Low rpm boost ok, but lays down at higher rpms

[Jetrosr]

Bone stock 1G w/ BCS restrictor removed and air can opened up. Showing consistant 10-11 psi on my Auto meter boost gauge, steady all the way to shift points. Most times from a stop it will just about change lanes from the torque steer, then at higher rpms it acts like the boost is going somewhere else. Took it to the drag strip and went 17.0 then 17.7 @ about 80 mph, around 2.5 60 ft. Brought it up on the converter and launched with my little 13b pumping his guts out. I have been running 89 octane. From my research, it sounds like a wastegate problem? Compression is about 120 across the board, base timing was at 10 (now at 5). Also, when I had the timing light hooked up, I looked at the cam gears. Should the timimg marks line up with the timing connector grounded? I'm in the process of getting a logger in the car, but having a little shortage of green stuff. Any ideas?

 

[bojanglesracing]

Have you done a boost leak test?

 

[Jetrosr]

Have you done a boost leak test?

I picked up the stuff today, I will try at work tomorrow. I assumed since I showed 10-11 psi all the way to shift boost leak was not an issue. The gauge gets its signal from the intake (t'ed into the FPS) Thats why I was thinking wastegate, from my small understanding of turbo stuff.

 

[Backinajiffy12]

does the boost go up and down at high RPMS?

 

[Defiant]

You're boosting on regular?

Well, there's one thing.

 

[No_Skillz]

You're boosting on regular?

Well, there's one thing.

Get yourself some better boost fluid. 93 is a MUST. You are probably knocking up top and timing is being pulled. (Use a logger to confirm).

And boost leak is always an issue. Do a BLT. You will be surprised.

 

[Jetrosr]

The more I think about it, the more sense the boost fluid makes. He's pulling harder since the temp dropped like 20 degrees. I forgot the groceries, so I couldn't get the BLT done at work yesterday. The logger is in the works. Thanks for the input.

 

[wancsta]

The more I think about it, the more sense the boost fluid makes. He's pulling harder since the temp dropped like 20 degrees. I forgot the groceries, so I couldn't get the BLT done at work yesterday. The logger is in the works. Thanks for the input.

Boost fluid ....but seriously only use 93 octane or better like Defiant said. Also don't expect it to be a rocket ship at 7K @ 11psi, stock cams , 120 psi comp. and a 13b.

 

[Jetrosr]

Had a BLT for lunch today, just a slight hiss from the throttle plate, figured thats the idle air bleed. Do I need to reset the ECU to let it remap for premium boost fluid? Or is that unneccessary?

 

[jeepzj94]

No, no need to reset the ECU, it will adjust on its own

 

[Jetrosr]

Boost fluid ....but seriously only use 93 octane or better like Defiant said. Also don't expect it to be a rocket ship at 7K @ 11psi, stock cams , 120 psi comp. and a 13b.

I don't expect a rocket ship at all. I just went out and ran a 17.0 @ 80 mph. My stinkin Craftsman could run that with a stiff tailwind.

 

[Vert]

simply pressurizing the intake and listening isn't usually enough for a BLT. with the intake pressurized try spaying soapy water at everything in the intake system to locate leaks. The bubbles are a dead give away, and your eyes are usually more accurate than your ears. you might find leaks that your ears didn't find.

just my .02$

 

[Jetrosr]

simply pressurizing the intake and listening isn't usually enough for a BLT. with the intake pressurized try spaying soapy water at everything in the intake system to locate leaks. The bubbles are a dead give away, and your eyes are usually more accurate than your ears. you might find leaks that your ears didn't find.

just my .02$

Actually had enough sense to do the soapy water thing, no leaks. I knew I had an exhaust leak, so I changed the manifold gasket. Car sounds completely different. It acts like a plugged cat (I have a test pipe) at low speeds and now on the hi-way it's got a little more than before. The turbo used to be really loud, now I can't hear it. It still builds boost, and I can hear the BOV when I free rev it. I adjusted base timing with the leak (10 btdc to 5 btdc), so I though about checking that, but I left my light at work. I can't imagine it changed too much because the idle didn't change. I popped the hood after I got home and the wastegate housing was almost red hot. I was boosting and letting off all the way home.

 

[Jetrosr]

Well, I set the timimg to perfect 5 btdc, idle 750 and fixed a pin hole in the wastegate signal hose from the BCS. Tested the wastegate actuator to make sure it's opening. Still runs like junk. Now the radiator is broke, so my focus changed for a minute. I'll update again when the rad. is fixed.

 

[Jetrosr]

Sorry for the delay, but I think we're near resolution. Finally got a logger, knock counts are maxed out before 3000 rpm. Jacked it up to look at the knock sensor, and I can see it's guts! There is a trail down the back of the block where said guts melted/disintegrated. Apparently Mitsu computers and knock sensors have a finite lifespan. I'll update again when I confirm the fix.

 

[Jetrosr]

Replaced the head gasket, new intake valves, resurface the head and ARP headstuds. I can nail it from a stop, (auto trans.) the tires start spinning all the way thru first, then chirp in second. If I brake torque, it just instantly blows the tires off and I just sit there spinning. No knock at all.