my pcx stalls when I open the throttle(once a time per 200km

[kalai1622]

Good evening guys! I'm from Greece and I have pcx 125 with 22.000 km. The last two years I have a problem and can not understand what is it. I've visited two authorized honda services and they didn’t find a solution . My problem is that the engine shuts down under 20 km/hour. When I close the throttle, slow down and the clutch is releasing (almost 17-20km/h), when I open the throttle then it stalls. Then, I must push the rear brake and push the ignition button to start the engine again. For example: I am riding the pcx and in 20 metres there is a red traffic light. So, I decelarate. When the speed reaches 20 km/h and goes down and the clutch is releasing (you feel a small push from the engine at this time) the traffic light becomes green so I open the throttle. When I open the throttle, the engine stalls.
Moreover, when I am on idle (with 0 km/h) and waiting for the green light, when I open the throttle it has already stalled). This happens one time per 180-200km. but it is very dangerous when the roads are busy. I don’t know what is the problem. My air filter is clean, and I fill gas from different gas station every time and I never use the idle stop. I checked the fuel pump and iti is O.K., I changed battery last week but the problem remains.. I checked it with a honda tester machine and the results are normal. Did that happen to anyone else?? Please let me know. Thank you for your attention.

[Taz]

Is the idle speed too low? Check this thread for how to adjust as its a regular service item:

http://www.hondapcx.org/viewtopic.php?f=2&t=522

[kalai1622]

Is the idle speed too low? Check this thread for how to adjust as its a regular service item:

http://www.hondapcx.org/viewtopic.php?f=2&t=522

thanks taz for your help! from the results of the honda tester machine, my pcx has 1695 rpm/min, max is 1800 rpm and minimum is 1600 rpm/min...then my idle is Ok. but i will try to clean the iacv!

[maddiedog]

Either your valves need adjusted or your spark plug needs changed.

Does it run fine at full throttle? Does it respond quickly to throttle changes? Your injectors may be clogged, I'd try running some injector cleaner through it (I recommend Seafoam).

[kalai1622]

I changed spark plug immediately but it stalled again.. I adjusted the valves and after few km it stalled again.. yes, it responds quickly in throttle changes.. i cleaned the throttle body but it stalled again.. I changed the iacv of the throttle body and now I am waiting to stall again.. I have already driven 370 km and it didnt stall again..but i should wait at least 1000km without stalling to say that the problem was the iacv..

[kalai1622]

hello again, after 430 xlm and after changing the iacv (last chance of low cost parts), my pcx stalled again.. what should I check after changing: air filter, spark plug, battery, iacv, cleaning the throttle body, reseting the tps??

[maddiedog]

What did your spark plug look like when you replaced it? Are you sure the spark plug is seated well, and the wire connecting the spark plug is secured well?

If it does it every 200km like clockwork, maybe it's an ECU issue. Try disconnecting the battery, letting the scooter sit unplugged for an hour, then reconnect to reset the ECU.

[kalai1622]

I check the spark plug every 4000km. every 8000 I replace it with a new one of honda.. 200 km is an average of the stalls. it stalls every 150km, 200 km until 400km. only one time I drove 800km without stalling.. about disconnecting the battery and connected it again, i have already done this many times..

[Mel46]

This may have nothing at all to do with it but do you have one of those that shut themselves off when you Stop in order to save gas? I know the USA does not have them. I can't remember what they are called. I think it is called an Idle Stop. In any case, maybe That is acting up.

[kalai1622]

my pcx has a button idle stop! but i never use it...reraly i use it to check that it works..

[A1ex]

mine does that too once in awhile probably once in every 200-300 km. though it does not stall completely, it is like when i start twisting the throttle from the stop, the engine stops revving for a very short moment, and if i continue giving it some gas it starts again without me having to start the engine again. if i dont give it more throttle after it stops revving it stalls for real and i then have to use the ignition button start the engine. The idle stop button is off. I think it has something to do with that idle stop feature since none of the other motor bikes (that do not have this feature) experience that problem.

kalai1622 did you find the solution yet?

[kalai1622]

so you have something like "misfire" or a hesitation, right? when you twist the throttle you feel that the engine will stall but if you twist more throttle, you "save" it.. I haven't find the solution completely yet... few days ago I changed the TPS (throttle positiion sensor) I have travelled 200km from then and until now no hesitation and no stalling..but I want to travel 1000km without stalling to be sure that I found the solution.. how long ago do you have the same problem? how many km do you have? firstly, check your battery and your spark plug. then, check your ECU with a tester machine from your dealer for any problem..

[Mgalutia88]

What about the fuel pump? Turn the red run switch to off when approaching an intersection while coasting and open the throttle and see if this mimicks the problem. It could be your lacking fuel. Fuel pump?

[A1ex]

so you have something like "misfire" or a hesitation, right? when you twist the throttle you feel that the engine will stall but if you twist more throttle, you "save" it.. I haven't find the solution completely yet... few days ago I changed the TPS (throttle positiion sensor) I have travelled 200km from then and until now no hesitation and no stalling..but I want to travel 1000km without stalling to be sure that I found the solution.. how long ago do you have the same problem? how many km do you have? firstly, check your battery and your spark plug. then, check your ECU with a tester machine from your dealer for any problem..

yep, that is exactly the way it does sometimes. The thing is that my bike is second hand one, 40 000 km, i just got it 2 month ago, i doubt there has ever been any change of batery or a plug. But since you said that u changed those and it still does stall sometimes, maybe the problem is somewhere else. Here on the Koh Samui island they dont have ECU at the dealer, they barely know how to change the belt and the variator cover Lets see how it goes whith yours after you have changed TPS.

What about the fuel pump? Turn the red run switch to off when approaching an intersection while coasting and open the throttle and see if this mimicks the problem. It could be your lacking fuel. Fuel pump?

Sorry mate, dont exactly understand what u mean by red run switch, you might be right here, could be the pump!

[Mgalutia88]

On the right handle bar your red run/kill switch for the engine. If you kill the engine while coasting it sounds the same as when it's running until the clutch disengauges.

[dasshreddar]

On the right handle bar your red run/kill switch for the engine. If you kill the engine while coasting it sounds the same as when it's running until the clutch disengauges.

He's talking in "KMs" they don't have kill switches in km land

[kalai1622]

pcx has not kill switch!! its only 125cc...I have also changed fuel pump (it was dealer's present) and after the change, the same day engine stalled!! so, after a week I changes TPS and now after 250km everything is Ok. but my goal is to travel 1000 without stalling..

[A1ex]

pcx has not kill switch!! its only 125cc...I have also changed fuel pump (it was dealer's present) and after the change, the same day engine stalled!! so, after a week I changes TPS and now after 250km everything is Ok. but my goal is to travel 1000 without stalling..

..lets hope it will solve the problem keep us posted!

[kalai1622]

we have the same symptoms but not be sure we have the same problem!

[markz]

Does anybody have a spare ECU to loan kalal1622, for testing purposes?

As the fleet of PCX's age, more weirdness will come up. Folks will always justify any other part, before going for the expensive ECU.

I'm not saying it is or isn't his ECU. But if his weird issue continues, I know he would love to try one out, and not have to commit to owning a second one, if it didn't fix it.

The ECU is God on that scooter. And like any electronic device, it is subject to its own set of demons.

Perhaps someone on the groom has a wreck laying around for parts, and can help kalal1622 out.