L

luv2flypilot

Well Known Member
My RV-7A has just about hit the 10 hour mark and I have started having some engine issues in the last few hours. I first noticed it on Friday when I was staying in the pattern and working on full stop landings and heard some back firing and engine roughness when I pulled back the power to turn base to final. After I landed I performed a run up and it seemed to be running a little rough. I then cleaned the fuel injectors and well as checked the plugs. Nothing appeared to be wrong with what was found. Did another run up and everything seemed to be fine. I flew it for about an hour and did not appear to have any problems until I came in for landing and started hearing bad back-firing on final when I pulled back the power to around 15 MP. I did some research on here (VAF) Friday night and read that the "Shotgun Approach" was normal with an RV that has Vetterman exhaust (like I have) and was caused from unburned fuel, so I decided not too worry too much about it (however this was the first time I have heard this). Also, I should mention that from the start I have had intermittent issues with abnormal high EGT temps on #3, however the CHT temps seemed to be normal so I did not worry about it and thought that maybe I had a bad sensor and was planning on swapping it with another sensor to see if the problem followed. Yesterday when I went to go fly, I did my run up and everything seemed to be just fine. The only issue was the intermittent EGT temp going up around 1650 to around 1750 during the run up, but stabilized on normal idle . On take off and climb at about 150' and around 3/4 down the runway I heard a few backfires. I started looking for a good spot to put her down in the event I lost the engine since I knew I would not make it back to the runway at that point. I slowly pulled back on the power to around 70% and reduced my climb attitude and the backfiring stopped. I was able to keep a tight pattern and get back and land, but it did not seem to be running very smooth. I was worried about pulling back off the power until I new I could make the runway, so I slowly pulled back when I knew I would make it and kept a little power in until I was over the numbers. When I pulled power back right before flare, the engine never stopped but I thought it was going to by how rough it was running. While taxiing back to my hanger I leaned it a little, however it still sounded like a "Harley" popping and sputtering. An A&I on the airport that heard and saw what happened and said he thought it was running too fat and that I may have a timing issue, but was not familiar with the dual LASAR ignition I have. From what I have been reading the last day or so, it looks like I will have to get a hold of a syncro timing tool in order to check the timing or to see if it is possibly that the LASAR ignition is the problem. Today I went back and cleaned my fuel injectors again as well as checked the plugs again and did not see anything that appeared to be abnormal. I tried to do another high RPM run up and found the engine still seemed to be running rough at high RPMs and will not stay running at idle with quit a bit of sputtering and backfiring at low rpm below 900-950 RPM. It seems to run the best around 1300-1400 RPM, but not as smooth as it should. I plan on calling Eagle Engines tomorrow (where I purchased the brand new engine) to see if they have some recommendations. If anyone has any suggestions that could help me out, it would be greatly appreciated.

The following is my engine set up:
Engine: IO-360-B1BC3, 9 to 1, Roller Lifters, Flow Matched Cylinders, Dual Unison LASAR Ignition, Sky-Tec Starter, Silver Hawk Fuel Injection
 
Last edited:
Thanks Mike

I am going to call Eagle Engines in the morning to see what they suggest at this point. I am thinking that I may need to check the LASAR with the timing tool and really appreciate your offer and may take you up on it depending what suggestions Eagle Engines give me to try first.
 
YOU MUST HAVE A LASAR TIMING TOOL!

If you have a LASAR ignition system you must have a LASAR timing tool to make sure the timing is right both now and when you have to eventually replace a "MAG". My engine was delivered directly from Lycoming as a drop shipment ordered through Van's. It was accompanied by test cell data saying that everything was fine when the timing was off by approximately 65 degrees! I ran it and flew it that way until working with Unison and Lycoming via telephone I bought the tester from Van's and fixed the problem. The instructions for using the tool are easily misread and the first time I set the timing I came up with precisely the same setting as Lycoming which I knew was wrong! I went back and did it again without glossing over a single word and it worked perfectly. Things like TDC can be read as physical top dead center of the compression stroke of cylinder #1 when the instructions are actually referring to a light on the box labeled TDC. As soon as I started reading you problem description, even the number of hours if brought back memories of my early flights with the incorrect timing.

I recheck the timing every year as part of my annual condition inspection and I can assure you that once set it is very stable and reliable. I race my RV-6A in the Sport Air Racing League races (www.sportairrace.org) and I won the RV Blue class in 2007 and 2008. I had the non-sensor mag fail after around 400 hours but no other difficulty.

Bob Axsom
 
Bob's right......

You really need the timing tool. Have Lasar on mine, never misses at beat, but you just can't time it without one.
 
