Blacklt1ta1

i changed the opti to gm i changed all plugs and plug wires brand new TPS. BRAND NEW PIGTAIL FOR THE MAF.. MSD COIL AND Ignigtion control moduel.. new fuel filter.. EVERYTHING IS BRAND NEW and it stilll runs like a dog.. it just doesnt have any power what so ever. i can barely spin them in first and i have a fully built 355 i dont know whats wrong it ran perfect when i had all the old parts on it but then it started running like crap so i replace pretty much everything on the car and it still runs crappy i dont know what it could be..

Injuneer

Might want to start by listing the significant parts that you changed. Might also want to provide basic info about the car, like year, model, tranny, engine and any major mods. Use the "Signature" field.

Since this appears to involve a rebuilt engine, provide specs on the heads, cam, intake and exhaust system.

Blacklt1ta1

96 Trans AM 355 Ported intake,T-56 Tranny, Stage 3 clutch, 52mm holly TB, Ported and Polished Heads, Forged JE flattop pistons, JE rods, 30# SVO injectors, walbro 255 Fuel Pump, PCM forless tune, things i just changed out because i thought that was the problem is NEW: GM OPTI SPARK, MSD COIL,IGNITION MODULE, TAYLOR WIRES, NGK SPARK PLUGS, THROTTLE POSITION SENSOR, PIGTAIL FOR THE MAF, FUEL FILTER.. i just got it scanned again and here what is says.

1.p0100 obdII The pcm has determined that a malfunction exists in the electrical circuit for the mass air flow or volume air flow sensor. this code points towards a possible wiring problem.ie: short to ground, short to power, or an open circuit.

2. p0123 obdII the pcm has dtermined that the input from the throttle position sensor is higher than expected for the current engine operating conditions. which i just replaced it like 30 min ago its new..

those are they codes could one of those be a reason why im getting so big of a power loss. i mean huge loss i can barely spin them in first gear..

Injuneer

Key on, pull the harness connector off the MAF sensor. Measure the voltage across the pink wire and the black/white wire. Should be ~12 Volts. If the MAF sensor or the wiring fails, the PCM defaults to speed-density mode. In a stock engine, it will usually not be noticeable. In a highly modified engine, unless the tuner got the VE tables dead on, the engine may run poorly in speed-density mode.

With the key on, and the harness connector still on the TPS sensor, probe the voltage between the blue signal wire and the black ground. Should be between 0.20-0.90V at closed throttle. 0.67V is a typical stock voltage, but with your 52mm TB replacement, its not likely you are getting the stock voltage. Now start to open the throttle blades slowly. Voltage should slowly increase to about 4 volts higher than the closed throttle voltage. At no point should there be any sudden spikes, either up or down. Voltage should increase smoothly. WOT voltage should not exceed 4.90 Volts, because that is the voltage that triggers the code.

Blacklt1ta1

i checked the volts to the MAF and its reading 11.41 volts not 12.. when i stated the car and checked it it went to almost 14 volts

mdacton

thats good enough.


Stop replacing **** and start diagnosing......you may or may not get it fixed by throwing parts at it, but you sure will waste alot of money....

Hot rods are not always easy

Blacklt1ta1

i know.. i have spent alot of money lol.. its just my car has been down for so long and its so frustrating thats its not running like it use to.. im starting to think it might be my rear end.. cause the car will idle and rev fine.. when i jam on it feels like the right rear side raises up alot while i dont feel much movement from the driver side rear feels like only one wheel is spining.. but still i dont know i have a TCS switch in the car but its not hooked up previous owner disabled it so its always posi is there a way that its back to one wheel wonder? also i forgot to mention just rememberd my brake light is on in the dash like when you pull the ebrake.. it never use to come one and recently it came on i check my brake fluid but its full and still it didnt go off so is it telling me that something is wrong with rearend or what could that be i checked all the fuses also and all of them are ok..

Injuneer

The "BRAKE" light is supposed to come on when you pull up the E-brake. That's one of its 2 purposes. If it stays on when you release the E-brake, it means there is uneven pressure between the front and rear braking circuits. That can result from air in a line, fluid bypassing between circuits in the master cylinder, or a leak in one of the systems. It has nothing to do with the brake fluid level, other than that low fluid will put air in the line. It also would not come on because you had a problem with the rear axle assembly or posi unit.

What do you mean by "its always posi"?

maverickmk

just a thought, what kind of rockers do you have? could the nuts have loosened up/backed off some? I'm just thinking out loud that maybe if the lash is off then your not getting all the cam (?)

mpe331lx

Was the cam degreed in?

Blacklt1ta1

yea im pretty sure the cam was degreed in.. and what i mean about always posi is my TCS switch was eliminated and its always off.. meaning my tcs doesnt work.. they are 1.6 rockers but im not sure what brand. how would i check them just pop covers off and see if any are loose.. i dont really hear any valvetrain noise.. all the volts are correct to the TPS and MAF so that might be what it is cause the power was there before then all of the sudden i have a HUGE power loss like i said i can barely spin them in first gear and its a built 355

Injuneer

First you complain you can hardly spin them in first, then you indicate that you appear to be doing one wheel spins. I think you have to figure out which end of the car has a problem first.

If your TCS is off, you have the same "posi" that everyone else has. I still don't follow what you mean by "always posi". If you are getting one wheel spinning, the posi is deceased. Has nothing to do with TCS.

But there would seem to be a huge difference in the "feel" between an engine that is seriously down on power, and a broken posi.

maverickmk

put the rear axle on jack stands, put the car in neutral and turn the drive shaft by hand, it shouldn't be very hard to turn

83tpi_3rd-gen(sri)

i totally agree here,a dud motor and a dud rear diff are going to feel nothing alike.if your posi was going out it would still spin the one tire with the same force that it used to spin both with.i know for a fact that the car never had TCS on it(its a buddys old car),its a 96 with a 98-02 center console so its just there and does nothing.

The_Bishop

TCS has *nothing* to do with the limited slip differential working.