Kangeroo Effect!

[RustyRuss]

Picked up my 316i and drove the 350 miles home today - fantastic car, very pleased, i shall post pics soon. Of the 350 miles, about 280 miles were faultless but towards the emd of the journey the car started kinda lurching a bit when i touched or backed off the throttle - fine if you kept it constant, it was almost as if the car was holding back somehow - quite jerky at times. I stopped numerous times and left it for 20 mins or so and it cured it for a little while then it returned. Almost like kangaroo petrol at 50/60mph. Any ideas? My initial thoughts are clogged fuel filter and/or fuel pump on the way out. Plausible? I knoe fuel pumps are a pain to change from past expereience but hey. My haynes manual is on its way but where is the filter located? Any thoughts would be appreciated. Im not concerned as itll not be out till spring now - fair weathered car, but it will give me time to think about it!

[Martinaston]

Binding brakes ?
Drive it around until the car has warmed up and then on a quiet piece of road let the car roll to a stop on it's own and see if you can feel it pull to a stop quicker than expected.
You can some times feel the suspension bounce back up where the wheel is under load.
If it is this the brakes will lock even more when they are hot so may explain the symptoms you were having, you may be able to feel one of the wheels getting hotter than the others after driving for a while.

If its a 316 you have rear drum brakes so the guy may have tightened the handbrake cables to secure the sale and may have over done it. try gently lifting the handbrake while coasting along and see if you can feel it engage.

The alternative is a worn spring on the brake pedal that is not bringing the pedal back to the top when released, see if you can lift it with your foot after braking.

[RustyRuss]

Thanks Martin, much appreciated! Shall give them a try.

[optima]

it sounds more like a air leak check the hose between the afm and the throttle body that the usual one....

[E30Mark]

My iS had a intermittent miss-fire the other week, i changed the blue temp sender and now all is OK !

Does it smell rich when it's running bad, mine was hence why i changed the sender.

[Martinaston]

What kind of service history do you have with it?
If it's only done 37k most of the components will still be the original parts, see if the engine has a misfire at a certain rev range and give the distributor the once over.

37k, you lucky f**ker

so come on how much did you give for it ?

[RustyRuss]

Just the kinda e30 i wanted - totally standard n mint, full supplying bm dealer history, every piece of paper ever written about it etc etc, bill of sale, every mot n service sheet, receipts for tyres the lot, i paid 2k which i think is extremely fair! I shall post proper pics when we get a dry day and ill bring her out - unused spare wheel, jack, toolkit etc.

[fixedwheelnut]

One that occaisionally happens is usually associated with noisey valvegear, the rockers wear and create an ossilation in the valve operation, this inturn causes a reverse pressure wave in the inlet manifold that forces the airflow meter flap back and starves the fuel.
It feels like holding back around 4000rpm if you back off and slow down it will accelerate again.
It is easy to get the rocker cover off and look at the followers and see if they are worn.

[RustyRuss]

Right - certainly never thought of many of the suggestions here - thanks!