Yet another Pro.15 help post..  
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Yet another Pro.15 help post.. - 3/3/2007 6:36:26 AM   
Slo-V Flyer



Posts: 2190
Joined: 2/23/2006
From: arlington, TX, USA
Status: offline 		Hi, I'm hoping some nitro gurus can help me out here.

I've tried to search for another thread that might help me but most of them don't discuss the problem I seem to be having with my Pro .15 that I run in a 14 year old Nitro Hawk (it's funny how unexpectedly old plastic parts break...).

I've bought the engine last November, '06. I've got some experience with nitro from before when I had a Cen MT2 and the .16 it had. I've read articles on tuning nitros and such, I broke the Pro .15 in like the manual suggests, about 6-7 tanks to be safe (ran it through different speeds gradually leaning it 1/8 turn or so, waited 5-10 minutes down before next tank). I run it with a blue 360 Stinger pipe (nice and loud!! Plus it looks realistic sticking out the rear bumper)

I'm pretty good about watching the temp and keeping it below 250'F. I've recently realized I could lean the LSN another 1/4 turn so it was nice and peppy and crisp sounding at the low rpm end, as well as keeping the blue smoke streak at high speed.

My problem started a couple days ago, I was running it and I cartwheeled my Nitro Hawk a few feet after hitting a curb. Since then the engine's not behaving normally. Meaning, I'll be running it, and suddenly I'll notice it'll lean up and almost pull a wheelie hitting a small bump, or I'll come around and gun it, and the engine will act "rich" and slowly get up to full speed, as if it was lacking air and fuel altogether. I've ran it about 4 times since then and each time it seems it will randomly change its behavior. The other day it started blowing extra smoke , but then leaned out itself (reached 270+'F) to where I had to richen it almost another 3/4 turns (which is unusual because I always run it between 2 & 1/4 and 2.5 turns out for HSN depending on weather and around ~240'F). Then next time it ran "normal" so I had to re-lean the HSN back to ~2.5 turns out.

I've already taken the engine apart, cleaned out the tank, switched out the fuel line with a longer direct (w/o filter) feed to test it, removed the carb and checked it for junk/broken or needles (cant see anything wrong there either), washed out the air filter and oiled it again, visually checked inside the engine case for anything "unusual" (nothing).

Basically it's running mixed between rich-, then lean-ish next moment, all with a full tank of gas so I know it's not the low level of fuel sloshing and creating bubbles in the fuel flow, YET I notice that when it starts to run erratically, the fuel line (I run a filter which I triple checked for dirt) has "bubbles" or empty space between fuel as it's feeding into the carb. I can't remember if it did that before I started having this problem, but it seems the rpm rises as the bubbles travel to the engine (obviously it leans out a little with those "bubbles" . Only other thing left is besides taking it to the LHs nitro guru and dishing out $$$ is replacing the pressure line that runs from the pipe to the tank and see if it's clogged (it's opaque so I can't see dirt in it like my regular blue fuel line).

If you haven't fallen asleep reading this, well then do you have any experience with this kind of problem. I'm on a budget so I cant just replace it with an OS engine like some of you are eager to suggest. Besides, when I have it running right, it's a screaming little engine, fast enough for the old timer Hawk.

Thanks!

Edit: I just tested the fuel tank for pressure, and it seems the cap is sealing off well (I blow on one end of the tube and I have to open the cap to even let air go through) so I don't think the cap's seal is the problem. I'm thoroughly puzzled.

< Message edited by Slo-V Flyer -- 3/3/2007 6:40:29 AM >

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       Post #: 1

RE: Yet another Pro.15 help post.. - 3/3/2007 6:45:05 AM   
turbotb0205



Posts: 1023
Joined: 7/23/2005
From: Granville, WV, USA
Status: offline 		lol.. sounds like you got a fuel foaming issue..

and i may get flamed for this.. but imma tell you anyways.. there is a way to stop it..

go to your local parts store and buy a bottle of regular normal old fashioned oh did i say REGULAR armor all that stuff you spray on dash and leather in cars..

drop 3 drops DROPS not quarts.. or douses.. or hmm that looks like 3 drops.. use an eye dropper or something.. 3 drops of that to a full gallon of fuel.. it wont foam anymore
yes yes .. i know it sounds silly.. it wont hurt your engine.. or the fuel.. ive done it on my planes and cars for years it works wonders..

