Running rough!! Please help

[Jays2k]

Ok so just went to go to the bank and my s is running wierd. Under power, in low rpm, it is chugging and skipping. Feels like a fuel problem to me. Any ideas on what this is or what I should check? There is no CEL coming up. Would a reset of the ecu maybe help this?

[fltsfshr]

How old is your battery?

fltsfshr

[Jays2k]

they changed it when i bought it so like 4 months.

[emg88]

What's low RPM? 1000, 2000 or 6000? Low rpm is not usually fuel in my experience. That would be the first time this year if I'm wrong.:D Repiv should be along any minute to help you.

[emg88]

Bad Gas? As in gasoline!

[repiv]

Under power, in low rpm, it is chugging and skipping.
I'd like to clarify something right off the bat. Addressing the above quoted statement, please tell me if what I'm about to describe is correct ...........................

Was the length of drive long enough to get the engine well into operating temps and to get the underhood temps fairly hot? When it started to do this "thing", were you just moving off from a stop or at very low speed? And once you get the speed up a bit or if you push the clutch in and try again with more gas, did it stop? Could this behavior be described as "bucking" or "kangarooing"? If the answers to all these are "yes", then this is a fairly often reported occurence. I don't believe there is anything wrong with your car. I'll wait till you respond before I elaborate.

[Jays2k]

Yes the car was at full operating temp. And it happens from a start or while driving if im under 5k rpm and give it 3/4 throttle it hesitates and skips. The motor isnt smooth it feels like maybe a miss fire? The motor will do this even if the car is sitting idleing and I rev it. But once it gets to around 5k its fine again switches to vtec ok and pulls as strong as it always does.

[repiv]

I believe you are experiencing this "bucking" phenomenon. I'll try to explain ..........................

Once the engine bay temps rise, even though you have a CAI and even if it's in the middle of a cold winter day, the intake temps still rise. In response, the ECU backs off timing just enough that at such a low rpm, the engine is no longer producing the same amount of torque to motivate the car. It is on the fine line between lugging, trying to avoid knock, trying to maintain idle while at the same time, trying to increase in rpm. All the various sensor readings that the ECU is getting (Intake Air Temp, Throttle position, coolant temp, MAP sensor readings, rpm, speedo reading) is giving it a brain fart. It can't resolve so many conflicting commands and hence, you get this up and down rpm fluctuation. It's trying to both idle and speed up, but can't quite decide what to do, so it does both in alternating fashion. It will continue to do this till the rpm gets high enough or till the driver stops telling it to "go".
An engine needs a certain amount of power and torque to accelerate a given weight. Hot air, hot coolant temps, moves the torque band up the rpm scale. If you move off as if you normally would when everything is not so hot, you are trying to tap into the torque band that simply doesn't have enough grunt to move the car.
Sure, you could do more cooling mods and the situation will be alleviated, but I suggest you adjust your driving style somewhat. You should be able to feel this bucking beginning. When you do, simply push in the clutch, rev it up a little higher before re-engaging the clutch to get going again. To avoid it all together, just use more revs when moving off during these sorts of conditions.
Believe it or not, I have been able to make my old Viper and Vette do this. Even cars with apparently high torque, can be made to buck if you tell it to move off at too low an rpm given the right conditions of high engine bay heat, too much load, too low rpm.

NOTE: A poorly maintained car will do this far easier (dirty air filter, clogged injectors, dirty fuel sock), but even a brand new car can be made to this. This is an issue to do with operating parameters and so much an issue to do with mechanical malfunction.

[Jays2k]

It just feels so wrong when it happens. Will an ecu reset help? What maintenance items should i do right away. Oil has been done I use injector cleaner. The car has 41k on it.

