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rlborger(at)mac.com
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 Posted: Wed May 16, 2012 2:37 pm Post subject: 914 starts to surge at 3950 RPM |
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Friends,
As many of you know, my Europa has been down for about a year while it was converted it to tri-gear and I rebuilt the instrument panel. We ran the engine about 2 weeks ago to check the carb balance and idle. Those were OK at the time. I didn't run the engine any further that day because of other commitments (preparing for a 2 week trip to SC). Monday, I went out to do a full run-up and check of the engine. Started fine, idled OK as long as I held the "Choke" out while warming up. After it was warm it idled OK without the "Choke." Engine nice and smooth. I slowly applied throttle and as it approached 4000 RPM it began to surge. Engine RPM dropped to about 3250 and would return to almost 4000 then drop down to 3250 and return to almost 4000, repeat, repeat, down/up/down/up/down… Below 3950 RPM it ran smooth and fine. Advance the throttle and it began to surge.
EGTs & CHTs all normal and close to equal. Mag drop at 3900 RPM were almost equal. The lower plugs always have had a 50-75 RPM greater drop. Turning on the boost pump made no difference. Engine has about 25 hrs total time so far and has run like a sewing machine up to now.
Any ideas as to the source of the problem? Any suggestions as what to check? Could it be the Turbo or Turbo Controller?
For starters, I guess I need someone to help operate the throttle while I observe the turbo controller and wastegate operation. Tommy will probably help there.
Any input would be appreciated.
Thanks in advance!
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger(at)mac.com (rlborger(at)mac.com)
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n992dn(at)gmail.com
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| Posted: Wed May 16, 2012 3:01 pm Post subject: 914 starts to surge at 3950 RPM |
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I would start with checking fuel flow restriction, clogged filter etc.
Nati
RANS S6S 912uls
Illinois
On Thu, May 17, 2012 at 5:36 AM, Robert Borger <rlborger(at)mac.com (rlborger(at)mac.com)> wrote:
[quote] Friends,
As many of you know, my Europa has been down for about a year while it was converted it to tri-gear and I rebuilt the instrument panel. We ran the engine about 2 weeks ago to check the carb balance and idle. Those were OK at the time. I didn't run the engine any further that day because of other commitments (preparing for a 2 week trip to SC). Monday, I went out to do a full run-up and check of the engine. Started fine, idled OK as long as I held the "Choke" out while warming up. After it was warm it idled OK without the "Choke." Engine nice and smooth. I slowly applied throttle and as it approached 4000 RPM it began to surge. Engine RPM dropped to about 3250 and would return to almost 4000 then drop down to 3250 and return to almost 4000, repeat, repeat, down/up/down/up/down… Below 3950 RPM it ran smooth and fine. Advance the throttle and it began to surge.
EGTs & CHTs all normal and close to equal. Mag drop at 3900 RPM were almost equal. The lower plugs always have had a 50-75 RPM greater drop. Turning on the boost pump made no difference. Engine has about 25 hrs total time so far and has run like a sewing machine up to now.
Any ideas as to the source of the problem? Any suggestions as what to check? Could it be the Turbo or Turbo Controller?
For starters, I guess I need someone to help operate the throttle while I observe the turbo controller and wastegate operation. Tommy will probably help there.
Any input would be appreciated.
Thanks in advance!
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: [url=tel:817-992-1117]817-992-1117[/url]
rlborger(at)mac.com (rlborger(at)mac.com)
[b]
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klinefelter.kevin(at)gmai
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| Posted: Wed May 16, 2012 4:40 pm Post subject: 914 starts to surge at 3950 RPM |
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Bob,
Was there auto gas in the plane (or even just in the carbs) for a long time without running?
On May 16, 2012, at 4:00 PM, Nati Niv <n992dn(at)gmail.com (n992dn(at)gmail.com)> wrote:
[quote]
I would start with checking fuel flow restriction, clogged filter etc.
Nati
RANS S6S 912uls
Illinois
On Thu, May 17, 2012 at 5:36 AM, Robert Borger <rlborger(at)mac.com (rlborger(at)mac.com)> wrote:
| Quote: | Friends,
As many of you know, my Europa has been down for about a year while it was converted it to tri-gear and I rebuilt the instrument panel. We ran the engine about 2 weeks ago to check the carb balance and idle. Those were OK at the time. I didn't run the engine any further that day because of other commitments (preparing for a 2 week trip to SC). Monday, I went out to do a full run-up and check of the engine. Started fine, idled OK as long as I held the "Choke" out while warming up. After it was warm it idled OK without the "Choke." Engine nice and smooth. I slowly applied throttle and as it approached 4000 RPM it began to surge. Engine RPM dropped to about 3250 and would return to almost 4000 then drop down to 3250 and return to almost 4000, repeat, repeat, down/up/down/up/down… Below 3950 RPM it ran smooth and fine. Advance the throttle and it began to surge.
EGTs & CHTs all normal and close to equal. Mag drop at 3900 RPM were almost equal. The lower plugs always have had a 50-75 RPM greater drop. Turning on the boost pump made no difference. Engine has about 25 hrs total time so far and has run like a sewing machine up to now.
Any ideas as to the source of the problem? Any suggestions as what to check? Could it be the Turbo or Turbo Controller?
For starters, I guess I need someone to help operate the throttle while I observe the turbo controller and wastegate operation. Tommy will probably help there.
Any input would be appreciated.
Thanks in advance!
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: [url=tel:817-992-1117]817-992-1117[/url]
rlborger(at)mac.com (rlborger(at)mac.com)
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[b]
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rlborger(at)mac.com
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| Posted: Wed May 16, 2012 5:07 pm Post subject: 914 starts to surge at 3950 RPM |
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Kevin,
No auto gas, it has only had 100LL.
Nati,
No fuel filters as I have a gascolator. I'll go to the hanger in the morning and check it as well as do a fuel flow measurement.
Blue skies & tailwinds,
Bob Borger
Europa XS Tri, Rotax 914, Airmaster C/S Prop.
Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP
3705 Lynchburg Dr.
Corinth, TX 76208-5331
Cel: 817-992-1117
rlborger(at)mac.com (rlborger(at)mac.com)
On May 16, 2012, at 7:39 PM, klinefelter.kevin(at)gmail.com (klinefelter.kevin(at)gmail.com) wrote:
Bob,
Was there auto gas in the plane (or even just in the carbs) for a long time without running?
On May 16, 2012, at 4:00 PM, Nati Niv <n992dn(at)gmail.com (n992dn(at)gmail.com)> wrote:
| Quote: | I would start with checking fuel flow restriction, clogged filter etc.
Nati
RANS S6S 912uls
Illinois
On Thu, May 17, 2012 at 5:36 AM, Robert Borger <rlborger(at)mac.com (rlborger(at)mac.com)> wrote:
| Quote: | Friends,
As many of you know, my Europa has been down for about a year while it was converted it to tri-gear and I rebuilt the instrument panel. We ran the engine about 2 weeks ago to check the carb balance and idle. Those were OK at the time. I didn't run the engine any further that day because of other commitments (preparing for a 2 week trip to SC). Monday, I went out to do a full run-up and check of the engine. Started fine, idled OK as long as I held the "Choke" out while warming up. After it was warm it idled OK without the "Choke." Engine nice and smooth. I slowly applied throttle and as it approached 4000 RPM it began to surge. Engine RPM dropped to about 3250 and would return to almost 4000 then drop down to 3250 and return to almost 4000, repeat, repeat, down/up/down/up/down… Below 3950 RPM it ran smooth and fine. Advance the throttle and it began to surge.
EGTs & CHTs all normal and close to equal. Mag drop at 3900 RPM were almost equal. The lower plugs always have had a 50-75 RPM greater drop. Turning on the boost pump made no difference. Engine has about 25 hrs total time so far and has run like a sewing machine up to now.
Any ideas as to the source of the problem? Any suggestions as what to check? Could it be the Turbo or Turbo Controller?
For starters, I guess I need someone to help operate the throttle while I observe the turbo controller and wastegate operation. Tommy will probably help there.
Any input would be appreciated.
Thanks in advance!
|
|
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rparigoris
Joined: 24 Nov 2009
Posts: 796
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| Posted: Wed May 16, 2012 7:44 pm Post subject: 914 starts to surge at 3950 RPM |
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Hi Bob
A few ideas:
Is your gasculator rated for 375 horse power? Remember it is not just the fuel used by the motor on a 914 you need to deal with, but the fuel used by the motor and the return fuel flow to the tank. If you check fuel flow, make sure to do the cheat so the engine thinks you are at ~18K trick (I think in the Europa FWF?). It makes a world of sense to have a second fuel filter or gasculator come on line when you turn on your aux. fuel pump. Having a single fuel filter or gasculator somewhere in the circuit is no where near as nice as the current Europa fuel schematic that puts a second one on board with the aux fuel pump. Pretty clever Europa on this point!
Carb problems. OK you are using 100LL, but worth a check for the main jets and the small enriching circuit holes in the bottom of the fuel bowl that they are clear. Make sure that your constant depression slides are smooth and easy to move with no sticking. If you ever took off the float bowls, install new gaskets, leaking gaskets plays hell with 914s. Simple, but make sure your cables are doing their job and the butterflies are opening the same and balance is good. Is there any reason for me to suspect that the carb jet needles amy not be held in their proper position?
Check that the cross over balance tube has no leaks, you don't by chance have a vacuum/pressure tube that forgot to be put back on?
You have a non traditional for Europa air cleaner, perhaps it's clogged or restricting for some reason?/ take it off and give things a try.
Whats' your differential pressure when you get surging?
I don't think many folks have much experience with mechanical 914 pump. If easy bypass it and only try the electric pump?
Does it surge less if you put on full enrichment?
If you jog the wastegate until it's full closed and turn off your TCU, be careful you don't overboost, but does the surging go away?
Does it react the same way on both the left and right mag at surge scenario?
I don't know if you upgraded to the new fuel pressure regulator? If not if it were I and all else fails, I would carefully mark where the setting is at and fool with raising and lowering the pressure with the adjusting screw. If you didn't already do so: GET THAT FOOL DIFFERENTIAL FUEL PRESSURE GAUGE WORKING!
I am taking it for granted that you have the new style kevlar reinforced carb flanges. Inspect carefully for leaks around this joint.
Good luck, let us know what the resolve is.
Ron Parigoris
[quote][b]
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