Been having a few driveability issues with my manual 2002 KJ - as said in the title, feels a bit like it's mis-firing slightly under light throttle - just feels a bit jerky.

It did have an actual, albeit occasional, mis-fire under load at low revs & it was also very jerky on and off the throttle. These seem to have been fixed (so far anyway!) by replacing the plugs, leads, dizzy cap and rotor last weekend & it seems much happier to rev now.I also checked out the coil low and high tension resistances before I changed everything else; they were fine, so I had assumed that the dizzy itself is OK.

But... the issue under light throttle is still there. Any ideas what it might be?

I may or may not be on the right track - someone tell me if I'm wrong here but have you made sure the timing is spot on? as in....one of your cams isnt back/forward a tooth?

Had this problem myself a while ago, TS V6, at 237,000 km. 50 KPH in third gear (auto) at about 1,800 rpm would occasionally miss on light throttle and steady speed. Pulled the heads off (for other problems - oil leak, rattly lifters, snapped off exhaust manifold studs) and found a burnt exhaust valve, as well as very tired lifters. Heads were reworked with new lifters, exhaust valves and bronze valve guides for the exhaust. Miss has disappeared, so if yours has done similar Km might I suggest you do a compression check?

Thanks for the comments.

I believe the cam timing is fine, no problems there. It's got 168,000km on it now, belt changed at 100k & I know it didn't get put back on a tooth out as I did it myself.

I don't think there are any valve issues yet (could be wrong!), as there's no smoke from the exhaust & performance is pretty strong. The lifter are getting a little noisy now, but nothing serious as yet. Sure hope there's nothing as serious as re-working the heads to worry about!

. . . . there's no smoke from the exhaust & performance is pretty strong.


OK, but a valve can be leaking without these symptoms. I would still do a compression test.