I have, or my son has, a 2000 Civic Si DOHC VTEC with the CEL on. Mileage on the car is just over 52,000
Error code per the AutoXray Code Scout is P1399. I drove it around and got some 0301, 0302 and 0300 which are Miss Fire codes for each cylinder and a Multiple miss Fire code. I reset te codes and drove around some more and got miss fire for cyl1 and 2 and multiple misfire codes along with the 1399 again. P1399 is the first code that shows up.
The car sometimes Idle's low and sometimes is fine.
I recently replaced the Catalytic converter as that is what was the original problem, when the CEL came on, per the mechanic that works on the car.
He has been a Honda mechanic for about 25 years now and is one of the best in the area. I totally trust him.
Yes I did put the O2 sensor back in the catalytic converter.
I have replaced the spark plugs with Dbl platinums, the Distributor Cap and Rotor.
The engine compartment was recently washed down to clean it up. Possibly something got wet but I can't find it after
replacing everything but the Plug Wires, which I have on order and will be replacing.
I did notice some moisture in the 2nd plug from left which I did dry when I replaced the Plugs. All the plugs did have what looked like
a brownish stain on the insulator close to the threads.
Any Suggestion besides the Plug wires which I will be replacing?

 

The brownish stuff on the spark plugs is possibly flash over, which means that the spark is jumping from the wire to the ceramic on the spark plug. Did you replace the wires? Also, when you install plugs and/or wires, you should put some dielectric grease on the top of the spark plug and some thread lock on the threads of the spark plug. Both of these can be found at the local autoparts store. I'm gonna go look up the code and see wats up.

I looked up the codes, and it seems that they are all for misfires, P1399 is for random or multiple misfires. When the engine misfires, it should shake. When i searched, some1 posted on another forum that you should check the resistance across the injector to see if it is correct. I don't know if this is correct, but it might be the problem. The problem could be caused by an injector not firing or a spark plug not getting the spark. It is also possible that the sensor that tells the computer that there is a misfire is malfunctioning. If you car never shakes or anything, then the last possiblity may be true. You said (well implied) that your cat previously burned out, so this leads me to believe that you do have a misfire. Also, if the cat burned out then fuel was bieng sprayed because if fuel wasn't being sprayed then the cat wouldn't burn out. I would look at your ignition system first because it looks like the fuel is getting to the cylinder due to that cat burning out. If the car does start shaking, there is a probe that you point at the fuel injector and it will light up whenever the coil in the injector is bieng energized. If you hook up the probe and find out that the injector is bieng energized, either the injector is not recieving a signal from the computer or the injector is bad. Hope that helps, if you need any more help jus post some1 should be able to help.

 

I had Misfire codes for all 4 cylinders so wouldn't this eliminate the problem being an injector?
The car bogs down when I press down on the gas while driving and the Check Engine light will start blinking.

 

I think its gonna be an ignition problem for you. If the check engine light ever blinks, stop driving the car. The blinking light indicates that you are going to cause major damage to the cat, it could melt if you keep driving it. I think you are correct that it can't be a single injector and i doubt all four injectors have gone bad. Maybe the problem is an igntion coil. The coil is going to supply all the cylinders with the spark, so if this has gone bad than all the cylinder will lose spark. When you hit the gas, the engine will require a more powerful spark, if the coil is not capable of proving the spark the car will misfire. There is a kid in my auto class with almost the same problem. He will hit the gas, the car will shake and soon after die. We suspect that the problem is a bad coil. He is gonna change the rotor as well b/c it looks bad but the coil will be replaced if the rotor doesn't fix it. Tell the mechanic to hook up the scope to the ignition system. He is gonna want to check the coil for its output, i'm not completely sure how this works since i've never done it but we have discussed it in class. I think you check the firing line and the voltage but i'm not sure.

 

Thank for the info. I'll try the coil and update if that fixes it.

 

What about the flashover? If your plugs had flashover on them, and you didn't change the wires this could still be a problem. Your car will misfire if the spark jumps onto the porcelin (insulator close to plugs). I would change the wires before the coil just to make sure that this isn't the cause, plus the wires are prolly bad anyway.

 

I've got some new plugs coming. They are 10.2 MM plug wires for the Civic Si.
Hopefully that fixes the problem. I'll update the web either way.
Again thanks for your help and knowledge.

 

Make sure you gap the plugs. It should be 1.3mm or .050in. The plugs should also be torqued to 13 ft lbs.

 

I bought Double Platinums, $3.99ea and no Gapping is need with those plugs. They come ready to install and I already installed them.
They had Quads but they were $5.99 ea. A little to much for me as we are selling the car. I am just waiting on the plug wires.
I usually buy that kind of stuff off E-Bay as it is way cheaper than the Auto stores and I've never had any problems.
Reason were selling is Son bought a 2003 Lexus IS. Got a great deal on it. Now that is one nice car.

 

Not a fan of Toyota/Lexus, i'd rather have an Evo.