Hesitation at idle when poking gas pedal...

[Dizings2k]

Okay guys.. MY FIRST post!

I am from "the other site", I have been over there for 6 years. Anyway, this forum seems more mature.

I have a 2004 Honda S2000, Suzuka. 80k miles on it. I just bought the car on Monday.

It is equipped with an AEM cold air intake. Everything else is stock.

I did not install the intake, it came on the car.

When I am sitting still, whether I am in gear or not and I am idling, If I poke at the gas to make a quick rev the engine hesitates for a second. How do I say it... It revs rough for a split second and then smooth.

The motor revs freely, does not hesitate coming to a stop, leaving from a stop, running through the revs.. nothing. Only when I stab at the throttle quickly from a settled idle.

It *feels* like the motor gets too much air for a second and I could almost stall it by stabbing too hard at the gas. I have not tried, but it feels like I could drownd the motor with air through the aftermarket intake.

Anything to worry about or it is normal?

[repiv]

If I'm getting this correctly, it is reluctant to rev up if you stab the gas really quickly and NOT when the revs come back down to idle, correct? If it's stumbling coming back down, then look up one of my "Tip of the Day" threads here.
First, you need to indicate just how fast you are jabbing at the throttle. No engine likes to have the throttle plate opened too rapidly from idle. That's just too sudden a change and too much air being introduced. The fuel system can't keep up. The answer would be, "Don't do it". However, if you are just pushing on the throttle moderately and it can't keep up, then you may have a problem.
First, make sure you have the correct play in the throttle cable. Too much will make for a delayed response and too tight will confuse the ECU with a positive throttle position at idle.
Next, try the "MAP whack" (there's a "How To" here). It's not what it sounds like. It involves "freshening" up the MAP wiring harness and securing it with a zip tie. It may even involce cleaning the MAP sensor air passageway in the throttle body or possibly even replacing the sensor.
Oh, I'm assuming that you keep the car in a good state of repair and tune and have done all the proper maintenance (spark plugs, air filter, injector cleaner now and then, use good gas).

[Dizings2k]

Thanks Xviper.

Sounds like I have some checking/testing to do.

I am taking the car to my buddies personal garage with a lift to give the car a complete going over. I will let you know the results of further testing.

I should have mentioned...

The dealer delivered the car (2 hours away) drove it the whole way on 87, and filled me up with MORE 87! How nice!

The idiot at the dealer filled the car up with 87 in front of me (I didnt notice until it was too late).. so I assume the car had been run on 87 the entire time at the dealer.

I apologize, I should have mentioned this.

This could be the issue with my other problem as well.

I will check everything over and run 2 tanks of 93 through it and report back. FWIW I did add octane booster to this tank of gas.

Thanks again.

[dfws2k]

My car does this as well, I have a K&N CAI, not the FIPK.

It is only when I "stab" the throttle, not when I moderately increase the amount of the throttle, which would coincide with repiv's statement.

[Dizings2k]

I was playing with it a bit over the past 2 days.

I only have 1/4 tank of octane boosted 87 in her left.

It seems to be getting way way better.. so we will see once I get some real gas in her! No monkey piss!:nono:

[repiv]

I would suggest you don't rely too much upon the engine's response when you "stab" it rapidly anyway. It's an unnatural thing for it to try to rev up quickly under normal load from an idle, so don't expect it to do it without load. Furthermore, revving it when just sitting there can confuse the ECU if you do it as habit. You will discover this especially once the ambient temps get hotter. Then it will begin to studder when the rpm drops down and falls way below idle. You will have created a new problem.

[Dizings2k]

Following up on this as well:

The new spark plugs and air filter took this problem away completely.

The throttle response is incredible and she pulls very very clean through the RPMs!

Thanks again!

[Moddiction]

Here where is your tip of the day on ther shddering when going down in revs? I have that issue. Seems to be the map sensor but would like to read your tip on that.



If I'm getting this correctly, it is reluctant to rev up if you stab the gas really quickly and NOT when the revs come back down to idle, correct? If it's stumbling coming back down, then look up one of my "Tip of the Day" threads here.
First, you need to indicate just how fast you are jabbing at the throttle. No engine likes to have the throttle plate opened too rapidly from idle. That's just too sudden a change and too much air being introduced. The fuel system can't keep up. The answer would be, "Don't do it". However, if you are just pushing on the throttle moderately and it can't keep up, then you may have a problem.
First, make sure you have the correct play in the throttle cable. Too much will make for a delayed response and too tight will confuse the ECU with a positive throttle position at idle.
Next, try the "MAP whack" (there's a "How To" here). It's not what it sounds like. It involves "freshening" up the MAP wiring harness and securing it with a zip tie. It may even involce cleaning the MAP sensor air passageway in the throttle body or possibly even replacing the sensor.
Oh, I'm assuming that you keep the car in a good state of repair and tune and have done all the proper maintenance (spark plugs, air filter, injector cleaner now and then, use good gas).

[repiv]

Here where is your tip of the day on ther shddering when going down in revs? I have that issue. Seems to be the map sensor but would like to read your tip on that.

http://forums.s2kca.com/showthread.php?p=415020#post415020

[bcs]

I gotta say. I was reading your thread repiv about 2 months ago. Today, I used a lot of your tutorials and did a clutch, oil transmission and diff fluid change. I haven't driven the car in 6 months, so I was just getting it ready.

After I was done I drove it around for a while and it was kind of stuttering at idle. I remembered this thread and I must say that it worked perfectly. As soon as I started your method, it was all normal again.

Anyway, just wanted to say thanks for a great tip!

[repiv]

Glad to hear it's helped you. :thumbup: