It's been years, to just learn to drive it. The frustrating thing is my other car is what I'll call normal, or the throttle pedal does its thing without noticing any super sensitive reactions to letting off.
I swear the off throttle switch is working, and set to click off at the last possible moment. Far as I know it's timed correctly, throttle body clean and set to the FAQ specs and the AFM seems fine.
Throttle response is excellent for acceleration, it's just the off pedal, " Right now !" slow down that's obviously not right.
Any order in changing out suspect components ? Any chance it's the main brain box in the glove box ?
Still sensitive throttle.
How is the idle control valve?
Normally this picks up the dropping rpm and eases it down. When it's a bit stuck it can not respond in a delicate way so the engine starts bogging when the throttle is closed.
If you can switch it with a known good one that would be a good start. Otherwise give it a good internal clean with brake cleaner.
Normally this picks up the dropping rpm and eases it down. When it's a bit stuck it can not respond in a delicate way so the engine starts bogging when the throttle is closed.
If you can switch it with a known good one that would be a good start. Otherwise give it a good internal clean with brake cleaner.
E12 M30B35, VEMS, HX52 never getting finished.
1981 BMW 528i, or 1979 BMW 528i, or 1981 BMW 633csi or 1979 BMW 635 csi. M30, L Jet, far as I know all identical AFMs, throttle bodies, different Aux air valves, different throttle switches but all doing basically the same thing.
I understand the heads, cams, valves are all the same, the only difference being the blocks, pistons size.
Even the computer in the glove box is the same, interchangeable if the ends on a wiring harness match up.
I understand the heads, cams, valves are all the same, the only difference being the blocks, pistons size.
Even the computer in the glove box is the same, interchangeable if the ends on a wiring harness match up.
There is no idle control valve on US spec E12s. Two aux air valves for warm up and A/C compensation, but no idle air.
No good answer, but you need to start checking odd stuff, like are any of the centrifugal advance springs broken in the dist, or if it's a dual diaphragm dist, are both diaphragms still good.
Don't discount the obvious though, pull a wire off the idle switch and see what it's like. Misadjust it and see what happens. Looooooong shot could even theoretically be the bypass in the AFM. If none of this works start swapping parts between the two cars.
No good answer, but you need to start checking odd stuff, like are any of the centrifugal advance springs broken in the dist, or if it's a dual diaphragm dist, are both diaphragms still good.
Don't discount the obvious though, pull a wire off the idle switch and see what it's like. Misadjust it and see what happens. Looooooong shot could even theoretically be the bypass in the AFM. If none of this works start swapping parts between the two cars.
Mike W.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
Disconnected the idle switch to make a very large improvement in jerkiness and off throttle slowing. Makes me wonder what the drat switch is for.
Including, if I'm a picky purist, is the next step swapping in another switch ? Or is it no big deal at all to have the wires secured but disconnected ?
Must be faulty, as it makes a distinct click at the last possible instant the butterfly will allow.
Thank you for all the continued help.
Including, if I'm a picky purist, is the next step swapping in another switch ? Or is it no big deal at all to have the wires secured but disconnected ?
Must be faulty, as it makes a distinct click at the last possible instant the butterfly will allow.
Thank you for all the continued help.
T. Hanson, I have read so many of your posts about this issue because I have been struggling with similar drivability problems with my 81 528. For YEARS. I know mine are more than just the idle switch, but that part was troublesome for me for a long time and to this DAY does not feel all that smooth. I noticed that looseness in the throttle butterfly causes this switch adjustment to be difficult to set on mine. I have it adjusted so last instant that sometimes it does not trigger at all if I take my foot slowly off the pedal. If I adjust it so that it triggers reliably, I have that annoying jerky jerk. 
Very frustrating.
The main purpose of the switch is to turn off the injectors when engine speed is above 1200 rpm (US 528 models) and the throttle is closed. Like when you are slowing or going to stop with the car in gear or engine braking and your foot is off throttle. That's why it feels so jerky - because when the fuel is shut off, all the engine power stops suddenly.
I don't know if there is a secondary reason for it at idle, but I can't notice any difference with mine not connected other than the annoying jerkyness goes away. Best of luck... and you are not alone haha.
Very frustrating.The main purpose of the switch is to turn off the injectors when engine speed is above 1200 rpm (US 528 models) and the throttle is closed. Like when you are slowing or going to stop with the car in gear or engine braking and your foot is off throttle. That's why it feels so jerky - because when the fuel is shut off, all the engine power stops suddenly.
I don't know if there is a secondary reason for it at idle, but I can't notice any difference with mine not connected other than the annoying jerkyness goes away. Best of luck... and you are not alone haha.