smoses

First off, this is my first post. I’m a long time reader of this forum and would like to say that the information provided here has helped me immensely in upgrading and repairing various items on my S2K.

I’ve read a lot about people having various idling /misfiring problems on their S2K. There is also lots of info out there to diagnose and fix the problem. My story details exactly what my problem was and how I fixed it. If you have a similar problem, I hope this helps. Enjoy!

Car: S2000
Year: 2000
Milage: ~128K (I bought it used at around 80K miles)
All stock with an upgrade to a K&N air filter and an all aluminum Mishimoto radiator which was replaced when the stock radiator cracked on the plastic portion on the top (a common problem from what I hear). BTW, the Mishimoto radiator is awesome.

So, while sitting in the drive-thru of a Wendy’s, I noticed that the car was making a “putt-putt” or “poof-poof” noise at the exhaust that also came with some shaking/vibrating of the car. I didn’t give it much though until a few days later my check engine light (CEL) came on. The car still drove fine; no hesitation in acceleration from stop, nice power throughout the RPM band, still went into VTEC without any problems, etc. After a long drive (approx. 100 miles+) the CEL inexplicably turned off. Good! So I thought…

After another week, I noticed that the “putt-putt” sound and the shaking/vibrations were much more noticeable whenever I was idling. Then the CEL came back on… and stayed on.

I first checked all my vacuum hoses. I did find a cracked hose leading off the PCV. I replaced it with a generic hose. No change.

So, at a local Autozone (an autoparts store), they pulled the following codes: P0300, P0301, P0303, P0304. I re-gapped the spark plugs (NGK Platinums that were supposedly replaced at 80K), resetted the CEL, then drove around for another few days, at which time the CEL came back on. I then drove into an O’reilly’s (another autoparts store), and they pulled the flowing codes: P0300, P0302, P0303, P0304. WTF?!? Different cylinders? I bought new NGK Iridium plugs and replaced them. No change.

Due to the age of my car, I decided to get new Oxygen Sensors. I figured it was due any way. I bought a front and rear one, changed it out, reset the CEL… no change.

I then read that the throttle body(TB) and IAC can sometimes get a little dirty and cause idling problems, so I pulled those off and cleaned them (the hoses of the IAC were a bitch to take off!), paying special attention to the small channel on the TB which leads to the MAP sensor. No change.

Then I read that valve clearances can have an effect on idling, causing idling problems. I proceeded to buy an angled gap gauge (Craftsmen brand from Sears… it had all of the proper gauges needed, if you get one make sure it’s angled!), a torque wrench, and did the valve job myself (this was actually not very hard at all). At the same time I cleaned my K&N air filter. I did find two valves that were slightly off. Reset the CEL. Came back on within 20 miles. STILL no change, but I will say that it did make the engine itself sound nicer. There’s a video on you tube that shows a before and after if you are interested (it’s not my video). But the “putt-putt” was still present.

I then proceeded with a MAP whack. No Change.

Then I bought a new MAP sensor. No Change.

Then I proceeded to buy 4 new ignition coils and replaced them. I figured that, again, due to the age of my car, I might need to replace these soon anyway. Reset CEL. No change.

At this point, there was really only few options left; either I had a bad fuel injector(s), a bent valve, or somehow losing compression in the cylinder(s). I never really push the car hard, and maybe get into VTEC range about once a month, if that. That being said, I didn’t really believe there was a problem with valves or compression. The car for all intensive purposes drives just fine. So then, I concentrated on the fuel injectors.

Therefore, I first ran through two bottles of concentrated Chevron Techron fuel injector cleaner with no luck. Then I bought 4 very lightly used fuel injectors on Ebay. I could have sent out my injectors for service...the total cost (with shipping included) would have be a little less, but it’s Christmas time at the moment and I probably wouldn’t have a working car for 1-2 weeks, which I can’t have at this time as this is my daily driver. So, I replaced all of the fuel injectors (total time ~approx. 1 hour and I was really taking my time). Unfortunately, I didn’t take pictures of the fuel injectors, but they didn’t look very clean. There was some soot and grime on the rubber ring that goes into the manifold, especially on cylinders 1, 3, and 4. I cleaned out the soot inside the manifold before I replaced the new-to-me fuel injectors. Voila! No more “putt-putt”. My car idles beautifully! And best of all, no CEL! I will say though, with all of the “wrong” items I have replaced or fixed (O2 sensors, MAP sensor, spark plugs and ignition coils, valve job, TB and IAC clean) my car now runs better than when I bought it!

So, if you are having noticeable “putt-putt” or “poof-poof” sounds coupled with vibrations and shakes while idling, with no other problems with acceleration or power, definitely look at your fuel injectors especially if you are getting P0300 and multiple P0301/P0302/P0303/P0304 codes. By doing this, I hope that you will save yourself some time, $$$, frustrations, and most importantly preventing unnecessary down-time from driving your beloved S2K!

starchland

do you have a link to a DIY? I wonder if cleaning your existing injectors would have worked?

I had a misfire code as well. P300 and P301 and injector cleaner did the trick for me.

smoses

I don't have a DIY link... I have the technical manual in PDF form. I just printed out the two pages related to removing the fuel injectors and did it.

I did read this one before I changed mine. It helped a little. The most important thing to remember is: DO NOT DROP ANYTHING IN THE MANIFOLD AREA. You will probably lose it, unless you want to spend a lot of time trying to retrieve your lost screw, o-ring, etc.

https://www.s2ki.com/s2000/topic/929...removal-guide/

I do believe that servicing the injectors would have worked. But looking at how fouled they were, I'm not surprised at all that the fuel injector cleaner didn't work in my case. I've heard of some people using the cleaner as a preventive maintenance, for example, putting a bottle in every time you change the oil. But, I bought my car used at around 80K miles... I have no idea if the previous owner(s) used quality gas or not. I only use Shell or Chevron unless I can't find a station nearby.

TardiS2K

Just went through this same procedure but skipped the 02 and map sensor, and coils took care of it. Also during the last week of December, my dd as well. My plugs were HAMMERED though. Nice to have all that maintenance taken care of!


MY00 99k miles