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Old 07-20-2015, 10:10 PM   #21
jfoj
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I have both a 330 and E39 M5, both of these cars have mechanical fans with electric pusher fans in front of the AC condenser.

For the most part the mechanical fan moves all the air on these 2 cars, the electric fan only comes on when the AC is turned on. As the AC high side pressure increases, so does the electric fan speed.

It sounds like the OP has an airflow problem. I am just guessing/tossing some ideas out there, so not sure if any of these are problems or can be problems, but I find you always need to start with the obvious and assume nothing had bs been done correctly.

1. Serpentine belt routing, is it correct and is it tight enough.

2. Fan on the clucth, is it installed correctly and pulling air in the correct direction.

3. Plastic ducting around hood and lower engine cover, are they all installed and in place.

4. Has the radiator been removed to check for debris between the radiator and AC condenser.

5. Did the car sound like a school bus once the replacement fan clutch was installed? Many people claim the mechanical fan can be quite noisy for the first few weeks once a new fan clutch has been installed.

Read the 4th link below in my signature for info on the Hidden OBC Menu. You can monitoring the engine coolant temp directly on the dash so you will be able to watch the temp rise and lower in real time. Keep in mind the gauge on the dash is buffered and will not move from dead vertical over a wide temp windowl.

You could also get an OBDII smart phone App as well.

Get an OBDII smart phone/tablet App and interface, typically $30 or less. These Apps are usually best for drivability issues and they support Emission Readiness Monitor Status, Freeze Frame and Live/Realtime data. They are also great for Logging data for review after the car has been driven and can really help find unusual problems.

Android - Touch Scan for $3.95 and ELM327 OBDII to Bluetooth interface.

iProduct - OBD Fusion for $9.95 and ELM327 OBDII to Wifi interface.

I usually suggest getting the OBDII interfaces from Amazon if you are located in the US/North America. Make sure you choose an interface that indicates that the order will be "Fulfilled by Amazon" otherwise you may be waiting for WEEKS for an interface to arrive from Asia. Ebay is another option, but pay attention where the interface will be shipped from, again weeks for an interface from Asia, so if you can wait and want to try to save some money, go for it, but if you need an interface soon, choose wisely.
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Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299
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Old 07-21-2015, 07:21 AM   #22
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Quote:
Originally Posted by josephG View Post
Hi:

This time it happened again when it was really hot outside and when I was stuck in heavy stop and go traffic.

Very shortly after, sure enough, car overheated again on a hot day during heavy stop and go traffic. What's interesting is that it would overheat and go to the 3/4th mark and then go back down again within a minute or so.
OP - your electric fan is not functioning on all speeds. It might be functioning in the higher ranges 70-90% but it would appear that the mid range speeds are not kicking in. This is typically a problem with the control box on the shroud not the DME.


I have previously reported how difficult this fan is to diagnose as it may fail only on certain speeds and with a combination of certain parameters .

Do the test I posted earlier. If you have indeed swapped in a brand new fan assembly and it is NOT the Bosch OE but rather a Chinese after-market version I would find another fan assembly to test with also.
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Old 07-21-2015, 07:45 AM   #23
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Originally Posted by Sapote View Post
"What's interesting is that it would overheat and go to the 3/4th mark and then go back down again within a minute or so. "

This is very interesting piece of data that no one had touched on. This proved that the electric fan kicked in and cooled it down fast, and so the elec fan was fine. The only issue is why the fan kicked in too late, only after the needle got to 3/4 mark?

1) is it really overheated engine, or just a bad display caused by bad temp sensor or gauge? Set the dashboard to engine monitor mode to display the temperature in number to see how high it went before the fan kicked in to drop it down.
2) do the temp gauge and the fan use the same sensor or two different sensors, anyone? If two sensors then it could explain why.

Sapote

Very observant Sapote - Fan range speed failure is what I'm suspecting. This is why it is important to test the fan all ALL the ranges. When it fails only at certain speeds very hard to pinpoint. What I have difficulty with however is the OP says he put in a new fan (not sure if he just means motor or the control module also?)

Intermittent coolant temp sensor might also exhibit similar symptoms as might a failing t-stat?

