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IO-520BB - Rough running at idle and low RPM

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martymitchell

Joined: 14 Sep 2008
Posts: 10
Location: Newport Beach, CA

Posted: Sun Sep 14, 2008 9:13 am Post subject: IO-520BB - Rough running at idle and low RPM

I have an IO-520BB in my Beech Bonanza that runs rough at idle and low RPM.  I have changed the spark plugs, cleaned the injectors, checked the mag timing (just installed after 500 hour inspection and new distributor block), and had a mechanic check the idle fuel pump pressure and idle mixture setting.  



I also did a compression check and all cylinders are above 60/80. There doesn't seem to be any difference in drop with each mag at various RPM's.  I have not changed the ignition wires.



Any ideas on other things to look for?



Thanks!

_________________
Marty Mitchell
Bonanza N44GN

nov32394(at)yahoo.com
Guest

Posted: Sun Sep 14, 2008 10:58 am Post subject: IO-520BB - Rough running at idle and low RPM

Cleaning the injectors sometimes creates more problems. I would start there then go to the splitter and look for flow problems. You can test the flow I think at each injector. If you had an engine monitor it should tell you which cylinder to look at. Also look for an air leak in the intake system.

  

 Dan



--- On Sun, 9/14/08, martymitchell <orders(at)martymitchell.com> wrote:



  	  Quote: 	
		  From: martymitchell <orders(at)martymitchell.com>

Subject: IO-520BB - Rough running at idle and low RPM

To: continental-list(at)matronics.com

Date: Sunday, September 14, 2008, 12:13 PM



 	  Quote: 	
		  --> Continental-List message posted by: "martymitchell"

<orders(at)martymitchell.com>



I have an IO-520BB in my Beech Bonanza that runs rough at idle and low RPM.  I

have changed the spark plugs, cleaned the injectors, checked the mag timing

(just installed after 500 hour inspection and new distributor block), and had a

mechanic check the idle fuel pump pressure and idle mixture setting.  



I also did a compression check and all cylinders are above 60/80. There

doesn't seem to be any difference in drop with each mag at various

RPM's.  I have not changed the ignition wires.



Any ideas on other things to look for?



Thanks!



--------

Marty Mitchell

Bonanza N44GN





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 4247#204247





	
	


           [quote][b]

ftyoder(at)yoderbuilt.com
Guest

Posted: Sun Sep 14, 2008 1:05 pm Post subject: IO-520BB - Rough running at idle and low RPM

Does it smooth out if you lean it at idle?



Tim

---

martymitchell

Joined: 14 Sep 2008
Posts: 10
Location: Newport Beach, CA

Posted: Sun Sep 14, 2008 2:50 pm Post subject: Re: IO-520BB - Rough running at idle and low RPM

Thanks Tim and Dan.  Yes, it smooths out quite a bit when I lean it out (about two inches of throttle position) but still misfires.  I did clean the injectors with Hoppes #9 gun cleaner but no change. 



I'm not sure how to check for air leaks other than to verify tightness of all hose clamps and intake bolts.  



Also, how do you test injector flow?  Do you remove them, then capture fuel thru each one into a cup simultaneously and compare levels?  I have Gami's, so I would expect different levels in Front, Middle and Back positions.  Do you use the boost pump for the test (can't use the engine driven pump)?



I do have an engine monitor (EDM-700) and there's nothing too out of place at cruise, can't tell at idle as numbers tend to be all over the place.



Thanks...

_________________
Marty Mitchell
Bonanza N44GN

nov32394(at)yahoo.com
Guest

Posted: Mon Sep 15, 2008 8:50 am Post subject: IO-520BB - Rough running at idle and low RPM

Call over to GAMI.

  

 Dan



--- On Sun, 9/14/08, martymitchell <orders(at)martymitchell.com> wrote:



  	  Quote: 	
		  From: martymitchell <orders(at)martymitchell.com>

Subject: Re: IO-520BB - Rough running at idle and low RPM

To: continental-list(at)matronics.com

Date: Sunday, September 14, 2008, 5:50 PM



 	  Quote: 	
		  --> Continental-List message posted by: "martymitchell"

<orders(at)martymitchell.com>



Thanks Tim and Dan.  Yes, it smooths out quite a bit when I lean it out (about

two inches of throttle position) but still misfires.  I did clean the injectors

with Hoppes #9 gun cleaner but no change. 



