EK9 idle problem in warm-up phase


nfspeedy

EK9 addicted
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Joined
Jul 11, 2013
Messages
356
Car(s)
1996 Civic VTI EK4, 1998 Civic Type R EK9, 2020 Honda e
Hi guys I noticed a problem quite a while ago.

when I baught the car everything was fine. No problems with the idle at all.
At home I started to fix some things. Amongst others I did a valve clearance job. (0.15-0.19 inlet and 0.17-0.21 outlet valve clearance) If I remember correctly I had to tighten 15 valves to set the correct clearance.
After that I noticed the problem in the warm-up phase. The engine revs down below 500 rpm and sometimes the engine stalls.

I had to change the TPS (throttle position sensor) because something was broken from the housing and somebody sealed the hole in the TPS with some kind of metal putty. (anyway it didnt had infuence in the engine running) I set the TPS at the same electric ohm value as the old one was before I removed it.

I checked for vacuum leaks but didnt find anything.

I decided to check the spark plugs and found out that there were NGK IRIDIUM BKR7EIX inside.
I replaced them with aftermarket NGK PFR7G-11 and later with OEM Honda NGK PFR7G-11S
I also replaced the distributor cap and the distributor rotor with the correct OEM parts from Honda.

I also cleaned the IACV many times without any changes of the problem (The engine idles perfectly when the engine is icecold or warmed up)

I even did a ECU reset with the Honda HDS computer and learned again the idle without any changes.

I checked the O2 sensor with a exhaust tester (it says always lambda 1 as it should)

I replaced all negative cables. (the battery, the gearbox and the rocker cover one also)
and I cleaned the negative point near the ecu without success.

Now I changed all the 4 B16B injectors to other used B16B injectors without any changes.

Just changed the IACV. (Which finally solved my problem)


So what do you guys think is my problem? Is it the engine coolant temperature sensor ECT?
or should I double check the valve clearance again?

Thanks for your help
best regards
Oliver
 
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no because the engine idles perfect in cold and warmed up condition as it should I didnt pay much more attention to the IACV.
I thought if there is a problem with the IACV the idle problem would be also present when the engine is completely warmed up or completely cold. But its the first 2-3 minutes after cold start when the problem appears.
 
I have the same problem too! I'm interested to see your result.

Have you tried chipping your ECU and getting a tune?
 
Have you tried chipping your ECU and getting a tune?
no everything original except the Spoon Sports Street back box. I dont plan on chipping the ecu. It even have the 180km/h speedlimiter.
 
I just changed the IACV with no success
Do I have to "learn" the control valve by resetting the ecu?
 
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Do a compression test to see if any of your valves are to tight and leaking, or re check them manually,

Could also be worth looking at ECT sensor and MAP sensor
 
i had a similar problem with my ej9, diconnect the battery for 5 mins, then re connect start the car hold revs at 3000 for 3 mins then let it idel for 5 mins then turn it off let it cool down and then take it for a drive about 15-30 miles
 
Any fault codes? I had a similar issue as this although not as extreme as you described. Mine would cold start and idle fine but unless i drove off striaght away the car would start to idle erratically until it was up to temp.

I had a fault code using my scanner (NO EML) something like "Barometric pressure sensor signal incoherence" checked for any air/vacuum leaks to no avail so in the end i changed the sensor and it cured it.
 
If none off these solves your problems.... you might want to get a good tune.
 
you cant just get a tune... if its running badly there is a fault and "tuning" will just cover the fault, in case you don't know here's how to check for fault codes.

you'll need a short piece of wire or a split pin, behind the glove box there will be a 2 pin green plug it will usually have a rubber cover over the end if no one has been in there before and lost it... insert the wire bridging the 2 pins together jump in the drivers seat turn the ignition on, the EML will flash... count the flashes

short flash=1
long flash=10

e.g.: 2 long flashes and 1 short flash= 21

Im sure there is a post in here somewhere with a list of codes, I may have posted it myself i cant remember its been soooo long since I've been on here :D

let us know how you get on.

Ash
 
Ok I finally solved the problem. It was the IACV!
The IACV I tried out was not the right one. Now I changed it again for the right one and thats it.
The engine idles higher now in the warm-up phase so it have no chance to stall.
Thanks to everyone who tried to help me with their thoughts :)
Great forum

@ash I had the Honda HDS Computer connected to the ECU to reset it. And of course I checked for DTCs. There was no DTC recorded. I also checked via live viewer the engine coolant temperature if there is the trouble. But there was nothing wrong with it.
 
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Glad you got it sorted:nice:
 
The problem is back :-/
 
Now I solved the problem! It was the valve clearance job I did not do correctly. The clearance was too tight because I set it between the rocker arm and the valve. I looked up the engine specifications and it is been set correctly between the camshaft and the rocker arm.
Thanks again for all your help guys! :)
Nice forum :nice:
 
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