Hey, I am new to the forum and I guess have a good story. I recently purchased a 2003 996 Cabriolet with 20k miles. I put about 1200 miles on it and started to receive the dreaded CEL P0305. And yes, I was thinking OH CRAP!

So like all the other good soldiers, I purchased a new coil pack and spark plug. Guess what happened after I replaced them...you got it, nothing. Same CEL under the same condition.

So in my case, the condition was under light acceleration and easy driving, the car ran perfect and no CEL. When I would try and accelerate hard, noticeable misfire and the CEL would light and log a P0305.

The car had been serviced perfectly with annual services being done every 1800 to 2000 miles, so I called the dealer who had done all the work. They knew the car perfectly and thought it could be a sticky lifter that would only have issues when the variocam would push the lifters into the higher position. They recommended a product from GB called MOA.

Before I did that, I went to Chris's in Bellevue and had them look at it. By the way, if you live within 1000 miles of these guys, go and meet them. These guys spent about 45 minutes looking over the car, listening for issues, hooking it up to their computer, cleaned the MAF and said nothing glaring was showing up. So, I talked to them about the additive and they said, what the heck, could help and won't hurt. Oh yea, I went in to schedule an oil change and they asked when it had been done last and told me to wait awhile and wouldn't take my money because I said I was coming back for an oil change.

So, I put the additive in and 100 miles later and after about 20 hard accelerations, no CEL. While I am still a bit nervous, it appears the idea of the sticky lifter and additive are potentially affective.

So, all of you out their fighting this issue, stay calm, work the symptoms, listen to the experts and best of luck to you all.

There still is no substitute!

 

good story! what additive you used?

 

Correction: It's "BG" not GB. Good to know.

 

Yea...sorry, it absolutely is BG. So now you know besides being new to the forum, I learn slowly.

 

I'm sorry, no offense to you...but i can't help but think this is nothing but a shill.

<edit> sorry that was a bit harsh Too much of a cynic I guess.

 

I'm supposing the 20 hard accelerations probably did more for the stuck (or dirty/blocked) lifter than any sort of crap you poured down the filler neck.

 

Sorry, I don't think BG Motor Oil Additive will eliminate a misfire on #5 cylinder where new plugs and coils will not.

Condensation in the fuel tank can add water to the fuel which can and does under the right conditions cause a misfire. This is neither plug or coil related, so renewing either will make no difference. When the water which lies in the bottom of the tank is sucked up by the fuel pump and runs through the system there is no more poor running and misfire. Adding Heet or an alcohol to the fuel tank will allow the water to mix with the fuel preventing this.

Years ago we would add several ozs. of ATF to free up sticking lifters. This was mainly due to sludge and use of single weight oils. With today's modern lubricants this shouldn't be necessary.

If it worked for you, good. The manual advises against the use of oil additives. In reality they decrease the lubricating properties of oil and can cause other problems like creating deposits on valves and spark plugs.

 

No offense to any of the responses. I'm still nervous as a ***** in church waiting for the dang CEL to return. Again, another day with no issues. Maybe you are right about actually driving the car, because it was basically stuck in traffic it's whole life.

Hey, the good thing for you all is that when I come back in another 1000 miles whining about the misfire again...or not...you can tell me "I told you so"...or not.