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lots of smoke but good performance (is it tuned right)


newnitroer

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Hi all,

 

Took my HPI Bullet out tonight after it being left in my room for the pass four months it started right up on the 2nd pull and wanted to run away however that was fix by a quick adjustment to the idle screw.

 

I am now learning to tune the car myself instead of paying someone £20 to do it but I'm a bit confused tonight it was around 2 to 3 C (35 to 36F) the car had good performance all the way from idle up the WOT and could sit there idling for as long as I wanted to but there was a lot of smoke coming out the exhausted the smoke was blue in colour as it should be and even at idle the smoke was pouring out.

So was the car tuned correctly it did not sound bogged down and would idle for a good 5 or 6 mins before the engine cut out. It wasn't screaming as if it was about to blow up so couldn't of been running 2 lean. If you think of a diesel car starting up on a cold morning or a diesel locomotive being started up cold then this is around the level of smoke I had coming out the exhaust for the whole of my hour long bashing around the local car park. temperatures were between 200F (93C)  and 210F (98C) for the whole time and the engine was pre heated with a engine heater before starting. 

 

I may be worth pointing out that after the car had gone though its 1st tank of fuel after refueling it was very hard to restart and even restart after refueling gave a different result sometimes it would just start up other times it would take about 6 pulls to start and some times I would just be pulling pulling and pulling and all I would see is exhaust smoke puffing out the exhaust.

 

so what is the problem I'm guessing I might be just a little bit 2 rich (its my understand in cold weather u need to run rich) but the reason why I am not sure is because I'm getting good performance both at the high and the low end and on the idle but then at the same time I am also having problems restarting the car with a mix of different results per restart.

 

Thanks for your help

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Have you got a IR temp gun? Going by smoke is almost impossible to tune your car as with fuels like Optifuel, they can be really smokey no matter the tune. You really need to tune it by the temp around the glow plug area.

 

What fuel are you running?  

 

As for the restarting normally you should leave it for a few mins before firing it back up to let it cool for a bit, you might be trying to start it too soon? I always used to leave it about 4 mins off on my old .21 engine after a full tank before starting again and always started in less than 4/5 pulls most of the time less. 

 

 

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8 hours ago, HellaFlush said:

Have you got a IR temp gun?

 

What fuel are you running?  

 

I always used to leave it about 4 mins off

 

 

Yes I do have a IR temp gun that's were I got the engine temperature of between 200F and 210F from the fuel I'm using is HPI Power Fuel 25% and is the fuel I been using for the pass year now since I 1st got the truck (but this is the 1st time I am tuning it myself) I will try that trick when I take it out later and leave it for a good 4 mins before starting it up again.

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1 minute ago, newnitroer said:

Yes I do have a IR temp gun that's were I got the engine temperature of between 200F and 210F from the fuel I'm using is HPI Power Fuel 25% and is the fuel I been using for the pass year now since I 1st got the truck (but this is the 1st time I am tuning it myself) I will try that trick when I take it out later and leave it for a good 4 mins before starting it up again.

 

Sorry I didn't see that bit haha, was up very late. From memory I think them temps sound about right. Never used that fuel so can't really comment on it's smokeyness to be honest. 

 

Also have you tried resetting all the needles back to factory spec? 

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1 minute ago, HellaFlush said:

 

Sorry I didn't see that bit haha

 

Also have you tried resetting all the needles back to factory spec? 

:D no  problem I was up half the night just trying to get on to the site to see if someone had replied

 

No I haven't because when I 1st got the truck it took me about 2 months just to get the thing started at factory spec and that was only because I took it to the shop (trying to avoid that this time). I want to try and avoid going back to factory spec because the last the shop tuned it was in November and I'm sure I will not have to change the tune to much from what they set it to. 

 

The outside temperature in the pass two months has not changed that much so I am hoping I can just make slight adjustment to there tune and then as I get more use to tuning later on towards summer when the temperature really start changing I will be able to set it to factory spec and then tune it for the summer weather.

