Vibrations, RPM fluctuations when AC is on. Any Ideas
08-11-2012, 08:03 AM
#1
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My Ride: 05' 545i
I was not able to find any thread specific to this issue.
I have 72k on my 05 545i. Car runs smooth when the AC is off, no issues at all.
However, recently when the AC is on there is a slight vibration and more noticeable is the fluctuation in RPM; especially when I am stopped at a light. Occasionally an error is thrown, stating to "drive moderately, reduced power". There is no dimming on the dash ( I trickle charge my battery to maintain the juice when need be).
This only happens when the ac is on; just seems as if the load is too great. I am exaggeration a bit here but it seems as if the engine is about to stall and the rpm revs up to keep it alive. I believe the RPMs fluctuate between 900 to 1300 or there about.
I try to replicate this effect at cold start up in the garage, but this only happens once a I start driving for a minute with the ac load on.
Any ideas, suggestions or jokes are welcomed. Thank you everybody.
I have 72k on my 05 545i. Car runs smooth when the AC is off, no issues at all.
However, recently when the AC is on there is a slight vibration and more noticeable is the fluctuation in RPM; especially when I am stopped at a light. Occasionally an error is thrown, stating to "drive moderately, reduced power". There is no dimming on the dash ( I trickle charge my battery to maintain the juice when need be).
This only happens when the ac is on; just seems as if the load is too great. I am exaggeration a bit here but it seems as if the engine is about to stall and the rpm revs up to keep it alive. I believe the RPMs fluctuate between 900 to 1300 or there about.
I try to replicate this effect at cold start up in the garage, but this only happens once a I start driving for a minute with the ac load on.
Any ideas, suggestions or jokes are welcomed. Thank you everybody.
08-12-2012, 12:41 PM
#2
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Your idle RPM should be about 500.
Nothing changes when you turn AC on except more load on the engine.
Sounds like some sort of electrical malfunction which is only engaged when you turn on the AC. If I'm not mistaken I believe the compressor in these cars stay on all the time. At lease this is what I remember reading. Someone correct me if I'm wrong. However, I highly doubt a compressor would cause this, so we would go back to the electrical part of it. There may be a problem with a wire.
First thing, check the battery, make sure it is good cold and make sure that the alternator is putting out enough charge. It could be that the alternator is keeping up..JUST hanging in there until you kick on the AC.
Have you done anything recently such as a belt change etc?
Nothing changes when you turn AC on except more load on the engine.
Sounds like some sort of electrical malfunction which is only engaged when you turn on the AC. If I'm not mistaken I believe the compressor in these cars stay on all the time. At lease this is what I remember reading. Someone correct me if I'm wrong. However, I highly doubt a compressor would cause this, so we would go back to the electrical part of it. There may be a problem with a wire.
First thing, check the battery, make sure it is good cold and make sure that the alternator is putting out enough charge. It could be that the alternator is keeping up..JUST hanging in there until you kick on the AC.
Have you done anything recently such as a belt change etc?
08-12-2012, 01:54 PM
#3
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My Ride: 04 545i - Titanium Silver/Black, Sport pkg, Comfort Seats w/ Lumbar, Premium Sound, power rear sunshade, Adaptive Xenon Headlights, Steptronic, Park Distance Control, Fold down rear seats w/ski bag, Aux jack, 6-disk changer, puddle lamps...
Engine: Custom Remus cat-back exhaust w/chrome square tips, K&N Air Filter, Charcoal Filter Removed, Sprint Booster :-), 50/50 mix of 91+100 Octane, EuroRev ECU Remap (coming soon lol), Dinan High-Flow Throttle Body (coming soon...maybe lol)
Interior: Portable Sirius Stilletto 100 w/car kit, Garmin Nuvi 680 mounted below rear-view mirror, LCI-style I-drive knob, Dark Poplar Center Dashboard Trim.
Exterior: E60 forum clings, 5% rear tint, ACS roof spoiler (painted black for distinct look against limo tint), ACS trunk spoiler, ACS add-on front spoiler and rear apron (awaiting installation), "18 Black Staggered BeBeS Style OER (emergency replacement for cracked sport 124 rims), black kidney grill, white accessory lighting (including license and trunk lamps), Angel-eye upgrade, AIB xenon-matched fog lamps, AIB V3's on order, red rear reflectors
Your idle RPM should be about 500.
Nothing changes when you turn AC on except more load on the engine.
Sounds like some sort of electrical malfunction which is only engaged when you turn on the AC. If I'm not mistaken I believe the compressor in these cars stay on all the time. At lease this is what I remember reading. Someone correct me if I'm wrong. However, I highly doubt a compressor would cause this, so we would go back to the electrical part of it. There may be a problem with a wire.
