BMW Forums : BimmerForums banner

1 - 15 of 15 Posts

·
Registered
Joined
·
76 Posts
Discussion Starter #1
Hi all, I was advised by a BMW indie to replace my knock sensors after having knock sensor bank 4-6 earth fault and vanos mechanically stuck/jammed codes. Started to strip everything down and reached under to find that sensor was loose! I undid it with my fingers , checked the casing and bolted it back on. I had already undone the inlet manifold so tightened it back down then checked the intake bits I had removed and decided to do some intake mods, so the trumpet in the air box was removed and the Helmholtz resonator was taken off and a few tears were sealed up with tape and zip ties until i get replacements. The car fired up and was a bit lumpy and low rev response is poor but after 1500rpm it smooths out but still has low torque until about 4000rpm where it goes like hell.
Assuming I have no air leaks ,(the intake boot look very bad but the car ran so well I assumed there weren't any leaks) is the poor running due to the ecu trying to adjust for the knock sensor hopefully working and will the car settle down after some miles and give me some low end response and torque or should I disconnect the battery and see if that helps or should I put the intake back to standard?
Hope I haven't disturbed anything else, I only took off the intake up to the throttle body but did undo and lift the inlet manifold.
 

·
Registered
Joined
·
8,981 Posts
It might be a vanos issue, you can get o-ring repair kits from them, or even just buy the single O rings as they are a matter of pennies each.
With the knock sensor back on, codes cleared, it should sort itself out over a few miles as they can switch to a low octane map in some cases, but no data on how often it tries the higher octane version, or how long it takes to bounce back.

If you still get the vanos jammed code, look into the O rings, or also note any other codes that turn up.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #3
Will get a new boot and refit all the intake bits so that only the knock sensor is to be monitored, will disconnect the battery as a simple reset and keep fingers crossed. I posted the other week about doing the vanos seals but got no replies and when I asked my indie he said in 25 years he has never done one or seen one that needs doing, might as well have a go myself if it's still a problem.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #5
Have been looking at new intake boots and I have part no's 13541740073 looks like the OE unit I have but i should be able to fit an e36 unit part number 13541740073, any thoughts as to which one, unfortunately I am at work and unable to check for part numbers as the car is at home and want to order asap.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #8
Whilst waiting for new boot I have tried to seal up the old boot and returned the intake to stock, as far as I can tell all the tears are sealed. problem is the engine is difficult to start coughing and spluttering like it has either not enough fuel and misfiring but then it catches and idles nicely after a few seconds and when driven I have less power from tickover than I have ever had with the car, when I get the new boot I think I will fully remove the intake manifold this time and check all the vacuum pipes but also swap the knock sensor this time as the car was running lovelly before all this, just bloody thirsty eg; 14 mpg each way to work and recent 100 mile runs etc saw 20mpg each time so unless I have disturbed something the car should be running better as there should be less air leaks and the knock sensor has been tightened down! Could the sensor being left loose and possibly bouncing around just killed it?
Any suggestions on things to do under the manifold?
 

·
Registered
Joined
·
76 Posts
Discussion Starter #10
Manifold completely removed and the knock sensor replaced, new intake boot and icv hose fitted, all connections checked and all other pipes looked surprisingly good but tonight would not start at all. Recharged battery after flattening it but only got a couple of coughs but would not fire up, now just spins very fast and turbine like in sound, I have had the car do that before when i turned back the key too quick and I believe its to do with oil in the valve lifters and needs cranking until oil is returned? Will try to find someone to come and read codes but I am after some ideas on what to check/test myself?
Fuel pressure?
Crank sensor?
Cam sensor?
What readings should I be getting? Throughout this time I have not had a Check engine light.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #12
OK then, all stripped and checked, pipes replaced, icv cleaned out, new manifold gaskets and new icv grommit but still no start. Then I got a Peake code reader and got about 8 codes then the car started! After a few minutes it ran lumpy then stalled so we reread the codes then tha car started again and had a drive but was low on power, was holding gears and when pulling away felt like we were missing a cylinder. Got home and figured how to clear the codes then ran it again and only returned crankshaft sensor! We repeated clearing codes, run car, read codes twice more and every time we only got that code. I can only assume the wires have degraded at the socket as that is under the intake manifold.
I will now try to identify the right sensor or are all m52 sensors suitable?
 

·
Registered
Joined
·
8,981 Posts
There's two main types, one on the front of the engine, on the edge of the crank pulley (which would have teeth) or they can sometimes be found right at the back of the engine under the intake manifold near the gearbox.

This is the famous nikasil check pic



That spot is the hole where a crank sensor would be fitted.
If you see a blank casting you have a nikasil engine, a cover plate means non nikasil, and if you don't see a sensor plugged in here, you have the crank senosr at the front.
 

·
Registered
Joined
·
76 Posts
Discussion Starter #14
Have already seen the sensor at the front of the engine, thank god! Had the manifold off enough. As far as I can tell the car had a nikasil block but was replaced about 98, I have no details though except the gbox filter had a 98 year stamp and the original viscous clutch had a part number that matched a 98 onwards engine, the best surprise was I never saw the vanos jammed code! I am keeping my fingers crossed on that.
The part number I have got is 12141703277, or are any of them OK?
 
1 - 15 of 15 Posts
Top