E30 Zone

Wonder if anyone can help? My 1990 320i has a slight issue where if you blip the throttle from idle, it will stumble for a second before picking up. It makes it slow pulling out of junctions cause you've got to bring the revs up for a sec before you can pull away. Once the engine's woken up it's fine, powers OK, economy's OK etc. etc.

I replaced the two temp sensors, fixed a hole in the intake rubber pipe with my trusty puncture repair kit, changed the plugs, played with the screw on the AFM, checked & adjusted the throttle switch, none of it made any difference at all! Daym.

Any ideas?

Cheers!

Mine does that too, exactly the same, sometimes I come very close to stalling it if I'm in a hurry.
I think it's a "feature" of the M20B20 but I'm hoping a mild chip will help (when I get round to it).

EDIT: I think it's because the TPS has opened but the ECU has yet to react.

I am having the exact same issue on my 325i. It is currently in the shop so will let you know what they have to say when I get it back.

NB

My '89 320i did that before the recent inspection 2 and mild chip. She now revs very cleanly even before being thoroughly warmed up. I also recently fitted a 325i throttle body so of course replaced the afm to tb rubber boot and tb to inlet manifold gasket. The rocker cover gasket is also quite recent all of which will have reduced air leaks.

I've done my TB too (last weekend), used the 320 rubber boot which was a struggle.
Also recently changed timing belt, leads, distributor cap & rotor (used condition), inlet gaskets, cam cover gasket, but the 'dip' before accelerating away has always been there and is still there. I think the chip will make the biggest difference.

It feels like the AFM is slow to respond - not sure why that would be, or how to fix it if it is. Might well have a poke at it over the weekend. (Taxi to work for me on monday then!!)

Well I don't think it's the AFM... I pulled the top off it and blasted the wiper track with carb cleaner. Also moved the wiper arm on the spindle so it would wipe new tracks because there were visible grooves on the existing ones. No change!

I started the engine with the top cover off the AFM and my multimeter hooked up to it. It was very cool being able to see the wiper arm moving and the voltage changing when the throttle moves. The arm moves a surprising amount just by turning the mixture adjustment screw as well, to start with on idle the thing was about 1/3 of the way round the scale but when I backed the screw off to just before the idle goes bad it was more like 1/4.

But the AFM does respond instantly to the throttle, no delay whatsoever. Leaning the mixure out has improved the problem a bit but it's still there. So the hunt continues. Feck knows.