Delay of revs when revving...
04-03-2014, 09:32 PM
#1
Delay of revs when revving...
Hi all,
after owning many Jags I decided to mature a little and go classy and buy my first Merc. This one is an S500 from 2000 (W220) and seemed great at first. However it has quickly developed a problem for which I would appreciate an experienced member's advice if anyone would be so kind!
Quite simply, let's say the car is idling in neutral (or park). I put my foot down and you can hear a big 'suck' of air, but a HUGE (OK, second or two) delay before the car actually revs.
If I'm driving, same thing. Put foot down, delay, then massive power all the way.
If I rev slowly, no problem.
Reading the stickies and searching others posts here, I'm thinking MAF. I disconnected it as a 'diagnostic step' and the problem seemed to improve - but only slightly, i.e. there's still a delay before it wants to rev properly, but this is reduced down to maybe half a second.
By the way, when it kicks in AFTER the delay (when driving in gear) it is like a rocket, so I can't imagine it being a misfire as such or a cylinder problem; it also idles fine so I don't think a coil or a plug has gone...
It's almost as if putting my foot down too quickly is pulling too much air in and not enough fuel - or of course the other way round, I'm not exactly an expert on how the engine works!
I've ordered a new MAF to try, but just in case does anyone else have any other suggestions? Does this sound familiar as a MAF problem or another issue?
I hope someone can offer advice, thank you all in advance.
Cheers
Joe
after owning many Jags I decided to mature a little and go classy and buy my first Merc. This one is an S500 from 2000 (W220) and seemed great at first. However it has quickly developed a problem for which I would appreciate an experienced member's advice if anyone would be so kind!
Quite simply, let's say the car is idling in neutral (or park). I put my foot down and you can hear a big 'suck' of air, but a HUGE (OK, second or two) delay before the car actually revs.
If I'm driving, same thing. Put foot down, delay, then massive power all the way.
If I rev slowly, no problem.
Reading the stickies and searching others posts here, I'm thinking MAF. I disconnected it as a 'diagnostic step' and the problem seemed to improve - but only slightly, i.e. there's still a delay before it wants to rev properly, but this is reduced down to maybe half a second.
By the way, when it kicks in AFTER the delay (when driving in gear) it is like a rocket, so I can't imagine it being a misfire as such or a cylinder problem; it also idles fine so I don't think a coil or a plug has gone...
It's almost as if putting my foot down too quickly is pulling too much air in and not enough fuel - or of course the other way round, I'm not exactly an expert on how the engine works!
I've ordered a new MAF to try, but just in case does anyone else have any other suggestions? Does this sound familiar as a MAF problem or another issue?
I hope someone can offer advice, thank you all in advance.
Cheers
Joe
04-04-2014, 09:23 AM
#3
MBWorld Fanatic!
Having the diagnostic codes pulled (and cleared) would be the most logical first step. The car will usually tell you exactly what is wrong.
04-04-2014, 09:53 AM
#5
MBWorld Fanatic!
I don't know for certain - but the diagnostic system stores and shows many more codes than ever show on the dash display...
The level of detail is astonishing. Just as an unrelated example - if the windshield wipers happen to stop in the middle of a sweep for some reason, the car will store a trouble code telling you that it happened.
The level of detail is astonishing. Just as an unrelated example - if the windshield wipers happen to stop in the middle of a sweep for some reason, the car will store a trouble code telling you that it happened.
04-07-2014, 01:38 PM
#6
Hi all,
thank you for your help above, very much appreciated.
As suggested (and as I should have done in the first place) I read the codes, and surprise surprise P0100 was showing for the MAF sensor. I ordered one online, it came today, I replaced it and the car is now running beautifully (touch wood).
I'm glad it wasn't the throttle assembly, as that looked a great deal harder to get hold of at a sensible price than the MAF sensor!
There's a few other little issues I'd love to fix (soft closing doors don't work but trunk does, keyless ignition button doesn't work) so I will be reading plenty of related posts to try and figure these out...
Once again, thanks!
Joe
thank you for your help above, very much appreciated.
As suggested (and as I should have done in the first place) I read the codes, and surprise surprise P0100 was showing for the MAF sensor. I ordered one online, it came today, I replaced it and the car is now running beautifully (touch wood).
I'm glad it wasn't the throttle assembly, as that looked a great deal harder to get hold of at a sensible price than the MAF sensor!
There's a few other little issues I'd love to fix (soft closing doors don't work but trunk does, keyless ignition button doesn't work) so I will be reading plenty of related posts to try and figure these out...
Once again, thanks!
Joe
