I agree wholeheartedly about spending the money. The point is these are CHEAP compared to the cost of Bosch injectors at most places, which is usually $120-$150 per injector! I may take you up on the offer, thanks!

I'm running the Platinum +4's....I have for the last 2 or 3 years, they've been a great plug for me in the past.

Ed,

I quickly read the other's posts, but concentrating on your post I'll toss this into the mix.

Pull the plugs and inspect after you let it idle a bit. Are the plugs wet? Carbon? I suspect the injectors are bleeding too much fuel into the cylinder at idle or small throttle opening. When you open the throttle, the additional air masks the problem and the engine runs normal enough.

During a long road trip in my Carrera, I noticed at cruising speed that there was a hint of what some of us might consider to be a miss-fire. When I first noticed it, I opened up the throttle for a bit, and the probelm when away. As I continued on my trip I began to notice the "miss" more and more. After the trip, the the problem got worst. I could tell there was something not right at idle or small TB opening. I tested the ignition and found nothing, but I knew one of the cylinders was not always firing right. I had rebuilt the engine that summer, and was fearful of a broken rocker, so I did a compression test. Every cylinder tested fine, but I noticed the #1 plugs didn't look as good as the others. I replaced it and the problem persisted.

I pull the plug again and noticed it was very wet after the start and idle test immediately after I replaced the plug. I replaced the #1 injector with a used injector from the spares parts collection, and the problem has never returned.

What was happening was that at idle and small TB opening the cylinder was sometimes too rich to fire, but at larger openings the mixture would be right and the problem went away. Spirited driving didn't fix it and only masked the bad cylinder when I pulled the plugs. It sounds like you are experiencing this on more than one cylinder. See if you can borrow some injectors locally to test with. If you can't shoot me an e-mail. I may have some used ones or I can help get you some at a discount.

Side ntoe: I used plain copper NGK plugs and love them. I've had a couple of bad episodes with Bosch plugs butnever with NGK, and haven't considered them since.

Ed, why don't you change around 2 injectors, one that you think is good and one that you think is bad and see if the problem moves around?

Thanks Souk for taking the time to explain your past experience. When I was first struggling on this, it was the exact opposite, the plugs were bone dry with no sign of fuel.

So, now for the update: I tried starting fluid on the intake, and I got a bit of a rise on the #2 and #4 cyls. So I retorqued the intake to 21lbs. It helped a little. I then went out and ran the car a bit. It seemed to get better. Then, I went and filled up with some new 93 octane, and put a can of Sea Foam in it (Ok Zoanas?? ;)) Ran it a bit more.....came home and checked the temps, I've got good cylinder temps on 5 of them, the #5 is a bit low when it gets to idle. They were all at similar temps (300+) when I first came back, however. The idle and part throttle is much smoother, when it's on the lift, and the idle speed is back up to about 750 RPM. I will say that the cam comes into play a bit on the idle, IMO, as the performance cam has a bit of a lope, so it doesn't sound as smooth as before.

So, the Sea Foam did it!!! Just kidding, but I figured it wouldn't hurt. I checked spark again on #5, and it is good. I also rigged up a test light for the injector harness, and it seems to be firing fine. So, I still suspect #5's injector as being marginal.

Now, we've got rain again, but we should clear tomorrow afternoon. So, I'm going to take it out a put a few more miles on it, and see what I get. If it runs right, problem solved. If not, then I'll swap the injectors on #4 and #5 to see if the problem migrates, if the injector doesn't clear. If it does, I think I'll bite the bullet and buy one new injector. I'm not springing for 6 of them at tis point.

Thanks to all, and I'll keep you updated when I get another drive in. I took some video of it running, I'll try and post on YouTube (I've not done that before) and let everyone see/hear.

That's what I'll do next if I don't like the way it drives. The engine was hot when I was messing with it, so I didn't want to crack the high pressure fuel lines on the hot engine.

OK, Porsche lovers, here is video:

http://www.youtube.com/watch?v=f8gl1orKzXM

:D:D:D:D:D

Where did you find that K&N air filter and adapter? Notice any difference after it was installed?

It's basically homemade with high-temp silicone hose. I put it on to clean the engine bay up, I don't know that it's done anything for performance. You can hear the intake a bit when you wind it up...

Another satisfied customer. :D

Do you affraid of sucking in water when it's rain, or car wash?

Not really.....she rarely sees rain, if any. I put a garbage bag over the engine/under the grill when I wash her.

I bought a set from them on ebay for a little cheaper than that. They are not the exact part # as the original 911 injectors (I think they are for a BMW), but they work and fit fine. I'm still running them.

ianc

Thanks ianc, that's good info. Same as the DME crank sensors, 911 parts are $150 per, BMW version which appears to be identical is only about $100 per.

Ed,
What is the wrap up?

Ed, if you got a bit of rise from cyls 2 and 4, and it still isn't sealed, your intake manifold flange could be slightly warped - over torquing the nuts usually does it . If so, you can plane them with some sandpaper on a granite countertop. I'd also replace the phenolic spacers with new ones.

Well, it is "pretty good". I've got about 100 miles on her, but I'm in SoCal for a week, so she'll be sitting a few days.

Steve-thanks for the tip on the flanges, I may pull it and check. The spacers (& gaskets) are new. I used 574 to seal one of the gaskets to the head surface and the other to the intake flanges, but kept the spacers dry, which I believe they are supposed to be.

Sunday, I got a bit of the low end miss again. I checked the intake barrel nuts, and they were most all a little loose. Again, I retorqued to 21lbs (vs 18.5 spec) and drove her about 25 miles yesterday before going to the airport. She was superb. I'm going to see what happens with more miles-basically see if it loosens again. I don't have split lock washers under the nuts, but the "wavy" lock washers which were there originally, I think.

Of course once we move back to SoCal, she gets a date on the dyno with Steve for optimization!