OTHERWISE you may have broken the pickup tube in the fuel tank.. cracked it or something causing it to suck air when its trying to draw fuel best way to test it is try a different tank on it and see what it does.. as you cant really see the pickup any which way you look

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RE: Yet another Pro.15 help post.. - 3/3/2007 7:02:15 AM   
Slo-V Flyer



Posts: 2190
Joined: 2/23/2006
From: arlington, TX, USA
Status: offline 		Thanks, and yes I notice when I pour the fuel into the tank from my filler bottle it looks foamy ...at the very top of course, but that goes away and looks normal again. However I don't know if foaming is the problem since it would have done that from the very beginning, no? I've ran about a gallon of fuel (from individual Quart sized cans at first) by now, and just yesterday bought a new 1 gallon 20% Traxxas fuel can, so it can't be bad fuel either. And I'm gonna try to check the fuel tank pick up tube. I don't see any oil stains on the chassis around that part of the tank, but I suspect something is wrong with the tank... or carb?

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Emaxx+Feigao 7XL+full CVDs, Bandit+GTB 3.5R, Rustler+Feigao 9L, TC4+Mamba 5700kv, Mini-T+Mamba 8000kv, Recoil+3800kv, 3s lip

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       Post #: 3

RE: Yet another Pro.15 help post.. - 3/3/2007 4:52:37 PM   
turbotb0205



Posts: 1023
Joined: 7/23/2005
From: Granville, WV, USA
Status: offline 		either way yes doubtfully the carb though its got something screwey in the tank if your seeing air pockets in the line 80% chance its the pickup or a related issue 20% its fuel foaming..

as far as doing it from the start.. ive bought 2 gallons of the same fuel produced about 1 weeks apart on the same day at the lhs .. one gallon foamed the other wouldnt.. its screwey sometimes

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RE: Yet another Pro.15 help post.. - 3/3/2007 6:21:21 PM   
Slo-V Flyer



Posts: 2190
Joined: 2/23/2006
From: arlington, TX, USA
Status: offline 		Well, I ran it today (for what duration I could) before the damn rear sh. tower decided to break so I called it quits. But it seemd to run more steadily than before, except I had to run it a little richer than I usually do, since the engine temp kept climbing up slowly if I didnt, and it seemed to be putting out more power than usual at lower throttle, as in reaching high speed before I even got to WOT. I kept checking for bubbles but it didn't seem to happen as obviously this time, though still it's not acting "normal" as it used to. Wel I've got the shock tower fixed so tomorrow Ill test some more. Thanks for your help though.

< Message edited by Slo-V Flyer -- 3/3/2007 6:22:58 PM >

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RE: Yet another Pro.15 help post.. - 3/4/2007 2:14:48 AM   
HeLLsGoD



Posts: 719
Joined: 2/10/2007
From: hellJP, ANTARCTICA
Status: offline 		Did you check for airleaks? thats whats usually giving people a unstable tune/idle. Also check your radio gear, could be twitching. Your car did do cartwheels

Try doin these http://www.rchobbies.org/engine-tuning.htm

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RE: Yet another Pro.15 help post.. - 3/6/2007 3:39:44 PM   
Slo-V Flyer



Posts: 2190
Joined: 2/23/2006
From: arlington, TX, USA
Status: offline 		Guess I'll try the soapy water trick, and JB-weld any leaks on the engine block that I can find.

