Nightfox07

I have a 2004 S2000 that I bought used with 97,000 miles on it. The CEL was on when I bought the car and have been trying to fix everything wrong with this car. After I changed the oil and started up the car it had troubles getting to idle, with one quick tap on the gas pedal and its fine. But I shouldn't need to do that as it started fine before I changed the oil. Also when the engine is cold the engine is stuttering/misfiring while between 1500-3000 rpms, once past that it revv's fine. But the car is impossible to drive until the engine gets hot, then I am able to drive it, but still has hesitation during 1500-3000 rpms in all gears. Also during hard acceleration the car doesn't move and starts misfiring. I changed the spark plugs with OEM NGK iridium spark plugs, did valve adjustments, replaced IAC valve, replaced TPS, replaced MAP sensor and did the MAP whack, replaced upstream and downstream O2 sensors, installed a K&N air intake due to the rubber piping going to the TB being torn, installed invidia N1 exhaust with 70mm test pipe with CEL fix due to the exhaust being bent and not hanging on the hangars. It look like this person might have had a little accident with it. I tested the IAT and all the coil packs by swapping them around with the other cylinder that isn't misfiring but getting the same misfires. I've had this car for a couple of months now and still can't figure out what is wrong with this car. The codes i get are P1399, P0300, P0303, P0302, P0301. Any help is much appreciated!

s2cho

coil packs, your getting misfires on all cylinders so swapping bad coil packs throughout cylinders wont do anything if all them are bad. This is what your codes mean.
P1399, multiple/random misfire
P0300, cylinder 1 misfire
P0301 cylinder 2 misfire
P0302, cylinder 3 misfire
P0303, cylinder 4 misfire
So moving coil from cylinder 1 to cylinder 2 will do nothing if your coils are bad to start with because each cylinder is misfiring. Does that make sense?

Everytime I've seen p1399 its coils. Unless your engine is blown, coils is the best place to start for you. But its quite odd to have all coils going out during the same time. Usually you'll get one or two stock coil packs last upwards of 150k+. Having a misfire on all cylinders makes me suspect it could be some other more serious issue. But clear the codes, go rip it and see what codes come up. I could be wrong and it could be all coil packs going out and causing the misfire in every single cylinder.

Autozones has replacements for 50-60 bucks. Any coil pack from the year 00-05 will work, there is some discussion saying that the 04-05 are better but its generally all the same. Since you have a misfire in each cylinder aka p0300,1,2,3, grab one or two packs and order the rest cause i doubt they'll have more than 1-2 on hand. Throw the coils where you want (ex. in cylinder 1 and 2), reset the codes and see which ones come back. If one and two arent misfiring aka no more P0300, P0301, then you narrowed it down to coils. If one and two still come back with the cel you have some bigger problems, the next step would lead to compression testing.

If the old coil packs are correlating to the check engine lights as i mentioned replace them and have a cream soda. Let me know if this doesnt work. It is possible that your injectors are crapped out and I know a couple quick cheap ways to check them.

s2000maniac

I would say it's dirty fuel injectors. Get some low mileage used ones or new ones.

vortamock

Possibly coil packs, possibly injectors, and also I've read that a weak alternator could possibly cause it. Seems unlikely if you're battery hasn't lost charge, but if you've got a multimeter then it's free to check. Seems like if that could legitimately cause it, then it would affect all cylinders.

Nightfox07

So I got a hold of the previous owner and figured it out, it was bad injectors. He had been tapping the fuel rail with a hammer to stop the misfiring, after he told me that I went out and tried it and everything is running perfectly now. My guess is the filters on the injectors might have some sediment or the injectors aren't seated properly and tapping the fuel rail breaks up the sediment or seats them properly. So I ordered a brand new set of OEM injectors and will be installing them this weekend as well as flushing out the fuel rail.

@s2cho I was swapping the one cylinder that wasn't misfiring coil pack with one of the cylinders that was misfiring, and CEL code wasn't changing. Also I forgot to mention that I did a compression test on all the cylinders and they were all at 205 exactly.

s2cho

Good to know, but dang oem injectors are a pricey penny. When mine act up I get them ultrasonically cleaned and flow/spray pattern tested for about 20 bucks a injector and they havent failed me yet. Seems like if I fill up anywhere other than shell they get clogged and misfire on me lol. But if you want, I got a couple of people on forums here that will sell a set of used injectors for around 80-110 shipped. That way you can have a set to get professionally cleaned and have another set ready to go. I really only do this because the s is my only car right now and I can throw another set in about 10 mins having no down time lol.

But if yours are just clogged a good way to test them is with a multi meter, go on the ohms setting and put a lead on each contact and see if the value is within 14-15 ohms. Then you can just get the set you pulled out cleaned and have a back up. When installing them make sure you lube the top o-rings connecting to the fuel rail with a decent amount of motor oil or you'll end up ripping the o rings. Any leftover oil will be dissipated by the gas and shot out the injectors. Twist it into place and make sure you dont force it in there or you'll tear the o-ring and chances are honda wont have them in stock and you'll have to order another! The bottom o-ring is just a seating o-ring so no need to worry about that one.

Nightfox07

Yeah I thought about having the injectors pulled/checked/cleaned but I just wanted to be on the safe side and replace them. Ballade sports website sell a set of OEM injectors for $350 which isn't that bad compared to the honda website at $155 per injector. But I will be keeping the old injectors and have them cleaned and tested so I have a back up set. I also only use shell gasoline. I have a 2015 turbo BR-Z and if you know anything about them the injectors make a cricket noise, but with shell v-power it reduces it greatly and sometimes you don't hear it at all. I will be installing the injectors in accordance with the service manual which tells you to lubricate the o-rings on the injectors. I appreciate you taking your time and helping me with my issue!

s2cho

No problem, good luck! Hope that fixes your problem! And dang a boosted brz must be a ton of fun to drive. I heard some horror stores about the brz's rusting, any truth to that?

Nightfox07

Not that I know of. My BR-Z is garage kept and only has 2000 miles on it. I have a 02 camaro and a 04 WRX as my dailies. So the BR-Z doesn't get out much.

s2cho

dam BALLERRRR haha