I put a 96' 305 vortec motor in my 88' truck and ran a vortec carb intake with an adaptor. This motor has no EGR, smog pump, or catalytic converter. The motor runs strong and most people don't believe me when I tell them it is a 305. The only problem I have with the motor is it wants to stumble off idle and will pop through the TBI. Sometimes I am able to change my throttle position and it will take off. Other time it will act as though it is running out of gas and it will very rarely stall on me. I have the EGR solenoid still hooked up and I have the O2 sensor in the Y-pipe. I replaced every sensor on the motor, new fuel pump and filter. Changed throttle bodies. I had a 350 throttle body on it and changed to a 305. The best combination I have run is a 305 throttle body with a 350 computer. I have the timming at about 6-8 degrees advenced, if I go any more it will ping, if I go any less it will act worse. I have not received a code from my computer. I have herd many things please let me know what you think. I have herd that the vortec cam is too big. The plenum space under the throttle body is too big. The EGR is not there. And the O2 sensor is in the Y-pipe not in the manifold.
Thank you very much for your help and your advice.

 

ive got the same problems only a little worse with my 350 vortec in my 93, i ordered a cable to plug into the diagnostic port to tune it so i'll see if i can straighten it out like that. if not i'll probably play around with the fuel pressure.
BTW: im also running a carb intake and headers with no EGR

 

You need to jump over to the DIY PROM forum and read up.

 

you probably have an intake leak or you valves springs are bad. usually the most common reasons why it does that atleast non-computer wise. mine did that all the time when i did heads and cam, and it ended up being that the cam didnt pull enough vacuum and the tbi intake wasnt sealing properly because i has a set of world heads. you have to drill the intake bolts to make it alighn and i fixed the problem. Somewhere to look i suppose. Hope that helps.

p.s. i ran a lot bigger roller cam in the motor before. took the whole motor out and put a stock motor with a roller vortec cam. runs really smooth and good, good for towing, "yes its a truck", it has no chip or tune what so ever. wish i could find a good set of vortec heads and the carbed intake and adaptor.
The other motors for sale all brand new internals, roller .462-.470 cam, sounds mean and lopy, torquer II heads ported. roller rockers

 

you probably have an intake leak or you valves springs are bad. usually the most common reasons why it does that atleast non-computer wise. mine did that all the time when i did heads and cam, and it ended up being that the cam didnt pull enough vacuum and the tbi intake wasnt sealing properly because i has a set of world heads. you have to drill the intake bolts to make it alighn and i fixed the problem. Somewhere to look i suppose. Hope that helps

 

Is the poping backfiring though the manifold? You're probably going lean and need more fuel when you get into it. That is correctable with a new chip and chaning your delta tps/fuel table.

Your tune is out of whack, Im sure of that because my **** was all ****ed up when running the stock chip and we probably have similar combos.

 

Chuck, they can't be similar, he doesn't have any of my parts