Spark plugs

[Dr. Gonzo]

Just replaced my sparkplugs and the old plugs were white/grey on the side wire and I was thinking that my car would be running lean with the side wire and the insulator being whiteish.
-note: All plugs look the same

What do you really want the plugs to look like, I always thought a light brown would be ideal. Just wondering if the S2K is a little different to my motorcycle knowlage.:confused:

Also, i am having some idle problems with a CEL code cylinder 1 misfire. I have checked and made sure its not the coils by process of elimination. I am wondering if it could be my plug wires. (my car has 50k miles by the way)

I am about to go listen to my injectors with a stethescope to see if a injector is dirty/bad, and possibly a compression test? Not to sure if that is something to do with a problem like i have.

Other than this i dont really know what to do to solve this problem and get my car to idle like it should. (its just shaky and not consistant)

Anyway any help will be greatly appreciated.
Thanks,
Stuart

[repiv]

In my experience, having looked at the plugs on several S2000s at various miles, they do tend to be a bit more whitish, with a ting of light brown. For a NA AP engine, this is fairly normal. At steady state driving, the a/f hovers around 14.7, which is mostly what the engine sees. During times of heavy throttle and moderate to high acceleration, the a/f does richen up and that's why so many S2000 owners report having such black, sooty exhaust tips. Again, this is normal.
I doubt it's your plugs that are contributing to your misfire code. You say you've eliminated the coilpacks, so I'll have to take your word on this and since we don't have plug wires, that is not a factor in the equation. What I mean by taking your word for it is, when you rotated the coilpacks around, did the misfire stay in the same cylinder?
A leakdown and compression test might be useful at this time, however, I also doubt this will tell much in terms of a misfire. Many misfire situations will still give good numbers in a compression test, while others may be quite telling. It all depends if your misfire is an electronic condition or a mechanical condition.
What remains would be valve clearance, fuel pressure and fuel injectors and finally, the ECU itself. Have you been periodically using fuel injector cleaner? Your injectors may be a bit clogged or sticky and not giving an adequate spray or a bad spray pattern. Fuel pressure can be checked using the appropriate gauge. Testing a known good ECU might be a bit tougher thing to do but may be the final step.
You need to be much more descriptive when you talk about the idle. "Shakey" doesn't mean much. Describe it in terms of rpm, using a time frame. When does it do it? After a cold start, when warm, when hot? "Not consistent" tells me that sometimes it is OK. When is it NOT OK?
You also need to give a bit of history of the car. What year? What mileage? Ownership history? Track car? Driven hard? Abused? Any work done? Mods? How is it normally driven? What kind of gas used? How long has it been doing this?

[Dr. Gonzo]

I always use 91 octane fuel, and the car has been doing this for 4 months or so but just recently ran a CEL. When i say shaky i mean that it will sputter at idle every say.... 10 seconds (its pretty random) No engine mods to the S. I drive it somewhat hard but no excessive redlines unless at the Autocross events. The car has 50k miles. The car "shakes" all the time just at idle cold start or not. My car has some problems starting when its cold tho, but it says in the book that that is normal because i live in colorado at high altitude. I have to give it a little gas to get it to start smoothly. I just put in a bottle of Lucas Fuel injector cleaner and it seemed to help a little. No CEL since. When i say not consistant just means that its pretty random when it sputters at idle maybe 2 second intervals or 10 second intervals. If i rev the engine a little and it goes back to idle it will sputter or shake a little every time. The car runs great everywhere else other than idle. AND... yes i moved the coils around and the CEL was still a cyl 1 misfire. doesnt seem like to big of a problem, to me it seems if there was a big problem in cyl 1 the spark plugs wouldnt all look the same...? the car is a 2001 BTW.

[repiv]

I'm going to highlight some of the things you just posted and make comments accordingly.

When i say shaky i mean that it will sputter at idle every say.... 10 seconds (its pretty random)
The car "shakes" all the time just at idle cold start or not.
Does this coincide with when you are slowing down to come to a stop? If so, I have done a fairly lengthy write in one of my "Tip of the Day" threads. This is more often a driving technique problem, rather than an actual car problem. Have a read of this:
http://forums.s2kca.com/showthread.php?p=415020#post415020

My car has some problems starting when its cold tho, but it says in the book that that is normal because i live in colorado at high altitude. I have to give it a little gas to get it to start smoothly.
This is pretty common when outside temps are cold and altitude is high. I'm at 3500 feet elevation and I used to get this every year till the ECU learned how to handle it. Giving it gas may be the WORST thing for you to do. It prevents the ECU from learning how to deal with the situation and only makes it worse. Get into the habit of waiting a couple of seconds after you key the ignition ON before hitting the start button. This allows the fuel pump to pressurize up the system on a cold day and allow the ECU to "get its bearings". NEVER, NEVER give any gas during this process. If it stumbles or even if it stalls, let it. Start it up again if you have to but let the ECU stabilize the idle on its own. Only when the idle is stable, would you give it gas to get moving. Blipping the throttle at times like this only confuses the ECU.