[repiv]

The motor will do this even if the car is sitting idleing and I rev it.
Sorry, I meant to comment on this as well. This is somewhat related (but not exclusively so) to the first situation I commented upon.
Dipping idle when coming to a stop is also related to hot engine bay temps and often is also related to putting an extra load on the engine like having the A/C on. Again, the ECU is trying to resolve an issue to do with sustaining idle but because of the heat and timing, it can be a bit slow in responding.
Try this to test my explanation out: Whenever you are coming to a stop, don't be so quick to push in the clutch and coast to a stop. Downshift as you should as you are slowing down till you get to 2nd gear. Don't bother going into 1st for routine stops. Now, wait till the revs get to 1000 rpm or just below before you push in the clutch to come to a stop. I think you'll find that your engine will not drop rpm so low anymore. By doing this, you are compelling it to hold idle and you are giving it more time to see it coming.
NOTE: Do NOT rev your engine during these times. The throttle input only confuses the ECU even more and it will just continue to have a hard time resolving the idle protocol. Once you've stopped in the fashion I've described, leave the gas alone till you are ready to move off, then do so with a bit more revs than you are accustomed to. It will seem like you are driving a totally different car.

[repiv]

It just feels so wrong when it happens. Will an ecu reset help? What maintenance items should i do right away. Oil has been done I use injector cleaner. The car has 41k on it.

A "MAP WHACK" and ECU reset may help but I'm almost positive it won't last. I strongly suggest you adjust your driving style as I've described and see what happens.

[Jays2k]

I dont have the low idle problem that I hear explained here my car idles fine its just when its under power around 2-5k rpm that this is happening. If i take it easy threw the throttle till i hit 5 k then it runs fine. But this is not why i bought this car. I dont wanna have to kreep threw every gear till i get to vtec.....

[Jays2k]

that sounded mean please dont take it that way......just frustrated this seems like there is something wrong because the car is driving completely diff then it has in the past.

[desmo4]

I have 92 k miles on my car. It has lived in Sunnyvale, San Francisco and Richmond VA. I have never experienced this ECU confusion and I attribute to the fact that when I first bought the car I added a Mugen low temp.thermostat, fan switch and high pressure radiator cap. And my newly located water temp. sensor indicates no temperatures above 184 degrees in stop and go traffic w/ a 95 degree ambient temp.

Jonathan

[repiv]

I dont have the low idle problem that I hear explained here my car idles fine its just when its under power around 2-5k rpm that this is happening. If i take it easy threw the throttle till i hit 5 k then it runs fine. But this is not why i bought this car. I dont wanna have to kreep threw every gear till i get to vtec.....

As far as the idle thing, I can only go by what you said previously:
The motor will do this even if the car is sitting idleing and I rev it.

If you try my suggestion, you don't have to "creep" through every gear. You simply push the clutch in, give it more rpm and take off. If you do this, it won't "buck" anymore and you can take off in brisk fashion.
You can do what Desmo has done or do like what most people do, drive it a little differently. I have found, in my travels, a lot of people who come from automatics or from big block cars with manuals, that they tend to use too little throttle when normally taking off. A "normal" take off in an S2000 uses nearly 3000 rpm to move off. If you are starting off with clutch engagement with much less than this, you will not be able to give it 3/4 gas once the clutch is engaged.
You can make the car suit your driving technique or you can make your driving technique suit the car. One costs more than the other.

Will you be at the Garden State meet? If so, may I go for a ride with you and observe this behavior? Then, if you are agreeable, may I take your car for a drive and show you that I can duplicate this behavior at will and show you how I drive to prevent it from happening?

[Jays2k]

But this will happen if im driving the car too. I could just be caosting in gear at around 3.5k rpm and if i go to hit the throttle more than halfway it does this.

[Jays2k]

I just read your "map whack" post over on s2ki and the hiccups that you refer to are what my car is doing and ive notice it before. Its just much worse. Do map sensors go bad?

[repiv]

I could just be caosting in gear at around 3.5k rpm and if i go to hit the throttle more than halfway it does this.

You mean you are in gear, clutch engaged, at 3.5K rpm, you give it 1/2 gas and it'll do this? If this is the case, then it's not normal.

Do map sensors go bad?
Well, they don't necessarily "go bad", however, as Ultimate Lurker (well know S2000 tuner) discovered many years ago, even brand new MAP sensors can be out of spec and still not throw a CEL. Honda S2000 MAP sensors are notorious for being of ununiform quality and performance. Do the MAP harness disconnect and wiggle it vigorously back on and find a way to hold it together tightly (zip tie) to prevent engine vibrations from degrading the connections.

Make sure you air filter is not really dirty and your spark plugs are in good condition and gapped correctly.

[wtmohr]

:poke: Note to Jonathan (Desmo4).... Is there nothing on this planet that can't somehow be improved by adding a Mugen part?

