My 2006 Volvo XC90 has a problem starting when the weather is cold or cool. If it is around 60°F or 65°F, it takes several starts to get it to start. When it’s warmer than that, it usually starts with no problem.In March/April I took it to an independent Volvo mechanic and he ran a scan on it and said the mass airflow sensor needed to be replaced, so we did that. Everything was fine and then a few days later the same problem started happening. Then as it warmed up and spring & summer came in, it stopped doing that all together. And now that fall is coming with cooler weather it has started to do it again when it is cool in the morning, but any other time of the day it has no problems starting. What the heck is going on?!

 

did you check the engine coolant temp sensor?

 

I have not checked the coolant temperature sensor. I’ve had other work done but not that. How would that affect cold starts in the morning?

 

how can I check it?

 

Coolant temp, and outside temp can both have an effect on cold starting - (if it thinks it's 100 degrees outside or the engine is warmer than it is - it can be hard to start) With a compatible scan tool or VIDA you can view what it thinks those temps are or you can check resistance on the sensors. These are for the 6cyl engine -what engine do you have? Sorry about you having to purchase an Air mass meter that was not bad - bet he won't put your old good one back on and give your money back after selling you something you did not need

 

I have a five cylinder. The temp gauge on the reads crazy numbers like 23F and 17F - I’m in DC and the temps are only getting down to 55 or 57 at night, or at least at 6 or 7 am. You recon I should have the ECT sensor and the outside temperature sensor change? The starter, and battery has been changed - the alternator was given an all clear too. In the AM it tries to start, but when the temps go up outside, it finally starts.

 

I believe there are two outside air temp sensors. One in each outside mirror. They are built into the base of the mirrors, and I have replaced many bad ones. But I don't remember which one is for the fuel injection system - if the ECU thinks it is the wrong temp outside the engine might be hard to start from being too lean or rich. You should be able to monitor what temp the sensors are sending - I know using VIDA that is possible, I would hope a quality scan tool could do the same.

I don't suggest replacement of any part that is not proven to be bad - So if it were me I would make sure the temp is being reported incorrectly and if so that the sensor is what is causing the problem BEFORE randomly replacing parts that you THINK might be bad. It can get very expensive and frustrating randomly replacing parts. .

 

All of that makes so much sense now. The readings when I get to the car is usually really low on the temperature outside. Is there a way to trick the sensors into thinking it’s warmer? Also if I replace the engine coolant temperature sensor, do I have to replace the housing unit as well? My car burns a lot of gas but I imagine it’s because the combustible mixture inside the engine isn’t right.

 

I unfortunately need to be at work early tomorrow so I wouldn’t be able to do anything else with the car until later in the day.