High idle at startup. Gone after restart
 

Car: 2000 Civic Si with 130xxx B16 engine

Problem: For some reason my car idles around 1500 to 1700 rpms when it is first started and will remain that way even when it reaches operating temperature. The weird thing is that if you shut it off and turn it back on it idles perfect. There are no cells and I have cleaned the IACV. Could anybody point me to what might be the problem?

Re: High idle at startup. Gone after restart
 

my Si did the same thing but I blew the b16 before I could figure it out lol

Re: High idle at startup. Gone after restart
 

Same here and also have B16A2.

Its really not a common problem, so I still couldnt find any solution written on the net.
I've cleaned the IACV too, but it didnt cause anything.

I think it might be a faulty ECT sensor (Engine coolant temperature), i will check it next time.

Let me know if u got a solution!!!:scared:

Re: High idle at startup. Gone after restart
 

Haha sorry about your b16 REDEM1FTW! I hope thats not a sign for me lol. Im still researching the problem. The only thing I think might be messed up is the idle adjustment screw. It looks like the previous owner played around with it' but it doesnt make sense that it idles fine after you restart it.... I know somone on Honda-tech has an answer to it!

Re: High idle at startup. Gone after restart
 

Do b16s have a FITV? If so it's meant to rev higher when the engine is cold to help it get up to operating temp.

Re: High idle at startup. Gone after restart
 

I dont believe they do because after 96 Honda stopped using them. But if that was the culprit the idle would go back down once it reaches operating temperature. The cars idle refuses to go down until you restart it.

Re: High idle at startup. Gone after restart
 

Oh I see, has to be electrical in that case. Throwing any codes?

Re: High idle at startup. Gone after restart
 

My friends Si w/ jdm b16a does the same thing too so mabye it is just something with the b16 itself; my car did this until I blew my b16 and now that I have a GSR in my car it doesn't do it anymore? At first I thought it could be electrical like Hill4589 said bc it happened to mine AND my friends Si but after I swapped motors while keeping the SAME wiring This problem hasn't occurred again? You can always blow your b16 and get a gsr like I did to make it go away lol ;)

Re: High idle at startup. Gone after restart
 

I had a conversation yesterday with a DC2 owner, who had the same problem.

TP sensor (throttle position) failure caused his idle problem.

I think we should check the voltage values given in the service manual with a multimeter, to make sure our TP sensor works fine.

Im going to the local honda dealer tomorrow.

Re: High idle at startup. Gone after restart
 

Has anyone found an answer to this problem? Can't find anything on this

Re: High idle at startup. Gone after restart
 

I got this same problem last year . I replaced my iacv and bingo! the rpm is normal . Bur few days back I cleaned my iacv and did the same thing again now it rev high upto 1800 till I restart it

Re: High idle at startup. Gone after restart
 

hey ! everyone , i got the answer just disconect your map sensor and your idel will be normal .i am 100% confident . today i was trying to make idel right when i forgot to connect the map sensor and i was totally amezed by what i saw . idel was 850 with ac off and same with ac on . that mean map sensor is bad !!!!!!!!!!!

Re: High idle at startup. Gone after restart
 

ok ... hi guys...
i have the same allmost problem too but with a d15b 3 stage vtec engine .... obd2a manual eco ecu ...
except mine idles higher the warmer it gets ... no cel except ELD ... (because of the swap ... the d14 did not came with the ELD module in the engine fise box)I have to restart the engine when it warn (over 75C or so coolant temperature) for the problem to go away...

Did enybody find thge culprit of this problem ... ???

Re: High idle at startup. Gone after restart
 

yes i found the CULPRIT !!!
You are the culprit , not the car n its systems definitely
We as humans think we are smart than car , but we forget that car works on a defined set of commands and protocols which is commanded by ECU .
by disconnecting the MAP sensor you are doing nothing just giving a message to ECU that something is wrong with the electronics of car , and ECU adjusts itself to the situation by not using the data coming from sensors , and using a average value which ,which temporarily solves the issue of rough/irratic idle , but this is not the solution!!

What you actually have to do is let the car decide and adjusts its values acc to the situation( temperature,altitude,load) it is in !
1. Disconnect the negative point of battery
2. Disconnect all sensors on throttle body ( MAP, TPS, IACV)
3. remove throttle body
4. Remove IACV( idle air control valve)
5. Clean it with a carb cleaner or throttle body cleaner or alcohol.
6. reinstall the valve
7.reinstall the throttle body
8. ADJUST THE SCREW WHICH IS LOCATED ON RIGHT JUST UNDER WHERE THE THROTTLE CABLE CONNECTS TO THE THROTTLE BUTTERFLY VALVE ( DO NOT TRY TO ADJUST THE RPM OF ENGINE WITH THIS SCREW, IT IS JUST FOR PREVENTING THE BUTTERFLY VALVE FROM STICKING INSIDE THE THROTTLE BODY BORE)
9. tighten the air screw completly (placed on top right of throttle body)
10. Connect all the hoses you disconnected.
11.check all the hoses and connectors once again.
12. Connect the negative terminal of battery
13. Now start the engine without a/c ( for about 4-5mins) ECU will relearn its idle acc to load ,temp. And altitude

The real problem is when we try to adjust idle of car we do alot of thing ,diffrent people and their diffrent techniques and we end up messing with our car
We adjust idle with either air screw or butterfly valve anti-stick screw, so idle increases. And car cannot check the position of screws electronically ,so it gets confused.and can't figure out the source of extra air coming in and tries to componsate for it by decreasing the amount of air passing throung IACV. Then ECU realize that the new adjusted value of IACV is lower than the min. Value needed, so it increases it again.
this cycle of idle increase and decrease continues.
AND THE RESULT IS IRRATIC IDLE.

AND THEN WE TRY A BUNCH OF DIFFRENT THING TO MAKE IT RIGHT . https://cimg3.ibsrv.net/gimg/honda-t...fb5d774aa4.jpg
https://cimg4.ibsrv.net/gimg/honda-t...d422efef3a.png

Re: High idle at startup. Gone after restart
 

ok....so i did try a fiends map sensor ...and i have the same issue ....
i will try to do the steps you wrote ....here.
thank you