[FredGarvin]

I've got about 250 break-in miles on my new build so far (see parts list below) and am using a PCIIIUSB map off their site. Not perfect, but close. Problem is it has a rough idle and sputters at 2-4% throttle. The sputter clears out completely by 5% throttle and runs fine after that. I've enrichened and leaned out the fuel settings in the 2% throttle settings table, but neither fixes the idle/sputtering. With some of the different settings I have made it run worse, but nothing makes it run better.

I am scheduled to have it dyno tuned in early Dec, but I need to get it broken in first. Idle and sputtering aside, I checked the rear plug and the porcelan was pretty clean/white...so I assume this means it's running a little lean. But right now, I'm more concerned about the other stuff and hope there isn't some cause other than a fuel management issue.

here's a summary of my new build:
2005 FLSTFI 15th Anniversary Model, 95", Stage 1 A/C, SE forged pistons w/10.25:1 cr, TW-6HG, Baisley Pro Street ported heads, Baisley custom cut roller rockers, Baisley spring, V&H ProPipe HS, PCIIIUSB, M6.

 

[Steve Handy]

Sputtering

Fatty,
Not enough info to be sure, but I have good luck adding 5 deg timing and 10-20 % fuel (at 0to20 % throttle with big cams they like fuel and timing) .
On the dyno I can work it out....... here its just a guess..:whisper:

Good Luck

STEVE THE DYNO GUY :cheers:

 

[mlewis]

If you haven’t performed the throttle calibration procedure via your PCIII software, you might be unable to properly target fuel change in the low throttle positions. Check your PC help menu or visit the PC website for calibration procedure instruction. A ±10% change in those fuel cells (for starters) should result in a noticeable difference.

 

[FredGarvin]

I verified that the throttle was set correctly, and then again downloaded a map with added fuel and timing as Steve suggested. It did not improve the problem, which seems strange..you'd think it would run noticably different with extra fuel and timing???

 

[mlewis]

When you have the PCIII linked to your computer software with the bike running you can attempt changes on the fly. If you’re doing this at or near idle, it’s best to try similar fuel changes to the RPM cells above and below the software indicated real-time RPM/throttle position should the motor RPM respond up or down from the fuel change. Applying fuel changes to more than one RPM cell helps ensure that a reaction to fuel change doesn’t go unnoticed. The software indicated real-time ‘fuel change’ and ‘% duty cycle’ changes should also reflect any fuel change made, if recognized, following any map update. You probably have already tired all this, I can’t phantom why yours won’t response in a positive direction. We’ll you’re dyno tuner bound anyway, they should be able to get it worked out.

 

[GRock]

The high lift, short duration of the cam in combination with the Baisley high velocity heads and high scavenge rate of the VH pipe can wreak havoc with the ECU tables (especially idle and low speed running) that the PCIII simply cannot correct with just fuel and timing. I can almost guarantee that the IAC is not open enough at idle (rough and uneven, right?) to compensate for the air needed by the heads and cam. And it takes a couple of seconds to get open enough after you hit the throttle to allow the engine to "clear" the sputter. As the throttle blade opens you now get the air you need and it runs better. Right?

Just my humble opinion.

 

[Antonio Pendejo]

Also might wanna check for air leaking into the heads past the intake manifold seals. This can cause tuning difficulties at the low load, low throttle positions.

 

[FredGarvin]

The high lift, short duration of the cam in combination with the Baisley high velocity heads and high scavenge rate of the VH pipe can wreak havoc with the ECU tables (especially idle and low speed running) that the PCIII simply cannot correct with just fuel and timing. I can almost guarantee that the IAC is not open enough at idle (rough and uneven, right?) to compensate for the air needed by the heads and cam. And it takes a couple of seconds to get open enough after you hit the throttle to allow the engine to "clear" the sputter. As the throttle blade opens you now get the air you need and it runs better. Right?

Just my humble opinion.

Yes, the idle is rough and uneven, and lopey too. But, I attributed that to the cam - maybe I'm wrong on that...?

But, it doesn't take a couple of seconds to clear out the sputter. At idle, I can open the throttle (slow or quickly) and it runs right up the RPM range without hesitation. Even if I hold the throttle so it sputters for a while, and then open it up, it will again react without any noticable "clearing". If fact, I have to open the throttle just right and slowly to hit that 2% range so the sputter is noticable.

If this is a condition that can't be corrected with the PC, what's IS needed to fix it?

later edit...I added fuel in 2 value increments until it reached 10 in both 0 and 2% throttle. The more fuel the rougher it ran, even back fired once on start up. Ended up just reloading the original map from PC.

 

[GRock]

later edit...I added fuel in 2 value increments until it reached 10 in both 0 and 2% throttle. The more fuel the rougher it ran, even back fired once on start up. Ended up just reloading the original map from PC.

fatty,

Told you you needed MORE air in the last post so don't know why you are adding MORE fuel. You are already too rich.

 

[FredGarvin]

fatty,

Told you you needed MORE air in the last post so don't know why you are adding MORE fuel. You are already too rich.

now that you've made that point crystal clear...what steps can I take to accomplish this? Are you saying a less restrictive intake than the SE a/c?

 

[Totenkopf]

now that you've made that point crystal clear...what steps can I take to accomplish this? Are you saying a less restrictive intake than the SE a/c?

The Idle Air Control is adjustable in the SE Race Tuner.

Another thought with your nice free flowing heads and cam, look at changing the stock Delphi throttle body and intake out.

I went with the Dakota Kid reworked unit that is funnel bored 48mm/44mm. Increases intake velocity charge and increases flow, 196cfm on Branch heads at 10psi.
http://www.dakotakidcarbs.com/WhatsNew.htm
Mine is going on the dyno for tuning in the next 3 or 4 days.

Another one that I found is BC Gerolamy........
http://www.bcheads.com/fuel.htm

 

[Vetteman]

GRock hit the nail on the head!

:cheers:

 

[fullbore]

Why ever get PC instead of SERT???

Can someone explain why anybody would get PC instead of SERT? The PC is an add-on device that can increase fuel that the ECU would otherwise provide. The SERT reprograms the ECU settings and has control over more parameters (more or less fuel, timing, RPM limit, decel enleanment, accel enrichment, etc.). There is minimal cost difference.

I can't understand why anybody would ever buy a PC!!

 

[mlewis]

Some of us had PC’s long before SERT’s were available. They do work well for many common builds. For those of us already using them, there is a certain comfort level in being familiar with how they work. Many top end dyno systems provide specialized software links to the PC to enhance dyno analysis. From other posts I’ve read, even Doc thinks highly of the PC.