I was driving my car down the freeway a few weeks ago when I hear a loud vibration noise coming from the front of the car, it only lasted like 2 seconds and went away. 3 miles later it happened again, then again ½ a mile later. When the noise happens the car tends to lose a little power until the noise stops. So I pulled off the road to see if something was hanging down or stuck to the bottom of the car. Nothing. So I had kept driving and for about a week or so I have been able to drive normally with the noise coming only maybe once or twice per 20 mile trip. Then a few days ago the noise came really strong and long, like 4 seconds and killed the engine, this time I was traveling 30 mph on a city street. The car started right back up and I was able to drive home with no further problems. I have since stopped driving it as I do not want to further damage whatever is wrong.

The noise is hard to describe, It's a low vibration noise, kinda like a quiet version of a Jake Brake on a semi. The day before it started my prelude got an air-conditioning service where they replaced a valve in the dashboard and recharged the AC. Air works great, and the night I drove it home from the shop I had no problems. I have shut off the AC when the noise starts and that did not seem to stop the noise, it stops itself within 2-3 seconds, so do not think the AC is the issue. I think the mechanic is a good guy, has saved me money in the past. I spoke with him over the phone, he said to bring it in but did not think it sounded like an AC issue.

Has anyone heard a noise like this before?

 

very strange, does the steering wheel vibrate as well when this happens ?
Its odd that this killed your engine, makes it seem timing related. Check your crank pulley and see if its on there tight and that it doesn't move.

 

No, steering is not affected by the noise,

Only killed the engine the one time, the rest of the time it just reduced power very slightly, almost like in a weaker car when the compressor kicks on. But I do not think it is AC related as it only happens a few times in a 20 mile trip and the compresser kicks on and off several times.

For checking the crank pully, I might have to have a mechanic do that.

 

its your AC or your AC fan coming On. it killed your engine when you were in idle, it takes power from the motor to run AC, and thus decreasing idle rpm slightly. If your idle is low as is (below 700 rpm) then this will happen. It only happens when your engine is at idle, this should not happen when you have load on the motor from the tranny. And you would feel a loss of power (when driving and accelerating) when AC is operating due to the AC compressor to crank pulley attachment with your Alt-AC belt. This is normal with AC, increase your idle RPMs.

The sound might be coming from the AC compressor, might need to lube-up the pulley .. IDK, no AC here.

 

IMO he is describing an intermittent engine miss from one cylinder.

 

I suppose it could be the AC as the problem occured after it was repaired, however the condition (loss of power and noise) only lasts for 2-3 seconds and the compressor is engaged for 3-4 min at a time.

 

hey thanks for the reply, loss of power yes, but what would cause the noise?

 

the noise could be from the fan assembly for the AC during first few seconds of being turned On, and then when the blades speed up to full RPMs then the noise goes away.

 

You will have to drive it without the AC to see if it actually is not the AC that is affecting your engine. Tape a playing card to the radiator fan framework so when the fan comes on you will hear the noise just like when you were a kid and put a card on your bike to make noise when it hit the spokes of your wheel. This way you will know if its the radiator fan if you hear the noise and feel the power loss at the same time.

Otherwise I would thing the IAC is going bad, I have heard growling sounds from these before on several different types of cars. Can you power through the noise and the engine pick up ok, while you are cruising at lower speeds, your throttle is only open a little but the IAC should be open 100%, if the IAC closes for a few seconds then you would loose power.

 

I might try that, I can drive to work without the AC as it is cool enough to just use the vent fan, just concerned that I might mess up something else if that is not the issue.

 

Update: Took it to the mechanic, the noise is so sparatic he can't hear it to descipher what it is. I am driving to work in the morning without AC and home with AC to see if the noise only happens when the AC is running. So still in work.

 

Next thing is to drive without the air intake tube connected, such as a CAI. This of course means driving a little while without an air filter. You will definetly hear the difference it the sound is coming from the IAC.

 

Thanks, update, the sound has not happened in about 7-8 days, I am not sure what is going on, but oh well, good.

 

Have you checked the pullies on the other accessories such as alternator or power steering pump?

 

hmmm... now that i actually read your post fully. again. i wouldn't look anywhere but the air conditioning service. take it back to the place that did your ac recharge, and tell them you want a refund. sounds like your compressor could even blow while driving [did that.....ek hatch rip] and as a consequence the engine could go up as well. def don't drive it. i was going to make a neat comparison to my 5th gen noise[s], but i'm blind as a bat. my bad

 

Before you actually get a refund, the shop is going to want to listen to the problem at hand and lately its not making a noise, you also have to let the shop know that there is a problem with the work they performed as soon as you experience the problem, not a month later. The IACV does operate differently with AC than without, it also can malfunction and make the noise you are talking about, that is why I gave some input to troubleshoot it above. I understand that is seems to be working right now but no shop is going to refund your money without proof that the work they performed caused your problem weeks later without being given heads up as soon as the problem arised, if they are a lisenced shop, the law is on their side, they pay a lot more taxes than you do.