[My_yella_s2k]

Mugen = godlike ;)

[Jays2k]

You mean you are in gear, clutch engaged, at 3.5K rpm, you give it 1/2 gas and it'll do this? If this is the case, then it's not normal.


Well, they don't necessarily "go bad", however, as Ultimate Lurker (well know S2000 tuner) discovered many years ago, even brand new MAP sensors can be out of spec and still not throw a CEL. Honda S2000 MAP sensors are notorious for being of ununiform quality and performance. Do the MAP harness disconnect and wiggle it vigorously back on and find a way to hold it together tightly (zip tie) to prevent engine vibrations from degrading the connections.

Make sure you air filter is not really dirty and your spark plugs are in good condition and gapped correctly.

Ok so i'm going to try your map whack and ecu reset in about 30 mins. By the way great write ups on these, you have a real nack for taking pictures to match your writting. I cant stand it when someone takes a picture to explain something and you cant even see what they are talking about in the picture.

[desmo4]

:poke: Note to Jonathan (Desmo4).... Is there nothing on this planet that can't somehow be improved by adding a Mugen part?

Sex

[Jays2k]

So "map whack" and ecu reset made things worse......I'm gonna take it in to the dealer :(

[emg88]

Are you going to take it to Mikey?

[Jays2k]

Maybe if I cant get it in today.....

[My_yella_s2k]

if u do, i have u all set up for a loaner car too...
but itll be either a civic or.... a ciivc... like it or leave it

[emg88]

Take it to Mikey! He'll make sure they only drive it hard a few times!:D

[emg88]

Hey if you're coming here, why don't You, Mikey and Me get a bite to eat?

[My_yella_s2k]

i can never pass up food...... nor can Ed.... its all on ur shoulders jay

[Jays2k]

We'll see what happens today. But if they wont get it in till tomarrow ill prob bring it down there. Im just a lil iffy driving it for an hour to get down there......

[Larmoe]

Look at the map sensor. I had the same problem and replacing the map sensor solved the issue. You can do it yourself it is just a plug in proceedure.

My gas milage dropped and I had a miss just below 5,000 and a sputtering in the power band.

AP1 cars had a modification on the map sensor because it worked loose. You may want to just try putting a wire tie on your current unit and see if it solves the problem.

[emg88]

Just drive it in 3rd gear. You should be over 6500 rpm! then everything will be good right?:D
We'll see what happens today. But if they wont get it in till tomarrow ill prob bring it down there. Im just a lil iffy driving it for an hour to get down there......

[repiv]

So "map whack" and ecu reset made things worse......I'm gonna take it in to the dealer :(

I hope it's just a bad MAP sensor. Do you have any other electronic devices hooked up to the car? Do you know if a previous owner had something that perhaps was uninstalled before selling it to you? VAFC? S/C? Another ECU? Ebay low temp resister? (Assuming this wasn't brand new when you bought it.) I'm thinking along the lines that maybe the original wiring that was put back together when such a device was removed, have now degraded.

[Jays2k]

No other electric divices right now. And im pretty sure the previous owner never did anything like that but I dont know for sure. I know he kept the car bone stock and had all service done at honda.

[Jays2k]

OK so I dropped it off with Mike today and got a sweet CRV thats pimped out with Mahwah Honda vynle!!! I'll keep everyone posted.....

[Jays2k]

Dave I am sorry that I didnt see your offer to drive my car at the Gathering. And of course I would let you drive it. I would be more than happy if i cant get things figured out by then.

[raymo19]

Dave I am sorry that I didnt see your offer to drive my car at the Gathering. And of course I would let you drive it. I would be more than happy if i cant get things figured out by then.

That would be wise. I hope you have it sorted before then.

[IMPETUS]

Let us know what you find out. I have had very occasional hiccup issues. Honda said it was normal, almost sounded like a GM dealership. "...oh yeah, its no problem. all gm trucks have at least an eighth turn of dead area on the steering wheel... "

[My_yella_s2k]

im replacing the map sensor... as part of the service bulletin...
we'll see on monday

[repiv]

Dave I am sorry that I didnt see your offer to drive my car at the Gathering. And of course I would let you drive it. I would be more than happy if i cant get things figured out by then.

