problems boosting

[highrever]

Hi guys im having a problem? I cant seem to stop the car from hittting fuel cut i have a boost gauge and when im full throttle it hits like 20 psi and feels like it hits a brick wall.

I had a small 16g turbo and recently put a evo 3 big 16g turbo and i have manual boost controller. I have it turned all the way down and it still hits 20 and hits fuel cut. So last night i removed the boost controller and just ran a hose from the j pipe nipple to the waste gate and it still hit 20 psi and hit fuel cut. I notice if i don't push the pedal all the way to floor and keep at 3/4 open throttle it wont cut on me. When it doesn't cut on me it will spike up and then drop to like 10 or 11 psi.

I need to figure this out please help where should i start looking. i also heard that you can crush a 1g bov which i have and how do i do this

 

[XiKeiyaZI]

Sounds like you're having an issue with your wastegate. Have you attempted to pressurize the line running to the wastegate to see if it would open? You can use a small airtank to do this. After this I would begin looking into checking the wastegate flapper.

 

[crash89]

I would begin looking into checking the wastegate flapper.

Thats where I would start. Id say unhook the wastegate actuator and try to move the flapper open/close by hand and see if its sticking or hard to move..

 

[1g92_TSi_XWD]

Definetily would check the flapper. Pull the hose out and hook it up to an air tank and turn on the compressor. see what psi the wastegate opens at. Crushing a 1g BOV is quite simple. put it in a vise and hit the top of the BOV until the boost fitting is touching the rim. be careful not to break the fitting. Check your maf too. I was hitting fuel cut like crazy and i hacked my Maf and it never did it again.

 

[highrever]

well this is a brand new turbo form extreme psi and my old small 16g did the same thing. wonder if the flapper is hitting the o2 housing because the o2 housing is from the garrett t25 turbo

 

[coltuner]

I have seen similar problems before where the actuator line was pinched between a frame and intake or similar areas. It took a higher pressure to decompress the line before letting pressure reach the actuator. Make sure the line isnt smashed or anything of that sort. Also, on my car I had to trim the coupling slightly on the in side where the jpipe meets the lower hotside as the pin on the wastegate arm would bump it and not allow it to swing open. I doubt this is the case but it sounds like your wastegate is catching or the actuator is not moving correctly.

 

[MrBoxx]

Number one thing to do is to start using proper spelling, punctuation, capitalization, and grammar in your posts. It makes it easier to read and diagnose your problem when we don't have "wall of text" to sift through for pertinent information. Thank you in advance.

Second thing to do is to do a boost leak test. You're leaking somewhere. Find the leak, fix it, and then worry about your boost spike. Make sure the line from the J-pipe to the wastegate actuator doesn't have any leaks or holes in it.

 

[RedGST98]

The boost leak sounds like its the culpret there. Buy or make a tester to pressurize the system and use water and soapy water on all couplers and fittings to make sure there's no leak. If there's a leak on the couplers, use hairspray then put the couplers back on and tighten them down. It will help grip to the pipe.

If you check the wg actuator use a air tank with a pressure gauge if you have one. You can see the psi it opens at and also if it opens all the way. If not it might be getting blocked somehow from opening all the way in the housing, might even try porting the hole a bit so more air flow. That might help as well. Just my 2 cents with theirs.

 

[1983gsp]

Sounds like boost creep or a malfunctioning wastegate caused by a bad diaphragm or sticking flapper. Could also be a crack in the vacuum line somewhere between the jpipe and wastegate. Take the Turbo off the car and double check that the flapper moves freely and opens completly. While its off the car also make sure the wastegate arm has full range of motion by watching it move with compressed air.

Search for threads on boost creep. There's lots of info on how to port the wastegate hole to control the problem. If all else fails, go external wastegate.

 

[highrever]

Hi guys. I am still having this problem with boost.

I don't know whats wrong, I have went threw everything. I have taken all of the intercooler pipes off and sprayed hairspray around the pipe to make the silicone stick to the pipes. I have done several boost leak test's and found some leaks and fixed them. I have crushed the 1g BOV. I have a big 16g evo 3 turbo and a manual boost controller hooked up. I have checked all the lines to and from the controller nothing?

One thing I notice is that while i was driving last night the boost spiked to like 16 or 17 and then dropped down to 10 or 9, the boost won't maintain high levels.

My boost gauge when I hammer the throttle flutters also, is this normal? Please give me some advice

 

[DSM pHrEaK]

If you've done a boost leak check with an air compressor at ~20psi and have found no leaks anywhere then you may start suspecting the wastegate actuator. We custom fabricated a 14g (yes 14g not b) on my buddy's starion and the way we had the wastegate setup it never completely closed the flapper. This is what I would suspect is going on.

 

[Aerofury]

If it isnt boost leaking, i would also suspect that your bypassing and blowing the wastegate open under high boost. A simple thing to try to give the wastegate more holding tension is to shim the mounting bolts by placing washers under the bolts mouting to the compressor housing. This holds the wastegate shut at more extreme pressures.

 

[DSM pHrEaK]

A simple thing to try to give the wastegate more holding tension is to shim the mounting bolts by placing washers under the bolts mouting to the compressor housing. This holds the wastegate shut at more extreme pressures.

^Ditto

 

[highrever]

ok found something out when i dont push the throttle wide open it seems to keep the boost pressure a little higher why would it be doing that

 

[Aerofury]

It does that because at lower throttle position, you have less engine load. Turbos are primarily driven off engine load via exhaust, so the amount or quickness of boost being generated is also lower. This principle is easier to understand while the car is in an idle position and is rev'ed, however no boost is produced - no load. Like some have said earlier, I would be checking wastegate function before anything else.