Boost Leak? Or Knock?

[GSTdude06]

When im driving I can floor it in 1st gear and it boost PERFECT...but then in

2nd gear right at 5000rpm it makes like a knock noist stops boosting for a second then boosts again then I have to shift

3rd gear goes good till 5000 makes the noise boosts then at 6000 it does it again then I have to shift

4th gear it starts at 5000 like before but does it like 4 to 5 times.....


I use to get fire out of my exhaust pipe but I dont think I do now, I cant see tho....

Could it be a boost leak? Knock? What?

I can hold 20psi on my boost gauge for over 30 seconds BUT I can hear air leaking out around my EGR valve still.....I dont know how I can h old 20psi for that long when I can hear it hissing out the EGR (pressuring 20psi throught the turbo from a compressor)


Anyone have a idea of whats going on?

Mods on updated in my profile.

 

[blcknspo0ln]

could be a number of things, have you:

checked for shaft play? oil in turbo?
checked for compression?
leakdown test?
new plugs/wires?

what vacuum are you holding? are you on bigger injectors? what boost are you running? etc.

let us know more

 

[SkyLineGtR-R34]

looks like u r either having missfire or fuel cut

 

[alex]

looks like u r either having missfire or fuel cut

I dont think that would be it. It sounds like you need to check your turbo. Just take off the intake piping and check for shaft play in the turbo, only takes about 2 minutes to do. While your at it, check all your oil lines.

I would do a compression test on it as well, make sure that your compression is good throughout all 4 cylinders. Shouldn't have about a 16 PSI drop between any of the cylinders.

First thing I would check would be the turbo.

 

[blcknspo0ln]

you shouldn't type like that (makes you look unintellegent), but it doesn't sound like fuel cut he is describing.

fuel cut feels like you're hitting a brick wall. misfire is more of a hardcore sputter than anything.

 

[GSTdude06]

No shaft play at all. I have brand new spark plugs and wires.

Oil in the turbo, I dont know how to test that but how would that case it to mess up once in second twice in third and so on?

Stock Injectors
20psi I believe
Vacuum on the gauge stays around 20


I DO KNOW that I have a leak at my ERG Valve and nothing I do fixes that problem. Ive bought over 3 different gaskets and ive put high temp silicon sealant on both saids to seal it and it still leaks.

The leak isnt big cause I can hold 20psi on my boost gauge for over 30seconds.

 

[GSTdude06]

help?

 

[jepherz]

Did you put a blockoff in your EGR? You might as well fix that leak before anything else. If you put the block off plate in and it still leaks, make sure that is where the leak is.

 

[GSTdude06]

Ive put a block plate on it and did a soapy water test and bubbles came out.....


20psi to much for 450cc?

 

[ericbev]

Get oldman in here so he can tell you to do a........ anyone?






Boostleak test! It would be good to isolate the leak and make sure it is definitley the EGR and not another contributing factor. Even though you are holding boost you could still be leaking some already metered air.

 

[GSTdude06]

How to fix that leak?! Nothing works......

 

[SethA]

Are you running 20 psi of boost with stock injectors or did you just leak test to 20?

If you are trying to run 20 psi with a 14b, exhaust, and intake along with stock injectors that could definitely be fuel cut. Turn down the boost to 15 psi and see if the problem persists. As soon as you can get a logger so you can watch your timing (what are you using now to monitor the results of your AFC tweaking?). 20 psi even with a rewired 255 and regulator is really pushing it.

Seth

 

[GSTdude06]

In about a week or 2 im buying a logger....money is running short right now, im only 17 haha

Ill try and turn down the boost but no matter the setting on my mbc it doesnt control my boost

How can I fix that leak tho? Sealant doesnt seal it and ive used alot of gaskets.

I followed a tech post for the SAFC tuning, only went as far as it said to without a logger.