Need help fixing surging while going downgrade at light load steady throttle.

[HD_04Ultra]

Going upgrade at steady throttle bike is smooth as silk.

On flat road surface at steady throttle exhaust note fluctuates a little bit 2200-2700 RPM, otherwise the exhaust note is steady and bike rolls smoothly.

As soon as I start heading downgrade it acts like it is lean surging.

Any advice is appreciated.

Thanks,
HD_04ultra

[7hogs]

You should post more info about your build and bike.

[rigidthumper]

IME, MAP sensor values tend to get smaller with a lighter load, and larger with a heavier load, ie: WOT ~ 100 KPA, roll ons 40-80KPA, steady cruise control on flat level 30-40 KPA, cruise control on + going up hill = 50-80KPA, decel 10-20KPA, etc. As you transition from flat to downhill, KPA goes from 30-40 KPA, down to 20-30 KPA, so you may need to increase VEs or add timing or both at the surging RPM / lower MAP area.
HTH

[FLTRI]

IME, MAP sensor values tend to get smaller with a lighter load, and larger with a heavier load, ie: WOT ~ 100 KPA, roll ons 40-80KPA, steady cruise control on flat level 30-40 KPA, cruise control on + going up hill = 50-80KPA, decel 10-20KPA, etc. As you transition from flat to downhill, KPA goes from 30-40 KPA, down to 20-30 KPA, so you may need to increase VEs or add timing or both at the surging RPM / lower MAP area.
HTH

Robin, excellent explanation and good advice,
Bob

[HD_04Ultra]

Robin, Bob:

Thanks.  I will give that a try tonight.

HD_04ultra

[HD_04Ultra]

Robin, Bob:

Here is what I did.  If I understand correctly this is the area you were talking about.

Incremented VEs by 5 Units (both front and rear)
from 2000-3000 RPM
from 0-10% Throttle Position

That should be approximately 10-40 kPa I think.

Bike seems about the same, any comments about the changes or suggestions about what to do now?

HD_04ultra

[HD_04Ultra]

7hogs

Build info below

Application (Model/Year)    = FLHTCUI-04
Stock or Modified       = 103 High Output
SE Calibration File Used    = 105HG018-D0
CID         = 103
Cylinders         = 3.875 Big Bore
Pistons         = SE Flat Top Stroker Forged
Crank Stroke      = 4.375
Air Cleaner      = K&N HD-0800 (early SE Hi-Flow)
Exhaust         = V&H ProPipe High Output 2-1
Throttle Body      = HPI 53mm
Cams         = Tman TR-625
Injector (gm/sec)      = 4.35
Head Work (cc/Int/Exh)   = 80cc/1.900/1.615 CNC Ported
CCP (Frt/Rr)      = 201/197
C/R Mechanical      = 10.6 : 1
C/R Dynamic @ 810’ ASL   = ~ 9.7 : 1
Dyno Results (HP/TQ)   = 124/118

The MT6 file is attached and the dyno is posted in the dyno section on the forum.

HD_04ultra

[attachment removed after 60 days by system]

[HD_04Ultra]

Dyno with A/F trace attached.

HD_04ultra


[attachment removed after 60 days by system]

[lonewolf]

That dyno sheet is showing the right side of your map. Like Robin and Bob say your issues are on the left side. Very different set of timing tables. Curious as to why so much timing is removed right where you are having the surge. What happens if you set the timing back to original in 20-40 kpa columns?

[7hogs]

That dyno sheet is showing the right side of your map. Like Robin and Bob say your issues are on the left side. Very different set of timing tables. Curious as to why so much timing is removed right where you are having the surge. What happens if you set the timing back to original in 20-40 kpa columns?

or a couple of degrees more.

[HD_04Ultra]

Lonewolf,

Do you mean that the dyno sheet is a WOT pull when you say "the right side of the map"?  I really cannot give you any good reason regarding the lack of timing on the left side.

Timing is the one area where I haven't really played around yet.  All my mods have either been to the AFR table or the Front & Rear VE tables.  That and the Decelleration Enleanment table to address some exhaust popping when decelerating.  Basically I just set everything in the Deceleration Enleanment table back to the standard SE calibration of 0.50.  That seemed to take care of the exhaust popping.

The left side is where my issues are that is for sure.  Steady state cruise and downgrade as well as trying to maintain a smooth 25MPH in first gear or 30MPH in second gear.

I will make the suggested changes to the timing tables in the 20-40 kPa columns tonight. Or, as 7hogs suggests, even a couple of degrees more.

Thanks for the help.

