Built a lope tune

[Chevy1925]

Yeah.... NOT! :rofl:

Anyhow, since i got the truck running, once i hit operating temp and put the truck in park or neutral i get a noticable lope from the truck. Wont do it cold and wont do it in gear. It will do it on a 100% stock tune or a modded tune. Ive attached a log for you guys to see.

anyone got ideas on hard parts that can cause this? going to log crank and cam sensor as well as unplug my lift pump to see if anything changes. I have NO CODES and no codes for injector miss fires or any of that have been shut off. only the variable vane stuff and egr stuff.

Log attached below. its like the truck is shutting off as soon as 680 idle is achieved, then catching its self before completely dieing

 

[Ridin'GMC]

Check the MAF.

 

[Chevy1925]

Check the MAF.

thats all apart of the log. its between 43-46 as its loping. MAF was adjusted in the big tune and had no affect on loping

 

[ScreaminDuramax]

Might have too much pressure on the lift pump, I remember reading something a while back about it causing a mild lope. That's an easy start.

 

[Chevy1925]

Might have too much pressure on the lift pump, I remember reading something a while back about it causing a mild lope. That's an easy start.

Yup, had that issue last year but being that i have not changed regulator or pressure since, makes me think its not that but ill be giving it a shot after work.

 

[henery97]

FWIW I had a lift pump in my LB7 for a year with no issues, then when I replaced injectors I had a lope at idle that was solved by lowering the lift pump pressure. IDK why, but thats what fixed it.

 

[Big Chris]

fpr, FPR control circuit issues, or bad ecm???You are describing the same symptoms I have with my lmm and I checked it all out and have to replace the ecm. Mine sets codes though.

 

[JoshH]

Are you running an LLY or LB7 ECM?

 

[paint94979]

Its an LLY ECM.

 

[Chevy1925]

Are you running an LLY or LB7 ECM?

Its an LLY ECM.

yup! LLY ecm.

 

[Chevy1925]

Unplugged lift pump. No change

Checked balance rates. In drive I have a few at 3ish. In park when it lopes, you can't see them. Shut the truck off then restart 5 sec later and it won't lope. Balance rates are all 1 or less BUT main mm3 is 2.5. That seems extremely low but I have no haze at idle or any "tell tail signs" of injectors. May have to check return rates

As soon as I mess with rail pressure, the lope starts again. Whether that's putting it in gear or using the DVTs to change rail. Then it will not smooth out unless you shut the truck down and restart.

I also tried shutting each injector down 1 by 1 feeling for a no change. Never happened. You could feel each injector die even through the lope.

Soooo, I'm thinking return rate issue or FICM??

 

[IOWA LLY]

I've seen this before, change your pulse width table so you it idles around 10-15 mm3 in park or neutral.

Start decreasing pulse width in everything less then 40mpa, and 15mm3. Blend out from there.

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[THEFERMANATOR]

Your lope and balance rates is because your fuel rate is dropping to low at which point the ecm freaks out and quits equaling out the cylinders to each other. Stocvkbinjectors or oversized? Ideally you should have 8-9mm3 of fuel at a hot 680 idle. If oversized injectors, your going to need to rescale the idle areas of your pulse width tables.

 

[THEFERMANATOR]

Just looked at your build thread and seen no mention of oversized injectors, but were planning on them down the road. If so, sounds like you'll be doing them sooner rather than later as yes, even LLY's eat injectors. When your fuel rate drops that low, its either from fuel pressure being ALOT higher than what the ECM is reading, or all your injectors are injecting to much fuel. Balance rates are simply how much fuel +/- each injector is injecting from the average of all the injectors, and the average is your fuel rate. So if all your injectors are onjecting to much fuel, your fuel rate will drop instead of balance rates going way out. You can try flushing them, but the SAC micro pocket injectors don't normally plug up and dribble like the LB7's VCO nozzles did, so cleaning them normally isnt as effective.

 

[JoshH]

I would do what the last two guys said and lower the pulse width in the lower fuel quantity and fuel pressure areas where the truck idles.

 

[Chevy1925]

The injectors are stock and Brian and I both figured them as cores. I threw them in just to see if they would work. Just funny they all are that equally worn out to create balance rates so close together. I'm going to pull back fuel at idle for the time being. They drive extremely clean and I hold rail on 3250 uS no issue but I also have dual pumps. No haze or smell at idle. Just the normal no cat smell. I'll check return rates after I order the kit to check each injector.

Looks like I'll be buying injectors along with my bigger tips

 

[WVRigrat05]

My truck didn't have dual pumps, but with a rail plug and my lift pump wide open mine wouldn't hold rail pressure, when the motor popped we sent the injectors out and the returns were basically wide open, balance rates were perfect.