Need help with 2011 Husqvarna 576xp autotune

[Inter674]

Cant Find the Problem

so I pulled it all apart - checked the carby again, the piston and bore is fine, the muffler is not blocked, petrol feeds okay, but still it wont rev up.

I noticed that it stalls as soon as the air head butterfly opens. It will run and rev a bit on part choke and if you completely block the main carby inlet port, it will rev up when the second air head port opens. Thinking this proved a petrol supply problem, I pulled the carby again, but again no problem could be seen with all venturis etc clear.

I think therefore that the electronic device atop the carby and which replaces the high and low needles is the problem, and blocking the main carby port simply overrides it and forces fuel into the engine somehow - like the choke does I guess. You can get the same effect if you spray fuel into the engine

Has anyone had any experience with the (presumed) AT device atop the carby in this regard?

Secondly has anyone got a part number for the conventional carby for this saw?

Thanks

 

[Inter674]

...and how do you reset the AT?

 

[Inter674]

just a lttile update - tried another dealer and paid over 40 bucks to confirm that the AT unit appears to have gone west, and will cost 600 dolars to swap out and more if it is something else, eg., the magneto coil or wiring. They can't test it - as already mentioned on here. So this will become a project saw, to be modded when I get the time. Meanwhile, back to the old and dusty, simple and reliable Stihls. Just as well I kept them eh.

When you are on to a good thing....stick to it

 

[flighttime]

...and how do you reset the AT?

Connect 2x 9 Volt battery (18v).. red carb wire to +, negative to cylinder. Move the throttle 5 times throught the whole range. This sets the TPS & takes it to factory default value.
The inlet valve will make some clicking noises when you do it, but thats normal.
The only know issue is if left sitting unused for a long period of time the needle can stick due to some two stroke oils.

Any Husqvarna dealer should know this stuff. It's not really rocket science. Husqvarna sent out the info on how to do resets a long time ago. Usually though you would only need to reset the AT if something major has changed that has caused the AT to go out to full adjustment trying to compensate for some issue.

 

[Inter674]

wow thanks for the advice - I will try it tonight.

I suspect that sitting for a while may have cause this issue, but I also noticed (but the dealer did not) that the magnet in the throttle butterfly bracket is out of place.

I asked him to uncover a new saw to compare and it was obvious that the magnet is out of place. he did not care so I will check this also tonight.

As expected ther main dealer was as hopeless as the last one - I knew more about the machine than he did - thanks to this web site. Even though they are the main dealer for Tas they do not have any means of interogating the software on any machine regardless of age. They simply holler to Husky Aus and replace the machine if it is a non-mechanical issue found out under warranty.

BTW the part they quoted me 600 dollar for is available ex USA for 30 bucks or so.

Does this give you some idea about the dead heads I am dealing with here? They simply don't care and don't deserve to be in business

 

[deepsouth]

That sounds normal for most. Devonports dealer seems ok for Husky, and the Stihl/Honda/JD dealer in Burnie is good.

 

[MarkEagleUSA]

Connect 2x 9 Volt battery (18v).. red carb wire to +, negative to cylinder. Move the throttle 5 times throught the whole range. This sets the TPS & takes it to factory default value.
The inlet valve will make some clicking noises when you do it, but thats normal.

Does this reset procedure work on all AT carbs or just the 576?

 

[TK]

Does this reset procedure work on all AT carbs or just the 576?

Just the 576 and the few 570AT saws that are out there.

 

[MarkEagleUSA]

Just the 576 and the few 570AT saws that are out there.

So 550's and 562's can only be reset with the software?

 

[hamish]

Its a chainsaw........not rocket science, 20 minutes on the bench and you should have found your problem. Vac/pressure test and include inlet pipe in test, check fuel lines and tank vent, verify compression, visually inspect piston/cyl, pull carb check it out. Reset AT system.

Done deal.

 

[Inter674]

God Bless America

Update on the Husky 576xp at 12 month old lemon....

I tried the 18v re-set but that made no difference at all. So I purchased a standard carby and valve housing/brain unit from the US for @100 dollars delivered. I replaced the valve unit working on the basis that if that did not work, I only wasted 23 bucks, and could still covert to conventional carb.

Choo Choo parts are highly recommended. The costs were amazingly low given that the local stealer quoted me 600 bucks for the valve unit alone and basically threw their hands in the air pleading complete ignorance as to how these machines work etc. Not a good recommendation for Husky Au at all.

Choo choo prices were: 576694201 VALVE HOUSING ASSY $23.10 and 580735801 CARBURETOR $51.25

Wired up the valve unit, set the choke, gave a couple of pulls and bingo it started and revved up like a F1 engine and idled nice and smooth too. No more stalling and plenty of grunt too.

Thank you all for your help.

PS I will try to contact Husky Aus to see if they are interested in looking into what went wrong with my valve unit, or I may even cut it open to see how it works

 

[Inter674]

quick update - I put 5 tanks thru the saw yesterday cutting blue gum which used to be used for boat keels and wharfe piles years ago because it is hard and dense and resists rot. The max diameter was about 48" in the butt and the saw flew thru it. I was reminded how impressive this saw really is - no vibration, heaps of power and no smoke whatsoever from the exhaust. It ran hard all day, never missed a beat. Swapped out only 1 blunt chain all day for over 10 tonnes of green firewood I guess. This was a big straight tree and even the old D47U struggled to move it to the pile:msp_biggrin:

 

[Inter674]

well I'm back and the AT Module has gone again. I have a suspicion these modules do not like to be left over winter, they perhaps gum up a bit and then the electronics burn out. Even the local dealer now admits they are unreliable but offered no fix, except to say buy the new versions saw which I will not be doing.

Anyway I'm converting the saw to normal carby (I have that already) and have a question.

Is there a need to change the ignition module?

I have heard you don't but wonder then how to re-direct the wires in particuklar the red wire that originally connected to the AT Module atop the carby. A new ign module will cost me 100 plus dollars from the US and given the amount of money I have already spent keeping this saw going, I am keen to avoid that if possible.

Thanks again for your great advice!!