billdawg23

my 305 tbi is still running like a dud after replacing cts, plug wires, cap, coil, rotor. I dont get it, the exhaust even sounds stupid like a dud is the best i can explain it. Just sounds like junk and out of tune bad. The car is lacking any throw you in the back of the seat power too. When i floor it dont really take off very fast, sorta takes off like a 4 banger cavalier would. What may be the problem this is making me so mad!

billdawg23

one thing i did notice car was having trouble starting till i hit the gas the other day which leads me to think fuel problem? fuel filter??

billdawg23

so nobody has any idea of what it may be? the timing?

Fredless

Run some STP Complete fuel system cleaner in it, unless you do that already.

YES replace the fuel filter. Take off your air cleaner and watch the gas spray into the throttle body, see if its flowing ok and the throttle bodies are clean. You also did not mention anything about an O2 sensor or plugs. My 305 ran like CRAP before I replaced the spark plugs, which 5 were fouled, badly. I bought the gimmicky do nothing Bosch +4's but I didn't have to gap them and the car has never run better.

Timing is adjusted by your computer chip, to my knowledge. When/if you do run that Stp stuff through there (use the complete one in the gray bottle, every 4k) run it with a tank of 92-93 octane gas too.

Good luck.

jc33

i would check for computer codes and fuel pressure, paying attention to see if it holds pressure after the pump shuts off with just the key on. if it doesnt it could be bad or dirty injectors or a pump, regulator problem. check plugs and timing with computer disconnected also. i had this problem in a jeep and i narrowed down to bad injector(s) or fuel pump.

Fast67chev

just an idea, I've heard of internal baffles coming loose in a muffler and almost completly blocking the flow, or a clogged cat. This would make it run like crap and sound funny. Good luck
Jesse

billdawg23

well advanced timing but i think its a clogged cat!!!!!! funny my v8 sounds quieter than my friends 3.1 v6 camaro.

Fredless

I got an O.E. replacement Dynomax Highflow cat from Jegs for 90 bucks. Installed it in 30 minutes up on the ramps with a Sawzall. Be careful with the A.I.R. tube, I just whacked mine off and eventually removed the smog pump. Then I took it to a shop and had them weld it in for 10 bucks. Car sounded better and performed better. Good luck.

brharris27370

I got a highly recommended 3" Carsound cat on ebay for $60 shipped. Works great but I was replacing all exhaust for 3" for more performance. The exhaust shop can stretch the 2.5" pipe to that you can use the 3" Cat until you replace the entire exhaust which is always a good modification. If you plan on always running the 2.5" pipe you can get the carsound 2.5" cat for $50 shipped on ebay.

Open_Slot

i got an 86 Silverado and all I did to get back hp was to add Z-Max(you can get from AutoZone).

Man on cold mornings after warmup my truck would have to have a little speed to make it up the small hill to the road(backing out). I put Z-Max in it and now it I barley push the gass and I'm out(I can stop half way up with the engine cold and then back out). I put the Edelbrock 600 caarb in it cause I bent the Q-Crap carb(on mine there is a diaphram to keep the secondary closed) and I can go up hills and not come off the idel jets(I've got it mettered so it gets like no gas comming off the idel jets).

Z-Max added a lot of power to it but it still is slow @ high rpm. Say I'm driving 35 and I immediatly need to be @60 mph, when the gas is fully deppresed it changes down to 1st and until around 42mph. Durring that time it's almost like I'm not really accelerating(cat? just put on new muffler).