Hello all, thanks for any and all help. Here is what I have:

2006 S60R, 73K miles, new plugs at 66K. Just recently got P0303 and P0305 with CEL. Never had this before now. It came on after start and idle. Swapped coils around and misfires stay with the cylinder. Swapped plugs - same result. Tried older coils (exact match) from V50, no joy. Connectors are in good condition and receiving proper voltage. Plugs are only 7k miles old - all good there. Injectors are operating, getting the proper voltage, and have proper resistance. This problem is intermittent - I clear the codes after the above troubleshooting and get a short drive cycle or several idle periods in before the codes come back. However, no CEL again. Is that because I'm clearing the codes?

What else can I check/try before I take it to a shop? I'm a bit anxious about the possibilities - timing, compression, leaky gaskets, etc. Complicated always means expensive!!

Thanks in advance for any help.

Jeff

 

could be an injector or perhaps a knock sensor gone astray but the next step would be to do a compression check and see if you have any signs of a head gasket leak or perhaps an intake air leak... Do you notice any misfires or surging under power?

 

No noticeable problems under power. The injectors seem to be fine - I hear the tapping from both and the voltage/resistance is normal. Having two misfires has me baffled. Are they companion cylinders? One misfire and a sympathetic one perhaps?

However, I do on occasion notice a "grumbly" idle after a cold start. I just figured that was the car getting "settled" after sitting. That said, sometimes I get the codes, and sometimes not. I'm not finely tuned enough to detect the misfire when it happens - so, when I feel or sense the rough idle that doesn't necessarily match up to the misfire codes. They seem to appear on their own mysteriously. Given the start/idle scenario described, I actually think this has been happening for a while now as I recollect that happening before. I just never got a CEL until now and never plugged in my scanner to see if anything was wrong just for the heck of it.

I don't have the tools necessary for a compression check - unfortunately. I don't like the idea of a head gasket leak and would be shocked if that was the cause. The car isn't perfect, but it's garage kept and driven roughly 5k/year. Not that I baby it, but I use it gently (although I like to drive it fast!)

The one thing I wasn't able to do was bench check the coils. The few tutorials I found didn't help and I couldn't find any procedures for which leads to check and what resistance to expect. I actually got 0 Ohms on every reading I took. I obviously did something wrong.

 

you should be able to rent/borrow a compression gauge from a big box parts store like Autozone. You need to pop off the coils (not always that easy on some cars...) removed the plugs, screw in the gauge and crank for 5-10 seconds. Best to do this on a warm engine. You'd be looking for consistency across all the cylinders. For a turbo, I'd expect something in the 150 PSI range, for an NA block with higher compression its like 180. Now that you've got the coils off and plugs out, inspect the plugs, consider replacing (go with OEMs - they come pre gapped etc), inspect the wire harness to the coils looking for cracked connectors and I'd even consider buying one new coil and drop that on #3. If you happen to find an odd PSI reading on a cylinder, drop 1-2 tablespoons of motor oil down the plug hole, then repeat. The oil will help seal the piston rings temporarily (this is the "wet" test). If the PSIs go up = it means you have internal issues :-( Next I'd be checking for intake air leaks. Try spraying some carb cleaner around the injectors to make sure their seals are ok and consider getting a smoke test done to look for a vacuum line or intake boot issue.

 

Thanks for the info. As I said, plugs (new OEM 7k ago), connectors, harness, etc are all good - no problems. At this point, if I'm connecting a compression gauge, it's beyond my weekend mechanic abilities and toolbox. Sad to say, but I need to take it to my mechanic. Wish it were a simple fix like my V50 misfires - standard coil replacement.

I'll post the findings from my mechanic on what the problem was in hopes that may help someone else later.

 

​​​​​​Did you ever get a diagnosis?

 

Yes - and sorry for the forgetful response.

As it turns out it was a faulty injector. #3 was bad - had gas leaking around it. My mechanic found it after doing an extensive amount of troubleshooting in many different areas - compression, smoke check, scoped valves, etc. I'm happy to have paid him for the thorough work, but disappointed that the problem wasn't noticeable to me. I never pulled the fuel rail off, so my only diagnosis of injectors was to listen to them and confirm they were "clicking" away as expected.

The car is back to running smoothly and no problems since. I replaced all the injectors as a matter of principal and to keep them all on the same timeline. The old ones only had 73,000 miles on them but this is an '06 so age is more detrimental than miles at this point.

Thanks for the follow-up (sorry I was forgetful), and I hope this helps anyone in a similar situation.

 

Thanks man. Reason I asked is because I'm dealing with a similar situation. Mines an 05 R with about 145k on it. I bought it 6 years ago with 100k. It was a 1 owner car, impeccably maintained, near mint condition. I brought it to my buddy who is a Volvo dealer master tech and told him to go through the engine and do whatever it needs to be 100%. Did the timing belt, water pump, new radiator, pcv service, relocate some sensor to the trunk, (can't remember which one but it's a common failure point), and did the fuel pressure sensor. And of course oil change and all that routine stuff. Car has never been beat on, always up to date with oil changes, always synthetic 5w-30. Always ran super for fuel and never put in any additives. Never ran low on oil or coolant. Car ran immaculate for the first 5.5 years. Then one day, on the coldest day of the year last winter, I'm going to a contractor showcase about 2 hours from home. Halfway way the car starts misfiring like crazy. Out of nowhere. Especially under load. I pulled off and got it towed to where I could work on it. Ended up near a Napa so I borrowed their scanner and scanned it. Came back with misfires across all cylinders! Since I was so far from home I decided to start with the easy and most obvious, plugs and coils. After swapping all of them I got the misfire only on one or two cylinders. Got it running enough to get it home. While it's been sitting I've been researching when I have time and eliminating everything it could potentially be. I changed the fuel filter (it was disgusting), got all new OEM Volvo plugs and made sure they were gapped at 28, cleaned and eventually replaced the MAF, new air filter, while I was in there I added a snabb intake and a forge cbv I've had kicking around, I replaced the tcv, new vacuum lines, and pulled/cleaned and tested my injectors. Got the misfire down to only cylinder 5. Was just about to spring for a laptop and vida when I read about the coil harness degrading and being a potential cause. Sure enough a wire to the plug for cylinder 5 was knicked and exposed. Thought I finally found the problem. Replaced the entire coil harness with a brand new one. Fired it up and same thing! Swapped injector 5 with 4 and the misfire followed and stayed on 5. So I bought all new injectors thinking that has to do it. Nope! Still missing on 5! I can't do a compression test at the moment because I have it all apart again. I'm cleaning the pcv, cleaned the throttle body (which was FILTHY), replacing the rest of the vacuum lines, upgrading a few hoses, and double checking everything. I bought a borescope that should be delivered tomorrow so I'm going to inspect the sleeves. I really don't think that's it because I didn't burn any coolant, never overheated it, doesn't smoke, doesn't burn coolant. I've narrowed it down to either a bad O2 sensor, the filthy throttle body I since cleaned, or a fuel pressure issue. When I replaced the filter I broke the clip on the line from the fuel pump to the filter and had to rig up a temp. And the temp is slightly leaking. Almost nothing but enough to lose pressure after a couple days. I'm praying it's not a sleeve or a cooked valve but I guess I'm going to find out tomorrow. If you or anyone else has any input on what I should look at next I'd appreciate any help. I'm not currently in the position to buy a laptop and vida at the moment. I just moved and have spent a lot of money the past few months. I'll post my findings as soon as I find something out.