'94 318i Fluctuating Idle At Start Up Power Loss - BMW Forum - BimmerWerkz.com
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#1 (permalink) Old 10-28-2009, 03:53 AM
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'94 318i Fluctuating Idle At Start Up Power Loss

Would appreciate anyhelp on this one anyone can give me,
Here's some background on the issue.
Brought the car 2 months ago and it has always had the idling issue since the begining. Cold starting the idle is steady and when driving cold i don't notice any lose of power, but when hot starting most times the idle will fluctuate between 1300 - 200rpm (sometimes stall) only during first 20 seconds of running and i notice on occasions when hot putting foot down it can be slugish other times its perfectly fine.
I have done a major service on it, replaced all vacum hoses, cleaned throttle body, cheched intake for leaks, replaced pcv valve and hose, and cleaned icv thoroughly plus checked it operating. I notice when unpluging icv the car generally drive's happier and smother except the fact it idles high (1300rpm)when warm cause mixture rich but then again the rich micture might just mask the problem to begin with.
Not sure weather to start looking in to Throttle Position Sensor Or Possible Fuel pressure issue?
Was also wondering if its normally to have slight ticking noise from Injector area not sure exactly where tho? dosen't appear to occur alond side with idling issue
Here are some more details on the car:
1994 318i 4dr Sedan
M43 with 5sp manual
Chassis number KB00773
Just done 200,000kms too
Willing to chuck $20 bucks someone's way if they can help me out
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#2 (permalink) Old 10-28-2009, 04:28 AM
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Could be your AFM/MAF as you havent mentioned this in the above,with the car running disconnect it, if there's no or vey little change I would say this is the problem, its situated between the throttle body and air box.

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Last edited by marti5; 10-28-2009 at 04:30 AM.
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#3 (permalink) Old 10-28-2009, 05:12 AM
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Cheers bud for quick reply,
had looked at it at one staged but yeh have sort of overlooked it as they are expensive to replace. I was always under the impression that if they were giving bad readings then fault codes would be logged and idle would remain really inconsistent instead of settling down after 20 or so seconds ;like mine does but ill have another look at it maybe even try to get a swap over unit to test against
thanks again
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#4 (permalink) Old 10-28-2009, 05:43 AM
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It may also be ICV ( idle control valve ) but you say youve cleaned that, so I would go for the AFM.

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#5 (permalink) Old 10-29-2009, 06:28 AM
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Had a look at MAF today tested as you said. Appears to ok, unplugging it while idling makes it pretty much stall and it runs rough for bout 30 seconds till it corrects itself but definitely runs worse while unplugged.
Could still be ICV measured its resistance which was 17 ohms should be 20 ohms according to bentley repair manual +- 5 ohms so appears to be in spec.
Just still questionable weather it is actually functioning correctly 100% of time? What position is it supposed to sit in when unplugged cuz mine sits 3mm open when unplugged (in rest position)?
Guess only way to confirm if its icv would be to get new one to test against?
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#6 (permalink) Old 02-22-2010, 04:46 AM
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Hi! have you found a solution to this problem?

I have the same issue now.

Thanks.
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#7 (permalink) Old 02-22-2010, 08:07 AM
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high idle at warm in E30's is almost always attributed to the ECT sensor and/or the Thermo Time Switch. Both are located on the thermostat head. the thermo time switch being the blue colored sensor, and i forget now the color of the ECT sensor

Anyway, they often fail and end up open or grounded.

TEST: warm engine... pull out the connector on that blue sensor. Idle should normalize to 750-850rpm. Yes? No?

If no, get a paper clip and short the plug at the harness... Idles now? Yes, change the sensor.

Good Luck
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#8 (permalink) Old 02-22-2010, 09:13 AM
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Thanks Darkhorse,

are we talking about the M43 engine here?

No blue things on my engine.

I got an e46 BMW 318 with the same M43 engine and the same issues as the topic-starter with his E36.

(cold, no problems. hot, irregular idle, sometimes stall and sometimes loss of power. No Engine warning light)

Last edited by doezel; 02-22-2010 at 09:18 AM.
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#9 (permalink) Old 02-22-2010, 11:29 AM
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My apologies. I need to correct my last post:

The Thermo Time Switch i mentioned( the blue sensor) applies to E30(M20).

for M43 engines - it is the ECT sensor that measures the cold and warm start temps and communicates that to DME for fuel metering et. al.

It is located in the left side of the engine under the intake manifold - quite close to the oil filter housing.
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#10 (permalink) Old 02-22-2010, 01:18 PM
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Hi Darnkhorse,

Are you referring to part #13 in this image?

RealOEM.com BMW E46 318i Cylinder Head Attached Parts
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#11 (permalink) Old 02-22-2010, 07:04 PM
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Thumbs up

Quote:
Originally Posted by doezel View Post
Hi Darnkhorse,

Are you referring to part #13 in this image?

RealOEM.com BMW E46 318i Cylinder Head Attached Parts
YES! #13
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#12 (permalink) Old 02-23-2010, 01:45 AM
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Thanks! I'll look into it saturday and post my results.
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#13 (permalink) Old 02-23-2010, 06:32 AM
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Hi, just had a look at my engine and I see only 1 wire connected to that sensor. Is that normal?
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#14 (permalink) Old 02-23-2010, 07:04 AM
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This image suggests there should be 2 wires: Schaltplan Viewer - Copyright BMW AG 2004
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#15 (permalink) Old 02-26-2010, 01:39 AM
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Sorry haven't checked post in a while.
Lately car has been good,idle has normalised for most of the time (95% time)
But i am experiencing another two symtons with the my idling issue i didn't notice.
Idling issue only occurs on hotter days 30 degress c and up along with this i experience after about 10 minutes of stop start driving a loss of power (leaning out fuel mix possibly) then she try's to overheat watch temp creep up above operating so i kill her before 3/4 qauaters on the temp gauge to reduce risk of damage.
Also got light surging in 1st gear when steady of throttle when all this occurs.
I'm not sure weather all this related or ifit possible ihave a head gasket problem causing
excessive pressure in cooling system causing overheating thus poor running.
I am loosing a slight amount of coolant maybe 100ml (1 inch on expansion tank) every 1 - 2 weeks but experience no other symptons of a head gasket (did find throttle body cooling hose dripping a while ago possibly leaking again)
What are your symptons doezel?
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