ibmthinkpad99

This is a great forum. I have found plenty of useful information here and grateful it is here.

2007 s2000 with 70k miles.

My problem is CEL with codes P0300, P0303, P0304. The s2000 still seems to run smooth with no noticeable problems. I was going through the list of things to check and replace.

I have already changed my spark plugs with oem with no change in codes. I then called a Japanese repair shop and asked how much a valve adjustment would cost. He suggested I replace my coil packs first and the call him. Is this the case? Should I go ahead and replace my coils first. When changing out the spark plugs, I did not notice any damage to them.

I guess my test this weekend would be to swap out 1 and 2 coils and put them in 3 and 4. But I really cant see this being the coils. Should I find another place to get the valves adjusted. Any input will be greatly appreciated.

starchland

I would do a va if it has never been done just for maintenance, can be done free or cheaper than new coils. Not hard to do if your handy with a wrench or know trust someone who is. Oem plugs, torque properly, check gap, do va when cold.

xviper

Did you clear the codes? And then they came back? Or did you just change the plugs and waited for the CEL to go off?
Have you ever used injector cleaner? That might be your problem. Dump a couple bottles of injector cleaner into the tank and run it down. Fill up with new gas, clear codes, then see what happens. This would be the cheapest trial and error of them all.

sillyboybmxer

Xviper since you are here, I have the exact same issue as OP. Same codes, except it came on right at the end of the tank I was using Redline Injector Cleaner in( i forget which one exactly) Is that just coincidence or could that stuff mess up the injectors ??????? (clogging them maybe??)

I replaced plugs, reset, back on soon after.
Reset, back, on.
One time it came on and then it went off on its own within a minute.
I swapped coilpacks, reset, and I waited for it to return, and after 30 minutes or so of idling, nothing. Next day, another 20 or so minutes of idling it came back, same codes as before the swap. Next is obviously a valve adjustment for me as well.

xviper

Make sure you're using injector safe fuel system cleaner. Also, don't use any of the old cleaner meant for carbs. Modern day injector cleaner shouldn't mess up injectors. They should unclog them, help lubricate them, not clog them. Poorly functioning injectors is but only one cause of misfire codes. Trying injector cleaner is the cheapest and easiest place to start. It's odd that it waited till you were nearly finished the tank of gas. If it were the cleaners fault, it would have thrown the code sooner.
Now you have to look at the other stuff in order of how much money and time you wish to spend. You could still have odd injector function, plugs not gapped properly, coilpacks that have gone out of acceptable operational condition, needed valve adjustment, bum O2 sensor, bad gas, inappropriate fuel pressure, dirty air cleaner, bad ECU.
Misfire codes that do NOT throw a binking CEL, is usually associated with the "random" misfire code (P1399). This means that the misfire is not consistent. It comes and goes. This can explain why the CEL went off on it's own that one time.
Idling for 30 minutes may not be a good way to see if the CEL will go off or to see if it will come on. Just drive it. Idling produces operating parameters that may not give sufficient sensor readings for the ECU to determine if the misfire still exists (or not).

sillyboybmxer

I just found the bottle, it was Redline SI-1 injector cleaner(so it is ok to use, but it did notice it treats WAY more gas than the S2k holds, and I used the whole bottle. In that situation should we only use half the bottle???? Is it possible to be toooo concentrated in the gas?)
I was unaware a bad o2 sensor could lend to misfire codes, I thought they had their own code. Good to know.
Does the misfire code happening more/faster than while driven mean anything at all???? It seems to work that way which is why I always let it sit to see if it reappeared.

xviper

That cleaner should be fine and should not have contributed to the injectors acting up. If you are using the cleaner as a "maintenance" product, then follow the dilution as indicated on the bottle. However, when you have rarely used it and a very long interval has occurred since the last use, then you need a more concentrated amount in the fuel system to do a more concerted cleaning. I put one in just before each oil change and toss in the whole bottle. I've been doing that since the car was brand new. If you use it every month or 2 (which I don't feel is necessary), then go by the label. Remember that they also sell the super concentrated product (costs about 3 to 4 times as much) where you dump the whole bottle in. It all depends on what you are trying to do. The stuff you screw into the fuel rail and empty the can is much, much more concentrated even still.
The ECU uses (in part) exhaust gas readings to determine if a misfire has happened. These readings happen dozens, maybe hundreds of times a second. The ECU knows when an injector pulses and when a sparkplug should have fired. From those calculations, it can determine which cylinder actually misfired. O2 sensors have their own code for when the heating circuit malfunctions or when (for example) the one in the cat senses a general condition that would indicate that the cat is not functioning properly. Also, the primary and secondary O2 sensors perform different tasks and the ECU knows which one is doing what and how to interpret those signals.
Idling is a unique condition that sees a rhythmic jump between "open and closed loop" operation, particularly right after a cold start. You can see this when you have an aftermarket air/fuel gauge. "Normal" driving also switches back and forth between open/closed loop but it's not so rhythmic and it also involves the vehicle speed sensor picking up a continually varying or elevated signal, along with TPS readings. Driving is not quite the same as idling for extended periods of time. When the CEL comes on, it's generally from "driving", not from just sitting there and idling for a long time. In fact, idling at elevated rpm for more than X minutes will throw it's own code, so who knows what else it can affect. It's not something a street car drivetrain "likes" to see. If it throws a code during idling, you can never know if that was a contrived occurrence or the "real" thing.

ibmthinkpad99

Thanks for the reply. Yes I did clear the code and it came back about ten mins after idle. Also, I did dump Chevron with techron injector cleaner prior to the spark plug replacement.

This weekend I am thinking about switching the coils to see if it is the coils. I feel that it is not but need to rule it out. Also, someone mention trying Redline fuel injector cleaner instead. Also, do some research on how to do a valve adjustment or find someone I can pay to do it. I'm just worried that it might be something more damaging.

starchland

always wondered how a misfire was calculated Xv

xviper

Unless you've replaced the sparkplugs with known brands that work and at the correct gap, don't rule that out just yet. Most people just assume plugs come gapped to the correct distance, when in fact, you don't know that till you check each one before putting them in. Also, "goofy" plugs like those Bosche+4 are known NOT to work and even some Iridium plugs have been know to produce high rpm misses on some engines. Then there were those not so highly rated "pulse" plugs. Best is to stick with OEM plugs to be sure.