V-Twin Forum banner
1 - 7 of 7 Posts

·
AXTELLERATOR
Joined
·
441 Posts
Discussion Starter · #1 · (Edited)
Put my bike on dyno for base line before new build. Dyno showed that there was a problem. Afr went from originial buid 13/1 straight across(at full throttle) to huge dip worse than 10/1 Afr. Did new build and put on dyno. Same thing. While on dyno at steady speeds with no load -afr is 14.5/1 When minor load (20%) afr is 12.8 -13.0/1. this seems good to me. But, when full throttle, afr goes 10.0/1 and worse. I have run it with two different power commanders(using same map) and also with power commander removed and just using HD Stage 2 download on ECM. Pretty much exact same line. I have a Twin Scan hooked up also and when full throttle the fuel injector pulse (from the ecm)for the front and back injectors are completely different. The back cylinder pulse looks follows pretty much the same line as the throttle position sensor line, but the front injector pulse goes about half as high as back pulse and stays flat until reaches back pulse on down side. The back pulse looks like a mountain peak(diagonal line up and down). Front pulse looks like a picnic table(straight up then flat and then drops straight down on other side). I'm thinking the front injector gets stuck or some thing , but I'd rather get an opinion before I go buying unnecessary parts. Thanks for any info!!!
Originial build was :95" / HD 257 cams / Hd performance heads / Forged HD 10.5/1 pistons / Sampson 2/2 pipes
New build is : 95" / Woods tw-6hg cams / modified HD performance heads/ roller rockers / rocker arm support pates / HD 10.5/1 pistons / Sampson 2/2 pipes
 

·
Registered
Joined
·
297 Posts
relxn88 said:
Put my bike on dyno for base line before new build. Dyno showed that there was a problem. Afr went from originial buid 13/1 straight across(at full throttle) to huge dip worse than 10/1 Afr. Did new build and put on dyno. Same thing. While on dyno at steady speeds with no load -afr is 14.5/1 When minor load (20%) afr is 12.8 -13.0/1. this seems good to me. But, when full throttle, afr goes 10.0/1 and worse. I have run it with two different power commanders(using same map) and also with power commander removed and just using HD Stage 2 download on ECM. Pretty much exact same line. I have a Twin Scan hooked up also and when full throttle the fuel injector pulse (from the ecm)for the front and back injectors are completely different. The back cylinder pulse looks follows pretty much the same line as the throttle position sensor line, but the front injector pulse goes about half as high as back pulse and stays flat until reaches back pulse on down side. The back pulse looks like a mountain peak(diagonal line up and down). Front pulse looks like a picnic table(straight up then flat and then drops straight down on other side). I'm thinking the front injector gets stuck or some thing , but I'd rather get an opinion before I go buying unnecessary parts. Thanks for any info!!!
Originial build was :95" / HD 257 cams / Hd performance heads / Forged HD 10.5/1 pistons / Sampson 2/2 pipes
New build is : 95" / Woods tw-6hg cams / modified HD performance heads/ roller rockers / rocker arm support pates / HD 10.5/1 pistons / Sampson 2/2 pipes
I don't think that a bad injector will cause the pulse profile to change. It could cause the injector to leak and screw up the AFR but the ground from the ECM should remain the same. I guess that you could try disconnecting the ECM to try to reset it and see if it makes a difference. Did you try getting the AFR from both cylinders to see how they compare?.....Bill
 

·
AXTELLERATOR
Joined
·
441 Posts
Discussion Starter · #4 ·
reply to Naipro + Compressor#V

Nauipro - That's a good idea about sticking the probe in the left pipe to check for afr on back cylinder. Also, I'll repower the ECM . Thanks for info!!

Compressor #V - THE Sampson 2 ito 2 pipes have been on there since I did the originial Stage 2 build couple a years (2003) ago and the bike has been dyno'd a couple of times since with out any AFR problems, but thanks anyway.
 

·
IronButt
Joined
·
6,364 Posts
Sounds like you have a chunk of crud ( that is a tech term by the way OL) in the injector, causing it to stream the fuel, instead of spray it. Or the injector could be bad as well. If you need a pair of injectors to test I have several sets of new ones that you can try if you would like. Let me know. Steve
 

·
AXTELLERATOR
Joined
·
441 Posts
Discussion Starter · #6 ·
Thanks for info!

To Hdwrench: I had thought it was either the injector or the ecm. The TwinScan reads any trouble codes from the ECM(current and historical) and I never had any. So, I bought 2 new fuel injectors instead. (Lot cheaper then a ecm) I haven't installed them yet but, I'll post what happens when I do. Thanks for the re-inforcement of my thought about the injector.
 
1 - 7 of 7 Posts
Top