550xp strong in cut; sometimes hard to start and hesitates off idle

[JohnnyD]

I have about 10 tanks through my 550xp. It's flawlessly strong in the cut. It's sometimes a pain to get started and running, however. When cold, it fires on choke after 3 or 4 pulls, which is okay. I immediately drop the choke off, and then it usually fires with 1 or 2 pulls -- but it often won't keep running, even though the high-idle is still set. It often takes several re-starts, letting it try to idle (touching the throttle usually kills it), until it finally keeps going on its own. It also exhausts lots of smoke during this cold starting process. I've tried it with the air purge and without, but I don't see a repeatable pattern of better or worse from using it or not.

Finally, it can take some throttle and the smoke clears up. The whole cold starting dance takes about 2-3 minutes, but it's the only 2-stroke engine I've got that takes more than 30 seconds to get idling smoothly.

The saw also has a peculiar off-idle response. If it has idled only 1 or 2 seconds since the last cut, it responds instantly to the throttle pull for the next cut. If it idles for about 5 seconds or more, you can almost hear it drop a few rpms into a lower idle state. After those 5 seconds or so, the saw hestitates or bogs just a quarter-second before responding to a full throttle input. If I give it a quick 1/8 throttle blip, the saw will die just like I've hit the kill switch (full throttle blip doesn't kill it).

On a traditional carb, I'd adjust the L screw until these symptoms went away. With autotune, however, I've got nothing to adjust. I can take it back to my dealer to look at, but these aren't major issues that keep me from cutting -- just irksome behaviors that I can work around.

Have any other 550xp or autotune owners seen similar behaviors? Any suggestions?

Thanks.

 

[JohnnyD]

Any autotune or 550xp owners out there?

 

[Tzed250]

I would say that a trip to the dealer for some time with the diagnostic tool is in order. My 550 acts nothing like that.

 

[sunfish]

Not normal for a 550xp. Take it back to the dealer...

 

[Hustihler]

Sorry to hear about your issues with your 550xp. They truly are great saws. I own a 562xp and a 550xp and both are in the shop right now. I started 2 threads about mine 1) The truth about auto tunes and m-tronics and 2) auto tunes in the shop. Maybe you can check out both threads and gain a little insight. Both of my saws have warm/hot start issues, I don't know if that fits in with your problems or not, but just trying to help. I'll keep the threads updated as I hope my issues will be resolved this week and I'll pass along any info that the dealer gives me. Good luck. But like Tzed said, if your saw is still under warranty, I'd probably just let your dealer sort it out.

 

[blsnelling]

There's actually a L needle on the 550. It sounds like yours needs opened 1/4 turn. It's in a recess on the face of the carb, on the left side.

 

[H 2 H]

Seems the tuners here are not having the problem with these saws just the average Joe is

HMMMMM

For the record I haven't ran the 550 or 562 only seen pictures of them :jester:

 

[TK]

The large amounts of smoke indicate a poor quality fuel or oil or both, or a real heavy mix ratio to me. Smoke ain't an issue with mine at all. Hot or cold. First startup is a little numb for a couple of minutes but no dying problems. As soon as it gets a little heat into the cylinder it runs great. I'd be curious as to what your fuel mix looks like.

 

[mweba]

Sounds like it is loading up to me. No matter, its near impossible to diagnosed behind a computer screen. Take her in, that is what warranty is for. Auto tune or needles, carbs can still be defective. Tuning out an underlying issue isn't a fix.

 

[blsnelling]

Mine did have a bad carb that had to be replaced when new. Hopefully your dealer has the electronic tools needed to replace it.

 

[JohnnyD]

The large amounts of smoke indicate a poor quality fuel or oil or both, or a real heavy mix ratio to me. Smoke ain't an issue with mine at all. Hot or cold. First startup is a little numb for a couple of minutes but no dying problems. As soon as it gets a little heat into the cylinder it runs great. I'd be curious as to what your fuel mix looks like.

The fuel is 2 weeks old, with Stihl Ultra mixed at 50:1. The smoking is only temporary, maybe 10 or 15 seconds, when the saw won't take much throttle after a cold start. Once it's warmer, there's no smoke at all.

I don't want to exaggerate the symptoms here. The saw doesn't die on me at every cold start. It's just that some cold starts are problematic and require a few restarts. Also, the saw doesn't die under normal use once it's warm. It's only if I let it idle for 5 or 10 seconds and flick the throttle ever so slightly -- something I never do during normal operation.

