Mystery Kangaroo

Hi everyone,

I’m having a problem with my car kangarooing from cold and can’t seem to resolve it.

It’s a 1990 XR3i Cabriolet (SE500) CVH EFi engine, ISCV mounted on top of the airbox.

The symptoms: If I drive it from cold, after getting a couple of hundred meters down the road, it will start kangarooing. This will carry on until I let off the throttle, once I reapply the throttle, it has cleared. I can recreate this if I am not driving it and just sitting still from cold but applying revs up to about 2000 rpm and then it will start doing it. Again if I let the throttle off and then reapply, it clears itself. If I don’t let the throttle off (while sitting still) it will splutter, the revs jump up and down for about a minute before it clears (or warms up so it’s no longer an issue?).

If I start the car and leave it on tick over for a few minutes, without touching accelerator, and then drive it once it’s warmed up a bit the problem doesn’t occur.

Apart from this, it runs perfectly fine, idles smoothly, is responsive to throttle etc, just this annoying (albeit short lived) problem.

I have owned it since July and have had the following done to it:

New cambelt, water pump, air filter, oil, oil filter, fuel filter, plugs, leads, coil pack, exhaust, air temperature sensor. Removed and cleaned ISCV, base idle set, mixture etc adjusted with gas analyser machine. Cleaned throttle body with air intake carb cleaner (without removing it). Checked for air leaks. Few doses of Redex and every petrol fill up is with BP Ultimate. Not relevant but had new bearings all round, front discs and pads.

I am stumped as to what else to try and although I could live with the problem, if anyone had any suggestions, I’d be grateful to hear them.