Doesn't always start on all cylinders

canoeguy · Post by **canoeguy** » 23 Sep 2018, 06:33

Good morning
I have a 2001 S60 5cyl turbo with 130,000 on it.
Occasionally it doesn't start on all cylinders. If I turn it off,wait 30 seconds and restart it, it starts and runs normally.
This happened once about a year ago and has been fine until today when it did it twice. But today I had to restart 3 times in a row. In the past it only took one restart. I'm afraid something is beginning to fail but I don't have a clue what it might be. Any help would be greatly appreciated
Thank you
Brian

Post by **RickHaleParker** » 23 Sep 2018, 06:48

Check the condition of the wiring harness to the coil packs. Get a code reader so you get better information.

Post by **abscate** » 23 Sep 2018, 07:01

It’s probably a good age/mileage to remove and replace every vacuum hose

Post by **oragex** » 23 Sep 2018, 09:58

Hard for us to suggest something accurately. Gas delivery, tired ignition coil or cracked wiring to it (don't replace them all, just have a spare one in the car along with a ratchet or two), faulty spark plug, tired FPS, even the throttle body can act up.

Post by **vtl** » 23 Sep 2018, 10:28

Unscrew all ignition coils, remove oxidation on contact pads, both on engine and coils, put coils back, screw to the required moment. Many people overlook that the bolt that holds ignition coil in place, is also a ground point for high-voltage part of the coil.

I had this symptom too, not any more since the contact was restored.

Post by **mrbrian200** » 23 Sep 2018, 10:40

Sounds like a relay getting flaky to me (oxidation contact resistance 'sometimes', try again on the second/third try it makes a solid connection). Try replacing the 'engine management system' relay under the hood. It supplies +12v to the injectors, coil packs, MAF, as well as a few solenoids/PTC etc.

There are several like relays next to it, you can try switching it with one of the other relays that control a non critical system.

On a 2001, this behavior might also be associated with a failing ETM or stuck throttle plate (try cleaning it). Stuck closed not enough air gets in and the engine will sputter like it's not running on all cylinders.

Edit: I forget about this one, because it wasn't here on MVS or a car I got to look at. Friend of a friend in Chicago was having what sounds like an identical issue: His 2004 V70 would start and run fine sometimes, other times it would start rough, and trigger limp mode if he tried to drive it. Stopping and restarting the engine one or more times would eventually correct the issue. Got progressively worse over time. I was going to look at it for him next time I was in town but he found it himself: One or more of the relays under the hood had worked loose/weren't seated fully. I got the word that he merely pushed down on all of those relays and the problem resolved. We've borrowed that particular car since then to take out to the suburbs to pick up a dishwasher to install at my friends condo. Aside from desperately needing front suspension work and maybe a new rack (the steering wheel would 'fight you' anytime you tried to turn right), that V70 started and ran just fine. The car has somewhere in the neighborhood of 280,000 miles on it.

Post by **abscate** » 23 Sep 2018, 13:34

If you read my thread on poor cold idle eArlier this year, I had suggestions from bad head gasket to solar spots...all caused by a bad hose.

Post by **mrbrian200** » 24 Sep 2018, 00:23

Agreed, a loose hose connection could conceivably result in an intermittent 'choppy' running quality too. I recall my experience when I first picked up the S60 which had a bad throttle body. Throttle plate stuck part way open acts the same as a large hose leak. The words 'not running on all cylinders' might be an authentic, though somewhat non-scientific, set of terms that would describe what it was like.

However, mine is newer with the Bosch type throttle assembly. I would venture that a failure with the MM units resulting in a similar condition (throttle plate stuck closed or part way open) would result in the same running condition.

If it's not a relay or loose hose connection, the next thing to look at might be the ETM and/or the fuel pressure. But you'll probably want to hook the car up to a good scan tool or VIDA to gather more useful information.