Author Topic: Things that make a engine cough or sneeze thru the intake  (Read 1442 times)

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Offline mc9395

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Things that make a engine cough or sneeze thru the intake
« on: Thursday, May 03, 2012. 09:16:00 AM. »
This pertains to a  06 touring model I just rebuilt, 103 " with flatop pistons, screaming eagle heads, S&S 551 compresion  relief cams, and thunderheader duals. Tring to tune with pcv and auto tune. Bike will not tune in the 1000-1500 range but rather sneeze or sneeze and die. I have changed the manifold seals 2 times, changed the map sensor seal, and built a block off plate to fill the motor with smoke and no smoke leaks. Then I changed the CPS just to cover all bases. Is there another sensor that can do this. After all the work the customer told me it was doing that before he brought it in but forgot to tell me. Doesn't matter the problem is still there. Can a ecm do this and i,m not helping with the pcv. Maybe a thundermax to get rid of the piggyback. What else can make one sneeze and die. Help and thanks .Black

Offline FLTRI

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #1 on: Thursday, May 03, 2012. 09:26:05 AM. »
Sneezing. coughing through the intake most always indicates lean condition.
Has the bike been tuned for the changes made?
Bob
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Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #2 on: Thursday, May 03, 2012. 09:33:04 AM. »
Diffinite lean condition tring to tune now but cant seem to get the sneeze out not mater how much fuel i add thanks

Offline Lew

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #3 on: Thursday, May 03, 2012. 09:36:42 AM. »
I've seen low voltage at the coil cause this.
-It is now later than it has ever been before-

Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #4 on: Thursday, May 03, 2012. 09:41:18 AM. »
I'll check Thanks

Offline rbabos

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #5 on: Thursday, May 03, 2012. 12:27:48 PM. »
Something as simple as a sparkplug will do this too.
Ron
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Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #6 on: Thursday, May 03, 2012. 01:36:33 PM. »
Coil voltage was ok about 11.90- 12 while relay was on, same thing 2 sets of plugs Thanks give me more

Offline N-gin

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #7 on: Thursday, May 03, 2012. 01:47:46 PM. »
What are u tunning with?
Also what are your O2s reading around that RPM.
You might want to seafoam your engine. Did a engine that would cough and sputter when takin off and It stopped after I seafoamed it.
Whats your timing look like?
You live more in 1 day on a machine like this, than most people do in a lifetime

Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #8 on: Thursday, May 03, 2012. 02:06:07 PM. »
trying to tune with pc 5 and auto tune but cant get past the cough. runs ok after about 1500 .wondering if there is a problem with the ecm. will look at the timing when I get it back together. Thanks

Offline ViennaHog

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #9 on: Thursday, May 03, 2012. 02:18:20 PM. »
did you work on the throttle postion sensor for some reason? if that is out of range, it will cause all kinds of trouble.

Offline topcat3815

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #10 on: Thursday, May 03, 2012. 02:36:15 PM. »
Agree with above post if your tps is is reading low it causes a lean condition by not being in sync with the throttle body opening causing a lean condition and a cough

Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #11 on: Thursday, May 03, 2012. 05:47:47 PM. »
I did pull it to make sure the shaft didnt have a problem and that the oring sealed good no change

Offline Ultrashovel

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #12 on: Thursday, May 03, 2012. 07:47:54 PM. »
Sneezing. coughing through the intake most always indicates lean condition.
Has the bike been tuned for the changes made?
Bob

Yep. too lean, or it could indicate a leak around the intake ports where the manifold connects to the head. The slang term I've heard for this phenomenon is "chuffing".


Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #13 on: Friday, May 04, 2012. 06:58:43 AM. »
no question lean but not manifold leak. used carb cleaner, no change, propane, no change, closed both intake blocked throttle body with plate and pumped smoke, no smoke, no intake leak,Thanks

Offline hollywood63

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #14 on: Friday, May 04, 2012. 10:15:42 AM. »
I did pull it to make sure the shaft didnt have a problem and that the oring sealed good no change

As stated above verify TPS setting

Offline mc9395

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Re: Things that make a engine cough or sneeze thru the intake
« Reply #15 on: Friday, May 04, 2012. 12:28:12 PM. »
Thats next as soon as I get back to it