temperature sensor in afm

[geoffrey318]

any sifu here can let me know what's the function of the temperature sensor inside the afm??

 

[geoffrey318]

how could i know the sensor is functionally??

 

[sesat88]

urm... since it is call a temperature sensor.. my best bet is that it is used to measure air temperature.

hehehhehehe.... soli la bro.. i also dunno... but seriously i really really think it is use to measure the air intake temperature.

 

[pussy]

hmmnn.. air tempreture maybe for a thermometer ? the engine is like a human organ too..

 

[absidian]

Temp values are used by the ECU to provide a corret air/fuel mixture - cooler air more dense (more oxygen) and hotter air less dense (less oxygen).

If it's spoilt then there should be a very slight loss of power, but not as bad as a faulty AFM itself, faulty crankshaft sensor or vacuum leak etc etc.

 

[geoffrey318]

after changing a used afm,found that the rpm is around 600-750rpm,is it normal??
before that,the rpm used to 800rpm..

 

[anaksarawak]

Any Sifu can share the following experience:

1. When engine is cold (1-3 minutes after start) Engine is lagging.. meaning press accerl but car dont really want to move.

2. Engine is smooth (850rpm) on P or N but when shifted to D or R engine vibrate as RPM drop 200rpm (650rpm) when gear is engaged. Normally the rpm will revert back to 850rpm after the gear is engaged.

Can the above be the cause by O2 sensors fault or the idle control valve.

 

[Russie]

geoffrey i also felt that sometimes my engine is also sluggish when the engine is cold. yeah after a while, then it turns out to be smoother. last time b4 i changed my gearbox oil also feel the same on my auto gearbox but now felt better after oil change on it.

 

[absidian]

1. O2 sensor is not used by ECU when engine is cold, as this takes time to heat up in order to provide correct readings. On cold start, engine relies on AFM, temp and TPS to tell it what to do.

2. Typical idle problems... could be ICV, vacuum leak, intake leak, AFM, etc etc.

But if your car runs prefectly fine when hot and on the go then I'd rule out 02 sensors.

 

[jarance]

1. O2 sensor is not used by ECU when engine is cold, as this takes time to heat up in order to provide correct readings. On cold start, engine relies on AFM, temp and TPS to tell it what to do.

2. Typical idle problems... could be ICV, vacuum leak, intake leak, AFM, etc etc.

But if your car runs prefectly fine when hot and on the go then I'd rule out 02 sensors.

This guy know what he is talking. Trust him..

BTW, you can check the temperature sensor with a ohmmeter. It is a RTD. (Resistance temperature Detector).

If you can freeze it to ZERO deg, you will get a 100 ohms. In industrial we call this PT100..

 

[K.M.]

2. Engine is smooth (850rpm) on P or N but when shifted to D or R engine vibrate as RPM drop 200rpm (650rpm) when gear is engaged. Normally the rpm will revert back to 850rpm after the gear is engaged.

I have this problem too. Some people said it's normal for auto car. But I don't think so. No time to look at it yet. Thinking of sending the car for full engine maintenance or just upgrade the engine.

 

[anaksarawak]

I have this problem too. Some people said it's normal for auto car. But I don't think so. No time to look at it yet. Thinking of sending the car for full engine maintenance or just upgrade the engine.

Same thing said by Mec. And I have to agree with you as even Produa MyVi's idle control did bring up the rpm from 650 to 850 when gear is engaged after it drop.

 

[jarance]

Please check your ICV. The ICV control the idling speed.

 

[absidian]

Please check your ICV. The ICV control the idling speed.

I agree with Jarance's recommendation.


Try a diy clean-up on the ICV for a start. Pretty straightforward before replacing.

Part No. 8 on an M43

Then check for split/cracked vacuum hoses/connectors while you're in there.

 

[anaksarawak]

Any DIY Step by step for M43 Engine? Only found M50 & M52 engine ICV DIY cleaning guide

 

[absidian]

Easier than M50/52.

TPS is also bolted onto the side of the throttle body. Large plastic part thats held on with two Torx screws.

 

[K.M.]

I don't think it got to do with ICV. ICV is for the idling. As Geof mentioned, the vibration only occur during when gear is engaged, not during idling. When the gear engaged to D and R, the engine rpm drop to around 650rpm which created the vibration.
The thing that need to be find out is what had caused the engine rpm drop when gear engaged to D and R???...only then can solve the problem.

 

[geoffrey318]

all of expert sifu here give me a lot of advise...thanks

 

[anaksarawak]

I don't think it got to do with ICV. ICV is for the idling. As Geof mentioned, the vibration only occur during when gear is engaged, not during idling. When the gear engaged to D and R, the engine rpm drop to around 650rpm which created the vibration.
The thing that need to be find out is what had caused the engine rpm drop when gear engaged to D and R???...only then can solve the problem.

K.M.

You are right, as on idle with gear on N or P.. my idle is rock solid on 850rpm.. on the aircon the rpm jump up to 950rpm then drop back to 850rpm.

The questions now is .. should the ICV bring the rpm back to 850rpm when the gear is engaged? It should ya? As I notice on other car M52 engine, it drop when gear is engaged to D or R but it resume to 850rpm again.

Please advice if the pic attached is the ICV of M43 engine?

 

[anaksarawak]

Found something interesting..

Hope it is alright for me to share this.

http://www.bimmersclub.com/viewtopic.php?t=632&mforum=bimmers