Boosting...but not feeling it?

[Gamble97]

So, here's my situation. I have a 97 gsx w/ a stock t25 and a few bolt on's, like intake, exhaust, uicp. The boost is up to 20psi (i know it's high) anyway when I give the car 3/4 throttle and keep the boost around 15psi it moves out. Some times when I hit it, the boost gauge will read 15psi but it feels as if there was no change in power or boost. If I lay off the gas then back on I will feel the boost. This doesn't happen all the time, just once in a while.
I know my turbo is on it's way out, but I'm just curious as to why the gauge will read boost, but I won't feel it.

 

[spoolup]

When you read boost your actually reading a real boost gauge right? Also being on the stock SMIC it will heatsoak and your car can drag ass since the air temp in the motor is warmer and the air not as dense.

could also have a boost leak or the stock BOV is leaking. Your profile did not list a upgrade BOV, jsut UICP, but I bet its upgraded to atleast a 1G. Never seen a aftermarket UICP that accepts the stock pastic BOV from a 2G

 

[Quasimondo]

Do you have a logger? With your boost set that high on a stock fuel setup you're probably knocking which is getting your timing yanked and killing your performance.

 

[spoolup]

I doubt his T25 is really at 20PSI, even more that his post reports 15 PSI twice. But good call on the knock. I think the added heat could even cause knock out of the little flamethrower.

 

[Addicted2DSM]

If your still running on the stock SMIC, I recommend using the Dejon Too Super sidemount IC, it retains the stock location but it's much bigger.

www.dejonpowerhouse.com

 

[stockfornow]

As mentioned before about IC, or get a Supra sidemount IC. At at that high of a boost with stock fuel pump isn't good. You just might be leaning your car. It might even be at the point of hitting a fuel cut.

 

[burntheblobs]

1. Make sure you are using an aftermarket guage and not the factory guage.
2. Make sure you have no boost leaks.
3. Turn the boost down so timing isn't destroyed/you don't get heat soak.

Just to throw a random figure out there, try setting it at 14lbs and you car will probably go faster.

 

[DSMFalcon]

Run a leak test. You may have a leak that will leak more at certian times than others. Not probably. Go out on a nice cool night and test it out. Spoolup is right, you could be heatsoaking your motor (bad) something could be wrong with your valve.

 

[Gamble97]

There is no boost leak from what I could tell. I did one not too long ago.
I am on a dejon uicp w/ a hks ssqv that is not vented.
I have a walbro 190 fuel pump.
Autometer boost gauge, and yes it's at 20psi, spiking at 22psi. There is no MBC installed in the car either. I haven't gotten around to installing the mbc and honestly don't care to. I never get on it, seeing how I know my turbo is going to blow soon.
If this is what heatsoak, then that's cool, at least I know what its all about.
I do have a new motor, turbo, and intercooler that are waiting for an install. All I'm waiting on is a new tranny.

 

[eclipsegsx1736]

If I lay off the gas then back on I will feel the boost.

100% definitely phantom knock.

The telltale sign is letting off the gas and getting back on it cures the problem. This is an annoying problem that many DSM'ers battle, including me. I had the exact same problems as you. Read up on phantom knock, some common fixes are new revised lifters (3rd gen lifters), new knock sensor to proper torque setting, and even using Restore engine oil additive or Lucas oil additive has helped many in fixing the problem. You'll get used to identifying the "feeling" when it phantom knocks, so before you step on it you can let off the gas and get back on it to clear it.
Borrow or buy a logger and watch your timing around town, it will often fall to the 10's even when lightly accelerating, and you'll feel the car hesitate, then resume as the timing goes back to a normal high-20 low-30 advance.
Another fix is DSMlink but that is expensive.

 

[spoolup]

How can you get 22 PSI out of a T25 without a BC? do you have the lines hooked up to the BCS? Just makes me wonder now. And super heated air on the little guy will cause heatsoak, but I do not see how you can get that much boost out of it without boost control OR a leak.

I would still want to find what my problem was regardless if I have spare everythings, that way the car would not breakdown and leave me stranded on a back farm road in BFE Illinois. My ex lived there and I swear some of the "shortcuts" she took would not be traveled by another soul in 5 hours.

 

[Gamble97]

100% definitely phantom knock.

The telltale sign is letting off the gas and getting back on it cures the problem. This is an annoying problem that many DSM'ers battle, including me. I had the exact same problems as you. Read up on phantom knock, some common fixes are new revised lifters (3rd gen lifters), new knock sensor to proper torque setting, and even using Restore engine oil additive or Lucas oil additive has helped many in fixing the problem. You'll get used to identifying the "feeling" when it phantom knocks, so before you step on it you can let off the gas and get back on it to clear it.
Borrow or buy a logger and watch your timing around town, it will often fall to the 10's even when lightly accelerating, and you'll feel the car hesitate, then resume as the timing goes back to a normal high-20 low-30 advance.
Another fix is DSMlink but that is expensive.

Sweet!, I'm not alone with this problem. I will do a search on this thank you.
The new motor will have revised lifters and dsmlink. I'll look into getting a new knock sensor as well. I've been meaning to install the dsmlink and do some logs, but work/school owns all my time right now.

How can you get 22 PSI out of a T25 without a BC? do you have the lines hooked up to the BCS? Just makes me wonder now. And super heated air on the little guy will cause heatsoak, but I do not see how you can get that much boost out of it without boost control OR a leak.

I would still want to find what my problem was regardless if I have spare everythings, that way the car would not breakdown and leave me stranded on a back farm road in BFE Illinois. My ex lived there and I swear some of the "shortcuts" she took would not be traveled by another soul in 5 hours.

How? I have no idea. Uicp, intake, 3" turbo back exhaust, walbro 190, the free mod and 122k miles. It rarely spikes at 22psi, it's mostly 21psi
Yes the stock lines are connected to the BCS as they should be from the factory.