LASAR Timing Tool

It looks like I will have another investment and tool to put in my hanger. Hopefully I can still purchase the tool somewhere since Unison is no longer from what I understand. I have read about people having problems with their LASAR systems and getting rid of them, so I would first like to borrow or rent a tool to make sure that is the problem and it corrects it. I would hate to invest the money in the tool and find out that my mags or LASAR box is bad and have to go with another electronic ignition or straight slick mags if I cannot get the parts under warranty since the engine is new. Thanks for all the replies so far.
 
Unison is still there

luv2flypilot said:
It looks like I will have another investment and tool to put in my hanger. Hopefully I can still purchase the tool somewhere since Unison is no longer from what I understand. I have read about people having problems with their LASAR systems and getting rid of them, so I would first like to borrow or rent a tool to make sure that is the problem and it corrects it. I would hate to invest the money in the tool and find out that my mags or LASAR box is bad and have to go with another electronic ignition or straight slick mags if I cannot get the parts under warranty since the engine is new. Thanks for all the replies so far.
Click to expand...

I just called Unison at 1-904-739-4000 and got the normal Unison Industries automatic menu system. I followed the number selection sequence to get to technical support for GA. I ended up with voice mail for some guy who was "in the office but away from my desk" response followed by please leave a message and I will call you back. Anyway, they are still there and if you are going to keep your LASAR system you need your own timing box for the independent ability to maintain your system. I bought mine through Van's.

Bob Axsom
 
Thanks Bob

Thanks Bob, I also called and left a message in hopes to get a call back. Mike Starkey is kind enough to let me borrow his timing tool so I will first make sure this is something that I can correct and verify is an ignition problem before I start running down the wrong rabbit trail. If I end up being able to get the problem fixed without junking the LASAR system, I plan on gpurchasing a timing tool and learning more about what is needed to keep the maintenance on the system.
 
I Think I Figured Out The Problem

After a few phone calls speaking with James Dean at Eagle Engines and Joe Logie with Champion Aerospace and formerly with Unison I think I have things figured out. Eagle Engines recommended I adjust the fuel servo on the throttle body back to be a bit more lean and see what happens and after speaking with Joe Logie with tech support for the LASAR he seemed to think it was NOT a LASAR ignition symptom based on what is going on. Joe seems to be the man to talk to regarding LASAR as he told me that he use to be with Unison and was the man guy working on the LASAR system and after GE then Champion purchased the rights he was recruited.

After slowly adjusting the fuel servo adjustment on the throttle body and chocking up my airplane, I was able to do high power run ups to 2500 RPM without the engine missing a beat. It took me 4-5 adjustments before it seemed to get better and better and then what seems to be the best and smooth setting. I am thinking that even though I have put 6 hours on the engine without any trace of a any problems with exception to what I thought was a possible bad EGT probe, that this was a problem from the start and was just getting worse and worse as it was too rich and the engine was breaking in. Now with the fuel flow adjusted, I even have stable EGT temps on #3 as well as a more consistent CHT temps that is even with the other cylinders. Another thing I noticed today before I made the adjustment was that the EGT on #3 was running really hot and the CHT seemed to be 40-60 degrees cooler than the other cylinders. Does this seem to make sense to anyone that is more familiar with engines? I feel much better that the EGT temps have stabilized and I have things back to normal. Tomorrow I plan on cowling her up and doing a few more run ups and hopefully go flying again.

Thanks for everyones help. It is awesome that there are so many helpful people on here!
 
Last edited:
The after-firing (popping in the exhaust) is normal for throttle reductions with FI, as is the crummy ground idle when hot. Was it hot outside then?

Seems like the non-normal event was during your takeoff. The popping on throttle reductions and crummy ground idle can be ignored for now, but your takeoff power problem is very concerning, and may or may not be related to fuel. Do you have a fuel flow sensor, and if so, what is the fuel burn during WOT take off power? C/S or fixed pitch? I'm not familiar with the Silver Hawk system, but isn't the adjustment only for idle and just above idle mixtures? If so, it shouldn't be related to your take off power problem.

As for checking the Lasar system, once you have verified TDC timing of the left Lasar mag, and base point timing of both mags, you could try running the Lasar in backup mode. This is simply where you pull the breaker on the Lasar's power (after you have started the engine), and run on magnetos at base timing. This will eliminate any possible misbehaving Lasar electronics. It is helpful to know that the Lasar is in backup mode for some number of seconds after you do a mag check, I don't remember how many. If it is running poorly at high power settings, you could switch off a mag, which also forces it into backup mode, then switch back to both. If it runs ok for xx seconds, and then goes awry, it is likely the Lasar system. (BTW - if the TDC of the left mag is correct, but the point break is not at the baseline timing of 20 or 25 degrees, the points need to be adjusted.)

