Chedder

I pulled a 1399 code, and I have narrowed it down to the coil packs or fuel injectors. I have already replaced spark plugs, but the problem remains.
The CEL light will start flashing at idle only, after it has warmed up. On a cold start, the light will stay off if cleared previously, and come on about 5-10 minutes of driving. When cruising, the light is solid, and will start to flash if I'm waiting at a red light for longer than thirty seconds or so.

I have read the giant misfire thread, but was seeing if someone experienced similar problems as mine before I choose which parts I buy.
I have tried swapping the coil packs from cylinder 1&2 to 3&4, but I'm not sure if that helped narrow down which cylinder is misfiring, as I get 1399, and sometimes codes for one or two, or all 4 cylinders misfiring.

Allday

Here you go buddy read over the sticky's some though if you don't mind. Its the last sticky Ultimate CEL blah blah lol

*If you have a CEL that is not blinking, here is what you need to do. Drive to your local autozone or advance auto parts or some similar store, and tell them you have a CEL and you need to pull the code. They will pull the code for free. With a CEL it will usually be a "P" number, such as P1399 or something similar. Once you have this code, post it on the forums, along with a full list of your mods and any observations you've noticed about your car lately, or changes that you've made.*

EDIT: (Add On)
So what to do if you get a CEL? First, look at the CEL. If it is ***blinking*** continuously, STOP and DO NOT DRIVE THE CAR!! A flashing CEL can be indicative of something catastrophic going on, and continued use of the engine or driving the car could exacerbate the problem and make the costs to repair it grow into a HUGE amount! If the CEL is blinking, you have no choice but to get it towed to the dealership to have it checked out and fixed.

wisdom

I've had a misfire lately and it turned out to be coilpacks. Buy a set and try it. Worth the $100 since the coilpacks will eventually fail.

MR.T

What year do you drive and how many miles?

You have misfires reported on all cylinders, I really doubt that all 4 of your coil packs have taken a dump, but you never know. Just not the first place I'd look.

I've read other threads where misfires at idle have been cured by simply doing a valve job. Ive also heard of people curing these problems with sending the injectors off for cleaning. Also, If you have an ap1 you may have cracked retainers.

Just curious, How did you narrow it down to c-packs or injectors?

Inspect/replace plugs if needed, do a valve job and while you're in there do a compression test, then look towards injectors. At least that'd be my order of operations. Basically make sure your foundation is solid before looking elsewhere.

The multiple cylinder misfires are also indicative of bad sensors, but if you're not throwing any more codes than misfires, I wouldn't no where to start.

Hopefully some real shade trees will chime in with better ideas.

MR.T

Also tapping the fuel rail at a machine shop and installing a simple gauge to check for correct pressures could be cheaply done. I'd probably put that in front of injector cleaning.

Chedder

My car is a 2003 with ~110k.
I've replaced my coilpacks today as the ones that were in the car were looking pretty old and discolored, but the problem remains.

I guess I haven't really narrowed it down, but from what I have read, I thought the problem could have either been fuel injectors or coil packs from posts that other people have posted. A valve adjustment was done on the car about a year ago by the previous owner, but I have no proof of that so I guess that should be my next step. I have bought a compression tester today, so I'll also have the compression checked while I make sure I torqued the spark plugs correctly.

Just curious, will cracked retainers show any symptoms other than a misfire? Will the car run worse or make any strange noises? The problem only happens during idle, and the car runs great unless the car comes to a stop at idle.
Thanks for all the inputs and suggestions.

This is one of the threads I read that made me think that I have narrowed it down to injectors or coil packs after I have replaced the spark plugs
https://www.s2ki.com/s2000/topic/101...lly-warmed-up/

Eluded

Could be the valvetrain. IMHO the 9K engines are a little delicate. Once you elimate the coils and fuel, I'd look at the retainers and do a compression/leakdown test. If you are seeing misfire due to valvetrain, the compession numbers should be off. Good luck.

MR.T

You'll have the valve cover off in order to do a valve job and you'll be setting them at top dead center, so that's perfect time to do both valve job and comp test. My first valve job I did was in the company of a real mechanic, because doing a vj requires knowing what drag to feel for. I'd suggest the same to you if you have anyone you trust.

Checking for cracked retainers can also be done while the valve cover is off. There is a sticky in the "under the hood" section that goes into detail on what to look for. And checking for proper seal on the plugs is not a bad idea either.

Like I said, start at the foundation and work your way up. From what I've read fuel pump and coil pack problems do happen, but are not usually the thing that's wrong.

MR.T

Also, didn't see anywhere where you said that you replaced the spark plugs. If you did, what kind did you buy and did you check gap?

And to answer your question about retainers, people run their cars for a long time with cracked retainers without know they are bad. I'm sure performance is affected, but in a lot of cases not bad enough to notice.

Throwing parts at it can get really expensive. Do the cheaper things first.

Plugs
Valve job
Checked for cracked retainers
Comp test
Fuel pressure test.
While you doing the fuel pressure test check the fuel pressure regulator for slits in the diaphragm.

MR.T

Sorry to ramble, but don't forget about loaner parts from fellow s2k'ers. A lot of folks have known good ecu's, injectors, O2sensors, coil packs, etc... Just hanging in their garage.