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Discussion Starter #1
I'm experiencing a weird idle issue and looking to see if anyone else has gone through this.

Symptoms:
  • Starts up fine when cold
  • Idles fine when cold
  • When it's at operating temperature, it will stall
  • I have to press on the gas pedal to increase the revs to prevent it from stalling (at operating temperature)
  • It does not overheat
  • If I'm not giving it gas, it will stall (at operating temperature)
  • If I turn the heater on (setting 1 of 4) the car will NOT stall (which doesn't make sense)
  • There's no CEL (previous CEL which got cleared was P0170 and P0172)
When bleeding the coolant, the car got to operating temperature and did NOT stall

IACV was cleaned last year
FITV was cleaned a few weeks ago <-- this helped for a bit but the problem came back
Coolant got flushed and replaced with Honda coolant
Primary 02 sensor was changed (secondary has yet to be replaced)
Oil change is done
Spark plugs are Bosch Iridium (new but the problem still persists)
Timing belt and water pump was replaced last year

No signs of any coolant leaks

Any ideas on what the problem may be?

Thanks in advance everyone!
 

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What is it idling at when it stalls?

You may need to adjust the idle air set screw. There is a procedure to do it properly - i'm sure it's floating around the internet.
 

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Discussion Starter #3
What is it idling at when it stalls?

You may need to adjust the idle air set screw. There is a procedure to do it properly - i'm sure it's floating around the internet.
It idles at 750, if I rev it, it will go up (depending how high I rev) then drop to as low as 0 and then stall.
 

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Is the throttle body sticking at all? PCV clean? It doesn't sound like it's too low at operating temp, but it certainly shouldn't drop low enough to stall.
 

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Discussion Starter #5
Is the throttle body sticking at all? PCV clean? It doesn't sound like it's too low at operating temp, but it certainly shouldn't drop low enough to stall.
It's not sticking. The PVC is new as well (forgot to mention that.

It's weird, because if I gas it while bleeding the coolant (funnel on the radiator) it doesn't stall at all.

I took the car to Honda to flush the coolant, since I had a mix before, but it's the same thing (just not as bad).

The only thing left is there's a leak involving the coolant system, intake manifold gasket may be on its way out.

I have a hard time believing it's a compression issue, otherwise it would stall even when bleeding the coolant.

I also can't put the link between having the heater set to on prevents the car from stalling.
 

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Have you tried unplugging the IACV and seeing how it idles? Possible the IACV or FITV is faulty.

(unplugging will give you a CEL, don't be alarmed)
 

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Have you tried unplugging the IACV and seeing how it idles? Possible the IACV or FITV is faulty.

(unplugging will give you a CEL, don't be alarmed)
I unplugged the IACV and the car stalled right away, that's been replaced last year.

The FITV was cleaned but it's not new, I don't recall there being a plug for the FITV. I didn't put a new one yet, since I don't wanna throw money at this not even knowing what the problem may be.
 

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Discussion Starter #8

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Aftermarket are a hit or miss. I suppose report back if it works out or not.


Has your throttle body every been tinkered with? As in the set screw remains untouched, correct?

And correct, the FITV does not have any form of sensor. It's just there to help the car idle higher during cold startups.
 

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"...And correct, the FITV does not have any form of sensor. It's just there to help the car idle higher during cold startups..."
If your idle at startup is not different from operating temperature idle, then I would have to suspect the FITV is not operating optimally. At cold startup, the system requires more fuel/air mixture to get to operating temperature, and therefore the idle is higher. Once optimal temperature is reached, the system idles down. From what you have indicated "Idles fine when cold," this fast idle is not occurring. Also, when did issue this begin - what changed on the car before you noted the problem???
 

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Aftermarket are a hit or miss. I suppose report back if it works out or not.


Has your throttle body every been tinkered with? As in the set screw remains untouched, correct?

And correct, the FITV does not have any form of sensor. It's just there to help the car idle higher during cold startups.
I just installed the one from Amazon today (quality is a lot weaker than the OEM one).

The idle dropped once, but it caught itself (before it would stall) so the new FITV must be doing something different.
I started it with the engine cold, it idles at ~2,000 rpm
Once the engine warms up, it lowers to ~750rpm

I took it for a drive, everytime I come to a stop (stop sign or red light), the idle sits a little above 1,000 RPM when stopped, no longer at 750.

Which brings me to your next question, I have no idea if the set screw was touched or not. How do I know where it's "supposed" to be?

Thanks again!



"...And correct, the FITV does not have any form of sensor. It's just there to help the car idle higher during cold startups..."
If your idle at startup is not different from operating temperature idle, then I would have to suspect the FITV is not operating optimally. At cold startup, the system requires more fuel/air mixture to get to operating temperature, and therefore the idle is higher. Once optimal temperature is reached, the system idles down. From what you have indicated "Idles fine when cold," this fast idle is not occurring. Also, when did issue this begin - what changed on the car before you noted the problem???
I just clarified what I met:
Cold start = ~2,000rpm
Operating temp = ~750rpm

The car was parked for 2 weeks and then this happened, no changes.

Like I mentioned earlier, if the heater is on, the car won't stall (the weird part in all of this)

And with the heater on, it does smell like burnt coolant :/
 
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