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Temps seem good, performance is good and it idles fine? Id consider yourself lucky and enjoy it how it is. Im sure youll have issues down the line where it wont even start so enjoy it as it is. Could be burning off old fuel, could be your new fuel is smokey, could be the fact it was cold out at the smoke was more visable than normal? I wouldnt worry if its running to temp and performing well.

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2 minutes ago, Guns said:

Temps seem good, performance is good and it idles fine? Id consider yourself lucky and enjoy it how it is. Im sure youll have issues down the line where it wont even start so enjoy it as it is. Could be burning off old fuel, could be your new fuel is smokey, could be the fact it was cold out at the smoke was more visable than normal? I wouldnt worry if its running to temp and performing well.

To be honest that what I was thinking and wanted confirming I did put loads of After run oil in it, the fuel was not that smoky in the summer but like it say it was cold out and I was driving in the dark after the store closed (about 8pm) so maybe it just shows up more in the dark. will see what a few other people say about it but I think you maybe right as this is what I was thinking as well.

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How old/used is the engine? Worn engines have less compression when hot. Make sure your fully priming when it is hot, squirt some fuel down the carb to be sure. This will also cool then engine. Temps are fine, about 200F is min after a tank, try leaning HSN a bit and test WOT runs for peak performance, monitor temps. You will feel and hear difference. Then tune LSN and idle, assuming it idles OK and doesnt cut out accelerating. Turn the flywheel when it's hot and feel the compression at TDC and compare when it's cold. Dont burn your fingers!

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Just now, locky said:

How old/used is the engine? Worn engines have less compression when hot. Make sure your fully priming when it is hot, squirt some fuel down the carb to be sure. This will also cool then engine. Temps are fine, about 200F is min after a tank, try leaning HSN a bit and test WOT runs for peak performance, monitor temps. You will feel and hear difference. Then tune LSN and idle, assuming it idles OK and doesnt cut out accelerating. Turn the flywheel when it's hot and feel the compression at TDC and compare when it's cold. Dont burn your fingers!

its a year and 1 month old and in that time has only been out about 4 times (thanks to me crashing it well it is my 1st nitro truck :D) Will have a go at leaning the HSN when I take it out in a bit and will do the WOT test and also the compression test I am hoping the engine should be fine still though after just a year and after not even being used that much most of them runs were only 1 or 2 tanks per run.

 

Please remind me which way is lean and am I right in thinking that after leaning the HSN I also have to lean the LSN or would there be a chance I might have to richen it. As with the idle I just set it to 1mm and the car should sit still was a good steady idle and not be wanting to move is that right ??

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Been watching the video in the tuning guide and I am now sure than ever that despite the cold weather I am running the car 2 rich and it needs leaning out a bit both on the top of bottom end going to take it out now so will come back and report what happened thanks to everyone how has helped so far and keep the replies rolling in just in case I still have problems when I get back.

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well I took it out and think I found the problem I most likely didn't see it yesterday because of driving in the dark and I had to boy shell on but I got a fuel leek right in the fuel tube and the hole in the tube is right before the hole that the fuel goes in to get into the engine I only noticed it when I saw smoke coming from (what I though was the engine) but then as I blocked the exhausted to turn it off fuel sprayed on to my hard and I could see the fuel sparying out I'm yet to see how big the hole is but considering it was spraying out like a hose pipe right onto the exhaust it must be big.

 

oh well quick bike ride to the LHS tomorrow for some fuel tube I'm also guessing this is causing the tuning problem and that now my so called good performance could of just be fake and caused by the fuel leek.

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58 minutes ago, locky said:

Just chop the split end off, you should have some slack, but spare tubing always helpful. Splits can occur in tubing just before the nipple as where it can rub.

good idea never though of that problem now fixed might buy some spare fuel tube any way. more testing tomorow

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58 minutes ago, locky said:

Just chop the split end off, you should have some slack, but spare tubing always helpful. Splits can occur in tubing just before the nipple as where it can rub.

good idea never though of that problem now fixed might buy some spare fuel tube any way. more testing tomorow

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One quick semi off topic question I got the sky RC engine heater and once it gets to about 25 to 30 c its starts smocking is that normal or should it not be doing that the engine heather is brand new having only just been taken out the box yesterday.

