W203 widespread electrical death!

Westheath

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Expect an hour or two, sometimes it can be a repeat exercise reconfiguring,
if the session goes well 30 mins.

Pricing varies especially if your calling out a MB Star operator.
 
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JSeaman

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Just a quick update, a third SAM is on and this one seems to be the best. I'm now just left with the injector codes 0202 and 0204

I unplugged injector 1 and put it on 2 (leaving 2 dangling) and it didn't change the code. So whatever it is detecting o/c is pre-the injectors... ECU?
 

Uncle Benz

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Go back and look at the ecu plugs in case you have bent any of the pins. I can't help feeling this problem is one you have created on the way
 
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JSeaman

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You would struggle to bend a pin if you wanted to, those connectors guide in very robustly and they are all fine. In fact, I'm quite sure you couldn't bend a pin in there!

Various electrical faults occurred as a consequence of the SAM and it looks highly likely that it has caused some damage to the injector pulsing.

James
 
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JSeaman

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As suspected, no issue with the pins

Pins.jpg


Do we have any bright sparks (excuse the pun!) who know their way around the PCB?

ECU.jpg
 

Steve@Avantgarde

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Why have you opened up the ECU? You are in dangerous territory doing that with no real evidence to take you there.

I think you need to stop everything you are doing and put the car back together with the original SAM, all you have done is guess, poke and prod with no actual diagnosis and have based any component replacement on other failures on other cars. It is completely the wrong way to go about fixing anything.

Proceedure should always be F-D-C. Fault - Diagnosis - Cure. You cannot get to the cure, without diagnosis, you can't do the correct diagnosis without understanding the fault and a clear knowledge of the system you are working on. To exaggerate but by way of hyperbole, its like finding a lump on your body and going straight to chemotherapy, without having the various blood tests and scans in between to see if you need it. Cars are kinda the same.

So put it all back together and forget everything else that has been done, swapped, poked with etc. Fault codes do not mean diagnosis, diagnosis is working with information from the car and sometimes means ignoring the fault codes as they may be totally irrelevant to the fault you are trying to fix, case in point being the ones relating to your injectors. You are being pulled about all over the car with no real direction or goal. You have "cracked off injectors and there is fuel at each", that is completely irrelevant and opening up a CDI system just means air gets in and any fuel pressure you have (needs 150 bar minimum to start) will be lost and runs back to the tank. So you are messing with things you don't even have a full working knowledge of. Its spinning you in a very quick circle. Im sorry if it sounds blunt, but you aren't doing yourself any favours here.

So start from the top.

What are the faults with the car in its complete state? Does the car start? If yes, what warning lights are there? Is the cooling fan running flat out?

If the car runs, scan the car, pull out all of the actual fault codes. Don't just focus on any particular unit, look at all of them. There will be a clue or link in there somewhere. Once you have done that, you can proceed to diagnosis.

If you disconnect any of the main ECU's there is no reconfiguration to be done. If you have fitted a SAM unit that will have to be configured to the car, the car should still start though, there is no drive authorisation data in the front SAM. All the drive authorisation data is in the EIS and the engine ECU, the SAM is used, but only to deliver 12v to the starter. If the engine cranks, then you can rule out any form of CAN or immobiliser trouble preventing engine start. Your issue will be engine side.

If you want me to help, do exactly as I say and post here, the next steps will be dependent on the information you give.
 
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JSeaman

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I have opened up the ECU to see if there is any obvious component damage and all evidence is pointing to the injector control failing.

I don't think you have been reading closely enough, I have put it together with the original SAM and diagnosis was impossible because the ECU wouldn't communicate with it attached. This entire thread is about diagnosis, I have one fault code which is injector open circuit and cracking off the injectors is very common practice.

Once again, the faults are injector open circuit on 2 and 4, no it doesn't start but does crank and the cooling fan does not run flat out now I have replaced the (obviously faulty SAM).
 

Steve@Avantgarde

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Im sorry to disagree but there is no evidence to support your assumption. Here's why.

Cracking off injectors is common practice on mechanical fuel injection engines where the turning pump supplies the fuel. But yours is a CDI and on CDI's you cannot do that to measure fuel pressure.

