took the balt on its first road trip (and a boat trip) this weekend. was taking a friend for a ride and i hammered on it from a stop and it really threw me back hard, a lot harder than usual and just ripped the tires loose unlike usual. the next time i tried it i watched the boost gauge and discovered i had a full 15psi in 1st gear, were it usualy would have around 12psi, and 15-16psi in 2nd.

mods are as follows- stage 2, 2.9" pulley, cobra h/e, header, custom exhaust, cai, usual stuff. the car has had this setup for over a year, nothing has changed. i know i need to look at the bypass valve and related stuff, just wondering if anyone has had the same issue. i have no drivability complaints, i like the full boost in 1st gear, however i know the limit is there to help with 1st gear traction (very evident right now) and i have no idea on why just all the sudden its doing this.

 

Thats a very good question. Do you have a custom tune, or just the stage 2 tune?

 

i used to have my boost tuned at 50% in first gear, still pulls hard and helps alot with traction

 

sounds like a good problem lol!! wish i had that =P

 

its a stage 2 tune with p0420 (cat inefficientcy) code deleted. i dont suspect a problem with the tune as its been fine for the past 8 months ive owned the car, this just started happening today.

 

ok i checked it all out today, the actuator is free and moves like it should by hand, i confirmed that the actuator is in good working order. anyone have any ideas???

 

Thats the way it should be, you should have full power in every gear unless someone custom tuned the car to limit boost.

 

well to my knowledge, stage 2 tune opens the boost controll solonoid at a 50% duty cycle limiting the boost in 1st gear to help with traction. for the past 8 months i have bee around 12psi in 1st gear and 16psi in 2nd and higher gears. other stage 2 cars ive riden in have been the simular.

 

the stock ecm has a boost limit of 12.5lbs any gear built in... if the code is deleted what else is

1. tourqe managment?
2. boost limit?
3. speed limiter



are you running the zzp pcm...

Speed limiter removed
Raised rev limiter to 7200
Altered fan turn on keeps the IC radiator cooler at all times
WOT fueling is revamped to provide a safe, flat air/fuel ratio at all RPMs
Works with high flow cats, 420 code removed
Torque abuse modes are modified to eliminate bog during WOT
12 PSI boost limit is removed
Timing revamped for increased power
MAF/MAP tables adjusted for running smaller pulleys
Idle hunting from installation of larger injectors improved



give us more info on your ecm...

 

Every stage tune I've seen, including the one in my car, has 100% boost in first and second. Unless one of the new variants started something different, I don't know. It never used to be limited.

Are you going off the factory boost gauge? It doesn't always react fast enough to accurately show in first gear.

 

Yeah stage 2 has boost at 100% in all gears. It is only limited by torque management/abuse. It is perfectly normal to see a full 15 psi in first gear.

 

what? im seeing under 10 psi in first gear

 

I normally see around 10-12 boost in first gear, but that is because I normally don't go WOT in first gear because it will just spin the tires if I do. IF I intentionally spin the tires and go WOT I do hit around 15 or so.

If the car detects abuse or if the torque management detects the transmission torque is above the threshold, it will limit boost.

Also I notice in your sig it says the car is tuned, so you don't have the stock stage 2 tune... when you were tuned the boost in first gear may have been limited.

 

your car should be doing that in first gear thats not a problem. There is not really enough time to look at the boost gauge in first becuase the gear is so short and usually involves spinning.

 

im running a stage 2 tune.

for the 8 months ive owned the car, its had around 12psi in 1st gear and 15 in 2nd, i just dont know what changed. the car is also noticibly faster and rips the tires loose like it never did before, so i know its not just a slow reacting gauge.

 

Nah...the factory stage 2 calibration is limited in 1st (but not 2nd) as far as I know. I checked hp tuners and I know it's limited (to 50% I believe). I'll recheck soon but that's what I recall seeing.

 

I was stuck on the #1 coming back from Vancouver to Chilliwack on Saturday. It was 39*C and a truck had caught on fire by 232 turning the highway into a parking lot. My car started to do funny things for a few hours after, probably just because of heat soak but it sorted its self out the next day. Maybe its a combination of your PCM being slightly cooked from the hot weather last week and you not ***** footing the throttle anymore?

 

What version is your tune, recent? Mine is from late 05, and all the other ones I've pulled from peoples cars and off of the net are 100% boost, actually they read 200% boost from GM.

 

Nah...I just checked it out, it's actually 200% boost. I just got jumbled.

 

previous owner did some tuning but flashed the stage 2 tune back in when i bought the car. no clue as to what version of the stage 2 tune it is.