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I've got a 1997 Civic LX with the following symptoms:

• Dies after starting when idling. Will continue to run if revved up.
• Can't idle when sitting at stop with A/C on. Will be okay for about 15 seconds then will start to idle down and die. This usually only happens after car has been driven for awhile.
• Check engine light on - IACV valve (cant remember code #)

So this is what I've managed to do this far:

• Replaced IAC valve
• New spark plugs and wires
• New fuel filter
• New MAP sensor
• Bunch of fuel injection cleaner
• Sprayed carb cleaner around vaccuum lines and also tried soapy water. Nothing found.
• "Calibrate" idle by running at 3K until fan kicks on then letting sit for 5 min then shutting off.
• Checked with Honda for recalls, especially ignition switch but nothing.

So what's next? Fuel main relay? Cap and rotor?

 
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bump...please help

 
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Just curious, what's your idle rpm after warmed up ? What I mean is does it have low rpm and with some hesitation before dying or it dies right away after warmed up.

 
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What's the OBD2 code number?

 
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Idle is 1500 RPM after warm-up. I can't remember the OBD code but I think it was P1508 - IAC Malfunction

I have my own bluetooth OBD2 scanner so I use that. It's the cheap one off Amazon. I also had AutoZone scan it with the same results.

 
Rep Power: 518

Which engine does this have? D16Y5, D16Y7, D16Y8?
Manual transmission or automatic?
Your IAC was ordered specifically for a manual transmission car....from a Honda dealer? (parts catalog says it is different for auto trans)

Uses this style throttle body and manifold?


Let me know if this is not what you have.
Service info doesn't always jibe with reality on these cars.


P1508 is a circuit code for the IAC.
Unplugged, worn out female pins in the harness connector, incorrect valve resistance, wiring issue, ECM, something of that nature.

 
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I believe it's a D16Y7. It's an automatic. IAC valve was from Autozone and should be for the right car but you know how that goes. IACV looks right in that diagram but I think the throttle body is horizontal, not vertical. Need to go check.

Might need to return valve to Autozone and get a new one. Or get money back and order an OEM one.

Edit: That diagram does appear to match car...not sure why I thought throttle body was horizontal.

 
Rep Power: 518

Ok so that should mean it has a 3 wire IAC.

Ohm test the IAC valve, each half should read 16-28 ohms (pins 1+2 then 2+3)...and check between pins 1 and 3 for a total resistance of both coil windings.

Next I like to check that the terminals in the connector have not lost tension, that they can still grip the thin blades of the male terminals securely. (pin drag test).
Then repeat the same checks at the PCM connector when I disconnect that one.

Then..Test
Key on, engine off:
Unplug IAC valve connector, connect voltmeter to battery negative and test for voltage on the yellow/black wire of the IAC connector
Should be battery voltage...Do you have it? If no, that's a wiring issue.

Then reconnect the IAC, unplug PCM connector A and ohm test between A13 (orange) and A14 (black/blue), you should see the ohm results of terminals 1+3 in the first test on the valve.

Disconnect IAC...go back to PCM and Test between either terminal (A13/A14) and ground, make sure neither wire shows any continuity to ground.


If it passed all these then try a known good PCM
Open up your PCM and look for signs of burns or leaking capacitors?

Boy I hope I wrote all that right.