On a similar topic, is it also possible that if I don't have the rubber tube between the pipe and exhaust manifold tubing clamping down enough, that it may cause inconsistant performance in the manner above? I've noticed behind my Stinger pipe, where the rubber connector hose meets the main exhaust manifold, there is a little oil residue on the metal part after some use. Is that usually normal or should I make sure that it's as dry as possible by clamping down with some zip-ties?

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Emaxx+Feigao 7XL+full CVDs, Bandit+GTB 3.5R, Rustler+Feigao 9L, TC4+Mamba 5700kv, Mini-T+Mamba 8000kv, Recoil+3800kv, 3s lip

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RE: Yet another Pro.15 help post.. - 3/6/2007 9:35:23 PM   
HeLLsGoD



Posts: 719
Joined: 2/10/2007
From: hellJP, ANTARCTICA
Status: offline 		Yes, you need an airtight system to keep the fuel feed in tune. Theres a chance its not a leak but the exhaust just spitting fuel into it. Check it out first this could be the solution to ur tuning problems. It probably wiggled loose when your car cartwheeled

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RE: Yet another Pro.15 help post.. - 3/9/2007 3:01:39 AM   
Slo-V Flyer



Posts: 2190
Joined: 2/23/2006
From: arlington, TX, USA
Status: offline 		Well, I bought a new rubber tube and tried to connect the muffler and exhaust pipe as tight as I could with zip-ties. It seems to have a better seal since the rubber tube is thicker and harder to get on. I ran the truck through 2 tanks and it seems to be ok now. It ran its usual consistant way, i.e. leaning out as the fuel-tank ran low. Might run it tomorrow and make sure everything is back to normal for sure.

On a related note I skimmed over the Nitro break-in thread and found some interesting perspectives on running an engine. Some of the posters there say that I shouldn't read into the temperature so much as keeping an ear for the sound and performance. Well, I can understand that but then if I don't watch my temps, I can easily get my Pro .15 upto 265-270' and I'll still see smoke (Traxxas 20%) and get great wheelie popping performance, which happens once in a while when I first start out on a warmer day. If what those people are saying is an acceptable method, then that leads me to believe what they're saying about engine companies is true, as far purposely telling us to run rich (The Pro .15 manual suggests temps of ~225-250'F ), even though I run it consistently around 240-250'F with still higher possible performance as I said earlier. In fact, today I let it run upto ~265'F in short WOT bursts (needless to say that let me run around 75% throttle for practical speeds on my field) to see if it acted adversely. Well I didn't melt anything 2 tanks later ,so I'm guessing with some care I should be ok.

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Emaxx+Feigao 7XL+full CVDs, Bandit+GTB 3.5R, Rustler+Feigao 9L, TC4+Mamba 5700kv, Mini-T+Mamba 8000kv, Recoil+3800kv, 3s lip

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RE: Yet another Pro.15 help post.. - 3/9/2007 3:12:36 AM   
hpi apollo



Posts: 2639
Joined: 5/13/2006
From: Georgetown, KY, USA
Status: offline 		this could help alot http://www.rcuniverse.com/forum/m_5517128/tm.htm it has a part on sealing your engine and lots of tuning stuff


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RE: Yet another Pro.15 help post.. - 3/9/2007 3:35:53 AM   
Slo-V Flyer



Posts: 2190
Joined: 2/23/2006
From: arlington, TX, USA
Status: offline 		Thanks, I coincidently just skimmed though that post.

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RE: Yet another Pro.15 help post.. - 4/9/2007 6:26:00 AM   
rccar101


 

Posts: 10
Joined: 4/4/2007
From: Lemon Grove, CA, USA
Status: offline 		its the bubbles in the fuel line it has to be the fuel pressure problem

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RE: Yet another Pro.15 help post.. - 4/12/2007 6:41:14 PM   
Vankata



Posts: 53
Joined: 4/8/2006
From: schaumburg, IL, USA
Status: offline 		I also have a foaming problem with my nitro hawks? the exact same problem, I think its the engine. My .15 tmaxx has the same problem and my 2.5 or 3.3 tmaxxes dont have it. The engine also leaks like crazy.

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