Cold air intake

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

I know not many use a cone filter or cold air intake on their CRD's for good reason but if you have or for those who do, What kind of sounds are you getting back through the intake? I'm getting a back "wusshhh" sound through the intake. I was getting it some what with the stock tube and air box. I found that the intake tube was bad so I ordered one. In the mean time I just vented the crankcase vent to atmosphere under the jeep (temporary) and put on a tube and cone filter that I already had. I posted about this problem before but it is much louder and more prevelent now that the intake air has been opened up. The sound is just like the sound that the BOV's sound that the Japanese vehicles use on the turbo cars only mine does it as I'm in throttle. It does it under 2k rpm's primarily in higher gears when lugging along. I talked to keith at gde and he said that the eco tune may help. It did help some but it is definately still there. Its like the air is backing up and back feeding through the turbo and intake/filter. Is this possible? Anybody experienced this before?
Thanks,
Steve

4x4kingx889 · **Joined:** Sun Jul 17, 2011 6:42 pm **Posts:** 235

I had a cone filter for awhile and it was much louder ( I liked it ) but then I went to the V6 airbox...also IMO any turbo engine doe's not need a "cold air" intake as the air go's threw the intercooler anyway and get's cooled maybe im wrong but that's how I alway's looked at it.

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Yeah, I agree that it isn't really needed. I'm just trying to iron out my problem with this thing. The sound I'm getting isn't normal. I've owned several turbo cars and this is abnormal. Also when I get the backfeed sound it wants to "hunch" a little and I know that isn't normal.

MRausch82 · **Posted:** Sun Aug 11, 2013 10:57 pm

I notice at low speeds with mine of I accelerate and immediately let off the throttle I get a "WHOOSH whoosh whoosh" sound, it does it three times in a row. Has not gotten any worse and I noticed it about 30+k ago. I only hear it if the windows are down and I am somewhere quiet or where the sound bounces off something, such as a guardrail or rock wall. I am not worried about it. Posted about it about a year an a half ago. It seems normal, to me.

GTS · **Posted:** Mon Aug 12, 2013 5:37 am

Ok a couple things. Does it do it when you're on the throttle or when you back off the throttle as MRausch82 describes? If it when you are on the throttle and it's a pft pft pft pft type sound that is called surge. If you mash the throttle or downshift it and get the rpm's up then it goes away that's another sign that it's surge. What is happening is that at mid to low rpm and mid throttle the turbo is trying to move more air than the engine wants to take and it more or less backs up in the intake, then it follows the compressor wheel around rather than going through the wheel like the air is supposed to. Think of this as the wheels hopping on the pavement when trying to do a burn out. The compressor wheel catches then air and moves it through the housing then the air rotates with the wheel, then when the pressure drops it moves again. It does this very quickly giving it that pft pft pft sound.

If this is the case it's possible that the vanes in the turbine housing are stuck more closed so it's trying to spool the turbo quicker. Or it could be partly due to the tuning. This is very common on the Ford superduties with 7.3L Powerstrokes after they chip them.

MRaush82 what you are describing is called stall. You get on the throttle building a lot of boost then when you back off all the drive pressure that is spinning the turbo up goes away but the intake still has a lot of pressure built it. It goes to the path of least resistance which is back out the compressor side of the turbo. When this happens the turbo goes from spinning at say 100,000 rpm to 0 or even reversed in some severe cases in a fraction of a second. While this is real hard on turbos and in some cases can snap a shaft, on stock applications it's generally not detrimental.

Anytime you go to a more open air filter the noise is less muffled and you'll start hearing it more. Not that it wasn't there before, just that now you can hear it.

As for the hotter or colder air, colder air is always king. However more hot air is generally better than less cold air. Even though the air goes through the intercooler to cool it back down colder air to start will always net colder temps at the intake valve. The air heats up the air as it compresses it. It does so by a percentage depending on how efficient it is at the given operating status. So a colder temp times X% is still going to be cooler. The intercooler also cools by a percentage so again the cooler you start out with the cooler you'll end up. Being exhaust gas temps are generally 1° cooler for every 1° cooler the intake is at the intake valve your EGT's will be cooler coming out the exhaust valve. Might not be a big deal if you are unladen but if you are towing much especially up a big hill this could be a huge deal.

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

GTS wrote:

Ok a couple things. Does it do it when you're on the throttle or when you back off the throttle as MRausch82 describes? If it when you are on the throttle and it's a pft pft pft pft type sound that is called surge. If you mash the throttle or downshift it and get the rpm's up then it goes away that's another sign that it's surge. What is happening is that at mid to low rpm and mid throttle the turbo is trying to move more air than the engine wants to take and it more or less backs up in the intake, then it follows the compressor wheel around rather than going through the wheel like the air is supposed to. Think of this as the wheels hopping on the pavement when trying to do a burn out. The compressor wheel catches then air and moves it through the housing then the air rotates with the wheel, then when the pressure drops it moves again. It does this very quickly giving it that pft pft pft sound.

If this is the case it's possible that the vanes in the turbine housing are stuck more closed so it's trying to spool the turbo quicker. Or it could be partly due to the tuning. This is very common on the Ford superduties with 7.3L Powerstrokes after they chip them.

MRaush82 what you are describing is called stall. You get on the throttle building a lot of boost then when you back off all the drive pressure that is spinning the turbo up goes away but the intake still has a lot of pressure built it. It goes to the path of least resistance which is back out the compressor side of the turbo. When this happens the turbo goes from spinning at say 100,000 rpm to 0 or even reversed in some severe cases in a fraction of a second. While this is real hard on turbos and in some cases can snap a shaft, on stock applications it's generally not detrimental.

Anytime you go to a more open air filter the noise is less muffled and you'll start hearing it more. Not that it wasn't there before, just that now you can hear it.

As for the hotter or colder air, colder air is always king. However more hot air is generally better than less cold air. Even though the air goes through the intercooler to cool it back down colder air to start will always net colder temps at the intake valve. The air heats up the air as it compresses it. It does so by a percentage depending on how efficient it is at the given operating status. So a colder temp times X% is still going to be cooler. The intercooler also cools by a percentage so again the cooler you start out with the cooler you'll end up. Being exhaust gas temps are generally 1° cooler for every 1° cooler the intake is at the intake valve your EGT's will be cooler coming out the exhaust valve. Might not be a big deal if you are unladen but if you are towing much especially up a big hill this could be a huge deal.

EXACTLY!!! That is what is happening with mine. I do get the stall at throttle stop but that is normal. What i'm getting that isn't normal is surge.It is doing it when I am in throttle up to 2k rpm then it smooths out. I'm sure it is surge now. The big question is what exactly is causing it and how do I fix it? Nw turbo?

Cold air intake

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