M20b25 swapped, hard cold start, stalls warm unless icv unlugged
car 1984 325e 5speed. a 1987 325i motor harness/ecm/sensors/afm/icv/gauge cluster/etc and 3.73 LSD diff were swapped in.
Initially the car had a consistent low rough idle around 600-650rpm. the fuel pressure regulator was tested and found faulty. it was swapped for a 2.5bar regulator until the replacement adjustable regulator came in. Idle improved and picked up to 700-800rpm but was still rough with the 2.5bar regulator. After installing the adjustable regulator at 3bar the idle dropped down to 350-500rpm and stalls constantly
with the initial faulty regulator the car ran in high idle when first started (1000-1100rpm still rough) once warm it would drop to 600-650rpm. with the new regulator installed on a cold start the throttle must be held open to keep from stalling, will not idle hot, the throttle must held open for a hot restart. With the motor warm and the idle control valve still physically hooked to the intake but the electrical connector unplugged the idle raises to 900rpm and the motor runs quite smoothly. The icv has been tested, cleaned and been swapped for another known good one but it made no difference. icv does not operate when the key is initially turned on, but it starts to function (and cause problems) once the ignition is is cranked over. the icv remains operating when the engine is warm causing the motor to stall.
the AFM, TPS & ICV have been tested and are OK. ALL other engine sensors have been replaced since the start of the rough idle problem (all were within spec or very close too but replaced from frustration) ALL of the motor seals and gaskets (head gasket also) were replaced. The distributor cap/rotor, o/p, w/p, t/b and tensioner were also replaced prior to motor installation. the timing marks are aligned. All of the vaccume hoses and intake elbow have been replaced. a smoke test was done, the intake/vaccume lines have been sprayed with carb cleaner as well as gone over with a propane bottle.
What would cause the icv to continue to operate with the engine warm and for the icv to to operate incorrectly on a cold start???
car runs great warm with icv electrically disconnected. the round c101 (i think) connector was spliced to mate to the chassis older rectangular connector, ecm was swapped to 173 module. if anyone can think of something that may have been overlooked or a possible wiring mistake made during the swap that could cause these symptoms help would be greatly appreciated. thanks in advance to everyones help
***Correction*** ICV does operate with key on, couldn't be heard over background noise before
Initially the car had a consistent low rough idle around 600-650rpm. the fuel pressure regulator was tested and found faulty. it was swapped for a 2.5bar regulator until the replacement adjustable regulator came in. Idle improved and picked up to 700-800rpm but was still rough with the 2.5bar regulator. After installing the adjustable regulator at 3bar the idle dropped down to 350-500rpm and stalls constantly
with the initial faulty regulator the car ran in high idle when first started (1000-1100rpm still rough) once warm it would drop to 600-650rpm. with the new regulator installed on a cold start the throttle must be held open to keep from stalling, will not idle hot, the throttle must held open for a hot restart. With the motor warm and the idle control valve still physically hooked to the intake but the electrical connector unplugged the idle raises to 900rpm and the motor runs quite smoothly. The icv has been tested, cleaned and been swapped for another known good one but it made no difference. icv does not operate when the key is initially turned on, but it starts to function (and cause problems) once the ignition is is cranked over. the icv remains operating when the engine is warm causing the motor to stall. the AFM, TPS & ICV have been tested and are OK. ALL other engine sensors have been replaced since the start of the rough idle problem (all were within spec or very close too but replaced from frustration) ALL of the motor seals and gaskets (head gasket also) were replaced. The distributor cap/rotor, o/p, w/p, t/b and tensioner were also replaced prior to motor installation. the timing marks are aligned. All of the vaccume hoses and intake elbow have been replaced. a smoke test was done, the intake/vaccume lines have been sprayed with carb cleaner as well as gone over with a propane bottle.
What would cause the icv to continue to operate with the engine warm and for the icv to to operate incorrectly on a cold start???
car runs great warm with icv electrically disconnected. the round c101 (i think) connector was spliced to mate to the chassis older rectangular connector, ecm was swapped to 173 module. if anyone can think of something that may have been overlooked or a possible wiring mistake made during the swap that could cause these symptoms help would be greatly appreciated. thanks in advance to everyones help ***Correction*** ICV does operate with key on, couldn't be heard over background noise before
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