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Jerky throttle

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Paul Fraser

New member
Ok, next problem (after having sorted out a crashing steering wheel by changing all the shocks) is one with the throttle. If I back off the throttle or apply it suddenly it is quite jerky. Don't know if I'm describing this very well but throttle off, car lurches forward a little, throttle on, lurches back. Very easy to set up a driver induced oscillation if you do the two quite close together.
What is this likely to be (you get similar symptoms, although not as bad, with a throttle response cam, but this one is a normal one)?
 
Hi Paul,
This may not be the throttle per se, it might be a fuelling problem.The pressure in the fuel rail could be either too high or too low. The pressure cans on top of the rail may be the cause. Does the car stand unused for several weeks at a time? as the valves in the pressure cans can get sticky giving the effect that you describe.They are operated by manifold vacuum so check the vacuum lines for leaks as well.
hope this helps,
jr.
 
Thanks, just got the car so I'll see what happens after some regular driving and read up on what you have mentioned.
 
When mine was suffering from similar symptoms it turned out to be the mix was off. It only happened when moving very slowly at low RPM with my foot off the accellarator, the car would 'kangaroo' until I just pressed the throttle enough to take the throttle off the idle microswitch. Once the A/F mixture was corrected she ran smooth as silk and continues to do so.
 
Hi,
Check out my topic on "Fao 944 Doctor".
These were exactly the symptoms I had.
If I took the foot off the throttle at speed the car would be a bit jerky and same when I put the foot down too fast.
It turns out it was the clutch and in particular a part of the clutch which instead of being a solid rubber plate was like a donut. Not sure if this is the pressure plate or not.
My initial thought was fuel mix or bad feul.
It's been in the garage now for a few days, expecting it back this week.
Kev
 
If the clutch has not been replaced with the later spring type arrangement then it could be the rubber doughnut bit that dampens. This failed (or nearly failed) on my lux well before the clutch was worn out and I had to replace the clutch. The feeling of jerkyness and momentary delay as it takes up slack in the drive chain was v.similar to what you discribe.

Hope this helps.

Regards,

Ben
 
Mine does this also but i've had my clutch changed for the spring type.Sometimes she drives great then on occassions i get the jerky business.
I wonder if the injectors need replacing.
 
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