I sincerely hope that by the time the Garden State meet happens, this situation will have been resolved to your satisfaction and there won't be a need for me to try and figure it out. If they can't fix it, then my offer still stands.

[Jays2k]

Thankyou Dave. I truely appreciate it.

[Jays2k]

So I just got back from picking my car up from Mike at mahwah honda and they changed the map sensor...things were better.....but not 100%. So I decided to take my spark plugs out and take a look. They all looked normal except for one. There is a tiny little needle that comes out of the plugs, I think this is the irridium? Anyway I purposly put the plugs back in in different order and BINGO!!! Problem fixed. So one last question....should I still get new plugs?

[Jays2k]

Thankyou everyone that had input on this!!! Mike thanks for everything....the loaner and the new map!!!!!

[joe_s2k]

I'm glad you figured it out.

[repiv]

They all looked normal except for one. There is a tiny little needle that comes out of the plugs, I think this is the irridium? Anyway I purposly put the plugs back in in different order and BINGO!!! Problem fixed. So one last question....should I still get new plugs?
What did the "not normal" one look like? Did you confirm that the gaps were all good?
From left to right ..................... (OEM platinum - used and stored for a long time, Copper - used, Iridium - brand new)
http://www.s2ki.com/forums/index.php?act=module&module=gallery&cmd=viewimage&img=167837&md=1

Interesting that you have Iridium plugs. The Denso Iridium plugs have been shown to not work very well after a few months on several supercharged S2000s. They were developing a high rpm miss. I've also seen reports from the occasional NA S owner who complained of Iridium plug body failures. Perhaps swapping plug positions put the one "deficient" plug under a coil pack that was a bit stronger and made for better compatibility. Run this for a while and see how things develop. If you get the symptoms back, then consider getting the OEM plugs as a replacement. Iridium plugs don't appear to give a significant advantage in performance over stock platinum plugs and the occurrences of odd operation makes them undesirable (IMO).

[Jays2k]

I thought the stock plugs were iridium plugs? I have stock plugs. They def dont look like your new plug. I would agree with the swapping that you said. But they have a small needle that comes out ofthe white part on your new plug. But one of the plugs had nothing there and you could see the small hole where it was. Im going to get new plugs and take pics of new and old to show everyone besause I dont think I'm explaining things very well here. As they say a picture is worth a thousand words right. Dave thanks for all of your input on this!!! You have been a great help!!!

[repiv]

No, the stock plugs are platinum, like the first one on the left in my picture. They come in either Denso or NGK.
Now, this "needle" you're talking about, which white end is it coming out of? The part that stick into the cylinder or the part that meets up with with the coil pack tube?
The only "needle" that I know of is the center electrode shown on the Iridium plug on the right of my picture. If that electrode is missing, then that plug is virtually useless and it's a wonder that you're getting any spark at all. This would definately explain your engine running problems. You might be getting a spark that jumps out of the hole to the negative electrode. Now that would be AMAZING! Higher rpm might be able to compensate for this but low rpm would have a tough time.
It is very thin compared to the other plugs. There should be no "needle" sticking out the long white end (plug shaft).
Some platinum plugs will have a very thin center electrode as you see in my Iridium plug. Bosche would be one such plug.

[Jays2k]

Its def the end that goes into the cylender. All of mine seem much thinner than the ones you have posted. Does this part wear away over time?

[repiv]

Its def the end that goes into the cylender. All of mine seem much thinner than the ones you have posted. Does this part wear away over time?

No, they wouldn't wear over time. I think that electrode may have been pushed on at one point and weakened. Then, during the rigors of internal combustion, the tip broke off.

[Jays2k]

Hey Dave I have another question....do you think i should stay with stoock plugs or are there better ones out there?

[repiv]

I've tried a couple of other types of plugs (Iridium, copper racing plugs) and I've come full circle. I'm going back to the OEM plugs (NGK PFR7G-11S double platinum). My car ran flawlessly on them when I was NA and for nearly a year when supercharged. Then I decided to go out and experiment. I regret the Iridium plugs and the copper racing plugs, though they worked well, didn't last more than about 3000 miles before they started to act up.
My suggestion would be to go with the OEM plugs, either NGK or Denso. The vast majority of S2000s run on these for their whole life. History and experience can't be wrong. Until you start to do drastic mods (like turbo), no need to try anything else.