Here are the reasons, CDI's work totally differently for starters. Firstly, an electric fuel pump feeds the engine where the high pressure pump pressurises the fuel to 300 bar for running pressure. Secondly, you need to have a constant 150bar fuel pressure at the injector rail pressure sensor on cranking for the engine to start. If you open up the injectors on cranking, the fuel pressure in the rail will drop to 0 straight away, the CDI system sees the drop and thinks it has a fuel leak, or an excessive leak off/inject. So by cracking off the injectors you prove nothing.

If you want to test the fuel pressure, which is a good place to start because the engine doesn't go, then you can either measure it at the rail pressure sensor, with live data from the ECU (not sure if Icarsoft has this, but STAR definitely does) or you measure it with a fuel pressure tester, in line after the high pressure pump but before the rail. Either way, this should be your next step. You don't actually know if fuel is getting to the rail. With no fuel pressure at the rail, it can signal faults with the injectors as they are trying to inject air and not fuel, causing them to shut down and signal open circuit.

If the fuel pressure is ok and if you want to check the injector signal for the ECU, grab a multimeter and check the pulse, it should be 5-6v direct current. To be completely sure you can then pin out from the ECU plug to the injector plug and do a continuity test, that will tell you your wiring is good, the live and earths are good and it will rule out the loom.

If all checks out then you need to check the injectors for performance, leak off, hub/mg value and solenoid switch.
 
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JSeaman

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I was wanting to prove I had diesel at the rail and through the rail, so it served its purpose.

If it was lack of fuel pressure then something like P0087 would be more logical rather than an injector open circuit condition. Also open circuit on the same 2 injectors each time, that doesn't seem to fit?

I certainly do want to check signal for the injectors though, where am I probing, on the injector directly or at the ECU (and if ECU which pins)? I didn't expect the pulse to be long enough for a DVM to pick it up but happy to try. This is the area I'm hoping to get some information on, from injector right back to the ECU

"a continuity test, that will tell you your wiring is good"
Not quite but I know what you mean, it will find a break at least and, again, happy to do this if you can help me ID where

If that fails then leak off sounds good
 

Steve@Avantgarde

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I was wanting to prove I had diesel at the rail and through the rail, so it served its purpose.

You would think that logic would apply, but if the high pressure pump is only producing 1.5 bar, it can seem a lot of pressure when you crack a joint, but in reality its nothing. Thats why I said check the fuel pressure with a tester or at the rail pressure sensor.

it was lack of fuel pressure then something like P0087 would be more logical rather than an injector open circuit condition. Also open circuit on the same 2 injectors each time, that doesn't seem to fit?

As you aren't using star, i wouldn't trust 100% what carsoft tells you, Ive had various incidences of them not deciphering codes and missing codes out.



certainly do want to check signal for the injectors though, where am I probing, on the injector directly or at the ECU (and if ECU which pins)? I didn't expect the pulse to be long enough for a DVM to pick it up but happy to try. This is the area I'm hoping to get some information on, from injector right back to the ECU

Check with STAR is the easiest way, you can see the injector performance on a graph. To check the signal using a meter you will need the in line plug testers that give you a test point. Or make one up!

"a continuity test, that will tell you your wiring is good"
Not quite but I know what you mean, it will find a break at least and, again, happy to do this if you can help me ID where

If something is open circuit, a break is exactly what you are looking for!


If you send me your chassis number i can pull up the wiring diagram.
 
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JSeaman

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Sure, appreciate the pressure will be different but getting some basics confirmed

Sadly I don't have STAR but can make up whatever I need - am I just breaking out the two pins to the injector and checking for a ~5V spike on there?

Thanks for the offer of the wiring, that's exactly the sort of thing I need - I'll PM the VIN
 
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JSeaman

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Bump for any new ideas
 
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JSeaman

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Last ditch attempt at getting some feedback or a wiring/circuit diagram...
 

bembo449

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I can tell you one thing , I had 1 of the 6 injectors go down on my range rover , this prevented it from starting due to lack of fuel pressure , no codes were showing and until I spill tested the injectors you could tell that was the issue , so as suggested , it needs to go on star , its the only way to guarantee all the codes will be found / read , then if the tester is competent , you will move closer to resolving this issue pal
 
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JSeaman

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Thanks, sadly the last time I paid for star I didn't really learn anything more than my OBDII. I'm struggling to find the cause of the codes beyond the fact everything points at ECU
 
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JSeaman

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Thanks for those that tried to help, now going for scrap. Never got the ECU diagram so beyond economical repair :(
 


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