okay, here goes, 1988 firebird with 305 roller motor, 102,000 miles. bought this car sight unseen from a family member. had it towed in and fired it up for the first time only to discover the retched smell of fuel. Removed the fuel tank and had it hot tanked. reinstalled it with a new fuel pump and strainer, as well as filter. fuel pressure at the filter is 20 pounds. fuel pressure at the throttle body is 18-19 pounds. installed new plugs wires cap rotor coil. egr is found to be stuck, in which direction, i dont know. but the fuel was being dumped into the throttle body and straight out the exhaust. when i hit the gas, it was like turning off the key, the engine just dies down but fuel continues to spray. i opted to remove the computer and found it to have a "super chip" installed, so i visited many salvage yards looking for the correct computer for my pontiac. i found a computer out of a throttle bodied truck and installed it and it helped with the fuel problem, but i still cant get past the throttle problem. when i tromp the gas, its like the engine isnt getting enough gas or air or something. barely touch the gas and the engine comes alive. tromp it down and it stutters and trembles. any suggestions?    

i should also mention that the vacuum is good and the idle is shakey between 700 and 1000 rpm. also, when trying to start this car on cold start first thing in the day, you have to crank on it for a while before it finally takes off.  

First off, replace the TPS sensor. I'll put good money on it being bad. The second thing is, it sounds like the fuel pressure regulator in the throttle body has also gone tits up on you. Change it out as well. Also, because of all the fuel fouling, it's a good bet the O2 sensor is toast.

I've got a '92 Silverado with a TBI system, and a '92 Camaro with the same. Also, don't be afraid of the aftermarket computer chip, that probably wasn't the problem.  

Fuel pressure should be 9 to 13 lbs.Pressure regulator is probably bad.But you could still have the wrong prom (chip). The computer out of the truck may have the same service nunber but the chip is programmed to the car.Look on your original computer,theres a label.The prom number is four letters.You'll have to go to a dealer to get the right one.  

i have a complete throttle body off of another donor sitting in the garage. ill try it tomorrow and let you know how it does. also, after doing some checking into the prom chip used, my brother in law says he ordered one for a chevy truck 350 motor. bad or good? i guess i should just iron out the whole running thing first then worry about performance after getting back to basics.  

tried the donor throttle body. it helped the fuel consumption but i still cannot hold wot. i also noticed that the wire to the o2 sensor is burned in 2. i replaced the burned wire with a spare piece i had laying around the garage and spliced in between with butt splices and shrink tube. this should be ok i hope(?) any suggestions as to why i still cant hold it wot?  

just curious.... how are you testing it at WOT.???

the computer will not let you operate the motor at wide open throttle in park... it may the ecm limiting the speed of the motor...

they do that on other TBI cars..  stops people from blowing the motor and the transmission.

do you have access to a scan tool....

and i am thinking ... there are also filter screens around the TBI injectors to stop debris from getting in...

and you really want to place a short length of hose over the larger fuel line when you have the tbi unit off...  put the open end in a plastic container.. cycle the key on and off a  few times without starting the motor.. the pump should run for 2 seconds as you turn the key on..  this will let any debris flow out of the line before it can get into the new pressure regulator.    and a 5.0/5.7 TPI fuel rail O ring kit has enough large and small o rings to replace the orings on the entire system..

when fuel line and fuel filter orings wear.. the cross section becomes D shapped ..  the fuel pressure can get by resulting in a leak..

the O rings also have to be the correct material..  they will be if they come in the 85 to 91 TPI fuel rail kit..

hope this helps....  

while the car is running, in park, i punch the gas and it spits and sputters. i can drive it down the road and same thing happens. i tried manually downshifting into first and stomping the gas but it still bogs and sputters. i have an obd2 scanner(which wont help in this situation) and a cool azz autozone code key. woo hoo...  as far as rebuilding the throttle body... im in process of finding a suitable kit for this venture. ive never had one apart, and i hope its as straight-forward as everyone says. i plan to complete the rebuild with a new pressure regulator etc. hope the kit comes with all of the aforementioned. i removed the fuel lines the other day and noticed the o-ring on the supply line is cracked. so all will be replaced. also found a stocker ecm on e-bay at a reasonable price. im going to try this as the ecm that came with the car is missing the paper tag.  

one more thing...   while you have the throttle body off..   or before you do it...

pull the dist cap and rotor..   take a bright flashlight if it is dark down in the housing...

see if you can see the reluctor ...  look carefully... it is riveted on.. there is a ceramic magnet riveted into the assembly on the shaft... if you see cracks in this magnet.. this might be causing many of your problems...

when these magnets crack...  instead of a nice smooth sign wave to the pick up coil... it sends out ramdom waves...     the sign wave from the pickup coil is used to trigger the next coil pulse.... not this one except when below 400 rpm...   so ramdom pulses thrown into the signals to the module and ECM really foul things up....

i take it that you have a timing light...    can you put it on various spark plug wires and watch the pulses... see if you are getting stray pulses in the nice steady flashing of the timing light...  the poor mans scope...  and really handy to know..  and since scopes start at $1,000 for a cheep unit..  a 30 buck timing light works well..

try it over the coil wire also....




on the throttle body....   check for throttle shaft bore wear...  engine off.. open the throttle a bit with your hand... then wiggle the throttle lever and see if the shaft moves in the bore...  this wear usually wont result in drivability issues other than turning on the check engine light and some idle stability problems.....  

cracks...? this thing looks like its been to the rehab center and back to the crack house quite a few times!!! sheesh. thanks dude. now, i know its called a reluctor, and now im reluctant to change it. it looks like an aweful job. does the distributor need to come out? maybe a step by step please? or a link to a step by step? i would like to rebuild the whole distributor if this thing looks like this, id like to refresh the whole kit n kaboodle.  

Did you change the TPS sensor? If there was one of the donor throttle body, it could be bad too.

The prom for a truck could be the problem. The car's had emissions equipment on them, the trucks didn't. Also, I'd have the ignition module tested. Autozone can do that for you.  

received an ecm via e-bay special and installed it. perfect.    couldnt ask for anything better. everyone was right. i guess i am just a worry wort. this engine revs like an angry demon outta hell. speedy up and down. perfect. still hard start at cold start but i think this is due to the worn o-rings on the fuel lines. thanks guys for all of your professional help. perfectionists, you all are!  

i would definitelyt still rebuild the tbi. it is so cheap and easy. and with the mileage you have on the thing it wouldnt hurt anything for you to rebuild it. it will only help.  those gaskets fall apart bad.   you should do it.  auto zone sells the kist for like 30 dollars and it will take you less than 2 hours to pull it, rebuild it, and reinstall it.  you should do it.