[emg88]

I love NGK plugs. I always use them in my Harleys. My 1988 Softail has 10.5 to 1 compression with 104 hp on pump gas. The plugs have 10,000 miles on them and look great today. Air cooled engines don't have the benefit of constant temperatures. They are copper not platinum.

[Jays2k]

Ok to finidh out this whole thing....I JUST FELL IN LOVE WITH MY CAR ALL OVER AGAIN!!!!!! I highly recomend to anyone that feels that their S isnt preforming like it used to, try checking out your spark plugs!!! I never thought that my spark plugs were an issue because I had the recall done on this car. And I only have 41k miles on it. Come to find out while I was changing the plugs today that there were a set of bosch plugs in my car :shocked: !!!! What is even funnier is that I put Bosch plugs back into it.... :( I know they were cheap and the wuick fix till the oem plugs I ordered get here. Back to the story.....I change the plugs and this car is a completely different car. It runs better and stronger than it ever has....it shifts better.....sounds better.....and put a smile on my face while driving it back home tonight with the top down. I will post pics of the old plugs that came out of my car tomarrow. Moral of this story, CHECK YOUR PLUGS!!!!!

[repiv]

because I had the recall done on this car.

Come to find out while I was changing the plugs today that there were a set of bosch plugs in my car :shocked: !!!!
I'm also shocked that a Honda dealer would have done the spark plug recall using non-OEM plugs. I'm sure Honda would not have approved.

[Jays2k]

or the previous owner changed them after that....not sure which happened as the recall was done when the previous owner had the car.....One thought I've had....the s2000 engine is a high performance race engine, right? Do you think that nascar and formula 1 use the same spark plugs for more than one race? I'm not saying we have to check our plugs after every drive, but maybe once a year. I mean honda says oem plugs will last up to 80k I think? Is this something comenly neglected by owners?

[repiv]

or the previous owner changed them after that....not sure which happened as the recall was done when the previous owner had the car.....One thought I've had....the s2000 engine is a high performance race engine, right? Do you think that nascar and formula 1 use the same spark plugs for more than one race? I'm not saying we have to check our plugs after every drive, but maybe once a year. I mean honda says oem plugs will last up to 80k I think? Is this something comenly neglected by owners?

It is true that the S2000 has a very high performance engine, but it is not quite a race engine, nor is it generally driven like a race car. A professional drag car changes their plugs after each run (along with an engine rebuild) and a professional circuit race car would have new plugs in the engine for each race (and an engine rebuild). A drag car runs at WOT anytime it's accelerating and with today's new shifters and trannies, they run WOT from beginning to end. They also output WAY more HP/displacement than our engines do. 120 hp/L if tiny compared to them.
A road race car tends to run at or near redline most of the time and again, their engine's output would be way more than ours. When existing in the world of professional racing, the cost of spark plugs is incidental and the effort needed to change them is miniscule considering everything else that gets done to the car.
As for checking the plug on our cars, there are pros and cons to this. Honda indicates that the original plugs are good for over 100,000 miles. This, of course, is for a normally, daily driven car. Rules change if you use your S2000 for frequent track duty. The pros of checking our plugs say on an annual basis is that you can see how your engine is doing by "reading" the plugs and if you are the type of owner who has modified the engine in any way, this is a good way of telling how those mods are affecting the engine. The cons, on the other hand, is that for some owners, this leads to the temptation of fixing something that ain't broke, like in the example of your previous owner, who put in a different plug. I'm not saying that this, in itself, was a bad thing, but it did lead to additional manipulation of a part that resulted in damage to that part. In some cases, it's better to "leave it well enough alone".
There are many, many examples of S2000 owners out there who use their cars as fun, daily transportation and leave the servicing entirely up to the dealer. Those cars have survived for astonishingly high mileage without any issues whatsoever. They just don't post about it on forums like this. I personally know of several such cars. Those owners have never complained about weak rear diffs, clutches that wear out prematurely, rear hubs clicking, CV joints that vibrate on acceleration. It's mostly when owners start to "mess" around with their cars, that issues arise. In such cases, the car has to be "checked" more frequently and more closely than normal.