Kangeroo hop!

Mon Dec 12, 2005 9:58 am

Heres a good one for you...

Ive got a 1990 316i that will be fine usually, but when driving along with my foot slightly on the throttle (usually about 2000 revs) sometimes the car starts bucking with increasing violence until i change gear (up or down) or put my foot down on the throttle.

And ideas?? It seems to be getting worse which is worring me a bit!

Mon Dec 12, 2005 4:16 pm

bit of a shot in the dark here mate but had a similar situation in my 320,changed plugs etc to no avail but then changed leads,distributor cap and rotor arm and the problem was solved

Mon Dec 12, 2005 4:37 pm

The distributor cap and rotor are new...however theold ones had bmwbosch 1990 stamped on them

/
So i suspect the leads are origanal, may be worth changing!!

Mon Dec 12, 2005 5:48 pm

Does it get worse when idling round corners ?

Sounds more like play in the drive train

Jack one rear wheel up, Handbrake off (and engine), put it in second gear and see if you can rotate the wheel backwards and forwards lightly more than about a half inch. (without turning the gearbox)

If you can then it's wear in either your driveshafts, gearbox or differential or all three

Mon Dec 12, 2005 8:54 pm

Could it be the air flow meter? I know that the spring for the main flap can wear but not sure if anyone can confirm if this would cause problems on a constant throttle?

Fri Dec 16, 2005 8:50 am

Sorry to jump in on your thread but my 88 325 tourer has developed this. Around town at low speeds it "Kangeroo hops" but as soon as you get onto country roads/ motorways it's fine. It does feel like it's more to do with the engine rather than drivetrain as increasing/decreasing throttle makes it disappear also idles around 600 and can hunt a bit. I had wondered about fuel pressure/injectors as the previous owner fitted an adjustable FPR and thought it might be set up wrong??

any other ideas of what could be causing it would be most welcome

Fri Dec 16, 2005 9:16 am

No one's mentioned the air hose between the AFM and the throttle body.
A split in this can open and close with engine movement and give kangaroom symptoms.
PS: I've NEVER come across a dud E30 ignition lead.

Fri Dec 16, 2005 6:01 pm

PS: I've NEVER come across a dud E30 ignition lead

I have, not a gen but was a brand new reproduction part brought from a well know retailer. Had running problems ever since fitting them and finally traced it to plug lead on cylinder #5, wire had somehow turned to white powdery crap and the the plug shroud and wire parted company

Stuck the vintage OEM ones back on and the problem misfire went