I just put in a bottle of Lucas Fuel injector cleaner and it seemed to help a little.
i moved the coils around and the CEL was still a cyl 1 misfire.
This would lead me to believe it is an injector issue. Again, the ECU can compensate to a certain degree if you don't something that confuses it.

If i rev the engine a little and it goes back to idle it will sputter or shake a little every time.
Again, this is NOT a good idea. It's just something else that confuses the ECU at a time it's trying to learn and compensate for an unstable idle. Changing your driving technique just a little may be all that's required.

to me it seems if there was a big problem in cyl 1 the spark plugs wouldnt all look the same...?
Not necessarily. Most misfire codes are "temporary" codes. A slightly lean condition in one of the cylinders due to a dirty or clogged injector may throw this code. That means it doesn't do it all the time, so the plug would not show any signs of being that much different than the other plugs. The ECU can learn to compensate in that cylinder only if you give it a chance and do a little simple maintenance like fuel injector cleaning from time to time.

[small_tyme98]

I've been having a similar issue lately (past couple weeks) in regards to a "shaky" or "shuddering" car at idle.

Independent of whether the engine is cold or fully warmed up, when at a complete stop whether the car is in neutral, or first gear with the clutch disengaged, the idle will dip extremely low (around 2-300 rpm) and the car will "shudder" and feel like it is going to stall out but it never quite does. I do not give it gas to correct it as i know this is bad because the ecu needs to learn, so i let the car shudder and the idle will eventually return to the normal rpm (1000) after a few seconds.

I know we have a sensitive ecu and i thought maybe it was just the car adjusting to different temperatures- but since this issue has been ongoing for about 2 weeks now with consistent weather temperatures it is beginning to worry me. And as for driver technique, i don't think it is a factor as my driving habits have not changed and I have driven the car over 30,000 miles in the 3 years i have owned it and just recently it has begun acting up at idle (my car is an 01 with 75,000 miles by the way- only modification is a cold air intake which has been on the car since i bought it). Car is never tracked, not driven excessively hard and has always been run on premium (91 octane where i live) fuel.

I am very confused as to what the problem may be. I am not throwing a CEL like the original poster so i'm not sure if i have any cylinder misfires. But similar to the original poster, my car is ONLY affected at idle- there is no difference in performance otherwise during acceleration.

My spark plugs were changed about 10,000 miles ago so they should be fine. My injectors shouldn't be clogged as I also ran some fuel system cleaner recently (about a month ago) and coincidentally or not i began having this "shuddering" issue just a couple weeks later. I recently changed my air filter and that didn't seem to help.

I have heard elsewhere it could be my MAP sensor or idle air control valve. I have tried the infamous "MAP sensor whack" trick, but that didn't seem to help me. I guess my next step will be to try to clean the idle air control valve, or maybe replace the MAP sensor since it is fairly cheap anyways.

Sorry not trying to hijack the thread, but i believe the original poster and I are experiencing the same problem.

Any suggestions viper? Your thoughts on MAP sensor or idle air control valve as possible culprits?

Thanks

[repiv]

And as for driver technique, i don't think it is a factor as my driving habits have not changed and I have driven the car over 30,000 miles in the 3 years i have owned it and just recently it has begun acting up at idle
Although there still may be a mechanical or electronic issue (which I have mentioned in that link to my "Tip"), this dipping idle is not seemingly consistent. Although your driving technique has not been changed, this doesn't mean that a change in technique now might not help in this situation. The ECU does a pretty good job most of the time in keeping the engine running glitch-free, however, these times may be "in spite" of the driving technique. Toss in a couple of parameters that you are not immediately aware of and it is entirely possible that the ECU simply has its hands full and can't cope anymore. You can chase the electronic or mechanical cure and never find the answer, however, a change in driving technique may give the ECU one last thing to deal with. I still strongly suggest you go read my "Tip of the Day" and give it a try. What else have you got to loose? It doesn't cost you anything.

