Hesitation on slight throttle - now with video
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Anonymous
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what's the AFM?Adam D said:
lacroupade
Veteran
As I'm sure you know, the MAF works very simply. The ECU sends a constant voltage through the wire to heat it....the more air goes over it (or the colder that air is), the cooler it gets and its resistance goes up. The ECU notes this and adjusts fuel input accordingly (colder air is denser and can burn more fuel more efficiently).
However, the changes it makes are relatively small....if the theory held good, your car would be doing 300mph when it was -10c....as it is, you probably notice its slightly more perky than when its +30c, but thats about it.
A throttle reset is always worth a punt, but as has been said, theres no substitute for a good, regular thrashing. Failing that, try driving your car.
However, the changes it makes are relatively small....if the theory held good, your car would be doing 300mph when it was -10c....as it is, you probably notice its slightly more perky than when its +30c, but thats about it.
A throttle reset is always worth a punt, but as has been said, theres no substitute for a good, regular thrashing. Failing that, try driving your car.
A
Anonymous
Guest
Alastair said:
What was wrong with 'MAF' then, as per all the other posts ?.....
Quic video showing whats happening. This is after I'd cleaned the MAF as as you can see its no better. In fact before I shot the video doing this actually casued it to stall once, it had never done that before
This is at a stand still. The tapping noise is when I hit the accelerator pedal (intentionally so that you could tell when I press it)
This is at a stand still. The tapping noise is when I hit the accelerator pedal (intentionally so that you could tell when I press it)
mark im not seeing anything major wrong here??? your blipping the revs and getting a under rev when it comes down, the s54 is a very highly tuned motor and the tuning is abit rough in places even from stock, but im not seeing anything alarming in your video, i dont get the rev drop but my car is setup very differently with no MAF......
Maybe you can't see it in the video, but when I first hit the accelerator pedal, it coughs and splutters (hesitates) before the revs rise. The double tap you hear is the first me hitting the pedal, the second is it hitting the floor, ie full throttle. Notice the delay in the increase in revs? You can't really hear the spluttering in the video
Mine doesn't do this. Occasionally I will get an under rev when blipping the throttle, but this is as the revs decay. Typically this will be when I've been absolutely nailing it then spend time sitting in traffic (eg after leaving a motorway) but there certainly isn't the hesitation you describe (it's hard to appreciate the hesitation on the vid).
So you guys who say you don't seem anything wrong, try the following:
1) At a standstill have your car in neutral
2) Plant the Throttle
Now, do your your revs increase immediately?
What mine does is hesitate, sort of cough and splutter for a second, then they rise.
1) At a standstill have your car in neutral
2) Plant the Throttle
Now, do your your revs increase immediately?
What mine does is hesitate, sort of cough and splutter for a second, then they rise.
So did replacing those solve the issue then?
A further update: went and filled my very empty tank with BP Ultimate after reading some people had seem significant improvements. Not surprisingly there is no improvement immediately so we'll see on that one.
But I did take it to a BMW Specialist local to my office in Northampton. M-Tec? Anyway they got in and tried and said "thats definitely not right" so I'm not being picky. However they didn't seem to have too much of an idea there and then and said they would need me to drop it off for the morning and get it plugged in. Ie they want paying, fair enough.
A further update: went and filled my very empty tank with BP Ultimate after reading some people had seem significant improvements. Not surprisingly there is no improvement immediately so we'll see on that one.
But I did take it to a BMW Specialist local to my office in Northampton. M-Tec? Anyway they got in and tried and said "thats definitely not right" so I'm not being picky. However they didn't seem to have too much of an idea there and then and said they would need me to drop it off for the morning and get it plugged in. Ie they want paying, fair enough.
pilchardthecat
Active member
I'll try it later, but i'm 99% sure i dont get a drop in revs like that under any conditions (it looks like you're dipping the clutch with the handbrake on!)
I'd agree with BMWZ4MC seems normal that when at lights especially after idling for a while the car will splutter if you just plant the throttle and try to pull away. In extreme cases this can cause you to stall or do the dreaded kangaroo hop 
I tend to give the throttle a quick blip in neutral to clear it's throat just before pulling away.. You may have to have a BMW tech to check it over and see if any fault codes are registering.
I tend to give the throttle a quick blip in neutral to clear it's throat just before pulling away.. You may have to have a BMW tech to check it over and see if any fault codes are registering.