Hi. I have a 2005 92k miles. I do oil changes routinely every 5k miles with Mobil 1. Changed the spark plugs at 50k. Did a valve adjustment about 5k miles ago (my first time).

Recently, in the morning, when I start the car, it fires up fine but then drops to 2-300 RPM, sputters then goes back to normal idle. It hasn't stalled out. I don't know what could be causing it. I thought about an injector possibly, but there's been no check engine light. I've never used any of the injector cleaners and thought I might give that a try. Any ideas? Thanks!

 

Mine does this from time to time as well. Not really sure what causes it, as I changed spark plugs, installed spoon style snorkel, and exhaust/test pipe all within a couple weeks of each other. I tried doing the ECU relearn procedure just yesterday to see if that makes a difference. Since it was infrequent to begin with, I'm still not sure if it has. For me, it would mostly happen as I slow to a stop light/sign. When I tap the throttle to inch forward as I wait for traffic, the revs blip, then drop to about 2/3k and the engine almost falls on it's face. But then it goes back to normal.

Have you made any modifications recently or switched fuel type/brand?

 

No changes recently. The car drives great other than at initial startup in the AM. I may try one of those injector cleaner bottles and see. Maybe an injector is clogged overnight or something (just theorizing, don't actually understand this stuff).

 

lol this stupid problem again

I have been chasing this ghost on my friends AP1

I haven't had a chance to but I think the culprit is going to be IAC valve. If it is the IACV, you can first try cleaning the IACV, including the motor, cleaning out the intake manifold and the throttle body.

What are the condition of the plugs? Hopefully they are all the same. If one is more fouled than the other, it would me think coil pack and that would be a hell of a lot easier to diagnose.

Out of curiosity once you are cruising on the fwy how is the throttle response?

Have you checked your primary and secondary 02 sensors?

 

Thanks for the response. Last I checked (about 5k miles ago, when I did the valve adjustment), all the plugs looked the same. I haven't noticed any change in throttle response when driving. Haven't checked the o2 sensors. Wouldn't they throw a code?

I cleaned the iac probably about 10k miles ago. It wasn't that dirty to begin with.

Thanks again for the reply.

 

For shits and giggles, try using some injector cleaner then doing the ECU relearn procedure. Might as well knock out the cheap potential fixes before you start dropping more money on other possibilities.

 

So everyone does iac clean on the throttle body side, did you check the motor side of the iac?

The o2 sensor codes are like a binary notification. It's either working or not their is no tolerance for "failing" so just pull them out for a quick look see

Then of course theirs also the map whack, which map do you have?

Also injectors have been know to fail too, but I would think if an injector is bad, it would stumble under maximum flow rather than near idle where flow should be lower


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A lot of idle problems trace back to the IAC valve or the map sensor/map sensor air channel (runs between the throttle body and the intake manifold). I'd suggest unbolting the map sensor and throttle body, and cleaning the air channel. You can also remove the IAC and carefully clean with carb cleaner following the DIY that's on this forum somewhere. Clogged map sensor air channel gave me issues before. It started as a slight stutter and quickly turned into inability to maintain idle at all (would die without throttle input).

 

Thanks y'all. I have carb cleaner at the house already. Do I need brake cleaner for the IAC valve?

 

no, just carb.