I'm not sure how to check for air leaks other than to verify tightness of

all hose clamps and intake bolts.  



Also, how do you test injector flow?  Do you remove them, then capture fuel

thru each one into a cup simultaneously and compare levels?  I have Gami's,

so I would expect different levels in Front, Middle and Back positions.  Do you

use the boost pump for the test (can't use the engine driven pump)?



I do have an engine monitor (EDM-700) and there's nothing too out of place

at cruise, can't tell at idle as numbers tend to be all over the place.



Thanks...



--------

Marty Mitchell

Bonanza N44GN





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 4292#204292





	
	


         [quote][b]

ftyoder(at)yoderbuilt.com
Guest

Posted: Mon Sep 15, 2008 9:15 am Post subject: IO-520BB - Rough running at idle and low RPM

How does it run at mag check?

  

 Right mag. drop?

  

 Left Mag. drop?

  

 Mags checked with mixture rich or lean?

  

 What year, model Bonanza is it?

  

 Tim

 [quote]   ---

martymitchell

Joined: 14 Sep 2008
Posts: 10
Location: Newport Beach, CA

Posted: Mon Sep 15, 2008 11:04 am Post subject: Re: IO-520BB - Rough running at idle and low RPM

It runs rough on either mag.  It's not bad at 1700 RPM, just at lower RPM's around 900-1100.  Single mag operation drops around 75-100 rpm on either mag.



Runs rougher with mixture full rich, better when leaned out quite a ways (2").



It's a 1976 F33A.

_________________
Marty Mitchell
Bonanza N44GN

archerwt(at)gmail.com
Guest

Posted: Mon Sep 15, 2008 11:28 am Post subject: IO-520BB - Rough running at idle and low RPM

What is the carb history?  How many rebuilds?  How much time on this rebuild?  

  

 With a worn mixture arm or needle jet/seat, your mixture control will induce a response but will always run rich.  You'll only really notice it at idle.  Just a guess.



   

  

 [quote]



It runs rough on either mag.  It's not bad at 1700 RPM, just at lower RPM's around 900-1100.  Single mag operation drops around 75-100 rpm on either mag.

 

Runs rougher with mixture full rich, better when leaned out quite a ways (2").



It's a 1976 F33A.



--------

Marty Mitchell

Bonanza N44GN





Read this topic online here:



  [quote][b]

nov32394(at)yahoo.com
Guest

Posted: Mon Sep 15, 2008 6:35 pm Post subject: IO-520BB - Rough running at idle and low RPM

Not a carb it is FI

  

 This sounds more like flow, Check your flow control.

  

 Dan



--- On Mon, 9/15/08, William Archer <archerwt(at)gmail.com> wrote:



  	  Quote: 	
		  From: William Archer <archerwt(at)gmail.com>

Subject: Re: Re: IO-520BB - Rough running at idle and low RPM

To: continental-list(at)matronics.com

Date: Monday, September 15, 2008, 2:25 PM



   What is the carb history?  How many rebuilds?  How much time on this rebuild?  

  

 With a worn mixture arm or needle jet/seat, your mixture control will induce a response but will always run rich.  You'll only really notice it at idle.  Just a guess.



   

  

  	  Quote: 	
		  



It runs rough on either mag.  It's not bad at 1700 RPM, just at lower RPM's around 900-1100.  Single mag operation drops around 75-100 rpm on either mag.



Runs rougher with mixture full rich, better when leaned out quite a ways (2").



It's a 1976 F33A.



--------

Marty Mitchell

Bonanza N44GN





Read this topic online here:



 	  Quote: 	
		  

	
	


	


         [quote][b]

martymitchell

Joined: 14 Sep 2008
Posts: 10
Location: Newport Beach, CA

Posted: Mon Sep 15, 2008 9:50 pm Post subject: Re: IO-520BB - Rough running at idle and low RPM

Problem Found!  I did a second compression check and took my time.  Although all of the compressions are in the low to mid 60's, it appears that each cylinder has a valve leak, one exhaust and 5 intakes.  I suppse that is why it idles so rough. 



Thank you all for your help and suggestions.  I should have started off with a careful compression check.

_________________
Marty Mitchell
Bonanza N44GN

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