EJ9 low idle/ rev dipping when clutch depressed

[Cipriani]

Ok so ive started to get a problem with my EJ9, it started last night when my check engine light came on with no symptoms of any problems.

This morning I used my OBD scan tool and got this code

this suggests the downstream o2 sensor had a high reading for 2 or more mins, the car is completely standard has had a new exhaust system a few months ago (unsure if any o2 sensors were replaced) I erased the code from the ECU with my OBD tool and the CEL has remained off only now the revs have started to dip on idle, for example driving up to the lights and depress the clutch the revs will dip to almost 0, stay there and very slowly creep up to about 500ish

heres a video i took!

Ej9 civic idle problem - YouTube

I cant see how a downstream sensor would cause this to happen :/

Any suggestions would be much appreciated!

***EDIT***

ive now established that this only happens when the engine is at normal operating temperature, it runs normal on a cold start.

 

[R13ngy]

mines doing the oposite and idleing at 1500 occasionaly dipping then back up to 1500. not a clue why

 

[cbalaam]

Yeah I've got that problem to and I've replaced the o2 sensor and it still there and I've turned it off a few times but It just comes back one person has told me to try shell V power (somin to do with the octane levels) also to the other person that's just because ur engine is cold it revs more to warm up, but I could be wrong but I'm gonna change my fuel x gd luck let me know how it's go's

 

[Cipriani]

Yeah I've got that problem to and I've replaced the o2 sensor and it still there and I've turned it off a few times but It just comes back one person has told me to try shell V power (somin to do with the octane levels) also to the other person that's just because ur engine is cold it revs more to warm up, but I could be wrong but I'm gonna change my fuel x gd luck let me know how it's go's

Let me know if that has an effect, will be interesting.

 

[Cipriani]

***UPDATE***

Ok i took the car for a long run 100 miles ish, most of it motorway 80-90 mph as its only used for short journeys just now. When i got home and after about half way through the trip the rev dipping stopped and hasn't come back :| I guess thats a good thing but ill see what happens over the next couple of days. (I havent filled up with high octane fuel btw)

 

[Cipriani]

found this today which may help some people

How To Solve Honda Idle Problems - EricTheCarGuy - YouTube

It seems the two most likely causes for this are the IACV or idle air control valve which can be cleaned or replaced, also the engine coolant level can have the same effect which is what happened to me although there appears to be no leak in the radiator or any head gasket issues :/

 

[cbalaam]

i will give that ago im just running my fuel down so i can put msome v-power in but if not i hope thats the case as i hate buying parts for my car which dont make it look better, sound better or dont increase performance haha

 

[Cipriani]

i will give that ago im just running my fuel down so i can put msome v-power in but if not i hope thats the case as i hate buying parts for my car which dont make it look better, sound better or dont increase performance haha

Let me know if it has any effect! Have you checked the coolant level?

 

[fatboi]

vpower isn't going to make any difference to these problems. your car will run fine on normal british fuel. plenty enough octanes for an ej9 or most other cars tbh.
either clean out you iacv... (or rotary air control valve on your throttle body if you have an ej9) or replace your map sensor on your throttle body as both of these things caused me to have a crappy idle in the past

 

[civic-tec]

I think thats a TPS problem..

 

[saxophonias]

check sensors and especially the racv that ej9s have. It's something with the sensors on the tb or the intake manifold. You can measure their voltage to see if they are within the normal levels

Your obd reader is great. Is this bolt on the ej9 ecu?