Hissing sound from under the car..
07-10-08, 09:03 AM
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Hissing sound from under the car..
After I started the engine this morning, I noticed hissing sound like "shhhhhh" (can be described as compressed air coming out of a hole) from under the car. It isnt from the tires because it goes away when engine is off. what can this be?? Is this normal?
07-10-08, 05:12 PM
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Could be a snake frying on the exhaust too.
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02-03-23, 05:31 AM
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2012 IS 250, I changed air filter and cleaned Maf sensor with CRC and now when I start the car from cold there is a hissing, spitting like sound for about twelve seconds then goes away.
This happens only when the car is cold, otherwise the car runs perfectly. I live in Cape Town where we have warm weather.
I will appreciate any knowledge of this. Thank you, Ivan
This happens only when the car is cold, otherwise the car runs perfectly. I live in Cape Town where we have warm weather.
I will appreciate any knowledge of this. Thank you, Ivan
02-06-23, 03:46 AM
#11
Possible the cam gear issue? Cam Gear TSIB (Toyota Safety Recall 13V-395 Dealer Notification (Remedy)B. 2006 -2011 IS 350) covered by powertrain warranty.- : the symptom is a noise from the engine bay, usually right upon starting up the car. It's brief, only a second or two. Os is cam gear more of a grinding noise?
02-06-23, 10:04 AM
#12
So many people.......So many responses......So many guesses.....So much misinformation.
Real answer here:
This car has a part on it called "secondary air injection pump". This pump turns on at different times. You can't hear it when you're driving the car because you're sitting in the car while you're driving and the location of the pump is outside, under the car.
This pump also, occasionally turns on during cold starts when certain parameters are met. When it turns on during these cold starts, it only turns on for a short time.
The job of this pump is to send fresh air into the exhaust pipes. I'm not going to go into detail of how the system operates ...... It would take too much time to explain everything.
Suffice it to say.......
The hissing sound you hear is actually the sound of air getting sucked thru this pumps air filter.......you live in California mountains or New York mountains. Those two states have this pump on the cars. The dirt roads and mountain dust clog these filters.
The filter is available at any Lexus/Toyota dealer. The cost of the filter is $10.
Retail auto parts stores don't have these filters. To obtain one, you'll need to order one from a Lexus or Toyota dealership........the dealership will want the serial digits of VIN number of your car so they ensure you get the correct part as there may have been mid-year changes to the part.
You're welcome.
Real answer here:
This car has a part on it called "secondary air injection pump". This pump turns on at different times. You can't hear it when you're driving the car because you're sitting in the car while you're driving and the location of the pump is outside, under the car.
This pump also, occasionally turns on during cold starts when certain parameters are met. When it turns on during these cold starts, it only turns on for a short time.
The job of this pump is to send fresh air into the exhaust pipes. I'm not going to go into detail of how the system operates ...... It would take too much time to explain everything.
Suffice it to say.......
The hissing sound you hear is actually the sound of air getting sucked thru this pumps air filter.......you live in California mountains or New York mountains. Those two states have this pump on the cars. The dirt roads and mountain dust clog these filters.
The filter is available at any Lexus/Toyota dealer. The cost of the filter is $10.
Retail auto parts stores don't have these filters. To obtain one, you'll need to order one from a Lexus or Toyota dealership........the dealership will want the serial digits of VIN number of your car so they ensure you get the correct part as there may have been mid-year changes to the part.
You're welcome.
Last edited by JacobsDad; 02-06-23 at 11:06 AM.
02-06-23, 03:49 PM
#13
Thank you for confirming what the cause of the noise is!
To confirm, owners with California Emissions vehicle will experience this normal noise during startup, which dissipates after the warmup procedure. Will owners with Federal Emissions vehicle also experience this?
To confirm, owners with California Emissions vehicle will experience this normal noise during startup, which dissipates after the warmup procedure. Will owners with Federal Emissions vehicle also experience this?
02-06-23, 05:31 PM
#14
Depending on the year, make and model of the Federal Emissions car........yes, it may also experience this IF the Federal Emissions vehicle has a secondary air injection pump on it.
Not all Federal Emissions vehicles have these pumps on them. If a Federal Emissions car has this pump on it and the pump fails, the car won't pass emissions inspection.
Briefly:.......the car computer is doing a self-test of the EVAP system when the pump is pumping during certain cold start situations. The length of time this self-test can be as short as 5 seconds or as long as 2 minutes. Note: The longer the pump runs during the cold start self-test.....the worst off your cars EVAP system is.
You state that you heard the hissing noise for 12 seconds. This is a great indicator that the EVAP system on your car is "dry" and operating efficiently and has very good conditions within it's collective components.
The job of the pump is to send a measured amount of fresh air into the exhaust when the EVAP canister purge valve opens.
The EVAP canister purge valve opens to allow gas vapors to pass from a storage canister into the exhaust to be burned.....and to be burned in the exhaust, these vapors need fresh air (oxygen).
The gas vapors eventually enter the catalytic converters. When these vapors enter the converters, the converters are hot enough to ignite the vapors but they won't ignite because there is not enough air (oxygen) to burn the vapors......this is where the secondary air injection comes into play. The pump is injecting fresh air into the exhaust system and by doing this, the vapors have enough fresh air to ignite.
But like I said before explaining the process would take too long and I realized this comment is kind of long but it barely touches on a fraction of the way the system operates.
Not all Federal Emissions vehicles have these pumps on them. If a Federal Emissions car has this pump on it and the pump fails, the car won't pass emissions inspection.
Briefly:.......the car computer is doing a self-test of the EVAP system when the pump is pumping during certain cold start situations. The length of time this self-test can be as short as 5 seconds or as long as 2 minutes. Note: The longer the pump runs during the cold start self-test.....the worst off your cars EVAP system is.
You state that you heard the hissing noise for 12 seconds. This is a great indicator that the EVAP system on your car is "dry" and operating efficiently and has very good conditions within it's collective components.
The job of the pump is to send a measured amount of fresh air into the exhaust when the EVAP canister purge valve opens.
The EVAP canister purge valve opens to allow gas vapors to pass from a storage canister into the exhaust to be burned.....and to be burned in the exhaust, these vapors need fresh air (oxygen).
The gas vapors eventually enter the catalytic converters. When these vapors enter the converters, the converters are hot enough to ignite the vapors but they won't ignite because there is not enough air (oxygen) to burn the vapors......this is where the secondary air injection comes into play. The pump is injecting fresh air into the exhaust system and by doing this, the vapors have enough fresh air to ignite.
But like I said before explaining the process would take too long and I realized this comment is kind of long but it barely touches on a fraction of the way the system operates.
02-06-23, 06:30 PM
#15