First Drive after storage - BAD misfiring

I have a 2000 C4 Cabriolet. 70,500 miles. Have had it for 3 years now and have had ZERO issues with it. It has been a great car. Over the course of the past 3 years, I have put about 3500 miles on it without a hiccup. Yesterday was nice in Michigan so I washed her, aired up the tires, checked the oil and took her out for a spin. Initially she was running fine but after about 2 miles I noticed the check engine light came on, then it started flashing for a minute or so, then back to a steady light. Drove about 3 miles and parked it for 20 minutes. Prior to parking, I noticed there was a slight misfire, was running rough which was unusual. Got back in after 20 minute and started her up and the misfiring was BAD. Chugging along. Flashing check engine light, then steady once again. Seemed to get progressively worse as I drove it. I limped home and checked the codes on my cheap handheld scanner: P0300 - Multiple Misfire P0001 - Cylinder 1 misfire P0002 - Cylinder 2 misfire P0004 - Cylinder 4 misfire P0005 - Cylinder 5 misfire P0006 - Cylinder 6 misfire With this being the first drive after sitting for several months with 1/2 tank of gas and no stabilizer was added last fall, it seems like a fuel supply issue. I ordered a new fuel filter in the hopes that this is the cause of my issues. Again it was running fine initially, but got real bad real quick. Just throwing it out to the experts here....am I correct in thinking it might be something as simple as a fuel filter? Thanks in advance for any input/guidance. Been lurking her for a couple years, absorbing all the Pcar knowledge I can. These are certainly special cars.

First thought is bad fuel . Second thought ignition coils got wet and they are cracked . Anything beyond that needs further analysis .

Bad gas. Fill up with fresh gas...even if half a tank. Add some Techron. Clear codes and drive.

Pull off airbox and check to make sure you don't have a mouse nest plugging up the air flow.

Quotes source post: 19329772

I think you may have gotten the coils wet - pretty common

I agree with Peter, he might have a clear case of aging coil packs that when wet got all misfire crazy. Time to replace. But I also agree, it's never smart to store a car with a half tank of gas. Alway fill up with fuel stabilizer. Run a double dose of Driven Injector Defender or other fuel cleaner with PEA. Then one bottle with each fresh tank of gas.

[QUOTE][[color=#222222]I agree with Peter, he might have a clear case of aging coil packs that when wet got all misfire crazy. Time to replace. But I also agree, it's never smart to store a car with a half tank of gas. Alway fill up with fuel stabilizer. Run a double dose of Driven Injector Defender or other fuel cleaner with PEA. Then one bottle with each fresh tank of gas./QUOTE] I agree. This is exactly what I do every spring since it sometimes takes a week to plow the local roads where I live, let alone shovel the driveway and garage area. The use of mothballs, rodent traps, and drier material, along with sealing the entire stand-alone garage, becomes the other part of the storage routine. I usually attempt to move the car on a sunny day and just let it sit with the frunk and rear hatch open, but monitor the open areas before I attempt to do anything else. The car sits during the winter months with a battery tender and some Vaseline on the posts and a sealed ECU, it is a cab after all.

Appreciate all the feedback. I bought a big bottle of Techron and topped off the tank and took it for a 15 mile drive to try and burn through some fuel. It is improved over what I was experiencing yesterday, but there is still a miss. I also took off the airbox to confirm there isn't any airflow issues and it was all clear.. I cleared the codes and this time around I only had a misfire on #3. I don't think I got anything wet when washing it yesterday, I use the 'No Rinse' car wash product and maybe used 1/2 gallon of water to wash the entire car. this is not to say my coil packs haven't gone bad, but I am 99% sure I didn't get them wet yesterday. I think I will take it for a longer drive tonight as I need to head down to Ann Arbor, hoping to burn through what I hope is just bad fuel. Again, appreciate the feedback and I will check back in after i get some more miles behind me.

Washing the car is how I discovered my coil packs were cracked and I am careful about how much water I use. The good news is that if that is what it is, it's a simple fix, once repaired, you may never have to do that job again and you can cross it off the list of all the things that are known issues for a 20+ year old 996.

I would swap the coil in 3 with 2 and see if the miss follows before your next drive.