Last edited by BMW-North; 07-21-2015 at 07:55 AM.
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Old 07-21-2015, 04:42 PM   #24
josephG
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Thanks BMW-North and jfoj for the very detailed responses. BWM-North, to answer your question from earlier, the entire fan assembly was replaced. I had a chance to talk more in detail with the mechanic today. He mentioned that the DME is telling the electric fan to turn on, but it is not able to sustain the signal, so the fan turns off.

I asked him if there were any visible distress signs on the DME module itself, but that wasn't the case. His recommended solution, (which I incorrectly mentioned yesterday) was to add a resistor between the DME and the fan circuit to complete the loop. So DME would still control the fan. He gave a fairly technical explanation to this work-around - unfortunately I suspect I'm not doing a good job conveying what he said.
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Old 07-21-2015, 05:21 PM   #25
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Quote:
Originally Posted by josephG View Post
Thanks BMW-North and jfoj for the very detailed responses. BWM-North, to answer your question from earlier, the entire fan assembly was replaced. I had a chance to talk more in detail with the mechanic today. He mentioned that the DME is telling the electric fan to turn on, but it is not able to sustain the signal, so the fan turns off.

I asked him if there were any visible distress signs on the DME module itself, but that wasn't the case. His recommended solution, (which I incorrectly mentioned yesterday) was to add a resistor between the DME and the fan circuit to complete the loop. So DME would still control the fan. He gave a fairly technical explanation to this work-around - unfortunately I suspect I'm not doing a good job conveying what he said.
Thanks for the update Joe. If you're taking it to a mechanic I assume you don't have the BMW INPA diagnostic set-up available to you? Does the mechanic? The INPA fan test is a good way to understand if the DME is talking to the fan module correctly.

I would put out a call to another member around here who has INPA working at their home garage (also from the Boston area) to help you diagnose this.

The voltage signal on the DME PWM line is very small -not sure what would cause it to be disrupted if it wasn't corroded or damaged. I'd also like to swap out a known good fan assembly with the current to see if the problem followed the fan module. Just never heard of the DME signal "dying" like this.

Might be time to try to pick up a good diagnostic tool like INPA - the software is free - the cable is about $15.


You prior stated that the fan is working ok at high speed. If you are driving it in the meantime you could do one of a couple of things to prevent the overheat temporarily.

1. Disconnect the lower outlet radiator hose coolant temp sensor on the lower right side of the car down near the AC compressor. This will have the effect of telling the DME there is a fault and it's supposed to run the fan on full speed to prevent overheat.

2. When the car warms up to normal temp switch the ac ON - the AC ON request combined with the temperature reading should force the DME to send a high speed request to the fan module.

Temp fix #1 might be more practical for a short period.

I would test the effectiveness of either of these temporary solutions in your driveway before venturing too far from home. Remember that as your speed increases the DME tells the fan to slow down. After about 90mph the DME is telling the fan to not run at all. This should be overridden however with the fault from the temp sensor being disconnected taking precedence.

Last edited by BMW-North; 07-21-2015 at 05:30 PM.
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Old 07-21-2015, 06:36 PM   #26
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Hey BMW-North, i don't have access to the INPA diagnostic setup. 'm leaning towards the mechanic having it however - I can certainly inquire.

I know they've mentioned that they tried swapping out the fan assembly with a different one - the end result was that my fan checked out. Not sure if it was at all the different speeds that you detailed in one of your previous posts. But if the fan assembly is brand new, wouldn't that rule out the fan?

Not sure about me saying that the fan was working ok at high speed. The problem only occurs on hot days when the car is mostly idling in traffic. It was never an issue in winter/spring. And usually the AC is always turned on when it is hot outside anyway, but that didn't prevent the overheating in traffic.

I'm also a little confused because a) if the ac is supposed to tell the electric fan to turn on (in combination with the temperature), but the mechanic is saying that the fan is turning off immediately because the DME can't maintain a sustained signal, wouldn't my AC not work then?

b) I've also heard that when the car starts overheating, it's usually better to crank up the heat all the way.