The MAP sensor on this car has always been "problematic" at best. Even new ones have been known to be out of spec 66.6% of the time. It certainly wouldn't hurt to freshen up the wiring connections and use some dielectric grease and do the zip tie thing. It probably won't hurt anything to clean the MAP orifice in the throttle body. Same goes for the IAC passages.

Do keep in mind that I can make my car stumble and shake when coming to a stop almost at will. I just drive in such a way to not let it happen.

[small_tyme98]

I have seen your tip of the day video, if you are referring to the one where you keep the car in gear while slowing down smoothly all the way to idle speed at 1000rpm without any stutters.
I do this as well, and it does not seem to help. It's just strange how I never had this problem occur in the previous few years while using the same stopping technique.

This problem still occurs not just directly upon slowing down but even after i have been stopped for a while..sometimes the car won't start to "shudder" until 20 or 30 seconds after being fully stopped. In stop-and-go traffic where speeds are nearly at a standstill it also proves to be a problem.

But i will try further honing my driving technique, hopefully that will help. And as far as the dipping idle not being "seemingly consistent" it seems to be getting progressively worse and happening nearly everytime while stopped now as opposed to once in a while before.

I always thought a faulty MAP sensor would create problems with hesitation and such at high rpm's and not be a factor at idle...but i guess maybe the s2000 is different.

[repiv]

sometimes the car won't start to "shudder" until 20 or 30 seconds after being fully stopped. In stop-and-go traffic where speeds are nearly at a standstill it also proves to be a problem.

I always thought a faulty MAP sensor would create problems with hesitation and such at high rpm's and not be a factor at idle...but i guess maybe the s2000 is different.
Shuddering after a stable idle has been established IS need for concern and is NOT normal. This is likely a fuel metering problem or ignition problem. Do the standard stuff like check the sparkplugs for condition and gap. You may have an issue with the Idle Air Control solenoid. This has been a reported issue. See if you can get a good close up listen to it. If it's ticking with some regularity, something is amiss.
The stop and go traffic scenario is the toughest one to "drive around" in terms of preventing the dipping idle. What you are basically doing is "blipping" the throttle each time you try to get the car moving. You don't do it for long, so the car is not in gear hardly at all. My only suggestion would be to try and use as little throttle as possible, while feathering the clutch ever so delicately. I find that when I do this, the idle isn't quite so affected. Of course, this sort of thing is reported the most during the heat of the summer, however, it does seem to depend on intake temperatures and even in winter, intake temps can get quite high if you're stuck in stop and go traffic long enough.
Indeed, the MAP sensor comes into play mostly at high rpm, but I believe the ECU still uses the signal from it at low rpm. In a NA engine, the MAP sensor reads varying degrees of vacuum and even between idle and as low as 2000 rpm, vacuum alters depending on what the throttle plate is doing at the time.

[small_tyme98]

Problem solved. No need for panic or concern. All it was was simply an over-tightened throttle cable.

I loosened the throttle cable a touch and voila, car was back to 100% normal. I just got back from an extended one hour drive and the car never acted up once, and i was unable to replicate the problem. Idle never dipped below 1000 in any driving condition.

The reason i never thought of this being the issue before was that my car was parked for a few days after i tightened the cable and it must have slipped my mind.

Anyways, i don't think a properly tuned s2000 should ever have stumbling/shuddering at idle regardless of your driving technique. Viper, you say " I can make my car stumble and shake when coming to a stop almost at will"- Now in my mind this is NOT normal. How much slack is in your throttle cable??

I could not for the life of me make my car stumble or shudder when coming to a stop no matter what i tried (I even tried coasting my car in neutral when coming up to a stop and braking hard and it still wouldn't happen).

And here you had me questioning my driving technique!

[small_tyme98]

^I'm willing to bet your throttle cable is excessively tight, but perhaps you prefer it this way for the throttle response. Oh well to each their own i guess.

[repiv]

How much slack is in your throttle cable??

And here you had me questioning my driving technique!

Last I checked, it had what is prescribed as per the service manual. It's been some time, so I guess I should go check it again, but then, it's more likely to get looser than to get tighter. Besides, I've been able to do this with the S2000 most of its nearly 10 years I've had it. By driving differently, it doesn't do it anymore. I've also been able to do this with my '88 Vette, '90 Vette, '94 Viper.

