The revenge of the Knock Sensor

[LEAKER]

So a few years ago when i had my first gt4 i started having knock sensor problems. Turned out it had been replaced when they had done an engine swap and the cut the wire and re soldered the new plug on (presumably they couldnt find the same type.) The knock sensor it self was fine but over the course opf a year i had sparkys re solder it about half a dozen times before the car finally shit itself with this intermittent problem.

Fast forward to now and i have a mate with a honda accord that has the same problem and my flat mates tosser friend has a 20v silver top trueno with the same problem. So whats the answer to fixing it? The only logical thing i can think of is replace the entire wire and both terminals or to replace the whole loom.

So is there an easier way? Maybe a waterproof crimped connector would work?

[iOnic]

Had the same problem on my MR2 way back when.

The car never ran right for the first few months I had it, soon as it came up to around 5000rpm it would buck wildly like it had a huge misfire, bring on a CEL and be completely gutless. I replaced most of the ignition components (dizzy cap, rotor, leads, plugs, coil, ignitor) and did a full service but it was no different so I took it to an Auto Electrician.

Turns out the knock sensor wire had been broken at some point so previous owner soldered it back together. They cut out the soldered section of the knock sensor wire and crimped it and told me that they never solder them as they have a very low strength signal and soldering $&#$% with it. After that the car ran perfectly and had it's lost power back.

Having said that, I've seen others that were soldered that worked fine. But this is just what the pros told me and I couldn't fault it for the years it stayed like that. Got a new engine loom now with no cut/soldered bits in it.

[Dell'Orto]

I'd always crimp a connection like that, its gonna be a lot stronger than solder. Generic o2 sensors come with crimps, gotta be a reason why.

[crispy'86]

This^

Had similar troubles with previous cars doing things this way, it's way worse when you have a wire broken right on the sensor (in the instance where there's no terminal only wire) and you haven't got a spare to fit.
But 10 times out of 10 if the wire is ultra thin then try to apply a crimp terminal.
Sometimes soldering involves alot of f@$n about to get a good result. I'm not saying in every case but the low voltage situ it's a good rule of thumb to use.

[saft]

I have been told many times that crimps are far superior to soldering because of vibration/fatigue resistance.

[sergei]

The reason why people have problem with soldering is that it is not done right. Crimps are not superior to the solder in every aspect (there are uses for crimps and there uses for solder). Badly done crimp is as bad as badly soldered joint. If you ever pulled looms apart you would see that a lot of wires are soldered from factory. If solder is supported, then there is no problem with vibration. Crimps have oxidation problems. 99% of wiring problems I had in my cars came from crimps being oxidised inside, or simply lost tension.

The reason why Ox. sensor need to be crimped is because it breathes through wire.

Oh and this has nothing to do with voltage. if you think about it where does the wire goes? To ECU. How is the connector on the ECU attached to the board? Via solder. How is the next component attached to board? Via solder. In fact when the component sits on the board it does not even touches the copper track (unlike twisted soldered wire, where copper touches copper, in same manner as crimp).

Here what I think is happening when you had problem with soldering:

The wire most likely is laced with teflon, thus making soldering very difficult, additionally due to position of the sensor it most likely has been an awkward position.

A lot of people don't know how to solder, even "professionals". The solder is not just the thing that holds together like some hot glue. When the wire is proper soldered the solder infuses into the copper creating metallic bond between solder and wire. If a wire is tightly twisted and soldered properly (gotten to the temperature where solder/flux penetrates the oxide layer) there is no oxide layer that adds resistance.

The biggest mistake when people do is create blob of solder around the joint that holds the joint together due to friction - this is far worse than crimping as there is no pressure to hold things together, and definitely will fail (just as OP described).

Regarding knock sensor wire, whatever the repair is carried out, the wire MUST be shielded and of the same impedance. If you look closely, the wire is actually a COAX cable. Failing to shield the wire properly will bring CEL. Running wire too short or too long could also affect the operation of knock sensor.

In short: if you are not proud of your soldering skills do the crimps (with proper crimp and crimping tool), there is a less chance of $&#$% up the job. If wire runs by itself unsupported, crimp will also work better. Otherwise good solder will outlast the crimp.

[sergei]

One more thing:
If you have a proper ($300-$400) crimping tool and appropriate crimps, then by all means crimp, you will most likely get better result. On other hand if you have $20 crimping tools and random dog-ears type of crimps, you are far better off soldering.

[samlloyd]

You don't need to buy $300 crimpers unless you are crimping massive cables or they are hydraulic.

I've been using (correctly) $50 ratchet crimpers Cabac brand i think, for years. Get them from an electrical wholesaler. As long as you use the right size crimps you will never have a problem

[Grrrrrrr!]

Disagree. You need good quality crimpers designed for the type of crimps you are using. Even small crimps need good quality crimping tools. And $300 is cheap for good quality crimping tools. Wait till you have to buy crimping tools for propreitary connectors, $600 - $1k is normal.

[DVSMOTORSPORT]

Generic o2 sensors come with crimps, gotta be a reason why.

The wire is stainless.