Another "what part is this" riddle..with pictures :)

[svetor]

Hi guys,

I'm in my garage now working my way to the throttly body which I hope to clean today (been having low & high idle problems, along with occasional (but rare) rev hunting).

While disconnecting parts I disconnected a thing on the "air intake pipe" (the big black pipe which goes from the air intake & air filter into the throttle body) which must be a sensor of some kind. The thing is it is covered with some liquid or oil or something, which seems a bit strange to me.. I don't now if it should be that way.

Do you recognize it from the pictures below? I won't receive my MB owners bible until Monday so I couldn't look it up. Any ideas greatly appreciated!

 

[BarryG]

Pretty sure that is your Mass Air Flow sensor.

 

[BarryG]

Check out PODs excellent how to clean your MAF here .

http://forums.mercedesclub.org.uk/showthread.php?t=18298&highlight=maf+cleaning

 

[svetor]

Hi Barry

Actually, I think this is not the MAF. I have another sensor closer to the air filter which looks exactly like the one shown to be the MAF in the MAF cleaning DIY by the Parrot of Doom which you refered to and he shows in this picture:
http://static.flickr.com/51/149326537_4433d1cac8.jpg

And actually I did clean that one last week (great DIY by Parrot btw )

If you compare that to the sensor in my picture you see that they are not the same. So thats why I think it's not the MAF. I was thinking an O2 sensor perhaps?

 

[eric242340]

Hi guys,

I'm in my garage now working my way to the throttly body which I hope to clean today (been having low & high idle problems, along with occasional (but rare) rev hunting).

While disconnecting parts I disconnected a thing on the "air intake pipe" (the big black pipe which goes from the air intake & air filter into the throttle body) which must be a sensor of some kind. The thing is it is covered with some liquid or oil or something, which seems a bit strange to me.. I don't now if it should be that way.

Do you recognize it from the pictures below? I won't receive my MB owners bible until Monday so I couldn't look it up. Any ideas greatly appreciated!

Its the air intake temperature sensor and sends the signals for the Air Mass to function correctly. Not an important sensor.

 

[svetor]

Its the air intake temperature sensor and sends the signals for the Air Mass to function correctly. Not an important sensor.

Ah ok, I see that makes sense. Thanks for solving that one !

Why do you say it's not an important sensor, doesn't it cause some problems if it is broken?

Do you think it is supposed to be covered in oil, do you think it's ok to clean it with a tissue or something?

/svetor

 

[eric242340]

This sensor has no bearing on anything other than air intake temperature and can be disconnected or thrown away, trust me it does not affect anything that you may have a problem with

 

[svetor]

Ok, good to know

 

[BarryG]

This sensor has no bearing on anything other than air intake temperature and can be disconnected or thrown away, trust me it does not affect anything that you may have a problem with

If thats the case why did MB bother putting it there in the first place?

 

[eric242340]

If thats the case why did MB bother putting it there in the first place?

Appart from getting technical on this and Id rather not, please trust me it is not an important sensor.

 

[kth286]

svetor

The intake air temperature sensor is a cheap sensor, like £9, so if it is damaged no problems.

It provides one of the may input signals to the main engine computer (ECU).

The ECU is then able to provide (1) correct fueling and (2) ignition.

This sensor signal is required by the ECU to provide (1) correct warm-up enrichment on fueling
and
(2) correct ignition control of the charcoal canister purge function.

 

[svetor]

svetor

The intake air temperature sensor is a cheap sensor, like £9, so if it is damaged no problems.

It provides one of the may input signals to the main engine computer (ECU).

The ECU is then able to provide (1) correct fueling and (2) ignition.

This sensor signal is required by the ECU to provide (1) correct warm-up enrichment on fueling
and
(2) correct ignition control of the charcoal canister purge function.

Ok, thank you for a good answer !

I did clean it thoroughly since it was very oily and put it back in. Just to be on the safe side I will buy a new one since it's so cheap.

(oh and in other news I cleaned the throttle body as well - man was that dirty! And guess what: the car fires up now like new, and I don't have to press the gas when starting it anymore!! It has not solved the high idling problem though - but my first DIY has at least yielded some success yay )

 

[mattkh]

the car fires up now like new, and I don't have to press the gas when starting it anymore!! It has not solved the high idling problem though - )

Hi
That may be down to the coolant temperature sender being faulty...

 

[svetor]

Hi
That may be down to the coolant temperature sender being faulty...

Ok. Can you tell me where that part is?

 

[busby20]

Ok. Can you tell me where that part is?

At the front of the cylinder head there is a plastic cover (facing fan and radiator) if you pull this off you will see the coolant temp. sensor - it's the one with the multi-plug attached. Incidentally, the intake air sensor can be by- passed by connecting a custom made resistor that it is currently being sold on ebay for a few quid. The theory is that it "fools" the ECU into thinking that the air mass temp. is colder than it is, and the ECU compensates by enriching the fuel mixture - which apparently makes the car more responsive etc. - tried it on my C180, didn't make any differance - pays your money, learn the hard way.

 

[whitenemesis]

Appart from getting technical on this and Id rather not, please trust me it is not an important sensor.

Seems daft that MB would spend money on something that doesn't matter. Intake temperature will effect air density, so will effect air mass so IS important. Not critical but has a function on engine efficiency

 

[eric242340]

Seems daft that MB would spend money on something that doesn't matter. Intake temperature will effect air density, so will effect air mass so IS important. Not critical but has a function on engine efficiency

Hi, the intake air temperature sensor does have several purposes and is an integral part of the fuel/ignition system. Have disconnected it before with the Star Diagnostics running and taking actual values. The actual affect is the millisecond opening time on the fuel injectors will vary by 0.01 ms, on a warm engine and 0.04ms on a cold engine. As can be seen from this it will not cause the proplems he is having, and barley has any effect on the engine. However a faulty air intake temperature sensor combined with an other problem, say a faulty air mass meter will have a significant effect. In this case the 3.5ms normal running will vary between 2.6ms and 4.8ms thus causing the engine to surge and idle speed become very lumpy. Hope that explains it.I did not explain on my last post because it was 2 in the morning here and very tired.

 

[hmang]

might as well have a fully fuctional one if its only a few quid.

it's another variable out of the equation if you have running problems.....just "my two penn'orth"

 

[eric242340]

might as well have a fully fuctional one if its only a few quid.

it's another variable out of the equation if you have running problems.....just "my two penn'orth"

lol, totally agree, for a few quid. I certainly would not buy a resistor from EBay in order to cheat the computer. But you can try this on your car, dissconnect the sensor (with a cold engine) and start the engine, spot any difference in the engine running/idle speed? None. If you try this it will store a fault code on the computer, but only a temporary fault and when you reconnect the sensor and take the ignition key out and then in again/re-start the engine the fault code will be errased.

 

[eric242340]

Simpy put, if the air intake temperature sensor fails, then the effect on the engine is not noticable to the driver. And it will not put the check engine light on unless it is added to another fault code.