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Its like a hot rubber burning smell so which it must be the heat pad on the inside of the heater getting hot I had the temp gun on it and it starts smoking around 32 c I wont get a hot air gun now that I got the engine heater to be honest I'm on a tight budget with only a weekend (weather dependent) part time job and then college all week it took me 6 moths just to be able to afford the engine heater and the lipo to go with it.

 

Off college tomorrow so taking advantage of the daylight instead of getting home with only an hour or so day light left getting up at the crack of dawn and taking it down the park to see what happens tomorrow all replies will be done as things as happening. I may even take the camcorder down so that I can record what is happen if that would be of benefit to you guys.

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Took it out today for a good hour and a half and nearly got it tuned perfectly I think I can still get a bit more power out of it on the top end and the acceleration from stand still needs a bit of work looks like the problem I had with the smoke was all caused by that fuel leek as today I had the smoke trail I have always been use to and the car is no longer bellowing smoke out like a steam locomotive but there are still a few teething issues I could use your help with.

 

1. Once the car is hot if the engine cuts out for any reason its a pain to restart all I get is smoke coming out the exhaust and the pull feels very lose and as if its not doing nothing if you get what I mean. The pull start is still turning the engine but it just feels very lose kind of hard to put into word but hope you know what I mean. The only way to get the engine to start when hot is to open the throttle trim a bit.

 

2. (See the attached picture (tinypic) for this one) Once the tank get to that level of fuel (just in case you cant see it I put my finger where it is) the engine will cut out as above the same thing just exhaust smoke coming out but it wont start the pull start is not affected by this. The only way to get the engine to start again is to fill the tank up I use to be able to drive tell the tank was dry what's going on here is it the tune.

 

http://tinypic.com/r/vxcfix/9

 

3. Temps are always between 200 to 215 F (190 to 200 at idle and 215 just after for WOT runs

 

4. As I said above the low end stills needs adjusting when throttle is applied it will pull away but then all a sudden take off If I am correct it should just take off from the start? Also in relation into the high end sometimes when going to WOT the engine will not bog down but will drop RPM nearly still and then regain its self again if I quickly let my finger off the throttle but this only happens sometimes and is not a reoccurring problem so what could the cause be.

 

Thanks for all your continued help everyone as you can see progress is being made slowly and I am very happy that I now have the confidence to tune the engine and touch the needles something I would not of done with out the help of the forum..

 

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Hot engines will have less compression so feel easier to turn over. Cutting out when hot sounds like it is too lean or there is little compression, but you said that it was a new engine and only ran a few times. So try richening HSN. Cutting out when fuel level is low is strange but maybe linked to lean HSN, some tanks will cause leaner mix as it empties.

If your HSN is too lean, after a full throttle pass when you let off the throttle the engine is still lean causing the idle to hang and idle high until the LSN has a chance to take over and meter the right amount of fuel to bring the idle down to normal running speed (given the LSN is set correctly).

If the opposite happens, after a full throttle pass when you let off the throttle it drops to a good idle right away and then starts to idle back up too high, this is a sign that the LSN is too lean. If it comes off full throttle with a good tune and will drop RPM nicely then the HSN is metering the fuel properly but once it hits idle the LSN being too lean will quickly take over causing the RPM to go back up.

 

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Working tomorrow but will get there early to have a play with the car (its so convenient when you work in a park and have a hobby like this :D) and see if richening the HSN will help I though this might of been the case I have not notice what the car does when I let go and let it idle so will be sure to listen out tomorrow richen it and will then report back here.

 

Also contacted the company I brought that engine heater from about the smoking just to make sure I'm not about to blow the car myself or the lipo battery attached to the heater up better safe than sorry.

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