Sticking throttle…

[samoward]

Hello all,
This is my first post on this forum since picking up my Z3 a few weeks back. It’s a 2000 1.9 and I love it. It’s in great condition due to being well looked after and purchasing from a brilliant Z3 specialist garage. The only issue I’ve noticed since driving the car for a few weeks is the sticking throttle when I put my foot down. I did plenty of research on the matter and quickly discovered that it must be the throttle cable which can get a bit jerky over the years. Even though the most work I’ve ever done on a car is put air in the tyres, I decided this job would be easy enough for me to to tackle. So this past Sunday I fitted a brand new throttle cable, was particularly fiddly but I managed it. Although I feel very chuffed for successfully replacing it, that elation quickly disappeared as… the problem hasn’t gone away. The cable is brand new and I’ve fitted it following all the steps (those that have done it will know it’s very straight forward) but the problem remains? The accelerator pedal isn’t smooth or light like I’ve read it would be after a replacement and still has a sticking jerky movement, particularly starting from stationary. Is there anything else it could be? Did I need to oil the new cable before installing? Any help appreciated as I’m extremely new to all this! Thanks, Sam

 

[colb]

Check out the throttle body for smooth operation, they can get dirty and cause the throttle body butterfly valve, (The flap that is operated by the cable) to stick. A good dose of carb cleaner spray and a wipe out should sort out any issues with it.

 

[t-tony]

Also some lubricant, in the form of spray grease, allied to the throttle pedal pivot certainly won't hurt. It's probably never been lubricated since it was new.

Tony.

 

[samoward]

Check out the throttle body for smooth operation, they can get dirty and cause the throttle body butterfly valve, (The flap that is operated by the cable) to stick. A good dose of carb cleaner spray and a wipe out should sort out any issues with it.

Thanks very much, do I need to remove this in order to clean it or can I do it while still in the engine bay?
Thanks
Sam

 

[samoward]

Also some lubricant, in the form of spray grease, allied to the throttle pedal pivot certainly won't hurt. It's probably never been lubricated since it was new.

Tony.

Thanks Tony,
Would this be the part at the top of the pedal arm where the spring is? Sam

 

[colb]

Throttle body can be cleaned in situ, just undo the rubber intake boot to reveal the throttle butterfly and spray the cleaner in and give it a wipe, you should be able to move the butterfly pulling on where the cable connects to it so it gets a clean behind the butterfly.
For the gas pedal as @t-tony says lube that, it needs applying to the pedal pivot points, also clean out the base of the pedal, loose dirt and small grit seems to collect where the pedal hinges at the bottom over time.

 

[samoward]

Throttle body can be cleaned in situ, just undo the rubber intake boot to reveal the throttle butterfly and spray the cleaner in and give it a wipe, you should be able to move the butterfly pulling on where the cable connects to it so it gets a clean behind the butterfly.
For the gas pedal as @t-tony says lube that, it needs applying to the pedal pivot points, also clean out the base of the pedal, loose dirt and small grit seems to collect where the pedal hinges at the bottom over time.

Thanks very much for all this, I’ve ordered some cleaner however I may not need it in the end! This afternoon I decided to go back in and have a tweak of the cable tightness by turning the thread at the throttle body. I twisted carefully until the body started to turn and then went back slightly only leaving a minute amount of slack. I’m surprised this worked as when initially fitting the new cable, I did the same thing however idle revs were too high so the cable was obviously too tight so I loosened it until it idled normally. I can only assume the cable needed a few days driving in order to bed in (??). Anyways, throttle is lovely and smooth now so I’m relieved. Thanks for the help and advice though - I may have a look inside the butterfly valve regardless to see how it is. Cheers,
Sam