XC90 2.5T 2004 No spark cylinder 1

Dragoz001 · Post by **Dragoz001** » 16 Nov 2022, 12:48

Hi,
My 2004 2.5T XC90 was running perfectly when I parked it 2 weeks ago in my garage.
When I started it again I noticed a rough idle an some backfire in the exhaust.
Later I got the yellow engine light.
VIDA said Misfire cylinder 1.
When I unplug the cyl 1 coil nothing changes. And when I remove the coil and put a spark plug inside it I get no spark. (I do get some with cyl 2)
I swapped the coils without success. I removed the cable case to inspect the wires and they seem correct. I checked the wires with a multimeter and found no fault.

Any help would be greatly appreciated!

NB: I did a compression test just in case, no problem on the 5 cyls.

Dragoz001 · Post by **Dragoz001** » 16 Nov 2022, 13:57

I think it's the ECM.
Is there a special procedure to replace it?
I mean is it just plug and play or there's something to do in VIDA?

Dragoz001 · Post by **Dragoz001** » 17 Nov 2022, 03:17

Okay. After a quick search I found out that if I want to replace the ECM I need to buy a used one and have it "cloned" by a specialist.
I see Xemodex of course.
Are there such service providers in Europe?
Many thanks in advance

Post by **RickHaleParker** » 17 Nov 2022, 06:08

Disconnect the ECM. Clean the connector and reinstall. A lot of times its just a bad connection.

Dragoz001 · Post by **Dragoz001** » 17 Nov 2022, 08:01

Thanks a lot for your reply.
I did that once yesterday without success but I'm gonna give a retry.

Dragoz001 · Post by **Dragoz001** » 18 Nov 2022, 13:44

Hi,
I did several tests today.
- removed the ECM, cleaned the pins and socket with contact cleaner
- checked the wires for cut or grounded wire
- used a frequency meter on the trigger pins
I have no signal on the trigger pin coming on the ECM for cylinder #1: 0 Hz whereas I get about 45 Hz on other cylinders
I guess the ECM is faulty. Yet I read that it is very rare.
Could it be a sensor like the crankshaft position sensor?

Post by **RickHaleParker** » 19 Nov 2022, 02:12

Dragoz001 wrote: 18 Nov 2022, 13:44 I have no signal on the trigger pin coming on the ECM for cylinder #1: 0 Hz whereas I get about 45 Hz on other cylinders

Open circuit, with the coil pack disconnected or Closed circuit with the coil pack connected. Thinking there might be something pulling and holding #1 high or low that wound produce 0Hz. Did you check for shorts to that line?

Dragoz001 · Post by **Dragoz001** » 19 Nov 2022, 03:20

I'm not sure I understand your question.
When I unplug the ECM the trigger wire is not connected anywhere, I checked that.
To make really sure I even cut it just after the ECM and there's no signal with my frequency meter.
I had the same idea that the cause is external to the ECM hence in the wiring but no clue for that...
That's why I was wondering is something could cause the ECM to stop triggering that cylinder... like a faulty sensor.
Yet the other 4 cylinders run perfectly.

Post by **RickHaleParker** » 19 Nov 2022, 07:25

Dragoz001 wrote: 19 Nov 2022, 03:20 To make really sure I even cut it just after the ECM and there's no signal with my frequency meter.

That is an open circuit. It sounds like something burn out the ECM I/O port for #1. You might be able to drop a new ECM in and go or you may need to have somebody synchronize the ECM with the new CEM. If we can get Yagger to chime he could yell you for sure. He should be able to transfer your software to new hardware. He most likely can do it online if you have a DiCE unit. Only thing is your CEM is a CEM-B. It think he needs to have it on his bench to crack the PIN number. He is in California. Your in Paris ... France? Or is it Paris Texas?

Yagger wrote: https://www.datatransferring.com/cem-p2-1999

Dragoz001 · Post by **Dragoz001** » 19 Nov 2022, 09:18

RickHaleParker wrote: 19 Nov 2022, 07:25 That is an open circuit. It sounds like something burn out the ECM I/O port for #1.

Okay, we came to the same conclusion.
Now I fear the same problem could occur again with a new ECM. I've read that some bad coils may do that. The former owner of the car replaced all 5 coils with OEM parts 3 years and 20 000 Km ago...

RickHaleParker wrote: 19 Nov 2022, 07:25 You might be able to drop a new ECM in and go or you may need to have somebody synchronize the ECM with the new CEM.

Yes. I looked for that part used and it's not very hard to find one in Europe even though petrol engines are way less common than diesels here...
Some people around here advertise they can clone any ECU, I will call them on Monday.

RickHaleParker wrote: 19 Nov 2022, 07:25 If we can get Yagger ... He should be able to transfer your software to new hardware. He most likely can do it online if you have a DiCE unit. Only thing is your CEM is a CEM-B. It think he needs to have it on his bench to crack the PIN number. He is in California. Your in Paris ... France? Or is it Paris Texas?

Er... CEM-B sounds like Chinese to me... yet I guess it's a generation that has some PIN protection in case you want to program it from the ODB2 plug. Am I correct? I have a Chinese DiCE unit.
Actually I'm in France but not in Paris, the system chose that for me... I'm 500Km south of Paris.

Many thanks for the time you spend to help me. I'll keep you informed.