Other XC90 Problem: xc90 going into limp mode & cutting out when idle

[stephenmdavies1983]

Hi

My xc90 has started going into limp mode recently,more so when it's cold. It will do this 3 to 4 times and always sorts itself out when the engine is restarted.

After this, it will cut out completely at junctions when the car is stationary. Again, it starts fine when the engine is restarted.

I'm going to try some diesel magic to clean the injection as I guess it won't make things any worse.

Someone also suggested running the car with the MAF unplugged. If it runs ok then I need to clean / replace the MAF. If it still cuts out then I guess the MAF is fine.

Are there any downsides to running the car with the MAF unplugged. Will I lose any performance and how long can I run the car with the MAF unplugged? If this temporarily solves the problem, then I'll run like this if it's safe until I can get a replacement part sorted.

Any advice would be much appreciated

Cheers

[Tannaton]

If it's going into limp home mode it's because the computer thinks there is a problem. The only place to start here is to take the car to someone who has appropriate diagnostic gear and read the error codes. To do anything else you are more than likely to be wasting time and money.

With regards to disconnecting the MAF, this is a common trick used to diagnose issues on Rover TD4 engines but the Volvo is much more sophisticated.... putting more faults into the cars memory will not help.

[cheshired5]

A £5 ELM327 diagnostic dongle and the free Torque app on Android will tell you all you need to know.
A few minutes of data will reveal more than hours of guessing and random unplugging.

[Horton]

Fuel filter???

[stephenmdavies1983]

Thanks for your replies
Had the diagnostics done today and the guy suggested the ecu was showing a voltage fault.

Anyone ever come across this? He said it could be loose wiring into the ecu

He also said it sounded like I needed a new turbo valve

Going to try and take it to a Volvo specialist tomorrow to see what the damage is

[cheshired5]

Originally Posted by stephenmdavies1983

Thanks for your replies
Had the diagnostics done today and the guy suggested the ecu was showing a voltage fault.

Anyone ever come across this? He said it could be loose wiring into the ecu

He also said it sounded like I needed a new turbo valve

Going to try and take it to a Volvo specialist tomorrow to see what the damage is

What were the MAF readings?

[stephenmdavies1983]

It initially came up with a MAF fault code as well as about 8 others, but he reset all codes.

I took it for a drive and it died again instantly and he used those readings.

It also said engine was running at -40c, but this fault code disappeared second time around

[cheshired5]

Originally Posted by stephenmdavies1983

It initially came up with a MAF fault code as well as about 8 others, but he reset all codes.

I took it for a drive and it died again instantly and he used those readings.

What readings?

Originally Posted by stephenmdavies1983

It also said engine was running at -40c, but this fault code disappeared second time around

Sounds like your ECT sensor may be failing. Did he test it further?

I hope this guy didn't charge much. He doesn't sound very good.

[Tannaton]

A problem with the turbo control valve can cause it to go into limp home mode due to excessive boost pressure, but this would most likely happen whilst accelerating/under throttle. If you can avoid it going into limp home mode by driving very gently, this could be your problem. It's not too difficult to change the valve but the part is extortionately expensive for what it is. The operation of the vacuum pump and all the pipes should be checked also.

[stephenmdavies1983]

Originally Posted by cheshired5

What readings?

Sounds like your ECT sensor may be failing. Did he test it further?

I hope this guy didn't charge much. He doesn't sound very good.

So after I went for the drive the only readings showing were the voltage on ecu.

He was revving the car in park mode and it kept going into limp mode while it was parked.

I realise now he probably loves people like me. Complete amateur on these topics. He hooked a laptop up, told me there were a couple of things wrong and charged £30. Nice business model.