Engine cough on quick rev occasionally ... why?

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Jul 19, 2020 | 12:23 PM

#11

Ultra_RB

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Joined: May 2018

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From: Okanagan, BC

Quote:

Originally Posted by stevepacman

When you say “cough” are you talking about a slight hesitation? If that’s the case your fuel flow rate is inconsistent. I had an issue with dirty injectors once that caused that.

It's more of a "cough" in the intake side I think ... it's not an exhaust backfire. It feels like for a split second the engine is choking out then resumes fire, makes this cough/popping sound that sounds like it's around the intake as opposed to the rear out the exhaust. Otherwise the bike purrs perfectly, just every so often it does this little trick ... makes one just nervous about doing quick takeoffs to get out ahead of traffic at an intersection ...

Jul 19, 2020 | 12:24 PM

#12

Ultra_RB

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From: Okanagan, BC

The more I think and learn I think it's either and EFI map issue or an injector issue ...?

Jul 19, 2020 | 01:33 PM

#13

seniorsuperglideE8

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From: along the shore of Mishigami

I have an 02 Dyna with a carb and we called those carb farts due to the lean jetting or mix in the carb when starting off from the lights. We just richened up the mix a tiny bit and modified the needle a tad. If you did a standard reflash the ECM is reprogrammed to the EPA requirements. An indy might be able to adjust the ECM for you or maybe add XIEDS for your model if available, they add a little bit more fuel.

Jul 19, 2020 | 02:07 PM

#14

hattitude

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Joined: Sep 2008

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From: San Diego, CA

Quote:

Originally Posted by Ultra_RB

The more I think and learn I think it's either and EFI map issue or an injector issue ...?

Just my 2 cents...

Didn't you say you are on your 3rd season with the current mods/tune, nothing has changed, and it has previously run well....???

If so, I would look for something that got dirty, worn, broken.... rather than the tune...

Usually, a "tune" (software) doesn't go bad... but as the supporting parts (hardware) get dirty/worn/broken, issues will surface....

Some issues CAN be fixed by changing the tune. Yet, changing software for a hardware problem, will only work for awhile, and is just masking the real issue...

Based on your own above assessment, I'd vote for fuel injectors..... or other fuel system/spark system maintenance issues...

Good luck with the fix...

Jul 19, 2020 | 05:22 PM

#15

Mezo

3rd Gear

Joined: Apr 2019

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From: Arizona

Vacuum leak?

Jul 19, 2020 | 08:10 PM

#16

Ultra_RB

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Cruiser

Joined: May 2018

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From: Okanagan, BC

Quote:

Originally Posted by hattitude

I have dumped a whole bottle of injector cleaner in this fresh tank so we will see if that makes a difference.

BTW, removal of the injectors looks pretty straight forward ... is there any way to manually clean/clear them or are they just a parts you have to replace?

Jul 20, 2020 | 09:16 AM

#17

hattitude

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Joined: Sep 2008

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From: San Diego, CA

Quote:

Originally Posted by Ultra_RB

BTW, removal of the injectors looks pretty straight forward ... is there any way to manually clean/clear them or are they just a parts you have to replace?

There are fuel injector pulse testers, and complete pattern/pressure testers/cleaners/etc... but they can be quite expensive... Some shops have these tools/testers and can clean/test them for your if you just bring them into their shop......

Obviously, the tools are more expensive than a set of injectors... I'm not a big fan of throwing new parts at a problem to see if it fixes it, but if for some reason you really suspect a problem with the injectors, it would be cheaper to swap out new injectors than buy the tools for yourself...