odd wideband behaviour

[TimH]

FYI Where appropriate on my own stuff I solder pins then pot

Would be better using solder bucket D-types BTW Or crimp-type, and potting not really needed!

[RICE RACING]

Modify lots of sensors and actuators (hate OEM shit connectors!), so always presented with pins, I have tired crimped slide on female pins but that is never as good as a soldered joint...... think about it the whole ECU is soldered lol, its not crimped Potting just makes it mechanically unfuckable I used to avoid that cause of cost, time, set up, mess, consumables, but once you learn how to do it in a sick kind of way its enjoyable

[stevieturbo]

Modify lots of sensors and actuators (hate OEM shit connectors!), so always presented with pins, I have tired crimped slide on female pins but that is never as good as a soldered joint...... think about it the whole ECU is soldered lol, its not crimped Potting just makes it mechanically unfuckable I used to avoid that cause of cost, time, set up, mess, consumables, but once you learn how to do it in a sick kind of way its enjoyable

Til you forget a wire lol.

[TimH]

Each to their own!

For me, it all hinges on what strain relief and cable clamping is provided. A D-type has decent provision for this so potting up a D-type seems daft to me, and IP67 rated backshells are available so its not a case of waterproofing. Use a decent crimp D_type and I can't believe it would fail.

But a loom adapter made from an ECU header has no strain relief so potting is the only realistic way to give it mechanical strength - and soldering is the best way as a random crimp terminal may not be quite right and become intermittent...as has been observed!!

A soldered wire on a terminal is a dangerous thing without strain relief as it is inflexible and prone to stress cracking. For example, soldering a crimp terminal (done by people without the right crimp tool) is a total recipe for disaster!

As I said - each to their own and do what works for you

[RICE RACING]

As I said - each to their own and do what works for you

^ NTK O2 sensors work for me

[TimH]

As I said - each to their own and do what works for you

^ NTK O2 sensors work for me

100% agree lol. Have been asked to design a standalone NTK controller by a customer for just that reason!!

[rac]

I don't think the failure point of the potted connection in my case is the terminals, the thickness of the potted section is far to long for me to mechanical manipulate the wire through it, the failure point must be within ~2mm of the surface of the potted section. After digging up old papers on the internet what I found is certain potting material can place huge stresses on the wires due to a difference in thermal expansion between potting material and wire and this cycling can continue to occur after the potting material has set on each heat up and cool down. So instead of performing the intended job of strain relief you succeeded in trapping your wires in a permanent gym destined for cyclical fatigue failure. The selection of potting material is very important.

my harness is on its way to syvecs. for the sake of science i'll still get that egt and pipe surface data when I get the harness back. I got a really cool thermocouple that reacts as soon as I breath on it.... it would be shame if I never used it!

it would be interesting if anyone has data on oem sensor heat up time and how long does an oem ecu typically wait to go closed loop?

[TimH]

What vehicle is this on? Or, more specifically, is the loom adapter in the engine bay?

Polyamide hot glue has a higher coefficient of thermal expansion than copper - I'm not an expert in materials by any stretch of the imagination but I think that means the hot glue expands more than copper which would result in the wires being a little loose in the glue if warmed? If that guess is right, and the loom adapter is in the engine bay, so being heat cycled more than if it is in the footwell (for example) then this could explain it, especially if the wires on the loom adapter are bent back on themselves. Like in the Focus RS for example.

[rac]

Within an ecu compartment in the engine bay. Yeah unfortunately the wires have to get bent back on themselves to make it all fit.

[rac]

I've ordered some thermocouple bits and pieces to log both the egt and the pipe surface temperature at the wideband install location. will be interesting to see what the environment is like at cold start.

Will be very interested in the results of this - please share if you're willing

Makes me wonder about enhancing our mini expansion unit (MEU) to make use of the EGT circuitry as part of the LSU control strategy - perhaps using a strap-on sensor to give an indicative reading

so bit of a delay on this one, i was part way through re-wiring the ecu direct to oem harness and then broke my wrist playing futsal. wiring with a cast has been a joy....

anyway regards EGT at wideband location - my widebands are probably as far as they would normally get being a long runner top mounted turbo and the widebands at the base of the downpipe and the rear of the engine bay. so with this distance, running a rich start up from cold and with ~15 deg C ambient the EGT time to 100 deg C was pretty much bang on 6 mins.

the pipe surface temperature actually fell initially and rose after engine shut down (only a few degrees) so one can assume the pipe at this distance heats up very slowly, i didnt bother logging it. I imagine if i repeated this as a hot start, the warm up would be much faster.

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