Slight hesitation?

944cabby · Aug 5, 2006

I've noticed lately a slight hesitation (not clutch judder) if i'm driving the cab along at 30/40 mph in either 3rd or 4th gear but all is fine when i put my foot down.It almost feels like she's struggling a little for fuel and when i'm driving at 30/40mph i barely have to touch the pedal which makes me wonder if it's being starved.New clutch was fitted last year and i have a promax chip a k&n panel filter fitted.The only other thing i thought was maybe the Air flow sensor has got dirty.If so can you clean them in a similar way that the ISV is cleaned?It's not a major issue but is annoying if i'm in traffic.Anyone any thoughts?

Fen · Aug 5, 2006

My cab did the same. It was diagnosed as the air flow meter, but I didn't drive in such a way as to notice it very much and it wasn't very bad so I never bothered to fix it.

Kevin Welch · Aug 6, 2006

Might also be worth checking the engine speed sensor at the back of the block as I believe this gets disturbed when fitting a new clutch.

sawood12 · Aug 6, 2006

If by hesitation you mean like a jerking back and forth I had a similar symptom a while back. For example when I was travelling at a slow speed for the gear with RPM around 1500 - say if you are in slow moving traffic, and your foot is off the accellarator then the car would jerk or judder. It was found that I was running lean and my AFM was at fault. A new (well 2nd hand but it looked almost new) AFM later and the car was running fine. It might be worth checking if your car is running lean on tickover.

Just a quick question that is slightly off topic but slightly related - does the screw on the AFM that alters the mixture only alter the mixture at tick-over with the chips determining the A/F ratio under partial throttle? The symptoms I describe above only happened when my foot was off the accellarator i.e. the throttle position switch was activated. As soon as I was back on the throttle the juddering/jerking subsided.

944cabby · Aug 6, 2006

ORIGINAL: sawood12

If by hesitation you mean like a jerking back and forth I had a similar symptom a while back. For example when I was travelling at a slow speed for the gear with RPM around 1500 - say if you are in slow moving traffic, and your foot is off the accellarator then the car would jerk or judder. It was found that I was running lean and my AFM was at fault. A new (well 2nd hand but it looked almost new) AFM later and the car was running fine. It might be worth checking if your car is running lean on tickover.

Just a quick question that is slightly off topic but slightly related - does the screw on the AFM that alters the mixture only alter the mixture at tick-over with the chips determining the A/F ratio under partial throttle? The symptoms I describe above only happened when my foot was off the accellarator i.e. the throttle position switch was activated. As soon as I was back on the throttle the juddering/jerking subsided.

That sounds exactly the same symptoms but i have my foot on the pedal very slightly. I did wonder if the throttle cable needed adjusting to take up a little slack as it seems quite slack by the throttle postition switch bit in the engine bay.