Sorry, didn't mean to give you such anquish. Wasn't meaning to make you question your driving technique, but more to at least consider that it may have been a factor. Although I was remiss at overlooking an over tightened throttle cable, I didn't want to be remiss about leaving out driving style as a possible variable in the overall equation. Sometimes, it's the most simple things that give us the most grief. You can't get more simple than a throttle cable being too tight. It's tough to diagnose car troubles over the internet when one can't touch it, hear it, feel it or drive it. It's even tougher when not all the details are provided. The crystal ball doesn't always work.

[repiv]

^I'm willing to bet your throttle cable is excessively tight, but perhaps you prefer it this way for the throttle response. Oh well to each their own i guess.

I have never been a proponent of a tight throttle cable. It serves only to confuse the ECU. So I guess you'd lose that bet. ;)

[small_tyme98]

haha no worries, I feel dumb for overlooking such an obvious thing. I just found it odd that all of a sudden out of the blue the car I had been driving the same way for the past few years would start acting differently..so obviously driving technique was not the first thing that came to my mind.

I find it interesting how you could always do this stumbling when coming to a stop with your car though.. mine had never ever done that until i overtightened the throttle cable, and since i loosened it the car has gone back to the way it was before.

I'm just happy my problem was an easy fix and i took care of it before spending money on unnecessary parts...

[repiv]

I suppose all's fair in love and cars. Just as I may have compelled you to question your driving technique, you made me question the state of my car's maintenance and state of tune. I just went to check the throttle cable and as I suspected, it's as it should be. If anything, it may be just a tad on the slack side and could use a bit of tightening, but the car runs as good as it ever has and the throttle response has never been a problem. I'll probably just leave it.
As I've tried to demonstrate in the vid I made (from the link), I can make the engine stumble at will. It doesn't do it nearly as bad as it's been known to do it before I changed the way I drive it. The car has gotten used to a certain way of being driven for quite some time now. To make it nearly stall, I have to find new ways to confuse it all over again, not that I want that problem back again.

You must understand that not all S2000's have this problem. There's enough variations in ECUs and sensors, that it takes just the right combination of factors, within the car itself and with the driving environment (driver included in this) to create this idiosyncracy. With the one Vette, it was definately ECU EPROM programming, which I think I may have covered before.

[small_tyme98]

Just for fun, could you explain how you are able to make the s2000 stumble when coming to a stop?

[repiv]

I lumber along and get the intake temps as hot as I can. It's tough since I have an aftercooler now. Then, as I'm coming to a stop, I depress the clutch from about 15 mph and just coast to a stop. Before I started to drive by holding gear till at least 1000 rpm before declutching, that would make the car nearly stall every time. Sometimes, it did stall. Since holding gear, it has not done it, even on the hottest day.
I think a lot of new manual drivers drive like that and they continue to do it throughout their driving lives. Most cars, you can get away with it, but the S2000 seems particularly suseptible to this way of driving.

[Dr. Gonzo]

i know the problem is not do to my driving technique because its doing it while i am stopped in my garage. The idle drops way low almost dies but doesnt then goes back to 1000. and if i give it gas and then it slowly drops down till it does this again. I just dont know what the problem could be. its not that big of a deal just something that bugs me.

I didnt know that the ECU could learn from this and i now know not to do those things and to let it just flow and see if it helps.

I too can make my car studder at will but that is just driving technique when my problem is something different. I still havent listened to the injectors but i bought a stethescope today and will listen to them tomorrow.

Other than a dirty or bad injector idk what else could be the problem. I just feel like the car should have a perfect idle when stopped and not move AT ALL.

I dont think the fuel injector cleaner really did much, the CEL hasnt came back but the car is running the same. . . .


:confused:

[repiv]

and if i give it gas and then it slowly drops down till it does this again

Don't give it gas. When it's going through a phase where it's having a problem with a stable idle, giving it gas will only duplicate the problem and make it very repeatable. All you're proving by giving it gas, is that it will drop to an unstable idle.

[small_tyme98]

You haven't tightened your throttle cable lately by any chance have you?? That was my problem... make sure to rule out all the simple things before getting too concerned over the issue.

[Dr. Gonzo]

Don't give it gas. When it's going through a phase where it's having a problem with a stable idle, giving it gas will only duplicate the problem and make it very repeatable. All you're proving by giving it gas, is that it will drop to an unstable idle.

Ya i derfinately wont anymore thanks. i didnt know that the ecu could learn and somewhat fix itself.

and no i havent even touched my throttle cable since i bought the car used about 6-7 months ago. That is something i will definately look at.