2000 C70 B5204T4 harsh jerking

[rubylarock]

Have you tried the engine temperature sensor? I once had an Alfa Romeo that did the same thing. The temp sensor was reading OK when the engine was running but when i turned it off it was reading minus 40 celsius indicating the problem.

It was faulty even reading the engine temp OK.

[hss]

Have you tried the engine temperature sensor?

I checked the sensor reading in Vida (and even tried resistors in place of the sensor) but now that you mentioned it I will definitely try another sensor. If the sensor is not working there should be some kind of substitute value. Maybe I will try it without the sensor first.

Replacing the heater core was surprisingly easy task with this car. Let's hope the Behr core will be ok.

[hss]

Now we tested the CVVT solenoid with an adjustable power supply. The car works perfect with some voltage (like 6V) applied to the solenoid. There is no rpm drop when touching the accelerator and the engine runs smooth under 2000 rpm.

Any ideas? Is the ECM faulty or is the software faulty? Should I try to transfer the software to another ECM?

[abscate]

Have you done a wiring inspection between the ECU and CVVT solenoid, or looked at the output of the ECU pin directly?

Good work, sounds like you are narrowing it down finally!

[hss]

Have you done a wiring inspection between the ECU and CVVT solenoid, or looked at the output of the ECU pin directly?

The solenoid gets constant 12V from the battery and the ECU is grounding the other pin so there is no "output" from the ECU. This grounding is rapidly changing on and off (PWM). This is working when the engine is cold or when the engine is warm and idling so I think there's no problem with the wiring. It immediately stops grounding if I touch the accelerator when the engine is warm.

We even took the ECU covers off and tried to cool it but nothing changed even when the ECU was covered with frost. Next we might try to clone the ECU. Does a VAG-COM (kkl) cable work with ME7_95040? I found the boot mode pin and could try reading my spare ECU.

[hss]

We were able to clone the immobilizer eeprom to another ECM. This means we have different hardware and software. Unfortunately that didn't help. Well at least the ECM seems to be working.

All the camshaft adaptation values show 80 degrees KW in Vida. Why is that? Next we will take the VVT wheel off and make sure the timing is right.

[hss]

Problem solved. The head has been taken off at some point and the VVT was not properly set. Local Volvo dealer lent me the cam locking tool and now it is working perfect and a bit more low end torque too. Now it just needs a little bit more boost .