HD_04ultra 

[FLTRI]

FWIW, The Propipe's difference in primary length presents huge tuning issues right in the area of operation you are noticing it.
Take the original baffle (short) and cover up 2 rows of holes with hose clamps and install it.
That should help without costing power anywhere.
If you keep increasing the VE in the area of concern it will either get better or worse. Without actually measuring O2 you are guessing at best.
So if it gets worse reverse your procedure from baseline and see what happens then.
Take your pick as to what works best and keep in mind measurement is really the only way to quantify what you are doing.
HTH,
Bob
PS - The target AFR table ONLY WORKS AS EXPECTED IF THE VE's ARE ACCURATE FOR YOUR ENGINE AND ALL THE ANCILLERARIES ATTACHED THAT AFFECT AIRFLOW THROUGH THE ENGINE.

[rbabos]

Increase the fuel in the problem areas to about 13.5-13.8 and see if that works. That's the only thing that worked for me.
Ron

[7hogs]

Now that I think of it the only 2 into 1 that I have had that did not do it at any degree is a Super Meg.

[HD_04Ultra]

Bob,

FWIW from you means a lot so I will take your advice.  That means I have a couple of questions regarding your advice.
When you say cover two rows of holes with hose clamps, does it matter which rows of holes?  Any idea what diameter hose clamp (I will stop and get them on my way home).  I thought the bend in the ProPipes rear cylinder primary made the front and rear cylinder primary lengths the same and therefore would make tuning easier (am I way off base on that???)  Secondly, the VEs were adjusted by Aaron at Kutter when he tuned the bike.  So, assuming the VEs were set accurately for my engine, etc. - then are you advising that the VEs not be adjusted (from the dyno tune)?  If the VEs were adjusted by making WOT pulls on a dyno (the right side of the map), does that directly translate to accurate VEs on the left hand side of the map?

Increasing the VEs had little noticable affect, however increasing timing did improve the surging on the downgrade road surfaces.


Lonewolf,

To answer your question, the timing in the 20-40 kPa columns was a carbon copy of the timing tables from SE calibration #12 which includes the stroker crank and SE flat top forged stroker pistons.  Setting the timing values to the SE Calibration #11 defaults did help eliminate the surging while going downgrade.


Rabos,

I think I am at 13.9 in the problem areas right now.  As I recall, the VEs in the problem area are "generally" lower than the SE calibration called for so I bumped them up to the defaults from the #11 calibration file.  That is why I was wondering about the validity of the VEs when moving from the right side of the map (WOT) to the left side of the map (cruise).  Also how/why the VEs would be lower than the SE calibration file defaults with my heads.


7hogs,

When you sat, "the only 2 into 1 that I have had that did not do it . . .", are you referring to surging on the downgrade?


Thanks to all of you for helping out, it means a lot to me.

HD_04ultra
 

[7hogs]

No mine was at low MAP pressure and it was very minor. I have never had this with true duals.

[HD_04Ultra]

I called Vance & Hines today and spoke with Dave in tech support to see if they had any advice.  Here is what he said.  The Pro Pipe High Output is really meant for use on 110 CID and larger.  The straight-through competition baffle that comes standard with that exhaust system only provides about 7 pounds PSI back pressure and that is not enough back pressure to keep my 103" motor running smoothly where I am having "drivability" issues.  He further said that adding clamps over a couple of rows of holes will not really increase back pressure due to the straight-through design of the baffle.

Vance and Hines offers a "Quiet Baffle" for the Pro Pipe High Output that is plugged at the end (not straight-through) and has more rows of smaller diameter holes.  Dave in tech support tells me the quiet baffle is about 10dB quieter (not really a big deal to me since I am not looking to make a lot of noise).  He further estimated that swapping out the competition baffle with a quiet baffle would result in about a 10HP decrease and a 10TQ increase.  As my dyno shows, I am experiencing a pretty big torque dip at about 2200 RPM.  Dave, at Vance & Hines tech support, figures that switching to the quiet baffle would all but eliminate the torque dip.

What do you guys think, are Dave's thoughts about right?  The "Quiet Baffle" costs $95 through Vance & Hines.  Dennis Kirk sells a Quiet Baffle for $27 (see below).


$26.99 Vance & Hines Quiet Baffle for Pro Pip Hi-Output Systems/Hi-Output Slip-Ons
Dennis Kirk Part #: 4405311
Manufacturer Part #: 21905
Type: Baffle
Units: Each

I know this would change the VE front and rear meaning another trip to the Dyno.  Looking for opinions from the tuners here because $$$ are tight and I cannot afford to make any big mistakes.  How far off do you think the VEs would be by just changing the baffle and how much dyno time do you think would be required to get the VEs back to correct and finish up the tune.  I am willing to give up 10HP to gain 10TQ, especially if the TQ all happens on the lefy side of the dyno graph.  Going from 124HP/118TQ to 114HP/128TQ is a trade I will make especially if I can shift the toeque curve to the left by 500RPM or so.

Have at it, let me know what you guys would do if you were in my boat.

