What would cause misfire on 2,4,6 coil packs

disconect battery for 15 mins and try again

Look for "stuff" ozzing out below the coil pack, there is a circuit board that is potted to protect it from moisture, when it fails and then gets hot, the potting material starts to leak out and that is a clue the circuit board is bad.

Did you happen to figure out what the problem was? My 2010 enclave is doing the exact same thing plus it died on me yesterday on my way to take it to the shop to get the coils changed and now it wont start back up. We cant figure out what it is.

Timing chain

Do the timing chains really give problems on 3.6 engines or is that just an old wives tale. There may have been some problems early (2005) but GM puts that engine in everything including some performance Cadillacs......

It’s the main problem with 2008-10 traverse , Acadia and Enclave

Hey what's up guys I'm trying to see if any of you guys knows what should be the resistance on a coil pack for a 2009 Buick Enclave cxl 3.6L I'm having problems with misfires. And should I check terminal 2and3 or 1and3 on the coil pack for resistance

For a po300 and 302/304/306 here’s what u do. First lift cover off of under hood fuse box. Tighten both 10mm bolts until u feel resistance. Theses bolts will spin forever so stop when u feel some resistance. This will fix issues most of the time-just a poor connection internally that controls fuse for even coils in fuse box. Next u can remove the ground and left corner of front cylinder head below coil 6. Clean eyelet and reinstall this coil ground- g114, next disconnect 2 connectors on bracket between throttle body and firewall- injector connectors. Inspect and add dielectric grease to terminals and reconnect. I’m a g.m. Tech and have had at least 10 vehicles with this issue and it repaired them all. Most likely it’s the fuse box connectors being slightly loose. Good luck and ket me know how u make out.

I have the same issue after first test drive after doing chains guides tensioners,and phasers . 2010 traverse. Ran perfectly for 2 miles then acted like it ran out off gas. Now wont start , and if it does 2,4,6 misfires , checked the fuse box, injector connectors, swapped coils, new plugs, cleaned the ground still no luck. Anything will help.

Guru6jwj1 did you ever figure out what the issue was? I have the same problem, only ist cyls 1,3, and 5.

Mark and Brink .. I want to help you out and I know I can .. I just found the culprit. you will not believe me at first but HIGH probability your issue is the cable and its connection to the to the fuse box. I can't thank the guy who pointed me int the right direction .. I can't re find his post, but he told me this was a pattern failure in Acadia no one talks about. My SYMPTOMS Started one day out of no where as I drove. serious 2,4,6 misfires, stabli track going nuts. Frequent unburnt fuel detonating in the passenger side exhaust pipe. I was afraid I would brake a valve. Stabltrack pulsing a brake for no reason. Some days 2 4 and 6 really DID completely stop firing. I felt the vibration. Stop engin restart .. 50% of the time they ame back on. Here's what did nothing: 1.) replacing the plugs 2.) cleaning off the 3 ground wires between 4 and 6 So this guy said to start the motor then raise up & down the big cable entering the engine fuse box . I did & my engine sputtered then stopped! It restarted no prob. Depending on how I wiggled, pushed and pulled (only a little bit) it I could get 2,4,6 to stop, the engine to quit and also I could make it run smoothly every time when I pushed it straight toward the fuse box. I threaded a wire tie thru the plastic fuse box clip then loosely bound it around the cable to constrain it "towards the fuse box" (so if a wire is broken inside its insulation the wire tie would bias the broken wire ends to touch again) I did it a clip at a time till there was just a little force .. and I was hearing the engine run correctly. I have driven the car 2 week every day and NO misses. The CEL went out on its own after 2 starts. Hopefully between to day and New Years I can disassemble the fuse box and determine if a wire is really broken or if there is an electrical intermittent in the fuse box... but it is 100% one or the other. I hope I've helped !! -Dan-

PS ... Some posts I read are saying 1,3,5 is misfiring instead of 2,4,6 that I had. This still points us to the same problem back in the fuse box and/or connecting cable. Note there is one fuse is for 1,3,5 coils & another fuse is for 2,4,6 .. but note because the coils are returned to ground, BOTH fuses MUST be wired from the positive fuse block rail to the (coil driver) transidtors in the ECU. and NOT directly to the coils as you might be thinking. Therefore it is likely the fuse box connections are somehow failing due to tension from this big cable , corrosion, or a broken wire in the cable. I don't think there is any other possibility. -Dan-

Dan/ICYRselling. Im have the same issues. Did you take your fuse box out and if so, what did you find? Thank you!

Guru85MRF, THANK YOU!!! It was the fuse box that was loose!!! I was already almost $500 in, and it was a loose fuse box all along! From the bottom of my heart, thank you!

Just in case another GM owner comes looking on here, I want to let them know to check the fuse box first. PROBLEM: 2008 Buick Enclave. Suddenly it would start running rough, warning lights would come on... Service Stabilitrac, Traction Control Off, Service Engine Light (has been on steady for months but would start blinking when this occured). I would pull over, kill engine, wait few minutes, then crank and go. That would straighten it out sometimes for weeks. Then it kept becoming more frequently and finally all that just stayed on. Car was running very rough, drinking gas, sometimes the Engine Power Reduced warning would come on, and it was really bad then. Car would lose acceleration even thought foot never moved on gas pedal. Sometimes I would smell gas. I put a new throttle body on it after doing a lot of research. No help. Changed spark plugs. Did nothing. These were the codes it was throwing: 300 (random misfire), 102 Mass or Volume Air flow Circuit Low Input), 113 (Intake Air Temp Sensor 1 Circuit High Input), 202, 204, 206 (Injector Circuit/Open- cylinders 2, 4 ,6) and 449 (Evaporative Emission System Vent Control Circuit Intermittent). We cleaned the Mass Air Flow Sensor and checked and cleaned other lines. Nothing helped. Then Autozone's computer suggested a timing chain. But the sales rep told me he thought it had to be electric. So I started doing more research and ended up here. My car is fixed now and running great. It was all because of one of two of the 10mm bolts inside the engine fuse box that was over tightened past the threads. I hope I'm explaining that correctly. Read Guru85MRF's post above about the fuse box. GM also put out a bulletin to all the service technicians about this. You can find more information here. https://m.carcomplai nts.com/news/2020/ gm-fuse-block- lawsuit-loose- terminals-cause- problems.shtml I hope this helps anyone experiencing these problems. My Service Engine Light is on steady now again. The only code it's throwing is the 449. I can deal with that later. Car is purring like a kitten thanks to my son, who fixed the fuse box problem and God answering my prayers!

One more thing, there was a lot of white exhaust that came out of tailpipes right after the fuse box was fixed. It was burning all the junk off from cylinders 2,4,6 and only lasted about 5-10 minutes. It smelled like carbon burning off. No more gas fumes coming out.

I've found the connection to the ecm to be the issue on my 2009 traverse . I went through all of the suggestions above with no luck . Disconnected the ecm harness and cleaned the terminals, running fine now . Still getting an intermittent crank sensor and cam sensor code.