First thing, check the battery, make sure it is good cold and make sure that the alternator is putting out enough charge. It could be that the alternator is keeping up..JUST hanging in there until you kick on the AC.
Have you done anything recently such as a belt change etc?
Nothing changes when you turn AC on except more load on the engine.
Sounds like some sort of electrical malfunction which is only engaged when you turn on the AC. If I'm not mistaken I believe the compressor in these cars stay on all the time. At lease this is what I remember reading. Someone correct me if I'm wrong. However, I highly doubt a compressor would cause this, so we would go back to the electrical part of it. There may be a problem with a wire.
First thing, check the battery, make sure it is good cold and make sure that the alternator is putting out enough charge. It could be that the alternator is keeping up..JUST hanging in there until you kick on the AC.
Have you done anything recently such as a belt change etc?
08-12-2012, 03:49 PM
#4
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Are you absolutely sure about that with the E60? Or did I read that the compressor is clutchless?
08-12-2012, 03:55 PM
#5
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To me this has to be electrical. Check your battery and check alternator. It appears that your electrical system is being bogged down when you turn on A/C. What if you switch modes to automatic? What if you put on heat? It's a process of elimination.
08-13-2012, 07:22 AM
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Thank you for the responses! I have not done any work on her lately, besides the recent recall. I will check the automatic setting. I'm in Texas so using heat never crossed my mind, plus nights I just use the blower without ac and nothing happens.
Electrical may be the source because the engine does run fine alone, whether I am driving with spirit or going to work.
idle rpm without ac on is about 500/600 like normal. And yesterday the ac load would make it skip from there to 1000/1100
Electrical may be the source because the engine does run fine alone, whether I am driving with spirit or going to work.
idle rpm without ac on is about 500/600 like normal. And yesterday the ac load would make it skip from there to 1000/1100
To me this has to be electrical. Check your battery and check alternator. It appears that your electrical system is being bogged down when you turn on A/C. What if you switch modes to automatic? What if you put on heat? It's a process of elimination.
08-13-2012, 07:51 AM
#7
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I was thinking, if it was electrical/power in nature would all systems be effected? Lights and stereo? No dimming on lights, or gauges, stereo volume does not fluctuate either.
anyways, i am trickle charging battery now.
anyways, i am trickle charging battery now.
08-13-2012, 10:01 AM
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My Ride: 04 545i - Titanium Silver/Black, Sport pkg, Comfort Seats w/ Lumbar, Premium Sound, power rear sunshade, Adaptive Xenon Headlights, Steptronic, Park Distance Control, Fold down rear seats w/ski bag, Aux jack, 6-disk changer, puddle lamps...
Engine: Custom Remus cat-back exhaust w/chrome square tips, K&N Air Filter, Charcoal Filter Removed, Sprint Booster :-), 50/50 mix of 91+100 Octane, EuroRev ECU Remap (coming soon lol), Dinan High-Flow Throttle Body (coming soon...maybe lol)
Interior: Portable Sirius Stilletto 100 w/car kit, Garmin Nuvi 680 mounted below rear-view mirror, LCI-style I-drive knob, Dark Poplar Center Dashboard Trim.
Exterior: E60 forum clings, 5% rear tint, ACS roof spoiler (painted black for distinct look against limo tint), ACS trunk spoiler, ACS add-on front spoiler and rear apron (awaiting installation), "18 Black Staggered BeBeS Style OER (emergency replacement for cracked sport 124 rims), black kidney grill, white accessory lighting (including license and trunk lamps), Angel-eye upgrade, AIB xenon-matched fog lamps, AIB V3's on order, red rear reflectors
A clutchless compressor simply uses a variable swash/"wobble" plate to vary gas pressurization. However, this action, especially on initial cool down, will cause added load upon the engine until adequate pressurization of the refrigant is reached. It is still a cyclic action, especially if low refrigant conditions exist, sans the old style pressure plate clutch assembly (which would cause even more parasitic losses). However, as a variable unit, operation should be smooth if pressures are maintained.
08-13-2012, 12:22 PM
#10
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MANY things:
Vaccum leak (broken intake hose, oil cap not on correctly etc)
Air filter restriction
O2 sensor
MAFS dirty or not working
Leak diagnosis pump part # 16137193479 Should be highlighted in red in this link http://realoem.com/bmw/showparts.do?...=16&fg=10&hl=9
Secondary air pump failure
Vaccum leak (broken intake hose, oil cap not on correctly etc)
Air filter restriction
O2 sensor
MAFS dirty or not working
Leak diagnosis pump part # 16137193479 Should be highlighted in red in this link http://realoem.com/bmw/showparts.do?...=16&fg=10&hl=9
Secondary air pump failure