? I'm sure with those miles it can be getting weak. Im just wondering if your not getting enough fuel to spool the turbo hard enough to get the boost you was before now that your cp3 may be weak?

 

[TheBac]

The 12.14 run from last year, rebuilt motor, 30% injectors: