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Captiva never revs up over 1500-1800 RPM

12K views 20 replies 6 participants last post by  Aussie Ed 
My guess is that the missing DPF is generating the error and the rpm limitation. You might find a way to trick the signal from the differential pressure sensor, you can check what is the typical voltage that it should output and try to emulate it with a voltage source (even a battery+voltage divider if needed). it will be much harder to emulate the O2 sensors, right now the car sees that it has no catalyst sensor, so this could be another reason for rpm limit.

here is an tutorial regarding the O2 sensor that it could be helpful to diagnose your car. You will need a portable oscilloscope, I think it would be hard to diagnose both sensors with a multimeter.



You can try to ask DiagnoseDan on his facebook page what does he thinks about your issue. The guy surely knows more about this kind of errors and he can point you to the right direction.

Don't forget to post the outcome of your findings so we will have it documented here, on the forum.

Good luck!
 
Hi Mariano,

I have the same engine as on your Captiva (2.0 VCDI) on my Chevrolet Epica. If the car had DPF sensor for sure it had the differential pressure sensor. This sensor is used to check the pressure before and after the DPF and if the difference between the pressures (checked by the differential pressure sensor) is bigger than a threshold the ECU commands a DPF cleaning cycle. Maybe this sensor was removed and/or tricked by ECU mapping in order to make the car work without a DPF and after you disassembled the engine the dummy sensor was disconnected by mistake. Do you have a service manual? I guess it would be helpful to find the sensor location on your Captiva. At Epica it is placed on the firewall on the driver side and there are 2 small hoses (1cm diameter) that are connected to it.

Regarding the O2 sensors, you should have 2 of them, one before and one after the catalyst. There are some older cars that have one, but to close the loop you need to have at least one of them. The ECU continuously checks the O2 sensor/sensors voltage(s) and adjusts the amount of fuel that is delivered to the injectors to get the desired air-fuel ratio. The cars that have 2 sensors can also detect if the catalytic converter works fine.

If all these sensors are missing and were missing before you took the car apart, then most likely the car was hacked brutally by the guys on the service. I don't know what they did to the ECU mapping, but it seems that now it is not working properly.

Maybe someone who has a Chevy Captiva series 1 can help with some pictures and locations of sensors.
 
Check if you have the Bosch ECU like I had on my Epica. If yes, then it is tricky because on my Epica only with the original GM SCAN-100 I was able to diagnose. If you have the Delphi ECU, than you can go with a Delphi DS150 clone, it does the job. You can also check what others use on Captiva series 1.
 
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