Hi Ken
I did have the same problem with my 914,and the cause for me was the
2 inches rubber pipe from the cab to the air box to the turbo became
loose .check them!!!
Regards
Herve G.CHET
t 02:29 13/10/2008, you wrote:
>I have some follow-up on the surging problem. Turning off the TCU
>does not help anything. In fact, the engine seems to surge and be a
>little rougher. I have checked the plugs which were new two hours
>ago. The air filter has no effect on the problem. I have checked
>the tubing, it is six years old, but looks to be in good condition
>and no cracks...course you can't see the underside of a lot of the
>tubing. The surging varies. I ran it yesterday and it did not
>surge at all...manifold pressure up to 38 and it seemed to be
>cured. Then today I ran it again and the surging was back. The
>surging is over a range from 5000 down to 2000. Someone was of the
>opinion that it was almost like the engine was being turned off and
>as the RPM dropped, being turned back on. Since the problem occurs
>only at the higher throttle settings, I had assumed it could not be
>the electrical system. The engine does diesel some when t urned
>off. It has done that for a year or so. I usually turn off the
>fuel pumps first and when the pressure drops, then turn off the
>ignition. The dieseling is worse if the enginie is hot...like up at
>200 degrees or so. The surging is less severe when the engine is
>hot...up in the 200 range, and worse with the engine temp at 130.
>I am leary of the carbs but it sounds like I will have to tackle
>them if no one comes up with an alternate idea. No one around
>Knoxville has experience with a Rotax. I asked our AI if he knew
>anything about Rotax engines and he said, "Heck, I can't even spell
>it!" The intermittant nature of the surging has added to the
>frustration. I can't see anything being done to the engine that
>makes it behave different. I have the same gas(half auto high
>test and half 100LL) in the plane that was in there when I did two
>flights before the surging started. The mag check is
>normal. Running both fuel pumps increases the pressure reading but
>does not change the surging. It did not surge for 500 hours running
>on one pump. Thanks for the ideas thus far.
>Ken Carpenter
>-------------- Original message --------------
>From: "ALAN YERLY" <budyerly@msn.com>
>Guys, Here is my one and a half cents.
>
>When working with Jerry Hope's 914 we found that the reset switch
>was all that was necessary to cure the surging... That is always my
>first in-flight correction. For my older engine, the wiper on the
>pot in the turbo servo wore out with time and the servo began to
>hunt. By hitting the reset switch, it momentarily cuts the power
>and stabilizes the manifold/boost and the servo related surge/boost
>fluctuations stop.
>
>As for the carb related problems, With the engine at idle, servo
>locked out (reset switch held to eliminate the servo from
>operating), run the engine up until you see about 35-39 inches of
>MP. If the engine does not surge, it is not the carbs. If you have
>the dual manometers, and can watch the MP on each carb, that will
>tell you volumes about your carb health. If one of the altitude
>compensators is hanging up, the engine will sag, calling for more
>boost, then the engine boost clears the carb balance problem, but
>that causes a momentary over boost which then causes the servo to
>cut boost, which then causes the carbs to be out of balance
>again. In this case you will see it in the twin manometers and a
>carb rebuild kit for $45 will fix you up. The carbs on a 914 take
>about 2 hours to get on and off, and 1 hour to replace the seals in
>the carbs. Then you get to retune the throttles. Pay attention to
>the posit ion of the needle valve slide clip during the rebuild. If
>you get one position off, you will be running richer or leaner than
>normal. Bing has troubleshooting manual on the web and Rotax has
>the carb balancing video you can order, so check it out.
>
>If your throttle position sensor is worn, that too can cause the
>computer to force the engine into a surge on the older slower
>computer processor. The program sold by Rotax can check the position sensor.
>
>For low boost, or leaks, wow, that's a new one on me. I don't get
>to fly that high so I have no experience. My low boost problems is
>because I don't set the cable right on the servo or the cable slips.
>
>Rich Schultz found with running on AV Gas, his carbs stayed in tune
>if he added just a bit of Marvel Mystery Oil to his gas to lube his
>carb. His problems cleared up.
>
>Bud
>Custom Flight Creations
>(813) 653-4989
>----- Original Message -----
>From: <mailto:paul.the.aviator@gmail.com>Paul McAllister
>To: <mailto:europa-list@matronics.com>europa-list@matronics.com
>Sent: Thursday, October 09, 2008 9:20 PM
>Subject: Re: Europa-List: engine surging
>
><<mailto:paul.the.aviator@gmail.com>paul.the.aviator@gmail.com>
>
>Hi Folks,
>
>Could I offer a contrary view? I got to 600 hours on my 914 with no
>sign off issues wih the carbs, but on the adivce of many I sent my
>carbs into Lockwood to have them overhauled. What a mistake, the
>airplane now uses .3 to .4 more gallons per hour than before and it
>took me 4 tries to get the inlet system sealed up again so I could get
>maximum boost.
>
>Actually it still is not right, I can only get 27 inches and 16k feet
>and I should be able to get 34" so the darn thong is still leaking.
>
>With that said, it may well be your carbs, but the first place I would
>go is fuel filters, then look at the fuel pressure (needs to be
>measured differentially), then onto the turbo waste gate. What you
>will need to do is
>
>
><http://www.matronics.com/Navigator?Europa-List>http://www.matronics.com/Navigator?Europa-List
>
>
><http://www.matronics.com/contribution>http://www.matronics.com/contribution
>
>
>Checked by AVG.
>10/12/2008 12:00 PM
>
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