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Discussion Starter #1
Hi!

Does anyone know what the correct torque setting for the knock sensors ('91 model) is?
On various non-Bentley forums I've found 20Nm and 10lbft.....

Cheers

Es
 

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I can't find anything in IETIS. The figure (in lb-ft, I can't "instinctively" do metric) is entirely reasonable. These are just turn in until they stop, then a slight snugging up.
 
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Discussion Starter #3
I can't find anything in IETIS. The figure (in lb-ft, I can't "instinctively" do metric) is entirely reasonable. These are just turn in until they stop, then a slight snugging up.
Sounds quite reasonable to me too!
 

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I really wish that people understood how threaded fasteners actually work, and didn't automatically jump to the conclusion that "as tight as I can get it" is what is being sought.

I don't even use lock washers after the amount of research I've read saying that they're useless. Threaded fasteners for things like that knock sensor just need to be ever so slightly snug. There is no need for any substantial stretch in the fastener itself, because it's not being subjected to forces that require such.

Even for fasteners like lug nuts/bolts, the amount of torque should be just enough to deform, ever so slightly, the threads on each side of the connection such that they grip one another firmly, but within the limits of their elasticity so that when removed everything springs back to its initial shape with ease. Just that much "grip" is way more than enough to keep a wheel on, or an accumulator firmly mounted to its ACV, etc.

A lot of stuff (and in the case of our cars, lug nuts and sometimes the bolt, too) gets destroyed because of gross overtightening. The 45-50 ft-lb figure for our lug nuts is much lower than is typical because they're brass, not steel, and if you tighten them like they are steel, you've forced them past the elastic limits of brass (which isn't great for the safety of holding the wheels on, either).

Even on our cars, having worked on both of mine enough now, it's clear to me that there are some even "in the business" who simply think "as tight as I can get it" is how you tighten any threaded fastener. Well, it isn't how one should, as it damages things. On the vast majority of small fasteners, just tight, with a tiny nip-up to snug, is enough, whether you know what the formal torque value is for that level or not.
 

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The knock sensors have a specific torque. The torque change can affect the signal generated by the sensor.
It is not recommended the use of grease or washers on mounting the knock sensor.
 

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Discussion Starter #10
Hi!
The sensors were an absolute pain in the butt to change, and were torqued in as best as I could get a spanner on them, but it did seem to improve performance quite a lot!
The old sensors and plugs were very rusty, so there is a fair chance that the signal wasn't passed.
Next job is changing the TPS, and then I'm hoping that the performance will be as it should!

Cheers

Es
 

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Discussion Starter #12
Hi Mike ,
The wires seemed to be ok, but I did clean the contacts vigorously! The car did seem to have a lot more torque on the drive back from the "workshop", so I think the sensors were definitely faulty!

Next is TPS and the boost solenoid!
Cheers

Es
 
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