e39 540i 97 knock sensor circuit 3

[southsouth]

Hey guys

I have a p1384 code. Knock sensor circuit 3. When I clear this code, it comes back maybe the next day or two. Acceleration is noticeably sluggish, either with the engine light on or cleared and off. No other codes.

This problem was my doing as I just did the waterpump and valley pan gasket, so I removed the knock sensors. I guess I didn't retorque properly.
I am hoping its the passenger side ones as those are reachable without taking out the coolant pipes.
My question is what side is knock sensor circuit 3?

Thanks

[JimLev]

Welcome to the forum
I'm guessing it's on the drivers side, the one between cyl 5 and 6.
My reasoning is bank 1 is the pass side so those knock sensors probably are 1 & 2, which leaves bank 2 for circuits 3 & 4.

[edjack]

The sensors are apparently VERY sensitive to positioning. They may also be sensitive to manhandling. Replace it.

[JimLev]

Also the proper torque is important.

[geargrinder]

Yep. On a prev car w/ roughly (wouldn't be suprised if they were exact honestly) same Bosch sensors, I found that a KS code could be resolved by removing, cleaning up mating surface, and retorquing. For some reason with age/wear they got out of whack somehow. However they also could fail certainly.

Also, here's the requisite "Peepee codes suck" lecture. If you scan with a proper BMW tool (aka not just a generic P-code...) you may get more information. Most native codes for electronic failures are capable of indicating "short to ground" or "open circuit" or "short to power" if indeed there's an electrical fault. As opposed to the less useful P code which just tells you "errr something about this KS isn't right". So... if its possible, try and get a native code scan of that error...

[southsouth]

ok. im going to buy new knock sensors and install them. Another thing I noticed is i get p0505 pop up always with p1384. My revs are around 700. is that normal?

[southsouth]

Ordered from pelincanparts. Has anyone have any idea what the orientation of the sensors should be? cant find this info anywhere!

[geargrinder]

Not sure it’s critical. Why do you think your old ones are mis aligned? Pretty sure doesn’t make a difference but you should be able to copy the old ones obviously. to

[southsouth]

got new bosch sensors installed. Codes are gone, power is back. mpg is up, idles right on the line smooth.
For position reference, look at this video https://www.youtube.com/watch?v=2b20rUI1YiQ. torque is 15 pounds.
Also you do not need to remove the waterpump to remove the pipes. Remove the rear cross over manifold, 6 bolts.
Also if you jack up the rear of the car and drain the coolant, you won't spill any taking the pipes out and will be able to save most of the coolant.

[JimLev]

Thanks for the follow up. For those that didn't watch the video the sensors are numbered as follows.
Standing in front of the engine they are: 1&2 are pass side, 3&4 are drivers side.
2. 3.
1. 4.

[geargrinder]

Nice. Honestly I think I'd prefer to pull the water pump myself but, to each his own. As jim says thanks for the follow up - so often guys never post back their fixes!

[southsouth]

Nice. Honestly I think I'd prefer to pull the water pump myself but, to each his own. As jim says thanks for the follow up - so often guys never post back their fixes!

I also hate when there is no follow up.
I still think next time you should try the rear manifold pipes, itll be easier than dealing with that one impossible to reach lower waterpump bolt, and you dont even need to deal with taking off the clutch fan and serpentine belt.

And also I would suggest anyone going that deep into the motor to consider doing the catch can mod, just in case that stupid osv fails. I only mention this because now im fearful my osv failed, that or my 2 year old psv failed. I saw some oil in the manifold and in my valves. Maybe im just being paranoid, but i have this theory that if i fix one thing, something else has to go.

[geargrinder]

I also hate when there is no follow up.
I still think next time you should try the rear manifold pipes, itll be easier than dealing with that one impossible to reach lower waterpump bolt, and you dont even need to deal with taking off the clutch fan and serpentine belt.

Clutch fan? What clutch fan?

Serp isn't TOO hard to take off but normally if I'm doing anything on the front the whole fan shroud comes out and that is a little bit of a PITA... so if I ever have to embrace something like that (aka getting under the pipes...) I'll think about it thanks for the suggestion.

And also I would suggest anyone going that deep into the motor to consider doing the catch can mod, just in case that stupid osv fails.

Mmmnnmmn.

The actual OSV never actually 'fails'. There's nothing in it to fail... its essentially an empty vortex canister. Now I'm picking nits and being a pedantic wanker when I say that because sure yeah, the OSV assembly fails.. but what actually fails is the short piece of coupling tube between the metal outlet cap and the OSV body. Its made of some really poorly specified thin PVC (BAD engineering choice, nameless German guy!). Gets brittle and cracks. That said, it lasts something like 15yrs / 100k's of miles generally before that happens. If you just replace that when your guides need doing anyway (aka every 150k or whatever you decide that point is...) then you're fine. I wouldn't go through the whole catch-can unless you were in some special situation, like forced induction, or, you (or a PO) had done the guides already but failed to do the OSV at that time...

- - - Updated - - -

I only mention this because now im fearful my osv failed, that or my 2 year old psv failed. I saw some oil in the manifold and in my valves.

Actually that's 'normal'. Don't sweat the manifold being oily, its fine unless you're getting real giant pools and oil consumption issues and smoking... Even then its 100x more likely to just be the CCV (not sure what a PSV is... I am guessing you mean the CCV which is a PCV device..?)

[JimLev]

I'd pull the water pump too. I've read too many stories of guys snapping a bolt off trying to get that rear water manifold off.
You'd have to also remove the SAV crossover pipe in front of the pump, one bolt on each side.
That bolt behind the pump is a piece of cake to remove. Take your 10mm ratcheting wrench (you don't own one?) and stick in behind the pump from the pass side.

[philly98540]

Glad you got it fixed! I'd also remove the rear crossover pipe if I had a clutch fan vs the water pump route. I like the jack the rear end idea too! Curious on a couple things... Was the number 3 knock sensor bolt noticebly loose? Did you see anything wrong with how the old one was installed? Did you happen to scan with a BMW scanner before hand and get any specific codes? It may help some others down the line as these cars get really old and these type of sensors start going south.

[southsouth]

Other than the aforementioned codes, not much I can add to that. I used a maxidiag502 scanner but it gives a generic code like a 30 dollar reader would too.Was interesting how the ICV code came with the knock sensor code though, no many how many times cleared. I am pretty sure I over tightened the knock sensor bolts when I initially did my waterpump and valleypan job. Orientation was off as well, as when I did reinstall the old ones I didn't note which way they were. I am glad though that I replaced the sensors now because the car has a noticeably nicer idle and is now exactly on the line when warm. Before it would idle a bit over it. And the engine is smoother too. Eliminated almost all occasional hiccups on idle. I can hardly tell the engine is running on idle. I am pretty sure if replaced my MAF and o2 sensors I would eliminate all engine vibration hiccups at idle. But that's really being a perfectionist for a perfect idle.

The pcv I mentioned is the thing on the back of the manifold. pcv is probably wrong name but w.e. You know what I mean. I replaced it 2 years ago, it was unfortunately with a URO brand part, but the only thing that can possibly fail on it is the rubber diaphragm. So I don't think even a company like URO can mess that up. but I'm probably just being paranoid about seeing oil in the manifold. And you are correct there is nothing internally inside for them to fail. Its that neck piece on them that snaps. And I do not want to replace it until I do the timing chains, which shouldn't be for a long long time. I do have a small vanos sounding like rattle up to 2k but it goes away above 2k as I am assuming oil pressure pushes the tensioner out more. Its been like that for 2 years, since I got it. And when I did my oil changes there was never plastic, and when I took the upper timing chain covers off, the plastic looked fine. So if it is the guides, its the portion of them I cant see. As for the catch can idea, I like the knowledge knowing the car will never burn a drop of oil, and never have to worry about the osv, and its pretty simple 150 dollar job. Something to consider for anyone taking the manifold off. There's a ton of people on here that did it and rave about it.

As for removing the pipes via rear manifold or water pump, another reason to do the rear manifold way is you avoid losing more coolant. Because if you take out the waterpump, you'll be draining the valley pan. As for the rear manifold bolts, I could see them snapping maybe. Mine didn't take any huge amount of force, 150k miles mostly canada weather, BUT there was a lot of material between all the threads, so I could see them fusing on some cars. As for that bottom waterpump bolt, I wish i had a ratchet wrench. I did it painfully slow with a normal wrench. Not sure what the 'SAV cross over pipe infront of pump' is.

[JimLev]

Oh, it's a 97.....no vanos and probably no SAP of SAV tube in front of the waterpump.

[Chedley]

....
Also you do not need to remove the waterpump to remove the pipes. Remove the rear cross over manifold, 6 bolts.
Also if you jack up the rear of the car and drain the coolant, you won't spill any taking the pipes out and will be able to save most of the coolant.

Well, I followed this advice. It works.
I found it very practical to remove the rear cross manifold to pull the pipes. I did not have to touch the water pump or the clutch. Although access to those 6 bolts that hold the cross manifold is very frustrating, for a couple hard to reach bolts. Also, I did not jack up the car, but I did lose about half a gallon of coolant when you pull out the pipes.

So, with full access to the valley pan to replace the knock-sensor 3 , and "While you are there", I removed also the valley pan cover to clean up all that gunk around it.
Question : Should I reinstall it as is, or replace the gasket around it with RTV/gasket maker. ?? It is a thin gasket, still very soft, not leaking, maybe just seeping some coolant.

--Update : that valley pan cover is just a boat shaped pan with a tight black cover on top.
So, I removed the cover, and thoroughly cleaned the boat pan. -amazing the amount of solidified gunk in there over 20 years-!!
Next: Removing the old thin gasket and making my own with will black Permatex RTV, to reuse the valley pan cover/gasket. This is the first I make a gasket. Will see how it holds.