Car jolts when in low revs and after gear changes

[jonseysw]

Hi,

My E30 320i M20 jolts forwards and backwards when the car is in low revs normally after I've changed up a gear, as soon as I accelerate a little it stops.

Was thinking possibly a air leak somewhere but wanted another perspective as it is my first E30.

Thanks

[Speedtouch]

Welcome to the Zone! It could be all manner of things, ranging from inlet manifold air leaks to worn propshaft guibo joint, loose propshaft or even wheel bolts.

Is it a mechanical sounding jolt, or more related to the engine 'missing/kangarooing'?

[jonseysw]

Hi thanks.

Im not sure, inclined to say mechanical. Say I've just shifted up into 4th, if I take my foot off the accelerator, as the revs drop it will eventually start to jolt forwards and backwards. But if i accelerate so the car pulls the jolting will stop.

Strange one to try and explain!

[Speedtouch]

Search for posts on 'kangarooing' on here - it's a common problem with M20-engined E30s.

What age is your car? Pre-facelift chome bumper ones were L-Jetronic, while facelift rubber-bumper ones had Motronic.

[jonseysw]

OK thanks for your help mate.

Its 1986 and yeah chrome bumpers so it is L-Jetronic.