Keep us posted please.
 
Back to the drawing board...

After 3-4 what seem to be good high RPM run ups this afternoon, I went back to the hanger tonight to cowl her up and try it again. Unfortunately it started running rough again at high RPM (2250-2450 RPM) and I noticed it started when EGT #3 started getting high temps (around 1850 to 1900). It seems to be when the EGT temps get high that it runs rough and backfires. I tried adjusting the fuel servo at the throttle body richer then leaner to see if it improved or got worse and really could not tell, however after 5-6 run ups the temps on #3 seem to start looking normal and then EGT and CHT #4 started running really low compared to the other cylinders with it running really really rough above 1600-1700 RPM and seemed like I only had about 70% power available to the engine, so I did not push it past that point.

Alex, thanks for your input and to answer some of your questions it has been about 90-95 degrees here the last few days and I do have a constant speed Whirlwind 200RV propeller. I will have to check the fuel burn on WOT takeoff power since I do have an AFS 3400 that monitors all my temps and sensors as well as I will check with Eagle Engines tomorrow to see if the servo I am adjusting is just for idle as I may be chasing my tail on what I thought may be helping. I think I will go ahead and check the timing on the LASAR and borrow the tool from Mike Starkey, since he offered to let me borrow it to verify things with the ignition. I have tried running in back up mode on the LASAR with it turned off, but I did not turn it off after the engine was already started, I believe I had it turned off on start. I have a Vertical Power VP-200, so I can control power to any device by going in and turning on & off anything as needed. Based on my conversations with the LASAR tech support today, I am thinking its likely a fuel/air mixture problem or something else and not the ignition, but it won't hurt to check it. Thanks for everyones input and hopefully it is something simple that I am overlooking.
 
Last edited:
Although you have checked and cleaned the injectors I wonder if your #3 is getting enough fuel. Try removing the injectors and measuring the flow through the lines by using your boost pump. You can slip plastic hose over the lines and run them into four separate glass jars.
 
Look for a bad plug or ignition lead...

luv2flypilot said:
Another thing I noticed today before I made the adjustment was that the EGT on #3 was running really hot and the CHT seemed to be 40-60 degrees cooler than the other cylinders.
Click to expand...

A high EGT coupled with a low CHT is very likely to be a bad plug or ignition lead on that cylinder. When 1 plug stops firing at high power, it has the same effect as drastically retarding the timing on that cylinder, thus you lose power, you have lower peak cylinder pressures (hence the drop in temperature), and the hot expanding combustion gases go out the exhaust valve instead of putting most of the combustion energy into driving the piston (due to the retarded timing effect) resulting in the increased EGT.

It sounds like the problem appears when your engine compartment temperatures are high.

Try doing some more mag checks when the engine is warm and you begin to see the problem. You just might find a dead plug!

Skylor
RV-8 Under Construction
 
Last edited:
luv2flypilot said:
After 3-4 what seem to be good high RPM run ups this afternoon, I went back to the hanger tonight to cowl her up and try it again. Unfortunately it started running rough again at high RPM
Click to expand...

O.K., long shot here, but check that there is nothing that gets changed/altered/effected by putting the cowling on.

Look at induction air path, loose wiring for plugs, sensors. ETC.

Skylor has good advise, he is correct that a dead plug can present as a timing problem.
 
Today's Update....

OK, I read all of your helpful posts as well as spoke with James Dean at Eagle Engines and went back and tried the following:

1) I used small glass jars and disconnected the fuel lines from the cylinders and put them in the jars while still connected. With the mixture in I ran the fuel pump for 4-5 seconds and verified that each of the jars was getting fuel and appeared to have about the same amount of fuel in it.

2) I pulled all of the plugs and cleaned them with brake cleaner and a brass wire brush. All of the lower plugs seemed to be pretty black and oily and the upper plugs black and had a bit of carbon build up. I rotated the lower to the upper and installed plugs 3 and 4 to 1 and 2 and 1 and 2 to 3 and 4 to see if the abnormal high EGT and low CHT that I was having on #3 followed the plugs.

3) I ran the engine and it ran terrible and very rough and would not even allow me to power it up.

4) I pulled the fuel injectors and found that #1 and #2 were clogged. I soaked all of them with Hoppe's gun powder solvent and blew them out with an air compressor and re-installed them.

5) I started the engine and everything seemed to run really well with exception to the still high EGT temps (1700-1850F) and lower CHT temps (200-240F) on #3 at high RPM. No backfiring and everything seemed to run well, but this still bothers me. When I brought it back down to 900-1000 RPM and leaned it out a bit, the EGT temps came down to normal and stabilized with the others. I also tried running up on the left mag and then the right mag and had the same issue. I would think this would eliminate a possible bad plug or timing issue?