Thanks again for all the great responses...I'm certainly learning a lot
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Old 07-21-2015, 06:57 PM   #27
jfoj
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No idea if this is part of your problem, but a very easy check to rule either in or out, pay attention to post #12, do not worry about the problem in this thread specifically - http://forum.e46fanatics.com/showthread.php?t=1052977
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Fuel pump failures - http://forum.e46fanatics.com/showthread.php?t=929501

Temp Info - http://forum.e46fanatics.com/showthread.php?t=964491

Hidden OBC Menu - Check Voltage, Temp, Fuel Level - http://forum.e46fanatics.com/showthread.php?t=239619

E46/E39 GM5 Door Lock Info - www.bmwgm5.com

Lower hose temp switch O-ring - BMW #13621743299

Last edited by jfoj; 07-21-2015 at 06:58 PM.
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Old 07-21-2015, 07:12 PM   #28
kwise1258
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Id be looking at that thermostat


3c2i5Topless
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Old 07-21-2015, 07:44 PM   #29
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Quote:
Originally Posted by josephG View Post
Hey BMW-North, i don't have access to the INPA diagnostic setup. 'm leaning towards the mechanic having it however - I can certainly inquire.

I know they've mentioned that they tried swapping out the fan assembly with a different one - the end result was that my fan checked out. Not sure if it was at all the different speeds that you detailed in one of your previous posts. But if the fan assembly is brand new, wouldn't that rule out the fan?

Not sure about me saying that the fan was working ok at high speed. The problem only occurs on hot days when the car is mostly idling in traffic. It was never an issue in winter/spring. And usually the AC is always turned on when it is hot outside anyway, but that didn't prevent the overheating in traffic.

I'm also a little confused because a) if the ac is supposed to tell the electric fan to turn on (in combination with the temperature), but the mechanic is saying that the fan is turning off immediately because the DME can't maintain a sustained signal, wouldn't my AC not work then?

b) I've also heard that when the car starts overheating, it's usually better to crank up the heat all the way.

Thanks again for all the great responses...I'm certainly learning a lot
From what your saying then it sounds like the fan module must be ok. Your right, typically you would shut off the AC and crank the heat up with the cabin blower on full to assist cooling. However given the DME is supposed to crank the fan at full speed with certain parameters I wanted you to test in your driveway if you could manipulate the fan to running high Not sure if you have alternate transport while this car is not working?

I looked at the images jfoj linked and a DME like that would certainly have comm issues but you would think they might exhibit themselves in more than just the fan pwm signal. Sounds like your mechanic is gonna rig the old heat resistor setup that was in the e30? It was a two speed setup but very reliable. I don't believe you will get a cel light by disconnecting or bypassing the DME controlled fan module - just an error via scanning and there is no cluster light activated for the fan errors.

Keep us posted.

Edit: to answer your q about the AC. If a coolant temp exceeds a threshold the DME shuts off the AC in cycles and turns the fan up to full speed. All fan power is then directed to reduce the coolant temp and protect from overheat. That is how it is meant to work.

Last edited by BMW-North; 07-21-2015 at 07:47 PM.
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Old 07-21-2015, 08:41 PM   #30
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Originally Posted by josephG View Post
I had a chance to talk more in detail with the mechanic today. He mentioned that the DME is telling the electric fan to turn on, but it is not able to sustain the signal, so the fan turns off.

His recommended solution, (which I incorrectly mentioned yesterday) was to add a resistor between the DME and the fan circuit to complete the loop. So DME would still control the fan. He gave a fairly technical explanation to this work-around - unfortunately I suspect I'm not doing a good job conveying what he said.
"I had a chance to talk more in detail with the mechanic today. He mentioned that the DME is telling the electric fan to turn on, but it is not able to sustain the signal, so the fan turns off. "

DME sent a low voltage logic signal PWM (pulse width modulated) to the fan's Driver module. since it's a logic signal instead of power signal, there is no reason why DME was not able to sustain it. It either works or no, and there is no case that it only works for a short time then "weak off". One can think the PWM signal as an ON or OFF command at different speeds. (BMW_North, how does the fan's module report to the DME at engine start up diagnose that the fan speed is either ok or not, via the same PWM signal?)

"His recommended solution, (which I incorrectly mentioned yesterday) was to add a resistor between the DME and the fan circuit to complete the loop. So DME would still control the fan. "

This is BS. A resistor in series with the PWM signal will not complete any loop. It's only to drop the pwm voltage lower at the fan's module for nothing. Why paying someone like this? I'm an engineer designing motor control driver using PWM command signal, and so I fully understand at the chip and power transistors component level.

I understand your problem is that it will overheated on warm day in slow traffic / and AC on. No problem at higher speed.

