2008 s60 hard to start when warm

qpthigpen · Post by **qpthigpen** » 28 Jun 2014, 15:50

Hello,

My Girlfriends 2008 Volvo S60 T5 is becoming difficult to start after it has warmed up. When the engine is cold the car will start fine. Once the engine gets warmed up if you stop to go into the store, when you try to start the vehicle, it will turn over but not fire. Further after just a few seconds the starter will disengage. If I feather the throttle a little while turning the engine over it will eventually start. Once started the vehicle runs fine. No codes returned when scanned. Looking through her maintenance records I see that spark plugs were replaced 40,000 miles ago, no indication that coils have ever been changed, otherwise regular maintenance. Any suggestions would be appreciated.

Quentin

Post by **jimmy57** » 28 Jun 2014, 20:40

Fuel pressure needs to be checked after hot engine shut off. If the fuel pressure is not held at at least 2 bar (29 psi) for 20 minutes then it will form vapor and it will not fuel enough on vapor (vapor lock).

qpthigpen · Post by **qpthigpen** » 28 Jun 2014, 21:13

Thanks, I will check that.

qpthigpen · Post by **qpthigpen** » 29 Jun 2014, 13:37

The fuel pressure maintained 48psi for over 20 minutes after hot engine shutoff. I replaced the fuel filter this morning as I could find no record of it ever having been changed.

Post by **jimmy57** » 29 Jun 2014, 18:38

The most common cause of your symptoms has been ruled out with it holding fuel pressure.
Coils would all 5 get weak and then run fine once it starts without misfiring.
Crank sensor could give this problem and leave no code.

Are you saying that you hold the key in start position and after 10 seconds of starter operation the starter stops? That is autostart feature, a function of the CEM.
With thta feature you just turn key to start and release and it runs starter until engine speed passes the target indicating it is running.
This feature stops people flooding cars in cold weather by cranking .35 sec and another .35 sec etc. and never cranking it long enough to run but just long enough to get in the extra fuel injected the first few eng revolutions.

qpthigpen · Post by **qpthigpen** » 30 Jun 2014, 07:04

I was wondering about the coils, had not considered the crank sensor. The autostart feature describes the situation perfectly. I will look at replacing the crank sensor then coils and see what happens.

Thanks for your help.

Quentin

Post by **jimmy57** » 30 Jun 2014, 09:22

Coils will not fix it. The coils on these cars do not all hot soak fail simultaneously. They do not hot soak fail at all that I have ever seen or have seen reported.

When it does start after prolonged cranking, does it actually start after you or the CEM release starter?

Has the transmission ever been removed for any repair like a rear crank seal or to replace flywheel or?

Last, starter can cause this if the starter current draw is excessive due to anything internal to starter. The proximity of starter to crank sensor on this aluminum engine makes the crank sensor susceptible to any magnetic flux interference.