Help needed, poor throttle

[2dogs]

Took the Z out for a spin today all ok until I went to overtake, floored it but it was like I taken
my foot off the throttle for a spilt second it did pick up but slowly not the kick in the back.
came back on the motorway and try it in different gears but still the same pull in to a car park
tick over was fine no light engine running sweet, turn it off and went to the shops came back
about 20 mins later it has always started on the first turn but not this time turn over about
8 times before it started drove home but still with the same throttle problem
Any clues anyone!

 

[ChawenHalo]

coil? you should get some engione warning light though. Plug it in.

 

[Carol M]

This happened to my Z3 and it was the cat in the exhaust breaking down.
Worth a look.

 

[jamiez]

crank position sensor or o2 sensor i would say

 

[2dogs]

Thanks for all your input, but wouldn't an sensor put up a dashboard light?

 

[Grizzly9]

Only other thing not mentioned here that I can think of is Air Filter.

 

[stupot67]

Hi,
Possibly MAP sensor, when opening the throttle a defective MAP sensor will not detect the drop in vacuum and cause poor throttle response, The ECU wouldn't know you were trying to accelerate, and therefore would'nt inject more fuel and retard the timing, If the sensor is still giving s nominal feedback to the ECU it wouldnt see it as a fault.

Stuart.

 

[exdos]

Hi,
Possibly MAP sensor, when opening the throttle a defective MAP sensor will not detect the drop in vacuum and cause poor throttle response, The ECU wouldn't know you were trying to accelerate, and therefore would'nt inject more fuel and retard the timing, If the sensor is still giving s nominal feedback to the ECU it wouldnt see it as a fault.

Stuart.

Where's the MAP sensor on the Z4M?

 

[andysat]

Do you mean MAF?

 

[Machine monkey]

Hi,
Possibly MAP sensor, when opening the throttle a defective MAP sensor will not detect the drop in vacuum and cause poor throttle response, The ECU wouldn't know you were trying to accelerate, and therefore would'nt inject more fuel and retard the timing, If the sensor is still giving s nominal feedback to the ECU it wouldnt see it as a fault.

Stuart.

Where's the MAP sensor on the Z4M?

It's in the sat nav stupid.
I am 100% sure Stu was meaning MAF. I make more than the average typing error. I am sure Lux will be on to back me up on that!!!

 

[exdos]

It's in the sat nav stupid.

I am 100% sure Stu was meaning MAF. I make more than the average typing error. I am sure Lux will be on to back me up on that!!!

He doesn't mean MAF because he's described the drop in vacuum, whereas a MAF monitors airflow; a totally different way of operating.

 

[Machine monkey]

Ok ok!!!

 

[Stuart Truman]

Could be a lambda probe. I had a similar thing in an old Passat except it just died on you them came back to life. As others have said, plug it into diagnostics and see if there's a code...

 

[stupot67]

Hi,
The MAP sensor (Manifold absolute pressure) is either on or piped to the inlet manifold, It along with throttle position and/or MAF give the ECU info on engine load ( Accelerate, cruise or de accelerate). I had a quick look around the web and found mention of them on 6 pot BMW engines but not where they are fitted. On 4 pot 3 series its fitted to firewall.

Stuart.

 

[exdos]

Hi,
The MAP sensor (Manifold absolute pressure) is either on or piped to the inlet manifold, It along with throttle position and/or MAF give the ECU info on engine load ( Accelerate, cruise or de accelerate). I had a quick look around the web and found mention of them on 6 pot BMW engines but not where they are fitted. On 4 pot 3 series its fitted to firewall.

Stuart.

Here's a link to the electronics for the S54 engine: http://www.unofficialbmw.com/images/m3engineelectronic1.pdf
There's no mention of a MAP sensor. However, when I link my datalogger to the OBDII socket of my Z4MC it is possible to log a MAP, but when I look at the plot from it, it's hard to work out what has been recorded, because it doesn't look like a graph of what I would expect the pressure inside the intake system would be. If you can shed any light on this, I'd be grateful.

 

[stupot67]

Hi,
Looks as though the S54 engine doesn't use a MAP sensor (Sorry to lead people up thr wrong path), the MAP exudos refers to is the fueling and ignition map that the ECU follows depending upon feedback from the sensors I would assume. So it points to either to MAF sensor, throttle position sensor or something that would effect the fuelling (Air leak etc) - Please post the actual problem when you get it fixed.

Stuart.

 

[2dogs]

Been thinking about this and I know it's a bit of a long shot, but would changing the wheel
Have anything to do with this or having the car jacked up.
because all this started after I changed the the wheels :?
Bit of a update the problem goes when the car has been turned of if 30 mins or so.