50chevy

iTrader: (2)

I somewhat got the 408 LS1 in my 1950 Chevy truck running today! I primed the oil pump and fuel system and turned the key. It fired off right away for about 1 second. I tried it a few more times with the same results. I held the throttle open about 1/4th of the way and it fired off and was able to keep it about a 800-1000 rpm idle for about 30 seconds and let off the throttle and it died. I know that something isn't quite right so I did not want to push my luck to keep it running this way, so I did not try anymore. I plugged in my pocket scanner and got only code P1518. I swapped the IAC with another one I had in the shop and had the same results. The wiring for the IAC is also correct. I had a local experienced tuner put a baseline tune into the PCM and this is the only time that I have tried to use it. I know that the 1518 code can be assocaited with a newly reprogrammed PCM. Also the engine cranks over quickly and the battery is not sluggish. The PCM is a generic #12200411 and I am running a cable opereated throttle body not drive by wire. I don't have any other scanning devices or programmers. Any suggestions?