bad iac valve symptoms?

[xplorernewb]

So if an iac was bad, it would idle rough, or high, hesitate or bog, howl sound, right? Does the "howling" sound i keep reading about when the iac valve goes bad make the engine sound like an old small block?

 

[xplorernewb]

Or would it sound like a cold air intake, but stock? I can't describe the sound but its real loud, makes my ears pop.

 

[natenkiki2004]

I think howling means a restriction of sorts. Think whistle. A bad/sticking IAC would cause your engine to die if you turn the AC on while in gear (automatic) or turn the wheels lock to lock without moving. Basically putting stress on the engine while idling. Another symptom would be if you're accelerating hard and let off the gas completely and the engine dies/stumbles.

The other side to that is an over-speeding idle if the IAC was stuck open.

 

[xplorernewb]

My idle drops lower than usual when turning the defrost on and i have no ac. Seems like its only high for the first 10 mins of driving (while sputtering on acceleration), or if im stopped and tap the gas pedal, it will hang high for a few seconds. If im on the gas pedal and its sputtering, i can lift my foot off the pedal to where its barely pressed but just enough to accelerate, it will smoothen out and be ok at a higher rpm, but still a little rough. The sound will start when i make it smoothen out and will get quieter if i let off the gas while cruising. and it is a manual.

 

[natenkiki2004]

The idle will hang high after tapping the throttle, that's just how it works. Sputtering while you're on the gas means the IAC isn't the problem, that's usually TPS. The IAC can whine and be annoying but not cause any performance issues.

 

[xplorernewb]

I found a forum for lexus that a car had similar issues and it turned out to be the coils.

Symptoms were the exact same, even the sound. No cel either. Guess that's what ill check tomorrow. Kind of makes sense

 

[Jason94sport]

A bad IAC will cause high, low or erratic idle....take it off & clean it out. Clean the MAS & check the TPS voltage. All can be found in the sticky threads.

 

[xplorernewb]

I cleaned iac and maf, gapped and changed plugs and replaced tps. Replaced air filter, Replaced hoses and made sure the air intake was tight so no leaks there. Im putting in a new fuel filter as soon as i find the tool, which i can't find around here in the country. This things starting to piss me off