Lower boost with S&B filter

TolyM

TolyM

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Sep 8, 2013
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38
Hey guys.
I got a 07 5.9 megacab.
When i bought the truck it had a K&N filter kit, my boost gage was showing 35psi when i floored it. Read some bad reviews online about the k&ns so i installed s&b filter kit. Now i can't get the boost gage to go over 15 psi. I know k&n was wide open filter, but is it suppose to be that much difference ? Truck drives and runs good.
I don't have the scoop on the bottom of the filter box. Should i open that cap on the bottom of the box? Is it worth ($100) installing that scoop?
I know some of you probably have s&b fillets on your trucks.

Thanks

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On the interstate right now.
Going 70 MPH on CC my rpms are at 2.
EGTs are from 5 to 8 depends on the road. That's empty truck with 3 people inside.

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I would tend to think the boost could drop a little bit since it will most likely have an increased volumetric air flow and you will be at the same power level. Not sure that is your case, but I'd rather run 10 psi at a boo-kuu of CFM than 100 psi to achieve the same goal.

Going from 35 to 15 tells me you have an issue though. That is a huge drop.

I assuming your 2007 has a MAF and AIT sensor in the tube like my 2009? Did you not get one of them plugged in correctly or damage one in the process?
 
4x4dually said:
I would tend to think the boost could drop a little bit since it will most likely have an increased volumetric air flow and you will be at the same power level. Not sure that is your case, but I'd rather run 10 psi at a boo-kuu of CFM than 100 psi to achieve the same goal.

Going from 35 to 15 tells me you have an issue though. That is a huge drop.

I assuming your 2007 has a MAF and AIT sensor in the tube like my 2009? Did you not get one of them plugged in correctly or damage one in the process?
Click to expand...

Thanks for the reply.
my truck has only IAT sensor and i do have it connected.
i disassembled the whole kit today and reassembled it, checked the sensor, changed the O ring on the sensor and still couldn't get higher PSI.... though maybe the sensors O ring was bad..
here is the intake kit i had before i bought by S&B http://www.knfilters.com/search/product.aspx?prod=57-1532
see the IAT sensor is not in the pipe. it was on the side conected to that little filter.
now that i have the IAT sensor in the pipe maybe thats the reason it wont let my PSIs up to 30. its maybe controlling the air.
im new to this diesel trucks thing. had a few Tundras before.. sorry about these rookie question..
 

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It may not be related 15psi boost is way low either you have a boost leak or the waste gate is not fully closed or the turbo took a crap. How are you reading boost?
 
dangerous06 said:
It may not be related 15psi boost is way low either you have a boost leak or the waste gate is not fully closed or the turbo took a crap. How are you reading boost?
Click to expand...

I'm reading with a gage.
Ill try tomorrow to install my old k&n intake system and see what happens. If it goes back to normal i wonder what could be the problem?
It dropped as soon as i installed the s&b. Could it be a bad filter? I got the cleanable version.

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Unless that filter is completely clogged, you aren't dropping boost by doing an intake swap. 15psi is lower than stock. And your iat sensor would have nothing to do with the boost. I'm betting you tweaked the wastegate while monkeying around with the swap.

Wtf? My phone knows monkeying but not wastegate?
 
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BgBlDodge said:
Unless that filter is completely clogged, you aren't dropping boost by doing an intake swap. 15psi is lower than stock. And your iat sensor would have nothing to do with the boost. I'm betting you tweaked the wastegate while monkeying around with the swap.

Wtf? My phone knows monkeying but not wastegate?
Click to expand...

Lol @
"Wtf? My phone knows monkeying but not wastegate?"

So if I'm getting low boost is my wastegate stuck open or closed?
Can i keep driving the truck since it runs normal. Egts are under watch at all times and they look good to me.


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It would be open or close to open.

Take a look at the turbo and see if anything looks out of the ordinary or make a boost leak tester.
 
I've never seen a turbo. What should i look for? How can a boost leak test be done?
What about clamping the wastegate hose, what does that do? Ive seen people talk about it on the forums.
Sorry rookie here. 1st Diesel truck

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Fwiw, your truck has a map sensor, no maf. Are you reading boost through the obd2 port or is it read from your intake manifold/plenum? If it's through the obd2 port I'm betting its a map sensor. If it's an actual separate gauge, I'm betting it's the sending unit/gauge. You would notice the truck sounding and driving different if your wastegate was stuck open.
 
crf450x said:
Fwiw, your truck has a map sensor, no maf. Are you reading boost through the obd2 port or is it read from your intake manifold/plenum? If it's through the obd2 port I'm betting its a map sensor. If it's an actual separate gauge, I'm betting it's the sending unit/gauge. You would notice the truck sounding and driving different if your wastegate was stuck open.
Click to expand...

My gage is connected to the intake manifold

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Clamped my wastegate line and nothing changed.

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