Honda Civic / Del Sol (1992 - 2000) EG/EH/EJ/EK/EM1 Discussion

IAC / Idle Issue after Installing New Injectors

 
Old 05-06-2019, 12:34 PM
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Default IAC / Idle Issue after Installing New Injectors

Hi all, I'm looking for some advice with my 2000 Civic EX.

Background:
For a few months now, I've had a recurring issue with fouling spark plugs. The first time this happened, I had the Honda shop near my house do some diagnostic work. They identified the #1 cylinder plug as the primary plug responsible the rough idle. They checked a few other things in the process and identified fuel injectors as the most likely root cause if the issue came back.

Since then, the issue has come back a couple times. I'm on my 3rd set of spark plugs now so I decided to tackle the root of the issue. I put 4 new fuel injectors in over the weekend. As soon as I started the car for the first time after putting in new injectors, I am now getting an idle between 2000 - 3000 rpm, surging about half of the time.

I took the car back to the Honda shop today for another diagnostic. The code reported was P0505. (IAC Valve issue) They did not find any vacuum leaks. Initially, they wanted to sell me a new IAC Valve, installed for $700-something. (Not happening). While talking through it with their technician on speakerphone, I convinced them to try a reset of the idle speed. (I'm not sure what this process looks like, but I read some references to it and they seemed to know what I was talking about). They said they need to keep the car overnight so that they can try this in the morning after it cools down. Fair enough.

Any thoughts here as to what's going on? I did my best searching the forums and Google for IAC Valve issues as a result of changing fuel injectors, but I wasn't finding much. The best guess I can come up with is that the idle is still calibrated to behave with the old (gunked up) injectors and needs to be somehow adjusted to work with the new ones. As a side note, it wouldn't be the first time this shop tried to sell me more than what I needed. When I first got the car a few years ago, they insisted I had a dying catalytic converter due to the code P0420 showing up. Turns out it was merely a bad O2 sensor.

One more detail: I have a road trip scheduled from Florida to Vermont this Thursday! Help!
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Old 05-06-2019, 12:51 PM
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Default Re: IAC / Idle Issue after Installing New Injectors

The engine can't run that fast without extra air getting in somehow. Check the seals at the bottom of the injectors. Did you hook the PCV hose back up? Is the throttle cable slack when no one is pressing the gas pedal?

Rather than buy a new set of injectors right away it is conventional to swap them around and see if the problem moves with the #1 one.
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Old 05-06-2019, 02:57 PM
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Default Re: IAC / Idle Issue after Installing New Injectors

Originally Posted by mk378 View Post
The engine can't run that fast without extra air getting in somehow. Check the seals at the bottom of the injectors. Did you hook the PCV hose back up? Is the throttle cable slack when no one is pressing the gas pedal?

Rather than buy a new set of injectors right away it is conventional to swap them around and see if the problem moves with the #1 one.
The seals at the bottom of the injectors seemed nice and tight. I had to use a tiny amount of lithium grease to get them to fit in so I could tighten down the fuel rail. One thing to note is that the new injectors came with rubber spacers which did not appear to be required. The injectors (and their o-rings/gaskets) all looked the same going in as the old ones coming out. The injectors were after-market 'GP-Sorensen' which seem to be one of the better after-market brands out there as far as I could tell.

Unfortunately, I can't check the PVC valve or for cable slack until I get the car back tomorrow morning. I don't think I ever took the PCV valve hose off actually.
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Old 05-06-2019, 07:47 PM
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Default Re: IAC / Idle Issue after Installing New Injectors

Did you forget to reconnect the FIA hose on the IM?

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Old 05-08-2019, 08:21 AM
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Default Re: IAC / Idle Issue after Installing New Injectors

If you did, make sure you do not break the plastic on that valve assembly. The part is ridiculously expensive for no reason at all.....
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