My first thought was animal damage. I don�t think it�s a fuel issue. Gas doesn�t really go bad that fast, and any moisture in the tank would have been at the bottom and sucked through and burned off after 5 mins. Maybe a rodent ate some writes on the CPS or cam sensors or something like that. Definitely check the air box for animals. Check mufflers for nests, too. Check all wiring that you can see and any evidence of animals eating wires.

Thanks for your input Mike. I don't think it is animal damage. there are no signs of any rodents being present in my garage (attached to the house). I did take off the airbox and it was fine. The thing is, it ran great for the first 1/2 mile before the misfiring started. I want to think if there was an animal that caused this, it would have been immediately apparent. I have not had an opportunity to put any real miles on it since I put in the Techron and fresh gas. If the weather is decent this weekend, I will burn through some gas before I do anything else. I will probably be ordering a set of coil packs and plugs too. It is probably time to replace them, even if they might not be the cause of the issue (but they certainly could be).

Quotes source post: 19333737

I tend to agree with this. It�s also possible that something broke right then and there. I read that a Boxster owner parked his car for winter storage, and immediate startup ended up being a dropped valve seat. He was scratching his head, because it was just fine before storage. The timing for when things break is sometimes just random.

Ok, revisiting this thread. I purchased a set of plugs and coilpackss from Pelican Parts with the intent of changing them out. I realized I was not going to have time to do it, so I had my car towed to a local shop who agreed to do the work. Welp, the new plugs and coil packs were installed and it is still misfiring badly. The shop says it is throwing misfire codes for all cylinders except for #5. They are not a specialty shop, just a normal auto repair place, but I have used them in the past for other cars and they did good work for me. . Any idea what else might be to blame here? I know I will probably have to take it to a shop that works on speciality cars, but I am nervous about what they might tell me. The car ran fine last year when I put her down to sleep and ran fine for about a mile this spring when I first took her out. Anything else besides plugs and coli packs that might be causing this misfire issue?

Quotes source post: 19417242

Based on the limited information, sounds like you have a bad set of coils/plugs. What brand? Did the shop offer to use their parts and get the car running properly?

I doubt the coils and plugs r bad. Being that it happened after storage im betting mice got to the harness to the left of the engine bay. There is a ton of telemetry available with the correct scanner and a knowledgable shop should be able to diagnos the issue. It could be a few different sensors ot could be like a maf but at this point its all a guess and u will continue to waste money without diagnostics.

You had it towed. Good move, but did you/they do anything about the fuel: adding more and / or adding Techron or something to deal with likely moisture in the tank??

Quotes source post: 19417250

While it is possible, I don't think the coils were bad. It is OEM parts - part number 996IGNCLKT1 purchased from FPC Euro. These are the Beru coil packs and plugs. All OEM. I was not cheaping out on the parts.

Quotes source post: 19417609

When this first happened, I put a big bottle of Techron through the system and filled up the tank. It might have gotten better for a bit, but now I am back to where I started. It might be even worse now as far as missing goes. I will certainly top off the tank and add stabilizer in preparation for winter storage in the future. We had so much going on late this year (selling old house, moving into new one) I just didn't have time to store it correctly. Well, I didn't MAKE time, is more accurate.

Quotes source post: 19417552

Agreed, I am not going to throw any more parts at it. I don't consider the plugs and coils as 'wasted parts' as they were original to my knowledge and have 70,000 miles on them. I am looking for a good independent shop in SE Michigan to take it to. Does anyone have any suggestions?

Quotes source posts: 19417242, 19418992

What happened to the coil packs from Pelican parts? What did the shop say was the problem in their opinion? Did they offer any rememdy? As I mentioned before, you really need to run a fuel system cleaner with PEA. Techron is good, but you need fuel system cleaner like Driven Fuel Injector Defender IMHO. You can also grab PEA based Fuel System clearners at Walmart - Gumout ALL in ONE has PEA and worth a try. Also, others make a good point about harness damage. Did you by chance store the car outside over the winter? Was it covered?

Quotes source post: 19419151

I was mistaken, I didn't buy the OEM plugs and wires from Pelican Parts but from FPC Euro. Again, they are OEM, I have no doubts about the quality of the parts installed. The car was not outside during the winter. It was stored in my attached garage. There has bever been any sign of rodents in there, but anything is possible. I am still thinking it is a fuel related issue. .