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-   -   Knock Sensor #4 (http://www.bimmerfest.com/forums/showthread.php?t=228276)

sc 540i 09-04-2007 07:11 PM

Knock Sensor #4
 
I have a fault code, and it's for this. I had knock sensor #4 replaced, and the code still persists, can anyone help me out I didn't get much of a response on bf.c

rtw_travel 09-05-2007 08:21 AM

Where is knock sensor#4? On my M62 engine, I know there are two under the intake manifold on either side of the valley pan gasket. They would be very difficult to replace.

sc 540i 09-05-2007 06:56 PM

Quote:

Originally Posted by rtw_travel (Post 2623430)
Where is knock sensor#4? On my M62 engine, I know there are two under the intake manifold on either side of the valley pan gasket. They would be very difficult to replace.

I'm not sure, but I had my motor torn apart to replace a bunch of stuff, and had it done at that time, it's not easy to get to, but since the motor was apart it was right there.

sc 540i 09-25-2007 06:56 PM

Please help... still ongoing!

BMW_tech 09-25-2007 07:07 PM

F.Y.I. knock sensors are basically microphones listening to your motor.If not properly torqued to specifications it may be over sensitive or send erroneous signals.I would check the connectors and follow it all the way to the DME.Simple continuity test from end to end eliminates the thought of any broken wires.Since you stated that they were replaced and still persists,the next step is to check your harness and the DME.I have seen cases where the thermostat (map cooling) connector craps out and can carry coolant that seeps through the wire insulation all the way to the DME drowning it with coolant.

sc 540i 09-25-2007 07:17 PM

Quote:

Originally Posted by BMW_tech (Post 2674236)
F.Y.I. knock sensors are basically microphones listening to your motor.If not properly torqued to specifications it may be over sensitive or send erroneous signals.I would check the connectors and follow it all the way to the DME.Simple continuity test from end to end eliminates the thought of any broken wires.Since you stated that they were replaced and still persists,the next step is to check your harness and the DME.I have seen cases where the thermostat (map cooling) connector craps out and can carry coolant that seeps through the wire insulation all the way to the DME drowning it with coolant.

:thumbup:

Will def check that out coolant was everywhere, before I did the cooling system, and even after theres the smell of it. I'm guessing the process to check isn't very DIY ?

razzy530 09-25-2007 07:21 PM

Quote:

Originally Posted by BMW_tech (Post 2674236)
F.Y.I. knock sensors are basically microphones listening to your motor.If not properly torqued to specifications it may be over sensitive or send erroneous signals.I would check the connectors and follow it all the way to the DME.Simple continuity test from end to end eliminates the thought of any broken wires.Since you stated that they were replaced and still persists,the next step is to check your harness and the DME.I have seen cases where the thermostat (map cooling) connector craps out and can carry coolant that seeps through the wire insulation all the way to the DME drowning it with coolant.

BMW TECH!!! I have a question for you!!! Im getting engine "pinging" or you guys would call it "detonation" or "pre-ignition" or whatever the correct term is.
NOW, in the past 2 weeks the following have been replaced by the dealer under warranty in order to remedy this: MAF, VANOS, Knock Sensors, Air Intake Temp sensor, fuel system clean (seafoam) Nothing, i mean NOTHING has deleted the pinging.
And finally my question is.... Would the OXYGEN SENSORS be at fault? EVEN THOUGH there's no rough idling; no poor gas mileage; no codes.
The car has 90,000 on the clock. Could these "tired" O2 sensors be causing my pinging/detonation/pre-ignition?
Should i have them replaced???
Thank you in advance for your expert advice! :)

cn90 09-25-2007 07:24 PM

4 knock sensors on V8
 
http://www.realoem.com/bmw/showparts...11&fg=10&hl=39

Item #19 in the above link.

Replacing the knock sensors on the 540i is a royal pain in the butt.

There are 4 knock sensors. They are located in the V of the motor on both banks. Replacing them involves removing the intake manifold. If you need to replace the knock sensors on bank 2 (driver side head) you must drain the coolant, disconnect the water manifold on the back of the motor to remove the 2 long coolant pipes that run between the heads below the intake manifold. The bolts on the knock sensors will not clear these pipes.

