Same tune but one cylinder leaner than the other - Harley Davidson Forums

Ignition/Tuner/ECM/Fuel Injection Need advice on ignition issues? Questions about a tuner? Have questions about a EFI calibration or Fuel Injection? Tips on Engine Diagnostics, how to get codes, and what they mean. Find your answers here.

Same tune but one cylinder leaner than the other

  #1  
Old 10-12-2018, 01:24 AM
Z's Avatar
Z
Z is offline
Road Master
Thread Starter
Join Date: Nov 2005
Location: Mountain View, California
Posts: 1,208
Thanked 22 Times in 22 Posts
Default Same tune but one cylinder leaner than the other

I'm pretty sure this isn't an issue, but thought I'd run it by the community for feedback.

I have identical mixture maps front and rear, yet one cylinder is 1 AFR point leaner than the other, across the board. That is, if one cylinder averages 13.0:1 across the RPM range, the other will average 12.0:1. I'm just curious if this is the norm.
 
  #2  
Old 10-12-2018, 02:00 AM
Meatbag's Avatar
Meatbag
Meatbag is offline
New Member
Join Date: Sep 2018
Location: Bunbury
Posts: 6
Thanks: 0
Thanked 0 Times in 0 Posts
Default

Yeah seems to be very common. Was looking at this for mine as well last week and seemed to be a standard thing.
 
  #3  
Old 10-12-2018, 10:50 AM
Z's Avatar
Z
Z is offline
Road Master
Thread Starter
Join Date: Nov 2005
Location: Mountain View, California
Posts: 1,208
Thanked 22 Times in 22 Posts
Default

Rhanks meat
 
  #4  
Old 10-12-2018, 11:12 AM
bustert
bustert is offline
Road Master
Join Date: Aug 2008
Posts: 1,105
Thanked 135 Times in 130 Posts
Default

the same thing happens with a carb machine as well.
it wasn't uncommon to run diff heat range plugs back in the day before epa tighten things up. you have heat diff'l between cly and also the way it is fueled, look at the intake charge and the 45* separation which makes a pretty wicked pulse in the manifold. when they come out with direct injection, probably go away.
 
  #5  
Old 10-13-2018, 06:49 AM
marcodarq
marcodarq is offline
Road Master
Join Date: May 2014
Location: florida
Posts: 1,001
Thanks: 0
Thanked 114 Times in 104 Posts
Default

Actually, No, it ia not common to have that large a variance. A MM injected bike also does not not have a common plenum intake, it has individual runners and injectors. As i've suggested to you before your tune is no good. When these bikes went to fuel injection they were able to tune each cylinder for fuel and spark independently. That is why there are different Ve values and timing values between front and rear cylinders in the tables that the ecm uses.
take your bike to a different, and better qualified tuner and get it re tuned.
m
 

Last edited by marcodarq; 10-13-2018 at 06:50 AM.
  #6  
Old 10-13-2018, 08:58 AM
bustert
bustert is offline
Road Master
Join Date: Aug 2008
Posts: 1,105
Thanked 135 Times in 130 Posts
Default

even with a twin throat throttle body, there are diff things that can still effect numbers.
the cyl can and do see diff operating parameters(power balance). also, electronics do have skew.
it would be easier with the twin setup to use a vac gauge to see what each is pulling. some electronic fuel management systems can approximate it via onboard testing. no diff than a split plane manifold on a v8.
 
  #7  
Old 10-13-2018, 01:18 PM
marcodarq
marcodarq is offline
Road Master
Join Date: May 2014
Location: florida
Posts: 1,001
Thanks: 0
Thanked 114 Times in 104 Posts
Default

do you even understand anything that you are attempting to discuss?
cylinders can and do see operating parameters and that is EXACTLY why the VE tables and spark tables are different for one cylinder to the next, and there is even more to it with a HD common crank pin engine, trying to make a comparison to a split plane V8 is just apples and oranges.
I understand that we are all just trying to help the OP, so please dont take this a personal attack, because that is not how it is meant. the OP does not want to accept that he has a tuning issue. and or does not have faith in a shop that is available to him to fix it. but he also doesn't have the training and tools to correct it himself, although he is trying very hard.
Z please consider tying to find a tuning shop that you can try to have some faith in and get your bike tuned properly, then use the experience to monitor your systems and learn, then be ready for the next upgrade, OR for future diagnostic work if/when something wears out or breaks.
i really mean no offense to anyone!
m
 
  #8  
Old 10-13-2018, 01:58 PM
bustert
bustert is offline
Road Master
Join Date: Aug 2008
Posts: 1,105
Thanked 135 Times in 130 Posts
Default

no issues here. all i am saying is there can be normal variances. can he tune it out, well sure. will you get an exact balance, naw!
hummm, do not a v8 engine have two rods to a pin and fueled by two diff tracts?
ever work on an engine with only 6 rods but has 12 cylinders? common fuel injection but each cyl has to be power balanced to the others individually?
will one tune last a lifetime, naw. if it were mine, not enough apples and oranges to worry about since there isn't any issues. BTW: a dynometer tune really doesn't do anything for real life operation.
 
  #9  
Old 10-13-2018, 04:04 PM
Z's Avatar
Z
Z is offline
Road Master
Thread Starter
Join Date: Nov 2005
Location: Mountain View, California
Posts: 1,208
Thanked 22 Times in 22 Posts
Default

Guys, I absolutely 100% accept and acknowledge that I have a tuning issue - where I differ with many of you is in the belief that it takes a dyno tuner to resolve it.

i have a simple system: Crank & camshaft position. Engine temp, baro pressure and throttle position. The adjustable variables are mixture and spark timing.

I have invested a good deal of time and money into a data logging system and AFR / lambda gauge. I intend to tune my mixture myself. This is not magic, and I am not trying to get every freaking digit of horsepower possible from this motor.

I am happy with the timing map that I got from a few days ago, and will run that until I get 1000 miles on my top end and then I will take it back to my tuner for fine adjustments.

This thread is an attempt to learn more about tuning. Everyone keeps screaming that the only this is going to get resolved is on a dyno and I have been politely saying not truE, and I still say exactly that!

all that said, thank you all for your replies.
 
  #10  
Old 10-13-2018, 06:20 PM
marcodarq
marcodarq is offline
Road Master
Join Date: May 2014
Location: florida
Posts: 1,001
Thanks: 0
Thanked 114 Times in 104 Posts
Default

B,
yes a dyno tune will work for real life application, other wise i would not have invested the time or money in owning one, or learning how to use it. I can replicate just about any real world condition on my dyno short of anything to do with wet road surfaces. It's just a matter of doing the math and entering the correct test data and parameters. I can even test for wind resistance if i'm willing to do the extra math work and data entry. Is that level of tuning required for a good tune? No, not necessarily, but it can be done, and can be quantified right away, no need to ride, go home, download and analyze data, make adjustments and go out and log again, repeat. I'm not saying that data log tuning is not any good, it just takes much longer! and it does more than one bike!
m
 

Thread Tools
Search this Thread
Featured Sponsors
Vendor Directory

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: