Roger Lee Posted August 1, 2010 Report Share Posted August 1, 2010 Do you have a Dynon D120 EMS and the MAP pressure swings all over and you wish it was more steady? The answer is yes and it's an easy fix. First buy, beg, borrow or steal a Bing main jet of about 150-160. They are about 3/4" long. Now on top of the carb cross over balance tube you will see the small line coming off over on the left side aiming back towards the firewall. It may be a rubber vacuum line or a white plastic line. Pull that off and insert the Bing main jet in the line. I use a wire tire on the outside of the tubing to hold it in place, but it is so snug I doubt it would move. Just reattach MAP vacuum line back to the crossover tube. The small pin hole in the main jet will dampen the impulses through the line and make that MAP pressure rock solid. Link to comment Share on other sites More sharing options...
ozairangel Posted September 20, 2010 Report Share Posted September 20, 2010 Do you have a Dynon D120 EMS and the MAP pressure swings all over and you wish it was more steady? The answer is yes and it's an easy fix. First buy, beg, borrow or steal a Bing main jet of about 150-160. They are about 3/4" long. Now on top of the carb cross over balance tube you will see the small line coming off over on the left side aiming back towards the firewall. It may be a rubber vacuum line or a white plastic line. Pull that off and insert the Bing main jet in the line. I use a wire tire on the outside of the tubing to hold it in place, but it is so snug I doubt it would move. Just reattach MAP vacuum line back to the crossover tube. The small pin hole in the main jet will dampen the impulses through the line and make that MAP pressure rock solid. Link to comment Share on other sites More sharing options...
ozairangel Posted September 20, 2010 Report Share Posted September 20, 2010 Whacko, thanks for that its bothered me since day one. Link to comment Share on other sites More sharing options...
ozairangel Posted September 20, 2010 Report Share Posted September 20, 2010 Do you have a Dynon D120 EMS and the MAP pressure swings all over and you wish it was more steady? The answer is yes and it's an easy fix. First buy, beg, borrow or steal a Bing main jet of about 150-160. They are about 3/4" long. Now on top of the carb cross over balance tube you will see the small line coming off over on the left side aiming back towards the firewall. It may be a rubber vacuum line or a white plastic line. Pull that off and insert the Bing main jet in the line. I use a wire tire on the outside of the tubing to hold it in place, but it is so snug I doubt it would move. Just reattach MAP vacuum line back to the crossover tube. The small pin hole in the main jet will dampen the impulses through the line and make that MAP pressure rock solid. Link to comment Share on other sites More sharing options...
ozairangel Posted September 20, 2010 Report Share Posted September 20, 2010 OK Roger I should have asked this question first, as I am unlikely to get hold of a jet, but i can make a restrictor. what size would that be interms of Thou or mm. Rgds David Link to comment Share on other sites More sharing options...
Roger Lee Posted September 20, 2010 Author Report Share Posted September 20, 2010 Hi David, Just a note. When you reply don't use the button at the bottom of each post. Use the reply button at the top of the page or the bottom of the page. That way it won't quote everything and make these post really long. If you have a motorcycle shop around you can pick up a carb jet there. That's your best bet. If you don't then get a piece of brass or aluminum round stock / rod. Plastic would work, but it would need to be something like Delrin to be able to take the heat. If not the hole needs to be as small as possible. Drill the smallest hole you possible can down through the center. Put this in the hose line right where the tubing comes off the top left side of the carb cross over tube. Put a tie wrap around the outside of the tubing to keep the new part from moving. I have known some people to use a cigarette filter in line. Link to comment Share on other sites More sharing options...
ozairangel Posted September 20, 2010 Report Share Posted September 20, 2010 OK Many Thks...D Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 8, 2011 Report Share Posted March 8, 2011 Would this be a similar issue that may cause higher than normal oil pressure readings? If not, what might cause oil pressure to increase? Link to comment Share on other sites More sharing options...
