'89 525m intermitent rythmic stumble/chug.

[Gene in NC]

'89 525m intermittent rythmic stumble/chug. Not sharp break like ignition. Just replaced CPS that gave sharp stalls after engine fully hot.

Now does this fuel like intermittent "deep" chugging from cold to well beyond coolant gauge indication of normal full operating temp.

Recovery/control is to back way off on throttle until engine stabilizes and then it is OK. Seems to happen at lower rpm, probably low throttle as on first shift from 1st to second. Also occasionally from 2nd to 3rd.

Restart when hot, or after sitting for several hours after running is OK. Pulls strong after chug subsides.

Also has pretty persistent hunting at idle. Idle rpm drops from about 700 to 500. AC on raises idle to about 900 with hunt to about 600.

[bmwrp8]

'89 525m intermittent rythmic stumble/chug. Not sharp break like ignition. Just replaced CPS that gave sharp stalls after engine fully hot.

Now does this fuel like intermittent "deep" chugging from cold to well beyond coolant gauge indication of normal full operating temp.

Recovery/control is to back way off on throttle until engine stabilizes and then it is OK. Seems to happen at lower rpm, probably low throttle as on first shift from 1st to second. Also occasionally from 2nd to 3rd.

Restart when hot, or after sitting for several hours after running is OK. Pulls strong after chug subsides.

Also has pretty persistent hunting at idle. Idle rpm drops from about 700 to 500. AC on raises idle to about 900 with hunt to about 600.

I have the exact same problems esp. the hunting idle part. had this for almost 4 years dunno whatsup anymore. Anyone?

[Gene in NC]

Tried to carefully watch the "chug" today. Most common is 2k rpm with light throttle.

Chugged" once on shift to third, 2.5k rpm. Same recovery, just back off throttle slightly.

[shogun]

http://www.bba-reman.com/content.aspx?content=advanced_hints_and_tips_bmw_a bs_problems

http://www.bba-reman.com/content.aspx?content=hints_and_tips#bmw

Faults on BMW engine management
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Faults on BMW wiring harnesses
Faults on BMW sensors
Faults on BMW electrical systems auxiliary equipment
Faults on BMW starter motors
Faults on BMW alternators
Faults on BMW engine electrical systems

[ahlem]

My vote is fuel pressure too low. If you feather the throttle does it stop and if you gradually accelerate does it seem better than stomping down? Does the CEL go on or flicker then go off? My second vote is a vacuum leak.