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Insertion Life Cycle ( mating cycle ) of connectors
Sound sexy.... "mating"
When I was fixing ( not all by me ) the M271.820 engine for my friend the final problem haunting the car after a new ECM was the cylinder 1 mild misfire.
I manage to fix it, but not in any elegant way. That solved problem until today , I still think about it ...wondering when it will return.
It was caused by :
Item 1 : a "tired/worn" mating surfaces of the female terminal ( cable assy side ) , the ECM was new, so the male pin at the ECM should be good. Female terminal #1 below.
Item 2 : Also a "tired" female terminal at connector for the coil. I probed it like hell you see
Which one of the 2 is the real culprit ? Very much probably both.
The fix was as crude as making the female terminal a tighter fit.
I do know yet at that time what family/type of female terminal and male pin used by MB or even the brand of the connector. Now I know.
ECU side uses MLK 1.2 and the ignition coil side is using SLK 2.8
Size perspective, that is my pinky finger as reference.
To "make-tight" a female MLK 1.2 is a nightmare, it is so small I can't find the "tounge" which I can squeeze to make a tighter fit. The SLK 2.8 was easy, due to bigger size and the tounge was visible.
I use super fine small screwdriver to squeeze MKL 1.2 female terminal, it worked but it was a very crude fix. Documented here : https://mbworld.org/forums/e-class-w...ml#post8480097
Fast forward weeks later, I kept thinking about the performance of baby sized MLK 1.2 female terminal and the male pin too, albeit male pin belongs to the ECU.
I was very upset at the sizing logic of the pin/terminals for ECU most powerful power sucker and most offensive one, an inductive load, which is the 10 amps inductive pulses the ignition coil will need. This M271 s basically a 2 wire COP by electric load to ECM.
I get it that the ignition coil maybe a hotter working zone due to spark plug the COP is handling and hence bigger SLK 2.8 pin/terminal is appointed, but electrically this is bad.
Any power delivery is only as good as its weakest link, which is the MLK 1.2 at the ECU side.
Vibration wise it would be equal for these 2 sizes pin/terminal, because M271.820 ECM is at the intake manifold and its not at engine bay/chassis mounted configuration.
So I got itchy-handed and started to catalog my sensors/devices for the connector brand/model and pin/terminal type, hence I posted about it here : https://mbworld.org/forums/e-class-w...onnectors.html
The process of learning about my own engine connectors shed some light on how cheapo car manufactures are when it comes to the Insertion Life Cycle ( mating cycle ) for the male pin and female terminal
Here are some examples : This very same MLK 1.2 and SLK 2.8 are found in our engine wiring harness. I sure hope it is the silver coating one we get. Still 50 cycles for itchy handed guys is too little.
Some modules for interior I know uses MQS, not Nano but MQS which is a smaller than MLK1.2
MQS is 0.63mm wide male pin, MLK 1.2 is 1.2mm wide , SLK2.8 is 2.8mm wide. I dont mind paying extra US$2.5K for entire car pin/terminal if they choose the gold plated one 100 cycles is fair.
I experienced first hand how Insertion Life Cycle ( mating cycle ) is a big deal.
Back in 2010 to 2015 I was in charge of a warranty center for a well known action camera brand. As such my PC gets its USB A basically got "raped" everyday. Also memory card reader got gang-bang-ded everyday.
A good brand USB A ( PC side ) will start to be a poor performer by about 1,000 mating cyles, I kid you not. I destroyed many already, my USB A PC side connectors.
Memory card reader was 6 months life for me, the micro SDHC slot contact points gone bad, very intermittent. Phone side USB-C , that one is awesome USB connector for expected mating cycle endurance.
For my engine or any engine with 4 wire COP, its a consolation to know that by wiring, the wire assy using MLK1.2 for ECM only handles the super small load firing signal to the built-in driver/trigger inside the COP.
COP has direct positive power feed from Front SAM fuse block. The less load on any conductor, better life it should have regardless we are discussing insertion life cycle here.
This assumed only a 50 maximum GOOD condition insertion life cycle, is pissing me off. Its not good for those itchy-handed ones...
Anyway, if you guys get some electrical gremlins on the car, do remember a non-damaged looking female terminal from the outside, because you can't see its inside anway....... can be a probable suspect.
Well. ... even the screw-tightened terminal on my 100 years old Ford failed and I had to clean it before retorquing.
Than, before phone cameras come on the market, I had to junk couple pretty expensive cameras only because the memory card would not make connection.
Later learned to use the cable directly from the camera to the computer, instead of pulling the card and inserting it into computer reader.
03-17-2022, 11:12 AM