1) I would say your water pump and thermostat are ok
2) I think the issue is lacking cooling air, and points to the elec fan.

Test the elec fan: remove the mechanical fan (or tighten up the fan blade to stop it from rotating if we think its viscous clutch would not overheated and damaged). Drive around the block until the temp got up over mid range then pull over and park. open the hood and wait of the elec fan kick in when the temp needle got higher.

If the Efan not run, 2 reasons:
a) DME didn't send the PWM to the fan, or
b) The fan/module is bad. Normally any square wave (50% pwm duty cycle) 5v, 5Khz to 15Khz signal connected to the fan module should be able to command the fan to run at 1/2 full speed. A model airplane toy is a good source for pwm signal generator.

If the DME didn't send the pwm signal, it doesn't mean the DME is bad. DME depends on other input sensors data for it to generate the pwm signal.
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Old 07-21-2015, 08:52 PM   #31
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"I'm also a little confused because a) if the ac is supposed to tell the electric fan to turn on (in combination with the temperature), but the mechanic is saying that the fan is turning off immediately because the DME can't maintain a sustained signal, wouldn't my AC not work then? "

Depending on the car speed and temperature. At very high mph the Efan might not need to be ON because there is enough cool air flow at high speed.

I total don't understand anything about DME can't maintain a sustained signal (pwm signal?).BS here. Under high load the DME could shut off the AC compressor, but absolutely no reason why it shut off the fan with overheated condition!!!!
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Old 07-21-2015, 09:02 PM   #32
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"OP - your electric fan is not functioning on all speeds. It might be functioning in the higher ranges 70-90% but it would appear that the mid range speeds are not kicking in. This is typically a problem with the control box on the shroud not the DME. "

BMW-North, I kind of agree partially with the statement above. Normally an old fan motor with higher friction or weaker rotor magnets might not able to run at lower pwm command, say below 30% pwm but it runs ok at above 30%, for example, because this weaker fan does not have enough torque at 30% of 14V = 4.6V to turn, but it starts to turn at above 5V. I just don't see why a fan can run at 20% = 2.8v and above 50% = 7v but fails to run at 30%. There is no logical reasons for this.
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Old 07-22-2015, 05:36 AM   #33
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Quote:
Originally Posted by Sapote View Post
"OP - your electric fan is not functioning on all speeds. It might be functioning in the higher ranges 70-90% but it would appear that the mid range speeds are not kicking in. This is typically a problem with the control box on the shroud not the DME. "

BMW-North, I kind of agree partially with the statement above. Normally an old fan motor with higher friction or weaker rotor magnets might not able to run at lower pwm command, say below 30% pwm but it runs ok at above 30%, for example, because this weaker fan does not have enough torque at 30% of 14V = 4.6V to turn, but it starts to turn at above 5V. I just don't see why a fan can run at 20% = 2.8v and above 50% = 7v but fails to run at 30%. There is no logical reasons for this.
It has nothing to do with the motor. Motor is fine. The fan module stops processing certain ranges when one of the transistors burns out. The motor is simply not getting voltage in that range till the DME request moves out of that range.

The INPA test I posted puts the fan thru a series of simulated DME requested speeds so you can confirm that your fan will work in all ranges. This guy last week found after doing the test his fan module assy could not sustain the high range. http://forum.e46fanatics.com/showthr...t=70+90&page=3

Post 46.

I have found that a failing fan module will seem to function but fail in ranges. The motor is typically fine. Just one of the ic components within the fan module. These primarily contain a logic chip, three transistors, 2 coils and a motor capacitor.

Last edited by BMW-North; 07-22-2015 at 05:50 AM.
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Old 07-22-2015, 04:10 PM   #34
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Are these fans brushless motor?
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Old 07-22-2015, 08:08 PM   #35
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Are these fans brushless motor?
Open one. No wait open a whole bunch. Examine the wiring. There are three different makers. All have brushes.

The fan motors have never been an issue since the Siemens integrated motors were recalled in 2001 and replaced with Bosch. The fan motors rarely fail. Search in here for my threads that show the insides and the differences in the design and quality. I'd post them but I'm on an iPad and it's too much bother.
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Old 07-23-2015, 05:31 PM   #36
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Interesting. All of the PC power supplies have used brushless cooling fans, and I mean low cost products here, while the expensive and automotive grade cooling fans are old technology brush type? What's going on?
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