Claning the butterfly valve?
Discussion
Car just has 12K service. I asked them to clean the throttle butterfly valve (why?!?!?!). Now it starts from cold going to higher revs than before and hunts. I've had it from new and its always been absolutely rock solid around 750-800 revs idel and 1000 revs from cold).
Do I recall someone saying that, after a clean, it goes lumpy at first until it clears or something?
Also, how do I clean it (again)?
Do I recall someone saying that, after a clean, it goes lumpy at first until it clears or something?
Also, how do I clean it (again)?
JAZ 34 said:
Thnks Jaz but, as it didn't clear after the engine warmed up I guess they must have upset something else - maybe they created more dirt than clean by touching it - bugger!!!
Re lamba sensors being a possible cause - hmmm, why now, the minute it goes in for a service after running perfectly to date?!
Just a update on cleaning the throttle butterfly valve - DO NOT DO THIS unless you really need to!
My engine was running perfectly but I opted to have mine cleaned recently after taking the tip from earlier threads here (shulda gone to Specsavers - shulda left well alone!). Now the characteristics of cold-start have changed forever. Nothing damaging, just different (as mentioned earlier in this thread). There is a coating sprayed onto the rear of the valve plate that CAN disrupt on cleaning altering the seal with the body. And, messing with the map won't correct it either.
Facts confirmed by Trevor J. at Roush.
My engine was running perfectly but I opted to have mine cleaned recently after taking the tip from earlier threads here (shulda gone to Specsavers - shulda left well alone!). Now the characteristics of cold-start have changed forever. Nothing damaging, just different (as mentioned earlier in this thread). There is a coating sprayed onto the rear of the valve plate that CAN disrupt on cleaning altering the seal with the body. And, messing with the map won't correct it either.
Facts confirmed by Trevor J. at Roush.
NobleGuy said:
Is the idle screw easily found?
Yep, lurking beneath the throttle cable cam at the very end of the cable. 9 or 10mm screw IIRC. I wouldnt mess with this unless absolutely necessery. Messed my own idle up by fiddling trying to cure a problem that wasnt cos of the idle screw being set wrong 
ajg31 said:
NobleGuy said:
Is the idle screw easily found?
Yep, lurking beneath the throttle cable cam at the very end of the cable. 9 or 10mm screw IIRC. I wouldnt mess with this unless absolutely necessery. Messed my own idle up by fiddling trying to cure a problem that wasnt cos of the idle screw being set wrong Adrian W said:
ajg31 said:
NobleGuy said:
Is the idle screw easily found?
Yep, lurking beneath the throttle cable cam at the very end of the cable. 9 or 10mm screw IIRC. I wouldnt mess with this unless absolutely necessery. Messed my own idle up by fiddling trying to cure a problem that wasnt cos of the idle screw being set wrong AMG Merc said:
Car just has 12K service. I asked them to clean the throttle butterfly valve (why?!?!?!). Now it starts from cold going to higher revs than before and hunts. I've had it from new and its always been absolutely rock solid around 750-800 revs idel and 1000 revs from cold).
Do I recall someone saying that, after a clean, it goes lumpy at first until it clears or something?
Also, how do I clean it (again)?
Where did you have it serviced?Do I recall someone saying that, after a clean, it goes lumpy at first until it clears or something?
Also, how do I clean it (again)?
F.C.
You can clean the throttle assembly without damage by using a toothbrush and brake cleaner. You shouldn't use any abrasive material or harsh chemicals of course.
I've done this with hundreds of cars with poor idle characteristics, carbon build up is natural and thus affects the mechanical leakage built in which the ECU then compensates for (up to a point).
My GTO-3 used to stall and have little fast idle when cold, it now idles up from cold and no longer stalls....and only after a butterfly clean.
I've never a car come back after this although you do need to reset the base idle if it's really clagged up.
Dave
I've done this with hundreds of cars with poor idle characteristics, carbon build up is natural and thus affects the mechanical leakage built in which the ECU then compensates for (up to a point).
My GTO-3 used to stall and have little fast idle when cold, it now idles up from cold and no longer stalls....and only after a butterfly clean.
I've never a car come back after this although you do need to reset the base idle if it's really clagged up.
Dave
F.C. said:
AMG Merc said:
Car just has 12K service. I asked them to clean the throttle butterfly valve (why?!?!?!). Now it starts from cold going to higher revs than before and hunts. I've had it from new and its always been absolutely rock solid around 750-800 revs idel and 1000 revs from cold).
Do I recall someone saying that, after a clean, it goes lumpy at first until it clears or something?
Also, how do I clean it (again)?
Where did you have it serviced?Do I recall someone saying that, after a clean, it goes lumpy at first until it clears or something?
Also, how do I clean it (again)?
F.C.
D_G said:
You can clean the throttle assembly without damage by using a toothbrush and brake cleaner. You shouldn't use any abrasive material or harsh chemicals of course.
I've done this with hundreds of cars with poor idle characteristics, carbon build up is natural and thus affects the mechanical leakage built in which the ECU then compensates for (up to a point).
My GTO-3 used to stall and have little fast idle when cold, it now idles up from cold and no longer stalls....and only after a butterfly clean.
I've never a car come back after this although you do need to reset the base idle if it's really clagged up.
Dave
Hmmm, so why did the Rousch Maestro concur then?I've done this with hundreds of cars with poor idle characteristics, carbon build up is natural and thus affects the mechanical leakage built in which the ECU then compensates for (up to a point).
My GTO-3 used to stall and have little fast idle when cold, it now idles up from cold and no longer stalls....and only after a butterfly clean.
I've never a car come back after this although you do need to reset the base idle if it's really clagged up.
Dave
Trevor is right to say you can't necessarily map out an idle problem, but carbon build up can and will affect the idle characteristics. Don't forget it works the other way too, if you have a worn throttle body then the carbon build up actually helps limit the air which would normally pass the butterfly and give an abnormally high idle.
I only do this when the car experiences idling/stalling issues and not as part of a service as the old addidge 'if it ain't broke, don't fix it' normally applies.
I could quite easily just replace the throttle body on my customers cars at £££ but prefer just to clean, reset and have them go away happy.
It seems to have fixed others on this forum, sorry it seems to have affected your for the worse?
Dave
I only do this when the car experiences idling/stalling issues and not as part of a service as the old addidge 'if it ain't broke, don't fix it' normally applies.
I could quite easily just replace the throttle body on my customers cars at £££ but prefer just to clean, reset and have them go away happy.
It seems to have fixed others on this forum, sorry it seems to have affected your for the worse?
Dave
D_G said:
Trevor is right to say you can't necessarily map out an idle problem, but carbon build up can and will affect the idle characteristics. Don't forget it works the other way too, if you have a worn throttle body then the carbon build up actually helps limit the air which would normally pass the butterfly and give an abnormally high idle.
I only do this when the car experiences idling/stalling issues and not as part of a service as the old addidge 'if it ain't broke, don't fix it' normally applies.
I could quite easily just replace the throttle body on my customers cars at £££ but prefer just to clean, reset and have them go away happy.
It seems to have fixed others on this forum, sorry it seems to have affected your for the worse?
Dave
Dave, yes I could be a one-off. Out of interest, how much is a new throttle body?I only do this when the car experiences idling/stalling issues and not as part of a service as the old addidge 'if it ain't broke, don't fix it' normally applies.
I could quite easily just replace the throttle body on my customers cars at £££ but prefer just to clean, reset and have them go away happy.
It seems to have fixed others on this forum, sorry it seems to have affected your for the worse?
Dave
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