weird throttle lag issue

[More&Faster]

i bought an '89 325i a couple months ago. (guy told me to check here cause you guys are more familiar with this problem) it took me a while to learn to drive it smoothly. i realized that at idle, if i step on the throttle it won't respond for about 1 second. i can feather it or stomp it, same thing. if i stomp it, i can hear my foot hit the floor way before the engine revs. once it's spinnning the lag isnt so much, but it's still there.

any ideas? the car runs well aside from that. well taken car of and holds it's oil. i'm stumped.

[Blitzkrieg Bob]

and look for vacuum leaks, clean the ICV, AFM, throttle valve

[BillionPa]

doesnt have drive by wire does it?

[markus]

hell no! the drive by wire was being just introduced when the E30 was still around on the E32. The E30s use regular throttle cables. I had a lot of slack in mine and i adjusted it and the throttle response was greatly improved. I love free mods.

[632 Regal]

fly by wire? if not check for intake leaks. Keep us updated

[bsell]

i bought an '89 325i a couple months ago. (guy told me to check here cause you guys are more familiar with this problem) it took me a while to learn to drive it smoothly. i realized that at idle, if i step on the throttle it won't respond for about 1 second. i can feather it or stomp it, same thing. if i stomp it, i can hear my foot hit the floor way before the engine revs. once it's spinnning the lag isnt so much, but it's still there.

any ideas? the car runs well aside from that. well taken car of and holds it's oil. i'm stumped.

I assume you have gone through the ignition system to include checking the timing? Retarded timing will cause sluggish throttle response.

What style fuel injection? Is this the old fuel distributor with separate lines to the injectors deal? If so, pull the intake boot off the fuel distributor and see if the big disk that the air flow pulls up is free to move. I have seen Audi's and Saab's be sluggish to rev due to crud build up in the disk area. Cleaning this area was a standard part of a tune up. Also if the disk is riding too low in the rest position, the engine can be sluggish.

I have seen a bad fuel distributor cause sluggish off-idle response. Something broke internally, causing very high back-pressure on the valve that the airflow disk moves, holding the disk assy down until very high airflow pulled it up off the stop. Overly high fuel system pressure can cause this also. (Fuel pressure regulator check).

Check the throttle position switch assy also. If this is sticking or not otherwise correctly reporting what is happening to the DME unit, response could be poor.

[More&Faster]

wow, thanks for the responses. i just took apart the AFM and it's cool. i'll continue to check all the things mentioned and keep you guys updated.

[More&Faster]

ok well i messed around with stuff and read a bunch of stuff in my haynes manual. I tested the idle air stabilizer valve and it seems to be screwey. when you unhook it the idle is supposed to go up to about 2000 but mine dropped to 500. the voltage on the plug is supposed to be 10 on both sides but mine is 9 and 4. that points to the ECU and the valve being bad....doesnt seem right. i'll have a parts car in about a week so i'll take the idle valve off of that and see if it helps. is the ECU hard to replace?

[632 Regal]

clean out the idle control valve, it could be all gummed up.