Accelerator sticking

[Mazza]

Hi all,

With all leaks sorted thought I would take the Z3 out in the sun this morning. Give it a run and take the wife shopping. Couldn’t believe it when the car suddenly over revved and wouldn’t shut down. I turned off the engine, put it in neutral and coasted to a halt. I started the engine and it was still wide open, so turned it off and got under the bonnet ( or hood as they say in far off places!).
Fortunately there was a screwdriver in the boot kit so took off the plastic cover over the throttle linkage and flicked the spring back and forward a couple of times. It was covered in that white paste ( marine grease?)
but couldn’t see anything actually wrong. Started it again......and lo and behold back to normal!!

Has anyone come across this before where it just sticks open????

Any way, carried on and went shopping and did a round my trip of about 30 miles or so and it seemed to be ok other than the idle speed varied at times.
Got home took the cover off, released the cable and squirted wd40 down the cable. Cleaned the springs, (decreased and oiled them), and sprayed the pedal connections, bushes and spring with wd40 as well. Testing it in the garage it appears to be all ok now.
I can’t really see why this should have happened though.

Anyone have any ideas?

 

[Grumps]

I'm not a mechanic but sounds like you've found your issue. I'd just clean the old grease off and apply some new and see how it goes. If it continue maybe the cable has stretched a little and is in need of replacement.

 

[Jack Ratt]

These things happen sometimes. Had a similar occurrence with my Merc and that turned out to be a sticky microswitch return spring. I cleaned it with carb cleaner and it's been ok since.
Sometimes grease can harden just enough to overcome the resistance of a spring

 

[Dino D]

On the 2.8 the throttle cable gets stiff with time, on some of the bends it goes around it must chafe the inner sheath and becomes very stiff. Cheap to buy around £30 from BMW and throttle feels so much nicer after it.

 

[MRH1966]

Had this happen on my M43 1.9.........The throttle body gets carbon build up.......which in turn makes the flap stay open.........easy fixed with carb cleaner........remove throttle body (4 Bolts I think), leave cables attached, spray well and see the carbon deposits melt away.....may need a little elbow grease to help........re-connect and all will be well.........hope this helps

 

[Mazza]

I disconnected the cable again this morning and drip fed 3 in 1 oil down the cable. Went out and the accelerator seems so much smoother. But may well unbolt the throttle body to check the internal condition and clean if required.

Thanks to all for info

 

[handsomejackuk]

had my throttle body off a few times... first time was to free a sticky throttle on closed... as it was real sticky... fair bit of carbon gum on the butterflies and the throttle body where the butterfly touched the body...... 1.9 m44 engine.. got to say it made a real big difference.. well worth stripping the whole thing off only take like 10 mins to get off...

while you at it give the idle control valve a good clean.. i also removed the stuck rusted screws holding the icv and tps, and replaced with stainless steel items this necessitated the body to be pulled off again... i also polishe the whol throttle body while it was off just to smarten it up