If you are doing the knock sensors, you might was well replace your valley pan gasket, water manifold gaskets, o-rings, intake manifold gaskets and your CCV. The parts for all of that will run you a decent sum of money.... Then about 6 or so hours of labor on top of that.

sc 540i 09-25-2007 07:27 PM

Quote:

Originally Posted by cn90 (Post 2674274)
http://www.realoem.com/bmw/showparts...11&fg=10&hl=39

Item #19 in the above link.

Replacing the knock sensors on the 540i is a royal pain in the butt.

There are 4 knock sensors. They are located in the V of the motor on both banks. Replacing them involves removing the intake manifold. If you need to replace the knock sensors on bank 2 (driver side head) you must drain the coolant, disconnect the water manifold on the back of the motor to remove the 2 long coolant pipes that run between the heads below the intake manifold. The bolts on the knock sensors will not clear these pipes.

If you are doing the knock sensors, you might was well replace your valley pan gasket, water manifold gaskets, o-rings, intake manifold gaskets and your CCV. The parts for all of that will run you a decent sum of money.... Then about 6 or so hours of labor on top of that.

It was replaced while all the above was being done.

cn90 09-25-2007 07:35 PM

Was the knock sensor installed BACKWARD???

1228 Knock Sensor 4 This code is set when Knock Sensor #4 has sent multiple signals or a break or short has occurred in the sensor or its wiring. Check the Knock Sensor and its wiring for defects. Check the grade of fuel being used (RON>91). Increase octane if necessary.

sc 540i 09-25-2007 07:41 PM

Quote:

Originally Posted by cn90 (Post 2674309)
Was the knock sensor installed BACKWARD???

1228 Knock Sensor 4 This code is set when Knock Sensor #4 has sent multiple signals or a break or short has occurred in the sensor or its wiring. Check the Knock Sensor and its wiring for defects. Check the grade of fuel being used (RON>91). Increase octane if necessary.

I'm pretty sure it wasn't the guy doing the work has built a couple bmw race cars, and did all the other work performed flawlessly. I run 93 always I might try to find somewhere that has 100 octane or run an octane booster.

cn90 09-25-2007 07:45 PM

People make mistake.
Experienced doctors make mistakes (removing wrong kidney etc.).

I don't know, just a guess on human errors.

sc 540i 09-25-2007 08:12 PM

True but they spent 2 hours troubleshooting it so, I'd hope he would have checked. the CEL was also on before it was replaced.

cn90 09-26-2007 07:17 AM

Then it is wiring issue. Check for broken wiring or conatminated with coolant.

sc 540i 09-26-2007 05:02 PM

Quote:

Originally Posted by cn90 (Post 2675158)
Then it is wiring issue. Check for broken wiring or conatminated with coolant.

Do you know if there are any DIY instructions? A shop did all the work, so I don't even know where to begin looking for the knock sensor.

cn90 09-26-2007 07:48 PM

I am confused.
If the shop did all the work, they should be the one chasing the Knock sensor code # 4 for you.
How long ago did they do the work?

You might want to post a message on www.bimmerboard.com and ask for "Jim Cash"...he is the guru overthere.

sc 540i 09-26-2007 07:52 PM

Quote:

Originally Posted by cn90 (Post 2677336)
I am confused.
If the shop did all the work, they should be the one chasing the Knock sensor code # 4 for you.
How long ago did they do the work?

You might want to post a message on www.bimmerboard.com and ask for "Jim Cash"...he is the guru overthere.

It was on prior to the install of the stuff, so it's not really their problem they spent about 2 hours of uncharged time to figure out what was wrong, they said I might need a new ecu, but I doubt that.

cn90 09-27-2007 08:11 AM

Another thought:

1. Clear the code using a scanner or OBD-II tool. See if it comes back.

2. This is from 740i M62 intake job but the knock sensors are mentioned in Figure 4:
http://www.e38.org/intake/bmw740_intake.html

rtw_travel 09-27-2007 09:02 AM

I think the first thing you have to do is figure out where knock sensor#4 is. IIRC, there are only two near the valley pan.

sc 540i 09-27-2007 05:19 PM

Quote:

Originally Posted by cn90 (Post 2678303)
Another thought:

1. Clear the code using a scanner or OBD-II tool. See if it comes back.

2. This is from 740i M62 intake job but the knock sensors are mentioned in Figure 4:
http://www.e38.org/intake/bmw740_intake.html

Thanks for the link, it was cleared out, and it did come back unfortunately.

cn90 09-27-2007 07:23 PM

Anything vibrating in the same frequency of spectrum that a knock sensor is designed can trigger the knock sensor.

