S2000 Under The Hood S2000 Technical and Mechanical discussions.

Hesitation when engine is cold

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Old 05-20-2011 | 03:28 PM
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Default Hesitation when engine is cold

Hi, so the situation goes like this:

For the first start of the day, I usually let it warm up for a bit or until the air pump stops. Then I drive it very gingerly keeping the RPM's below 4k till i'm all warmed up. However when I try to accelerate the RPM's do not go anywhere and then suddenly the hesitation is gone and my car jolts forward. After a bit of driving and once the car is warm it stops happening. This has just recently started happening, I noticed this happened after I haven't driven the car for a few days.

Whats odd is that I've been driving it around yesterday and this happened again this morning. Kind of feels like clutch slipping but definitely more of a lack of throttle response. The rpm's don't move even when peddle is depressed 3/4 of the way and I can hear the intake taking in air (cold air whistling noise). Again after driving around for about 5minutes the problem is gone and the car runs strong, no CEL's no lights and vtec still pulls hard.

If anyone can help me out that would be great.

P.S. I've topped off engine oil, recently changed trans and diff fluid already.

Thanks.
Old 05-22-2011 | 08:25 AM
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So I went ahead and checked my plugs again to make sure they were doing alright. They were recently put in about 10k ago and all looked good.

However I did find for some odd reason the first two plugs were much easier to loosen than the two sitting closer to the rear. I know for sure that I used a torque wrench to tighten them down to 20# the last time yet the first two were much easier.

Now the question is how would my first two spark plugs loosen but the rear two not? Also can this attribute to the hesitation I've been feeling before?

Thanks.
Old 05-23-2011 | 03:36 PM
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It could be several things.Even though the plugs looked good,they could be gapped wrong,loose ( as you mentioned) or possibly too cold heat range or one or more going bad.

I would change them and see what happens.My 03S like the NGK Copper V-Power plugs.Either BKR6E or 7E is fine.

\rlr
carolina
Old 05-25-2011 | 05:51 PM
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Well, its still happening.

I'm using OEM Honda plugs straight from the dealership so they shouldn't be gapped wrong or fell out of spec within 10k kilometers.

Whats really odd is the fact that right when it hits 3 bars on my temp gauge (AP1), the hesitation instantly stops.

Anyone ever experience or heard of this happening before?
Old 05-25-2011 | 06:03 PM
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when the engine is cold (3 bars or lower on temp gauge) the motor cuts fuel at 6krpms so you dont damage the motor.
Make sure the motor is warm before you rev the motor high
Old 05-25-2011 | 08:05 PM
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That I know, but I'm not trying to vtec when its cold.

The hesitation feels just like the engine won't rev even when i'm on the gas. it slowly decreases RPM even though i'm on the throttle. I always make sure I give it a good amount time so it can warm up before I start giving it to her.

This hesitation is definitely does not feel like fuel cut off.
Old 09-23-2012 | 07:53 PM
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You ever figure this out, my 2005 is doing the same but only within 30 sec -1 min after startup.
Old 09-23-2012 | 08:37 PM
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Mine drives and shifts like crap for the first 10-20 minutes of driving.
Old 09-24-2012 | 06:05 PM
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Originally Posted by Adionik
Mine drives and shifts like crap for the first 10-20 minutes of driving.
That’s not good, something is very wrong as it should only take the car a few minutes of driving to get close to steady state temps.



I thought about it for a while and remembered that the previous owner installed a Bosch aftermarket primary 02. I am pretty sure this is the issue as the remainder of the car is in perfect condition. I have been told before that for some reason the Bosch generic 4 wire sensors don't work particularly well on our cars.

After that I did some searching and I found others that had the same issue and reported it was the Cat but the dealer also replaced the 02 and the problem was fixed. My guess is the 02 was the problem to start and caused the Cat to fail on their cars. Just bought an OEM sensor and will try it out then report back.
Old 09-25-2012 | 12:59 PM
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I never actually figured out the problem, but the problem hasn't presented itself in a long while. It happens maybe if I don't drive her for a week or more. If I consistently drive her the hesitation doesn't seem to happen. I'm guessing it might be the ECU adjusting for ambient temperature change maybe?

As for the O2 sensor thing, give it a try. These cars are very particular to their OEM parts especially with electrical such as sensors, spark plugs and such. If it does fix your problem please report back! I'm not even sure if my sensor is OEM or replacement.
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