VansAirForceForums  
Home > VansAirForceForums

- POSTING RULES
- Donate yearly (please).
- Advertise in here!

- Today's Posts | Insert Pics

  #1  
Old 08-17-2011, 08:54 PM
jcbarker jcbarker is offline
 
Join Date: May 2005
Posts: 133
Default occasional rough running

First my engine setup:
IO-360 Parallel Valve
Horizontal induction
dual Plasma III ignition

The problem:
Occasionally, my engine will run rough. I mean rough enough to shake the stick and make the horizontal stab visibly vibrate. All engine parameters look good and there is no perceptible loss of power. The first time it happened I started looking for a place to land. By the time I had figured out where to go and started heading there it started running smooth again. This happens almost every time I fly after a warm start. I've tried running the boost pump with no change. I'm mystified. I thought I'd post the question before I start poking around blindly.

Any thoughts?

Cheers,

JB
Reply With Quote
  #2  
Old 08-17-2011, 10:09 PM
Mike S's Avatar
Mike S Mike S is offline
Senior Curmudgeon
 
Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
Default

Any particular segment of the flight???

Take off, climb, cruise, ETC.

LOP or ROP??

Any specific RPM range?
__________________
Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
Reply With Quote
  #3  
Old 08-17-2011, 10:28 PM
yakdriver yakdriver is offline
 
Join Date: Aug 2006
Location: Twin Falls, ID
Posts: 683
Default

Check the FI flow divider. Take the top off of it and check to see if there is any particles in there. I had one with a little sliver from a fuel hose and it would flat drop a cylinder every once in a while then run fine after landing and doing a run up. Don
__________________
RV 7 N212MD Flying as of 12/22/2007
Backcountry/TCOW Super Cub flying 03/12/2011
Next project?
Reply With Quote
  #4  
Old 08-18-2011, 01:05 PM
jcbarker jcbarker is offline
 
Join Date: May 2005
Posts: 133
Default

Thanks Mike and Don,

The rough running doesn't start until I'm up cruising. It happens at all altitudes. It doesn't matter if I'm running ROP or LOP. Any RPM.

I'll check the flow divider.
Reply With Quote
  #5  
Old 08-18-2011, 01:12 PM
David-aviator David-aviator is offline
 
Join Date: Feb 2005
Location: Chesterfield, Missouri
Posts: 4,514
Default

Quote:
Originally Posted by jcbarker View Post
Thanks Mike and Don,

The rough running doesn't start until I'm up cruising. It happens at all altitudes. It doesn't matter if I'm running ROP or LOP. Any RPM.

I'll check the flow divider.
I've experienced rough running, so far it has always been cured by moving the mixture knob in just a bit.

A change in temperature from warm to cooler can cause the engine to run rough (too lean).
__________________
RV-12 Build Helper
RV-7A...Sold #70374
The RV-8...Sold #83261
I'm in, dues paid 2019 This place is worth it!
Reply With Quote
  #6  
Old 08-18-2011, 02:32 PM
jcbarker jcbarker is offline
 
Join Date: May 2005
Posts: 133
Default

Quote:
Originally Posted by David-aviator View Post
I've experienced rough running, so far it has always been cured by moving the mixture knob in just a bit.

A change in temperature from warm to cooler can cause the engine to run rough (too lean).
True, and that was my first thought. However, in this case, adjusting the mixture makes no difference.
Reply With Quote
  #7  
Old 08-18-2011, 02:56 PM
Ron B. Ron B. is offline
 
Join Date: Nov 2007
Location: Yarmouth, Nova Scotia
Posts: 2,408
Default

Not trying to hyjack this thread but it is similiar to my situation yesterday. Return flight, 8500' cruise, leaned ROP with a lower than normal fuel burn , 11 GPH (IO-540 , RV-10). The engine started running rough so I pushed in the mixture a little.No change so I went full rich, still no change. I was looking for the nearest airport and about four minutes later it smoothened out. The #4 EGT rose up 100 degrees or so and cooled down similiar to the other cylinders as the engine smoothened out. I leaned back to 14.5 GPH and the vibration did not return for the remainder of the flight of about one hr. Any ideas what caused this? Moderators , you can move this post to another thread if it is not appropriate here, but I thought they were similiar problems and dialog on both situations would help both of us.
Ron
Reply With Quote
  #8  
Old 08-18-2011, 03:05 PM
Mike S's Avatar
Mike S Mike S is offline
Senior Curmudgeon
 
Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
Default

Quote:
Originally Posted by Ron B. View Post
The #4 EGT rose up 100 degrees or so and cooled down similiar to the other cylinders as the engine smoothened out. .
Ron
Ron, did the CHT happen to go down on cyl #4 at the same time as the EGT went up????

If so, may be a sticking exhaust valve, or a bit of crud holding the valve open.
__________________
Mike Starkey
VAF 909

Rv-10, N210LM.

Flying as of 12/4/2010

Phase 1 done, 2/4/2011

Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
Reply With Quote
  #9  
Old 08-18-2011, 03:54 PM
Ron B. Ron B. is offline
 
Join Date: Nov 2007
Location: Yarmouth, Nova Scotia
Posts: 2,408
Default

I had not been monitoring the engine parameters before the rough running took place (more than the usual scan). When I noticed the higher#4 EGT the cylinder temps were all close as usual. I did not notice if #4 Cylinder temp was a lower one. I was looking to see if it was higher and it was not.
Ron
Reply With Quote
  #10  
Old 08-18-2011, 05:34 PM
RV10inOz's Avatar
RV10inOz RV10inOz is offline
 
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,271
Default

Ron

Do you have a datalog of the engine monitor.

Send it to me by email if you do.

Couple of things in no particular order that have caused rough running in RV10/IO540's

1. Fuel pump temperature causing vapour bubbles, and as these go through the engine will run rough. richer does not always fix it, although the extra fuel flow means the volume of fuel spends less time in the lines and less chance of heating up. Constant battle down here in summer even with the fuel pump cooling shroud. (although we have tried to improve airflow just this week, time will tell).

2. Plugs....many variables but I have seen this time and time again. Folk and in particulare LAME's (A&P's) seem to disregard this critical thing. If massive electrodes, set between 16-18 thou, do not let them get past 22 thou.

3. Inlet Gaskets. Don't ask me how we know Brand new engine installed and at 230 hrs 5 out of 6 gaskets were cracked, some considerably. Go looking for fuel stains around the inlet tubes and the gasket to head interface. Check all bolts/nuts on your inlet and exhaust flanges. You may well have a couple failing.

4. When you see any rough running, before you break out in a terrified sweat, and preferably while LOP turn a mag off and watch it for 10 seconds, note any changes then do the other. Very helpful in finding plugs, wires and maggies that are faulty.
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -6. The time now is 06:45 AM.


The VAFForums come to you courtesy Delta Romeo, LLC. By viewing and participating in them you agree to build your plane using standardized methods and practices and to fly it safely and in accordance with the laws governing the country you are located in.