car jerky when lightly accelerating at low speed in low gears

[JMcGill]

Dont know why but my car is quite jumpy when im very lightly on and off the accelerator at low speeds. E.g. for speed bumps. Any ideas why this is?

[martauto]

Have you had a look at the usual suspects as in the ignition system ,air leaks, etc ?

Mart.

[stones]

It could also be the throttle cable is past its best or not adjusted correctly, can make a big difference.

[Foe]

It could also be the throttle cable is past its best or not adjusted correctly, can make a big difference.

Sorry to hijack, how can do you adjust the Throttle cable?

[stones]

As the cable goes into the grommet on the throttle there is a threaded piece that you can turn to take up the slack, but only slightly you just want it so that as the pedal starts to move so does the throttle. (not sure how much sense that makes but i will add a pic if i can figure it out).
To be honest a new cable is/was about £25 so worth doing if it looks a bit suspect.
HTH

[HJ1981]

There are two adjustments for the trottle cable, according to the manual.

1-2 mm when slightly pulled at idle at the throttle body, which can be adjusted in the engine bay.

0.5 mm at the full throttle stop when the pedal is at full throttle., can be adjusted via full throttle stop.

[Foe]

As the cable goes into the grommet on the throttle there is a threaded piece that you can turn to take up the slack, but only slightly you just want it so that as the pedal starts to move so does the throttle. (not sure how much sense that makes but i will add a pic if i can figure it out).
To be honest a new cable is/was about £25 so worth doing if it looks a bit suspect.
HTH

A pic would be great. Just looked at mine. Two cable ties holding it place on the throttle body in the engine bay

[HJ1981]

As the cable goes into the grommet on the throttle there is a threaded piece that you can turn to take up the slack, but only slightly you just want it so that as the pedal starts to move so does the throttle. (not sure how much sense that makes but i will add a pic if i can figure it out).
To be honest a new cable is/was about £25 so worth doing if it looks a bit suspect.
HTH

A pic would be great. Just looked at mine. Two cable ties holding it place on the throttle body in the engine bay

Pics in this thread:

https://www.r3vlimited.com/board/showth ... p?t=317391

[stones]

[/quote]

Pics in this thread:

https://www.r3vlimited.com/board/showth ... p?t=317391
[/quote]

Indeed, good thread for M20 engines and also shows the grommet.

If that worked this pic shows M44 engine but it works the same as M40, the red mark is next to the 'adjuster' and the blue shows the end of the cable if it is slightly loose just twist the adjuster until it is tight to the linkage but not lifting it from its stop.
HTH

[stones]

As for the original question more info is needed on the car (M20 or M40 or M10)?

[ocde30]

Hi, if I can join in this thread with a similar issue. My car is 1991 318i Lux and I am a DIY owner with limited knowledge.
I have a slight "hesitation" "jerkiness" on very light throttle and on the over run down an incline. Car pulls strong without hesitation so discounted ignition coil.
I checked carefully the big air intake pipe and found very small crack. Fitted new hoping that I had found the problem but no it still persists. I always use quality fuel. I don't think it is throttle cable but will have a look as recommended. Open to any ideas / suggestions. Attached is the throttle adjustment area that I think you refer to?
Incidentally I have exactly the same issue with my B7 Audi A4 2.0TDI - no definitive online solution - so lived with it.

[JMcGill]

As for the original question more info is needed on the car (M20 or M40 or M10)?

Thanks for all the helpful replies, Ive got a M10.

[Foe]

Sorry JMcGill for hijacking the post.
And thanks for the use replies and pictures

[JMcGill]

Solved - Carbs needed tuning.
Every M10 problem = carbs

[martauto]

Solved - Carbs needed tuning.
Every M10 problem = carbs

What carb have you got on ?

Mart.

[JMcGill]

What carb have you got on ?

Weber mate but car had been sitting for years before I started bringing it back to life and gave its engine a refresh. Been driving it for 6 months and slowly ironing out all the little problems that come to light.

[martauto]

What carb have you got on ?

Weber mate but car had been sitting for years before I started bringing it back to life and gave its engine a refresh. Been driving it for 6 months and slowly ironing out all the little problems that come to light.

Did you tune it and what did you do please?

Mart.

[JMcGill]

What carb have you got on ?

Weber mate but car had been sitting for years before I started bringing it back to life and gave its engine a refresh. Been driving it for 6 months and slowly ironing out all the little problems that come to light.

Did you tune it and what did you do please?

Mart.

It was tuned in less than 10 mins, had it done by a professional. He was adjusting what seemed like screws which are below the big air filter in the middle of the M10 engine (Black circular cover).The cover didnt have to be removed. In terms of the refresh, have done all the standard servicing, belts, filters etc. Brake pipes and calipers needed work because of how long the car was sitting. Heater matrix was changed and so much more.

Im thinking about making a progress thread because the work is nowhere near finished and im keeping the M10 in the bay because I love it. Everyone seems to swap them for bigger motors but im all about OEM and its such a great runner, seems like soon there wont be any left

[BristolE30]

What carb have you got on ?

Weber mate but car had been sitting for years before I started bringing it back to life and gave its engine a refresh. Been driving it for 6 months and slowly ironing out all the little problems that come to light.

Did you tune it and what did you do please?

Mart.

Totally do able. Lightly Seat the air mix, do two full turns out and adjust from there. Look for optimum rpm and increases by ear. Anything above 3 turns out (richer) could probably use smaller jets, anything below 1.5 turns in (leaner) could do with bigger idle jets.

I did mine a few weeks ago, running a lot cleaner as the idle circuit on the Weber effects a lot of its performance