My experience is that these are the kinds of things that can frustrate both the dealer and the customer. They're not major performance issues. They're just nags. I may or may not be able to demonstrate the behaviors reliably for the dealer. The dealer may or may not experience the symptoms the same as I do since he doesn't use the saw under the same conditions. Even if the dealer makes a good faith effort to "fix" it, it may not be much better for me when I start living with it again. Then he feels like he's given a lot (he has), and I feel like I've given a lot (I have), and neither of us is particularly satisfied with the outcome.

Ever have one of those feelings that it just isn't quite right, but that you'd have a hard time convincing a jury about it? That's where I am.

 

[sunfish]

The large amounts of smoke indicate a poor quality fuel or oil or both, or a real heavy mix ratio to me. Smoke ain't an issue with mine at all. Hot or cold. First startup is a little numb for a couple of minutes but no dying problems. As soon as it gets a little heat into the cylinder it runs great. I'd be curious as to what your fuel mix looks like.

Sounds like it is loading up to me. No matter, its near impossible to diagnosed behind a computer screen. Take her in, that is what warranty is for. Auto tune or needles, carbs can still be defective. Tuning out an underlying issue isn't a fix.

Repeat and reread.

 

[blsnelling]

Adjust that L needle and I think you'll save both yourself and your dealer a lot of frustration.

 

[TK]

The fuel is 2 weeks old, with Stihl Ultra mixed at 50:1. The smoking is only temporary, maybe 10 or 15 seconds, when the saw won't take much throttle after a cold start. Once it's warmer, there's no smoke at all.

I don't want to exaggerate the symptoms here. The saw doesn't die on me at every cold start. It's just that some cold starts are problematic and require a few restarts. Also, the saw doesn't die under normal use once it's warm. It's only if I let it idle for 5 or 10 seconds and flick the throttle ever so slightly -- something I never do during normal operation.

My experience is that these are the kinds of things that can frustrate both the dealer and the customer. They're not major performance issues. They're just nags. I may or may not be able to demonstrate the behaviors reliably for the dealer. The dealer may or may not experience the symptoms the same as I do since he doesn't use the saw under the same conditions. Even if the dealer makes a good faith effort to "fix" it, it may not be much better for me when I start living with it again. Then he feels like he's given a lot (he has), and I feel like I've given a lot (I have), and neither of us is particularly satisfied with the outcome.

Ever have one of those feelings that it just isn't quite right, but that you'd have a hard time convincing a jury about it? That's where I am.

Sometimes they can be tricky to nail down, even with the right tools. The problem should be resolved for you, no need to sit on a saw that doesn't perform as it should. Use that warranty while you still have it.

 

[Tzed250]

Adjust that L needle and I think you'll save both yourself and your dealer a lot of frustration.

Brad, experience has shown me(more than ten years working in bike shops) that diagnostics over the telephone(or the Internet) rarely turn out well. If the saw is under warranty it is best not to fool with it before the dealer lays his hands on it. Getting things paid for is much easier if "customer tampering" is not an issue.

 

[Hermann]

I have had very similar issues here too, (I am closing in on 10 tanks as well), Like you it only happens when cold starting, although not as severe, it's as if it runs too rich at start?, smokes for a few seconds - quick blips after start are bogged down - a gradual pull on the throttle it smokes for 5 seconds and then all is good, never smokes when warm/hot at all (new gas one gallon tank, one bottle stihl ultra 50:1). Always starts with less than a full pull when warmed up, always great in the cut.

Now it always pops on 1-3 pulls on full choke, then starts with 1 to 2 pulls after dropping choke, idles a bit erratic, blips are bogged, smokes a bit, then idle is good. It has gotten better - except for smoke, slight bog there are no issues anymore.

I agree with you about your reservations about taking it to the dealer - I have asked on other post - and someone said this was a known issue that would show nothing with diag tool. For me it's pretty minor, and others said they had similar issues that cleared up - but I am keeping alert about it while under warranty.

 

[blsnelling]

How is this any different from any cold saw that doesn't want to take throttle right at first? The 346 does the same thing.

 

[sunfish]

How is this any different from any cold saw that doesn't want to take throttle right at first? The 346 does the same thing.

Half of my saws are that way. They have to warm up a bit before you can hit the trigger.

 

[watsonr]

How is this any different from any cold saw that doesn't want to take throttle right at first? The 346 does the same thing.

Sounds like it to me also.... cold saw.

 

[SawTroll]

How is this any different from any cold saw that doesn't want to take throttle right at first? The 346 does the same thing.

Well, the 346xp actually has an adjustable L needle.....:msp_biggrin: