How far can you go with a stock prom on a TPI based car? A long time ago, with my old TPI I had to go carb, due to lack of tuning ability on a prom burners part. I had two chips burned from [a sponsor] and both ran worse than teh stock chip did, but the stock tune would not idle at all. It would periodically idle up and down and then die going down the road. The cam was a very baby cam 224/230 on a 100 shelf grind from comp. I never could get it to idle and after 2 chips I gave up after a certain tuner told me the cam was too big.....??? So, IF I were to pick up another TPI car should I go ahead and go DFI or is there competent tuning available?

Thats a BABY cam....I had nearly as much cam in a 305 with TBI on it.

My G20 vans current 350 has almost identical specs at .050"....Ported Vortecs....TPI....Running on a later model TBI PCM from a 1995 Truck....My own custom calibration in it.

Yeah I know, As far as Cam's go, I had to ORDER that cam because we never kept things that small in stock. I don't know what the deal was but it rarely ever idled.

I see you are from Hurst, I used to live in NRH and graduated from Birdville. Cool to see people from places I know.

I am going to assume it was probably lack of fine tuning. My engine wouldn't even run on the Stock Vette prom when I was running the 7730 ECM. It would crank, fire, and almost imediately die with a nice backfire from the TB.

Yea Birdville is real close I had a few friends that went there, I went to Bell. I actually live across town by Trinity now.

The aftermarket tune I got burned more fuel than a refinery, and foulded plugs like it was going out of style. I tried one more time with this tuner and that one wouldn't run at all. After that, I called another tuner who immediately said that cam was too big for TPI cars. SO I went carb. Shame.

That is a shame... Sounds like they were just tossing extra fuel/timing at it rather than altering the shape of the fuel tables. A big cam idles at a different spot in the fuel map than a smaller cam does. My 305 ran with like 8 in/hg of vacuum at 800 RPM, in DRIVE with the A/C on. I had a 230/236* duration cam in it on a 114* LSA with like .480/.496" lift. I passed the emissions dyno test with it.

Who was the tuner?

Me

Ah I see, I did not gave access to the tuning software myself as we did not hardly ever see TPI cars in the shop, since we were primarily an LSX shop.

LSx engines are nice and can make killer power, but I still like the snappy low-end torque of a TPI just driving around town.

Another thing I have played with is an 0411 LS1 PCM running a TPI engine using an 02 Express Van L31 Vortec tune and electronics.

I am going back OBDI because the OBDII stuff is not as defined as the older stuff and its not as easy to completely dial in when you have tables that are not defined 100%.

Yeah don't get me wrong we did a ton of SBC/BBC/SBF/BBF and Modular stuff, and of course LT1 stuff because I was the resident LTX guy, but LSX was/is the primary market. And our record setting shop car was an LSX car. I gave the TPI a shot, but as little experience I had with it I could only go off of what I was told by other tuners which was to give up basically. Now I am currently selling the empty iroc-z shell and grabbing something else.