AP1 Rough Idle/Stall

[BBSick]

Recently my buddy picked up a 2000 s2000 with 75k on it from a private party, when then discovered the car has a rough idle when coming off a load (coming off the gas and into neutral to a stop, or at a dead stop and bliping the throttle) the idle drops way below the 800-900 rev range and sometimes even stalls. Absolutely no CELs what so ever, brand new IACV installed and cleaned the MAP sensor and still the same issues appear, next step according to other forums is a new MAP sensor or valve adjustment. The car has no other issues as far as performance or anything, motor runs strong and hard, just won't idle smoothly or normally. Any suggestions would be great thanks.

[bryan720]

what RPM is the idle right now?

[gunsup0331]

scan tool
check pids for normal conditions, identify which is acting up

[GunnRulF]

did you give the map sensor a good wack?

does it happen when the ac is on or off?

Did you check the TPS?

After you cleaned the TB did you reset the ecu?

I pulled this from s2ki.

http://www.s2ki.com/forums/index.php?showtopic=313536&st=0&#entry6045876

this is most likely the common "problem" that every S2000 can have.

this is covered in one of the FAQs at the top of this forum, and is probably asked every week.

our ECU is a learning ECU and has many sensors that it gets input from as well as high and low tolerances for those sensors. consider the high output nature of the engine, as well as the high redline, and you can see these tolerances are probably quite tight. if one sensor is reading a different extreme than another, etc, the ECU can become temporarily confused.

do NOT give the car gas to try to "prevent" it from stalling. this will only make it worse. simply drive as you normally do and after a few days at most it should clear itself up, assuming your weather isn't changing drastically every few days.

if your car does this for a solid week or two, there could be another issue.

[BBSick]

Ecu reset after every repair attempt, tried a map from another working s2000, wacked/cleaned old map sensor, cleaned old iacv/rotary, replaced with new iacv/rotary, cleaned throttle body, checked throttle cable slack. Car idles normal 800-900 (1 bar under 1000) but when you give it gas it drops way below, sputters, and stalls half the time, symptoms are worse with ac on. Returning the iacv/rotary assembly today, and letting the Honda techs work on it cause we've tried everything and without a check engine light there's nothing else I can do but hope it's nothing serious

[gunsup0331]

ahh fuck i know what this is but i cant get it off the tip of my tongue...errr fingers
ok now its gone :(
has to do with fuel pressure iirc

[JDM_CTR_EK9]

sounds to me like the gapping on your plugs are too wide of a gap for the spark to mate correctly when fuel and air are applied...

[BBSick]

Fuel pressure is normal, car went to chapman Honda today tech looked at it for free, scheduled for a valve adjustment on Tuesday will keep you posted. If anyone needs a 00-05 idle air control valve lmk I will sell it cheap thanks

[autox]

I had the same problem a while back. Did all the research on S2Ki, the MAP sensor whack, etc...
I had a K&N air filter (not over oiled either) and replaced it with the factory unit. The problem has never resurfaced.
That's where I'd start.

[BBSick]

Interesting....i will have to try that, his filter looked pretty oiled up

[BBSick]

Cleaned his filter, the over oiling might have gummed up some sensors, I have a k&n on my 06 with the much more sensitive ecu and have had no issues at all with it. He's still planning on going to the stealership to get the valve adjustment done tuesday so we will see what happens

[Mr.Burner]

When was the last time that thing had a valve adjustment? That could clean it up a bit, plus wouldn't hurt to have it done anyway.

[die in a dick fire noob]

sounded like valve adjustment or even something as simple as a pcv... i know i was having a similar issue with my fit and it turned out the pcv was clogged. i even did the valve adjustment, which helped the symptoms a bit but not entirely... replaced the pcv and it was perfect again.

[BBSick]

Thanks for the input everyone, he got a valve adjustment today, car runs perfect. Intake side was fine, exhaust was hella tight. I doubt the car has ever had one done and it just clocked 75000 miles, my car is an 2006 with 82000 and has never had a valve adjustment done but it doesn't have any issues at all, however I will get one done soon, along with the usual oil change, diff fluid change, and plugs.

[GunnRulF]

:thumbsup::thumbsup::thumbsup:

[S2Kid]

did you give the map sensor a good wack?

does it happen when the ac is on or off?

Did you check the TPS?

After you cleaned the TB did you reset the ecu?

I pulled this from s2ki.

http://www.s2ki.com/forums/index.php?showtopic=313536&st=0&#entry6045876


Wow thats an interesting read. I've had this problem before but it just kind've stopped happening. I bet this is it. Your quote didn't get quoted. I suck at forums.