Knock sensors picked up a binding water pump and tried to adjust the engine accordingly. Made the entire car rock at idle! Let's just say anyone who rode in the car at that time was less than impressed with the crown jewel of the BMW line-up! The defecytive WP can barely be turned by hand.
And in typical fashion that incident was followed shortly with a failed radiator!

What is your year and mileage?
WP original???

If you haven't done the cooling system overhaul, here is the info:
http://www.bimmerfest.com/forums/sho...d.php?t=213002

HTH

sc 540i 09-27-2007 07:29 PM

Quote:

Originally Posted by cn90 (Post 2679991)
Anything vibrating in the same frequency of spectrum that a knock sensor is designed can trigger the knock sensor.

Knock sensors picked up a binding water pump and tried to adjust the engine accordingly. Made the entire car rock at idle! Let's just say anyone who rode in the car at that time was less than impressed with the crown jewel of the BMW line-up! The defecytive WP can barely be turned by hand.
And in typical fashion that incident was followed shortly with a failed radiator!

What is your year and mileage?
WP original???

99 109,000, waterpump was replaced 500 miles ago. I think it might try and find a stock intake because I deleted the stock intake muffler, and put a plug in so that's a possibility, and I might try that crc maf cleaner. I appreciate all the help cn90 this is what the forums are about :thumbup:. Anymore ideas?

cn90 09-27-2007 07:50 PM

I used to have the same problem in my (now sold) 1996 VW Passat, the knock sensor (also made by BOSCH) was replaced 4 times by the dealer and still the same problem. A known issue in the 96 Passat. The engine otherwise was running fine.
Perhaps they designed the knock sensor a bit on the sensitive side, so any little vibration knocking set it off???

Sometimes it is very difficult, if not impossible, to find the root cause.
As long as the engine runs fine, there is no urgency to solve it right away but you have time to play detective work for the next few weeks and months.

Your other option is swap sensor between let's say #3 and #4, so now if the engine code turns into knock sensor #3 code then you know the wiring for #4 is OK, but rather the sensor is defective.

There are 2 strings of 2 sensors under the intake mainifold, so yes a total of 4. The cover, fuel injectors and rails and intake have to come out to get to them. They bolt down in the valley. The drivers side is cylinder 1-4 and the passenger side is 5-8.

Another thought: sp plugs, did you use the 4-prong??? Try OEM NGK.

This kind of detective work requires alot of patience and persistence!!!!!!

Back in the old days, when cars ran on carburator, we never have to worry about this crap...haha!

sc 540i 09-27-2007 07:52 PM

Quote:

Originally Posted by cn90 (Post 2680036)
I used to have the same problem in my (now sold) 1996 VW Passat, the knock sensor (also made by BOSCH) was replaced 4 times by the dealer and still the same problem. A known issue in the 96 Passat. The engine otherwise was running fine.
Perhaps they designed the knock sensor a bit on the sensitive side, so any little vibration knocking set it off???

Sometimes it is very difficult, if not impossible, to find the root cause.
As long as the engine runs fine, there is no urgency to solve it right away but you have time to play detective work for the next few weeks and months.

This kind of detective work requires alot of patience and persistence!!!!!!

Back in the old days, when cars ran on carburator, we never have to worry about this crap...haha!

I think I might take the cone filter out and put the stock one back in again and see what that does.

BMW_tech 09-27-2007 09:20 PM

Quote:

Originally Posted by sc 540i (Post 2674259)
:thumbup:

Will def check that out coolant was everywhere, before I did the cooling system, and even after theres the smell of it. I'm guessing the process to check isn't very DIY ?

Last 7 digits of the VIN? Ill look up functional description and pin assignments and ill inform/advise you.I need to know what particular DME system (M62/M62TU) production date may also be useful.M62TU uses a pigtailed knock sensors (2 sensors/1 connector) 1 on each side.Hoping you have a multi meter or your "mechanic" has some kind of scope you can determine the root cause.Have you physically looked at the DME connector(s)? Recheck the connector by unplugging it and looking at the pins making sure none are bent/misaligned/or corroded.I believe #4 is the drivers side rear (closest to firewall).F.Y.I. Bank 1 is passenger side (always the one with chain tensioner) cylinder 1 or 5 is closest to front of car.I will wait for the info and get back to you.


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