Roger Lee Posted March 8, 2011 Author Report Share Posted March 8, 2011 Oil pressure is an electronic signal. How high are we talking about? If it keeps going up fairly high or moves all over then you need to tighten the grounds. If it goes up and down with the throttle tighten the grounds. If it drops really low or tightening the grounds don't work buy a new oil pressure sender. Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 8, 2011 Report Share Posted March 8, 2011 The co-owner says that the oil pressure was going up and down with the throttle settings. Link to comment Share on other sites More sharing options...
Roger Lee Posted March 8, 2011 Author Report Share Posted March 8, 2011 It's the grounds. tighten them all. 5 of them, especially the ones behind the passenger side instrument panel on the back of the firewall. There are 4 on the firewall inside the cowl area just above the battery and one going down on the engine mount frame. You will have to loosen the front nut to tighten the rear nut on the 06's with the bolt through the firewall type ground. On later models with the buss bar type just tighten the bolt and then the individual screws that hold the buss bar down. If you don't know what I'm talking about you will once you look in the panel. Consider each ground loose until you put a wrench on it. They may be hand tight, but wrench loose. Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 15, 2011 Report Share Posted March 15, 2011 Update on the oil pressure. It's all over the place. Sometimes, when the RPM's are increased, the oil pressure goes up, but sometimes it goes down. Sometimes, when the RPM's are decreased, the oil pressure goes up, but sometimes it goes down. Sometimes, it's normal. Does that still sound like a "ground" problem? Next time I'm out at the airport, I'll tighten the grounds. Link to comment Share on other sites More sharing options...
Roger Lee Posted March 15, 2011 Author Report Share Posted March 15, 2011 Did the grounds all get tightened? This should have been the first check. Most likely not a ground any more, but the sender. There still is a possibility for the ground, but my money now lies with the sender since it is doing more odd fluctuations that aren't steady or predictable. Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 15, 2011 Report Share Posted March 15, 2011 Here are the comments from the co-owner of N293CT about the occasionally high oil pressure. Any other thoughts? I checked the wiring. All engine compartment grounds were solid, Dynon wiring is fine, connection to the oil pressure transducer was oily and a little loose - tight now. If weather works, I'll fly tomorrow and test it. Link to comment Share on other sites More sharing options...
Roger Lee Posted March 16, 2011 Author Report Share Posted March 16, 2011 I hope when you say the grounds are tight you put a wrench on them or they will be hand tight, but wrench loose. There is no other way to check these other than with a wrench. If those are tight then replace the sender. Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 16, 2011 Report Share Posted March 16, 2011 If it's the sender, does that mean I just had a bad reading - or that I actually had high oil pressure? I had already passed your terms "hand tight" and "wrench loose" on to the maintenance side of our business (not me). Link to comment Share on other sites More sharing options...
Roger Lee Posted March 16, 2011 Author Report Share Posted March 16, 2011 A bad sender means you need to replace the sending unit itself. Just a bad reading. I would highly doubt you have a real oil pressure problem. Rotax 912's are highly dependable. Oil pressure senders on the other hand do fail frequently. Bad readings are almost always bad grounds or bad pressure senders (98% of the time). Just ask Fast Eddie? The only way to tell for sure about any reading of course is to put a mechanical gauge in line with the electric one and see if they match. Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 19, 2011 Report Share Posted March 19, 2011 Looks like our oil pressure is in good shape now. And we removed the strip of radiator tape today. Spring has sprung! Link to comment Share on other sites More sharing options...
Roger Lee Posted March 19, 2011 Author Report Share Posted March 19, 2011 What did you do to fix the problem? Tape is off mine now too. Link to comment Share on other sites More sharing options...
wlfpckrs Posted March 21, 2011 Report Share Posted March 21, 2011 The sender had some oil on it and was loose. We cleaned and tightened it. In a few more hours, we'll get the 1,000-hour service done, and I think we'll re-secure the gearbox to the engine. We have a sneaking suspicion that that is where our phantom oil leak is coming from. Link to comment Share on other sites More sharing options...
Roger Lee Posted March 21, 2011 Author Report Share Posted March 21, 2011 If it is the normal sender and it was loose then you were getting a poor ground. The sender gets it's ground from the engine. This is also the reason they don't want just any Ol' thread locker on the threads because it may interfere with the ground. Link to comment Share on other sites More sharing options...
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