HD_04ultra 



   

[FLTRI]

Sorry for not paying more attention. I passed right over the High Output in the exhaust listing.
That said what the V&H tech told you would be what I also recommend.
Just too big of a pipe for that size build.

By installing the plugged baffle you will enjoy less beating of the ear drums at loaded uphill/accellerating runs.

Also will provide much better throttle response @ lower rpms.

Note: The high rpm loss of power will not be noticed over the much improved lower rpm power...where you ride.
Bob

[HD_04Ultra]

Bob,

No need to be sorry, thanks for your input.  I ordered the Quiet Baffle through Dennis Kirk, can't see paying $95 through V&H for what I believe is the exact same part (Mfr P/N 21905).

This probably means a new dyno tune is in order, right?  Or, do you think that by starting with the current dyno tune I could dial in reasonably acceptable results in terms of both power and drivability?

Otherwise, if I were to have to start over from scratch, it seems to me that SE Cal #12 - 105HL025-D1.MT6 would be a good starting point for my build.  The components list for that calibration are:
-SE 103 Stroker Fltwheels (my build)
-SE 1550 Big Bore Cylinders (my build)
-SE Flat Top Stroker Forged Pistons (my build)
-SE 258 (Tman TR-625 in my build)
-SE Air Cleaner (my build)
-SE Performance Heads (TC88 CNC ported heads by Hals Speedshop in New Berlin, WI in my build)
-SE Performance Touring Mufflers (V&H Pro Pipe HO [with quiet baffle] soon to be in my build)

Not in the list, but would count, is the HPI 53mm throttlebody.  The other "upgraded" parts do not really affect airflow through the engine.  SE clutch spring, S&S Roller rockers, adjustable pushrods etc.

I assume you would advise a fresh dyno tune after changing out the baffle.  However if I wanted to try using the SERT to open-loop tune the bike, which base map would you choose to start with - the previous dyno tune (based on SE cal #11) or SE cal #12?

Thanks again for all your input.  I am learning a lot and having fun as long as I have knowledgable people to bounce ideas off of.

HD_04ultra       

[FLTRI]

Start with the present "properly calibrated"? file if you have it. It should be better than any other canned map because it was developed for your exhaust system not the Harley exhaust, whuch produces quite different fueling requirements. Then mess with that until you are completely convinced you are not getting to where you want to be.
Then take it to your tuner of choice and get it properly calibrated by an experienced tuner who ahs the right tools to do the job.
As always, JMHO,
Bob
PS - Even the most experienced engine builders/tuners have a fits trying to dial in EFI by the seat of his pants. Just too many adjustable variables to guess at it.

[aharp]

Good advice has been given so far. I knew this pipe would be light years ahead of the stock head pipe with samson slip ons but i had a good idea that it would be pretty big for the build. Pipes that over scavenge at low rpm whether due to design or misapplication of intended use are a real bitch to tune at low rpm. A month or so ago i tuned an 03 FLHRSEI with heads that i did and a TR590. Unfortunatley, the guy hung V&H true duals and fish tails on it. I damn near had the ve tables maxed out below 3k at light throttle. Some of them hardly respond to fuel changes at all. Its not that the pipe was over scavenging at that rpm (it did make 119tq) but it was a poor choice of pipe for that combo for sure. Given the exhaust that was previously installed on Dennis's bike and the boat he is in now i would still have bought the HO pipe knowing it was too much and just modded it as needed. Dennis, if i recall correctly, i mentioned making some changes to the baffle setup to try and bring up that dip but i think one or both of us was under a time constraint at the time? Either way, i think ive got a propipe baffle hanging out in the dyno room. Let me know if you want to try it and see if it fits.

[HD_04Ultra]

Aaron,

Thanks for offering to let me try the baffle.  I already placed an order through Dennis Kirk for the baffle listed below.

$26.99 Vance & Hines Quiet Baffle for Pro Pip Hi-Output Systems/Hi-Output Slip-Ons
Dennis Kirk Part #: 4405311
Manufacturer Part #: 21905
Type: Baffle
Units: Each

As mentioned above, I believe this is the same "Quiet Baffle" that Vance & Hines sells for $95.  Planned to call V&H today to verify the manufacturer part # 21905 is what they sell for $95.
Dennis Kirk is out of stock at the moment but they said 7-10 business days.  I will install it as soon as I have it in my hands.  Cash is tight so I cannot afford a lot of dyno time.  I have 5 calibration options available right now.  The original tune you gave me when the ProPipe went on, SE cal #12, #13, #21, or bring it in to you for dyno time.  When the new baffle is installed I will have to try the first 4 options before I spend any more money.  If option #5 (your dyno time) is unavoidable; do you think you could iron things out fairly quickly?

Thanks,
HD_04ultra (Dennis)