SM IE: Replacement of the injection wiring harness

Following the electrical difficulties I had in September 2007, I ordered a new injection wiring harness. So here comes the moment to install this new wiring harness, this is early June 2008.

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Here are the two parts of the wiring harness. The first part starts from the calculator and goes to some valves and connectors for the second part, which connects to the injectors and other valves and sensors

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I start by removing the right front fender, to gain access to where the wiring goes right through the body

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Here is the calculator, located at the passenger’s feet, behind the carpet and a protecting plate

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I start moving the old wiring out of its location and I prepare the new one (the clean one)

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Here are both wiring harnesses. I gradually install the new one

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The new wiring is now going right through the body

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I connect it to the calculator

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Everything here is still disconnected, like the injectors, the water temperature sensor…

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… and here the throttle spindle connector and the air temperature sensor

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Connection of the full load switch. The wiring then goes through the left side of the engine compartment

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Connection of the injectors, with the second portion of the wiring harness

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Here is the junction of both portions. It’s now clean and reliable

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Special attention for waterproofness is needed here…

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… I use an automotive sealler, I hope it will be ok, but it’s not very nice

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One portion of the old wiring. It was in poor condition

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And here is everything back together

This intervention took me 4 or 5 evenings of work. I complete this work on a friday night and the day after I plan to take part to an event organized by my antique car club. So I crank, the engine quickly starts but it doesn’t work properly. On idle or at constant revs, it doesn’t work well but it seems ok under acceleration, if the car is stopped or when driving it.

I don’t have time to fix the problem. The can be driven so the day after I drive it for about 30 km to go to the planned event. The engine still doesn’t work correctly but I reach my destination.

The problem occurs when I try to go back home late the same day. The engine doesn’t want to start at all! I try to investigate a bit, I discover a disconnected vacuum hose because of a broken T-shape union, but I have nothing with me to repair so I go back home with a cab. The day after, Sunday, I call a towing to bring the car back home.

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The disconnected hose, still with the broken T-shape union part attached

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Here is what’s left of the union with the other two hoses attached. The two inlets that we see are a smaller diameter than the outlet part that’s broken

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It was not easy to find a replacement part. I finally found this plastic union on which we can select different diameters by cutting at the right place

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I secured the connection to the low pressure transmitter because it had tendency to easily disconnect when I was “playing” around

The vacuum hose should go to the low pressure transmitter. This problem perfectly explained why the engine was running odd, the mixture was way too rich because the pressure transmitter was not receiving the right vacuum information. But, as nothing is as simple on a SM, when I connected back the vacuum lines, the engine didn’t start better.

In fact, from Sunday to the next Thursday, I spent hours trying to have the engine back in running condition.

Of course, as I just replaced the injection wiring harness, I thought the problem was directly linked to this new wiring. So I spent a lot of time checking all the fuel injection devices I could check, I even temporarily put back the old wiring harness, but everything appeared to be just fine on this side. The ignition was creating sparks that I found fine also. The fuel tank was not empty, I even added more fuel to be sure. But it was still not working.

On Thursday I seriously begin to be discouraged and I have more and more pressure because I have to go to the annual Citroen Rendezvous in Saratoga Springs on Friday night or Saturday morning the latest, with a drive of about 350 km.

I eventually decide to remove the intake capacity boxes because I discover traces of fuel inside them. I plan to replace all spark plugs because access is ideal at that moment and to eliminate any doubt about these plugs. After putting everything back together, I give the engine a try and it starts right away. Yes! It’s around 10 PM. The engine is running and evacuated a good quantity of soot (or let’s say black residue).

So here is my understanding of the problem: when I replaced the injection wiring harness, I moved almost everything, so I certainly and without seeing it finished to brake the T-shape union from the circuit going to the pressure transmitter, this union was certainly already damaged. This problem caused the engine to run with a very rich mixture. As I drove the car with this problem, I certainly sooted up and even damaged the spark plugs, and it eventually caused the engine to not start any more. Then, the numerous tries I made to start the engine during my evenings of check and repair finished to soot up and flood the engine.

The day after, Friday, I take the SM to go to work and she works just fine. Later the same day I join Marcel and Othello (visiting Québec) and we make a part of the trip to Saratoga Springs for the famous annual meeting. They also had pressure finishing Marcel’s SM. A few days before, following a complete paint job, they had to put the car back together, a huge work done in record time. Visit Othello’s web site to see (much) more details about that work (french text but many pictures).

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Saturday morning, we just arrived in Saratoga. Marcel and Othello were not able to put back the headlight glasses of the black SM, so she runs without them

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On the trip back on Sunday, Marcel’s SM found back its headlight glasses

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Othello had the very good idea to take some pictures of my SM on the road. A big thank to him

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What a style!

The Saratoga meeting has been very friendly, as usual, and it was finally the occasion to meet Othello, who I thank for his friendship and for visiting us. Visit his website because he did a great page about his trip to Canada and United States.

Marcel’s SM and mine, which were ready only at the last minute or so for this trip, both worked just fine during this week-end. Air conditioning in Marcel’s car was also working fine but it doesn’t work on my car so it was very hot inside. So I decided that the next intervention on this car will be to put the air conditioning back in running condition.