Ok where do I begin? I bought my cls 6 about 5 yrs ago with 157k on her. I love this car btw it's a love I can only compare to that of my first dog. Any who, it had its timing belt water and front suspension changed at 120k. One owner btw the original clutch was practically new when I test drove at 157k the never even down shifted the beauty once. Ok so I've had this amazing machine going on five years now and only put 44 on it. It sat for a collected time of about 1yr twice for 6 months. Just got it back on the road after the last 6 month sitting. I'm far from a mechanic but I do get my hands dirty, mainly for lack of trust for some of the local shops around my way. Since I got her back on the road I've had a cel stating misfires in all cylinders. I ran some fuel injection cleaner, sea foamed, and autolite iridium plugs. Still had the misfires. then I removed the intake manifold cleaned entire manifold paying particular attention to egr passage. Removed egr valve cleaned it. During this whole process I had a coil completely crap out, replaced that. And still misfires in all cylinders. Heard from a friend that it could be the cheap spark plugs, made sense so i replaced them with NGK and once again reset the ecu. And to no avail cel back on 30 miles or so later. Only this time it read misfires in cylinders 1-5 cylinder 6 has the new coil. So naturally I'm going to switch the coil to another cylinder and reset ecu yet again to determine whether all five coil are goin bad. Though it doesn't seem likely to me that all five would be going bad at once. Then again what I now. Any help would be greatly appreciated. I should mentioned this already but along with the cel its tough to start more often than not and its got a rough idle when it does start up for atleast 5 minutes or so depending on how cold it is outside. Also even after it does warm up often times when I tap the gas pedal and raise the rpms quick the needle will fall below 800rmp then come back up and steady at idle. ????? Please help me fix my baby🙏

 

A clogged cat is the usual suspect when there's misfires on all cylinders

 

Thanks teh def something I'll look into a bit more. Actually since we're on the topic is hollowing out a cat common practice?? Only reason I ask is I just bought another cl I've been. Using for parts, got it for practical nothing rear end was smashed trunk still opens and closes. I paid 50$ for the car I think the guy was a drug addict. Anyway the car has a ULEV vtec in it and I noticed the cat was hollowed out and sitting in the passanger seat.

 

It's a common problem and I wouldn't often blame catalytic converter but that doesn't mean it isn't possible. Turn the car on, unplug each coil and plug back in until the sound remains the the same with the single coil unplugged. Replace the coil pack.

 

Thank you for replying, but I tried this method several times. There is a change in idle for each coil I pull. I'm not ready to quit just yet, but this sure is frustrating.

 

There is a possibility of your EGR valve leaking exhaust gases into the intake at idle causing random misfire codes, also the valves being too tight will cause gases to enter the intake manifold pretty much mirroring the EGR leaking. This won't throw a EGR code and is really only detectable by monitoring the Manifold Absolute Pressure (MAP) sensor with the car idling, idle voltage should be 1.19V if memory serves me right, if this voltage is too high its due to something entering the intake manifold that shouldn't be there. A quick way to check if the EGR valve is your culprit is to shut off the car, loosen the valve and slide a business card in between the EGR valve and the water pipe/exhaust/intake port that it is mounted to, and tighten up the valve, clear fault codes and start her up. This prevents any exhaust gases that may be leaking through the valve from entering the intake manifold. If your misfire vanishes you're going to need a new EGR valve. If this doesn't correct your issue I would check the intake valves for proper adjustment, they may be too tight. Hope this helps

 

Sorry, MAP should read .85-.90 volts at idle. Anything higher indicates excessive pressures. I believe most handheld scanners have the ability to read sensor data now a days, so that would be the easiest way to confirm there is a problem.

 

Thanks for the info. The egr or a valve adjustment have been on my mind for the past week. Still have the misfires just been so busy I haven't had time to schedule an apt for a proper scan. However I did have a valve adjustment done when vehicle had around 160k on her. What are the odds of it still being the culprit. I'll definitely try that card trick, thanks again.

 

I looked proper voltage and your correct it should read .90 any higher suggests tight valves. I appreciate the insight. I really hope I get to the bottom of this soon. Tired of obsessing over it. Thanks again.

 

I had the same random misfire problem then decided to do a valve adjustment. Did this at 140k miles and the frequent misfire codes completely went away.

 

I once saw a video on the youtube where this guy was getting misfires on his cl turns out that someone put the IM gasket on backwards and was blocking the ports all he had to was flip it the other way and no more misfires just my 2 cents

 

Thanks for ur time. And yeah I saw that video. It's a bit of a shame he didn't atleast peek under there before replacing all 6 coil packs. Ofcourse it's never a bad idea if you've got the coin.

 

Thanks and yeah unfortunately I think your right. I say unfortunate because I had an adjustment done at the dealer only 40 some odd thousand miles ago. Can hard driving weigh heavily on the issue of loosening or tightening or whatever's throwing them outa wack.

 

No, I don't believe so. Of course if the adjustment nut wasn't tightened properly its a possibility. The CL S was meant to be driven, so I wouldn't chalk it up to being driven harshly, especially if you keep up with all the maintenance. Refer to the owners manual, there should be your PDI checklist book, it will have all the recommended maintenance intervals listed....I don't remember exactly when the valves are supposed to be adjusted but I think its near or close to 100k. If you haven't tried blocking off the EGR valve yet, I would start there. It's quick and simple and won't cost you a dime.

 

A thousand thanks for your help with my issue. I will most definitely be tryin that card trick tomm morning. I spent a couple hours today swapping the Bose speakers from a smashed up cls I bought a few months ago, into my girls friends 2006 Altima. It was a perfect fit btw, after a few self tapping screws😉 And sounds amazing. I've got my fingers cross that it is in fact a faulty egr. If not I'll be taking the intake manifold off yet again to check the gap on those valves. I've watched a few videos on the whole procedure, and it doesnt seem too difficult. Well wish me luck and thanks again. I'll post the cure to this dilemma if and when I find it.

 

No problem, I look forward to hearing about your issue being resolved.