Hi everyone, I have a 2005 Volvo S40 T5. I'm experiencing a starting problem. I'll walk you through what I've been experiencing so you can hopefully point me in the right direction for a fix.

For a couple of months the RPMs would spike very high (around 4k RPM) at startup for a second or two then drop down to normal range. This spike would happen randomly and seemed to be after the engine hadn't been running for a while.

Now, after the car has sat for hours such as over night or while I'm at work; It will start up but the RPMs drop very low and it begins to gasp for fuel or air. After a second or two the engine will speed up and run normal. It's stalled a couple of times as it's gasped. If it stalls, it will start right up like nothing was wrong. If I have the engine running and shut it down, it'll start right back up. The car drives great. The engine feels strong and there doesn't seem to be any loss of power. This problem hasn't thrown a check engine code.

Here are the recent things I've done.
Changed the Timing Belt
Changed the Spark Plugs
Replaced the Air Filter
Cleaned the MAF Sensor

I've tried turning the ignition on and off several times before cranking the engine and it doesn't help.

Thanks for your help!

 

Fuel pressure regulator?

 

That's probably my next step since the part isn't that expensive and it's easy to change.

 

I ordered a fuel pressure sensor. I'll put it in next weekend. In the meantime, I think I'm confident in associating outside temperature to my starting troubles. When the RPMs would spike it always happened when it was cold outside. It's been 80's-90's lately and that's when the RPMs began dropping and sometimes stalling the engine. It only happens after the car has sat for hours. The last two days we've had a cold front and the temperature is around 50 in the morning and 70's in the afternoon and the car has been starting up fine. If it's temperature related, does that give any clearer indication of what my problem may be?

 

when you cleaned the MAF, did you also clean the ICV? The idle control valve controls the idle air intake - and acts like a choke when the engine is cold it lets in less air to enrich the mixture... worth a look and you can clean it with MAF or Carb cleaner for cheap...

 

I'm definitely going to do that as well. I'll do a DIY search but do you know if it's difficult to get to?

 

It is not difficult to get to. Once you have the black plastic cover off from just above the throttle body you have full access to the icv just below it. You may want to have a replacement gasket handy though just in case the old one falls apart when you take the icv off. Comes of by removing two bolts.

 

This engine has the Electronic Throttle Control. I've heard of issues when it gets dirty. Get some throttle body cleaner spray while you are in there.