2005ex

Hi guys, gals. I have an issue with my 2005 Honda civic ex. 1.7l. Any help would be appreciated. The rpms started surging anywhere from idle to over 3000 at times. I've cleaned the throttle body, cleaned the egr valve, replaced the idle control valve and throttle position sensor ( calibrated ) and all has failed. The upstream and downstream o2 sensors have also been replaced. The only thing I haven't done is the idle relearn. Is that supposed to be done afterwards to fix the surge? Thank you

Wankenstein

Which brand and model number of o2 sensor did you purchase/install?
Any CEL codes?
Checked it with a live data OBD2 scanner?

mac25

Make sure the Idle air control valve is factory as well.

If it's not the IACV then I'd look for a vacuum leak.

2005ex

The downstream o2 sensor is a Bosch 13534 and the upstream is Labworks 234-9017. It does run smoother and accelerate better after installing the upstream o2 sensor. I did the idle learn and it didn't help so I disconnected the battery for a couple of hours and still nothing. I took it to O'Reilly's again and it does show another code now. It is for the engine coolant temperature sensor, P0118 high circuit voltage

Colin42

Those are the wrong sensors, should be Denso or ntk. Do you still have the original ones?

2005ex

I don' think so. So those are the only two brands that will work with this car?

brags

I agree with Mack25 that surging high idle sure sounds like a Vacuum leak to me anyway. the Good thing is You can build Your own Smoke tester cheap Yourself like this Guy did.

rogerscivic

Actually seen both posts You posted brags on the super glue & this one. both were excellent i gave you.
extra youtube points thumps up on both.!!

brags

what is extra points? if its $$ bring it on.! LOL i could use some. LOL thumps up yeah, if Your clicking on the likes found on youtube videos i posted.? there going toward the youtube person that posted it. Not me.? i have many dyir projects i store in my dyi"r Pc favourites Pc that i find on youtube and from other sources i store them on my PC to help others on here solve there problems . I Volunteer my time & effort on here helping others in need. thats all.

2005ex

Let me add a couple more pieces of information in case its helpful. It surges whether the engine is warm or not. It will surge several times (sometimes more than others) then it will level off and idle at normal rpm, approximately 800. It will remain at idle until I touch the accelerator then it surges again several times etc. Also I have noticed that the temp gauge falls out then comes back up to normal operating temperature. I do believe that the engine relies on the engine coolant temperature sensor to control the air fuel ratio. When the engine is cold it shows a higher voltage and tells the engine to receive more fuel. Well the diagnostics at o'Reilly's shows an engine coolant temperature sensor code. I have one ordered now. My thinking is if it was a vacuum leaking wouldn't it surge constantly or remain at a constant rpm instead of leveling out until the accelerator is pressed again?

Wankenstein

Empty paint can, correct npt adapters, 3/8 vacuum hose , epoxy, air compressor and a cheap cigar will net you a great smoker.

Wankenstein

Air in coolant system can cause idle issues. Maybe needs a coolant bleed per service manual?

2005ex

Thank you. I have an engine coolant temp sensor ordered and will be here tomorrow. I'm planning on changing out the coolant at the same time. Hopefully that will work

2005ex

Alright, well I flushed the coolant and replaced the engine coolant temperature sensor. It still surges the same as before. I took it to autozone and had them test it. It still shows the codes p0134 for the upstream oxygen sensor and now a different code, p0113. I asked if it is necessary to have an OEM o2 sensor and he said no. I told him what all I have replaced. He basically said there is an air/fuel ratio issue and it keeps throwing random codes due to it. So far I've replaced the idle control valve, throttle position sensor, both o2 sensors, engine coolant temperature sensor, and flushed and replaced the coolant. This thing is driving me crazy. Does anyone have any more suggestions!? Also, one piece of info I didn't mention before. While driving it bucks or jerks when I press the accelerator and when I let off of it.

NDNV

I bet you would have better luck with OEM Honda/Denso O2 sensors for the P0134 code and an OEM IAT sensor for the P0113 code. Definitely not BOSCH.

Check your connections too.

Other far-reaching causes could be pressure washing your engine bay or rodents chewing on tasty wire insulation to the sensors.

2005ex

The OEM sensors are what I'm leaning towards. There are many people saying that. They're just expensive little parts lol. I appreciate all the info

Colin42

expensive and working is better than cheap and not working

2005ex

You're exactly right on that lol

Colin42

amazon or rockauto will be cheapest,
go to either denso's or ntk's website to get the correct part number

2005ex

Good deal, thank you

Wankenstein

Honda's engines seem to always do better with Honda Genuine (OEM) parts and especially o2 and A/F sensors. 7th gens ('01-'05) use and A/F sensor: https://www.tirereview.com/air-fuel-...xygen-sensors/ Looks like this is the one that fits your car's (1.7L) engine but reconfirm under the "check fit" drop down menus:
I'm pretty sure (but not 100%) that Denso, NTK and NGK are all interchangeable and are made by NTK but may have differing part numbers for the exact same part. Here's the same part on Ebay: https://www.ebay.com/i/173830018979?chn=ps

2005ex

Well guys, I installed the OEM air fuel ratio sensor and still no difference. I replaced the map sensor and fixed a small exhaust leak too. I then tried the idle relearn sequence and nothing. I cant hear any vacuum leaks either. The only code showing now is for the catylic converter and the reason is because it doesn't have one so that's normal. I know that's not the issue either because it has been that way since I bought it and this is a new problem. I don't know what to do or try next. Any more suggestions?

mac25

Did you check the IACV (idle air control valve)?

If it is stuck open then its basically a vacuum leak.

2005ex

Yes sir I did. That was one of the first things I replaced. Only thing, it isnt OEM. Do you think that would make a difference?

Colin42

it can

2005ex

More advice please! I replaced the whole throttle body with a new OEM one with OEM idle air control valve and TPS on it and it still acts the same way. I did however try blocking the air passage to the iacv inside the throttle body and it idled very low and rough but didn't die. I believe it should die right? Does this mean there's a vacuum leak?

Wankenstein

Could try adjusting the valves to spec but probably won't solve the issue. Fuel injectors working correctly? Leaking intake gasket? Other than that it may be a faulty ECU issue?

mac25

Compleatly cover the throttle body opening and it should die, if not there is a large vacuum leak.

If so cover the throttle body opening again, disconnect a vacuum line to the intake manifold and use a smoke machine to check for leaks.

You can make the smoker, there are diys on YouTube, or you can vape/smoke into the vac line.

2005ex

Ok, thanks guys for the information

2005ex

Well, that isn't the problem either. I covered the throttle body and it died immediately. I have no clue what to try next