I think the next step I am going to do is check my fuel filter. I am wondering why I found two injectors clogged? I have the standard Van's fuel pump and filter between the tanks so if I had any crud in my tanks (I purchased the plan from someone that already had the wings already completed) that the fuel filter should be catching it. I also verified that it does not appear anything is changing with the wires or sensors when the cowl is installed and all my testing today was with the cowl off.

Any more suggestions would be greatly appreciated.
 
Last edited:
Exhaust valve leaking perhaps? Sticking or floating at the higher rpms? Might want to do a compression check. A quick check even before that is to (verify the mags are off) pull the prop through all four cylinders' compression cycles. You will know if one is soft. Perhaps pull the rocker cover on #3 and look at the spring etc..

Is there an inlet filter in the Silver Hawk? If so, it seems that perhaps some crud has been assembled inside the system. Might be a good idea to pull the servo and send it back to the factory for disassembly and cleaning. A thorough cleaning of all the injector lines would also be a good idea.
 
AlexPeterson said:
Exhaust valve leaking perhaps? Sticking or floating at the higher rpms? Might want to do a compression check. A quick check even before that is to (verify the mags are off) pull the prop through all four cylinders' compression cycles. You will know if one is soft. Perhaps pull the rocker cover on #3 and look at the spring etc..
Click to expand...

Yep, the more I think about this the more I agree with Alex that this could be a sticking exhaust valve on #3...this will also lead to high EGT's and low CHT's. In fact, the EGT's that you're seeing on #3 are high enough that I think the sticking or leaking exhaust valve is more likely than the bad plug...


Is there an inlet filter in the Silver Hawk? If so, it seems that perhaps some crud has been assembled inside the system. Might be a good idea to pull the servo and send it back to the factory for disassembly and cleaning. A thorough cleaning of all the injector lines would also be a good idea.
Click to expand...

The issues that you've previously noted (before removing the injector lines) are not symptomatic of clogged injectors. A partially clogged injector will either cause the cylinder to lean from full rich towards peak egt, resulting in both EGT and CHT increase (but not 1900F EGT, normally aspirated) or for the cylinder to lean beyond peak, resulting in both reduce CHT and EGT...

The GAMI folks have suggested that the most common cause of clogged fuel injectors is debris introduced when the fuel system is disassembled or injectors are removed for cleaning. In fact, they (George Braly himself) recommend only cleaning injectors if they show signs of clogging, and otherwise they recommend that the injectors be left alone on a well running engine. Is it possible that the gunk you found could have been introduced when you took things apart to flow test the injectors? Again, the original symptoms that you've noted of very high EGT on 3 along with reduced CHT just doesn't fit the clogged injector scenario.

Skylor
 
Today's Update....

Thanks for everyones input. The last two days the engine has been running very smooth at all power settings during test run ups, so I am hoping the issue I had was clogged injectors and an intermittent bad EGT probe. Now that I have removed and cleaned the plugs and injectors, things are running great. I thought I may have found the possible high EGT problem by tightening the two hose clamps on the bottom of the exhaust intake, however I did another run up tonight and the high EGT is back and seems to be an intermittent problem. The temp was all over the board and at one point it jumped to 1950 F and stayed there for quit some time. The CHT on #3 seems to be within 10-30 degrees of all the other CHTs now. Eagle Engines told me that if the EGT probe has an open on it, it will read a very high reading and that they don't think it is even possible to get an EGT reading over 1700 if the CHT temp is within the proper limits. I am hoping it is just a bad EGT probe or connection at the crimp connector to the probe that was also soldered and then heat shrinked. Tomorrow I will move the EGT probe from #1 back to #3 (since #3 is in the back and #1 has enough length) and see if the high EGT temp follows. I will also try checking the terminal connections on the AFS EGT probe to assure I have a good solid connection to the thermalcouple wire connection. If I still get high readings on probe #1 moved to cylinder #3, I will take it to the next step and have a engine mechanic check it out to see if I have a sticking exhaust valve on #3. Thanks again for everyones help.
 
Final Update... Flying Again

I moved EGT #1 to #3 since it had enough length on it to reach #3 and did 3-4 run ups with no issues or high EGTs. At this point I figured it was a bad sensor. I pulled back the shrink tubing on the sensor and cut and soldered them directly to the thermalcouple wires since AFS told me that would be Ok to verify it was not a bad terminal connection and still got the intermittent readings. Looks like a bad EGT probe so I called AFS and they have one shipping out tomorrow.

I flew 1.8 hours tonight and everything ran great. The EGT probe even settled down during cruise with everything in the green.

Thanks for everyones help.
 
You must log in or register to reply here.