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BMW E36 Forum • knock sensor | BMW E36 Forum
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knock sensor

PostPosted: Mon Dec 29, 2008 6:21 pm
by paprkut
hi im having some strange idling issues on my 1994 318is

first up my cars idle randomly starts to fluctuate between 500 to 1400 rpms when the car is stationary, after a few revs the idle calms down but soon it starts again. people keep saying icv however i had a new one installed just under a year ago?

my cars headlights / dashboard lights dim for a second when i try to put up a window thats already up. ive checked the battery, its fine also i checked to see if my alternator was charging, and its also fine.

i stuck my car on carsoft... heres what came out:


[code]201 Lambda Regulation A Possibly the tank ran empty, because of the fact that the lambda = regulation recognized a too fat resp. a too poor mixture. It ? could be possible that also other faults appear, which explain this condition. Please check all possibilities which results ; into a change of the mixture as eg.: spark-plugs, exhaust, 8 injection valve, temperature sensor, intake tract etc !


70 Lambda Probe or Knock-sensor 1 (detonation-sensor) # Lambda Probe (DME1.7.x & 3.1) ( Knock-sensor 1 (detonation-sensor) [/code]

i know i need to replace my knock sensor however does anyone have any idea where knock sensor 1 is located? also do you think this could be linked with the problems that im currently having?

Re: knock sensor

PostPosted: Mon Dec 29, 2008 6:25 pm
by paprkut
thanks in advance.

Re: knock sensor

PostPosted: Wed Dec 31, 2008 8:42 am
by tonysticks
Hi,

I'm facing the same problem with my car (I suggest you read about what I did to solve this problem first [url=http://www.bmwe36blog.com/2008/07/24/bmw-e36-knock-sensors/]BMW E36 Knock Sensors[/url]) . I have replaced knock sensor #2 thinking that it's the reason of the problem. Unfortunately, it didn't fix it although the car runs smoother now. Luckily, replacing knock sensor #1 (in your case) is much easier than replacing knock sensor #2 which I had to visit a mechanic to do it. The sensor is located on the front left side of the cylinder block, so it can be replaced much easier than the 2nd one (in my case).

My car's idle still bounces 3 or 4 times when I start it then it becomes smooth. It bounces again occasionally, but not always.

About the car's lights, yes, I think I have your problem as well. Honestly, I'm feeling that my problem is related to car alternator more than a problem with the engine itself, but I can't prove that because my battery is running ok and my alternator is charging ... it's a little bit confusing.

I've noticed also that when I keep my AC/heat on when I turn off the engine, the car will smooth faster when I start it next time. I don't know why, but I think it's related to the car's electrical load or something...

Re: knock sensor

PostPosted: Wed Dec 31, 2008 11:44 am
by paprkut
thanks for the reply.

i delted the error codes on my car andthe car ran really smooth, so im guessing this must be a part of my problem?

when you say "front left side of the cylinder block" do you mean this one?

[img]http://img.photobucket.com/albums/v91/umiran/enginebay.jpg[/img]

Re: knock sensor

PostPosted: Wed Dec 31, 2008 1:36 pm
by tonysticks
No. This is the camshaft position sensor. The knock sensor looks like this:

[attachment=1]bmw-e36-knock-sensor.jpg


and it should be located behind the oil filter. Sorry, I couldn't find any picture for the M42 engine to show the knock sensor. All I could find is this:

[attachment=0]bmw-knock-sensor-location.jpg


for 6-cylinder engine, but pay attention to the arrow. It shows how the knock sensor is mounted to the engine. It's almost the same in the m42 engine. I'll try to take a picture for mine and post it here if you couldn't find it yourself.

So, now your car is running smoothly? Does it start fine too?

Re: knock sensor

PostPosted: Thu Jan 01, 2009 5:23 pm
by paprkut
hi well, its pretty much the same again. i did another diagnostic and the only error i have now is


"Lambda Regulation A Possibly the tank ran empty, because of the fact that the lambda = regulation recognized a too fat resp. a too poor mixture. It ? could be possible that also other faults appear, which explain this condition. Please check all possibilities which results ; into a change of the mixture as eg.: spark-plugs, exhaust, 8 injection valve, temperature sensor, intake tract etc !"

so, im left with nothing really. my exhaust manifolds blowing slightly which i know is happening but i dont this is the cause of my idle problem? i checked my intake pipe for cracks but it was fine but i noticed the smaller "butterfly" is very dirty so i might look into this.

Re: knock sensor

PostPosted: Sun Jan 04, 2009 3:35 pm
by tonysticks
hmmm.... I recall that the last code that I saw on my car right after replacing my knock sensor #2 was "Oxygen Sensor Control" which I'm guessing it's the same as your error above, but honestly, I didn't have the chance to check it out yet. Maybe I'll look into my car's manifold and see if there's any problem with it. By the way, if your exhaust manifold does have this blowing problem, there's a very good chance that it's the reason behind this fault as it will directly affect the readings of the O2 sensor.

Re: knock sensor

PostPosted: Sun Jan 04, 2009 5:35 pm
by paprkut
hmmm intersting..

after googlng my head off, i found this
[url]
http://uk.youtube.com/watch?v=VGQVX-wGYw0
[/url]
which is pretty much what my car is doing. but both when its hot and cold.

Re: knock sensor

PostPosted: Sun Jan 04, 2009 6:32 pm
by tonysticks
You're maybe right, but if the oxygen sensor was the reason behind your problem, you'd receive a different fault code "Oxygen Sensor failure". You can of course try to replace your O2 sensor and see if that would solve your problem. If it didn't which is what I'm expecting to happen, you then will need to check other solutions that you should try to solve (like the manifold problem that you mentioned above).

By the way, when your car idles. Does it idle at 700 RPM ? or lower like 500?

Re: knock sensor

PostPosted: Sun Jan 04, 2009 6:41 pm
by paprkut
it idles at around 800rpms

but that video is a perfect example of the problem im having. the car does it alot worse when its warmed up. however when its been raining i have noticed im getting alot of "kangerooing" when i let the car drive at idle in gear.