Various questions - NJFBOA - Home of New Jersey's Camaros and Firebirds

JerzyIroc · 03-24-2008, 05:31 PM

Well my first question is in regards to the tpi computers. do the 305 and 350s have the same tpi computer? second question is the throttle body coolant bypass free mod ive ben hearing about. mine is leaking from that hose so instead of getting anew one i figured i'd just do the bypass thingy. what exactly is involved with the bypass free mod? will i have any driveability issues? Another question is about the 9th injector. Ive been having a bit of a problem lately and i dont know maybe it involves it, let me explain:

When i first got the car i noticed that under a cold start it would turn on but idle really rough for about 3 seconds or so, then start idling perfect. about a month ago i noticed the fuel pump wouldnt turn off when the ignition was off unless you slammed the door shut or something. and the pump wouldnt turn on when the ignition was on either, it would take like a second or two of me cranking the motor that itll finally turn on. well about two weeks ago i noticed that now even when slamming the door, it still wont shut off. i have to pull a fuse out from under the hood for it to turn off. NOW, ever since i changed the alternator, instead of it just taking like 2 seconds or whatever to idle good, now it takes more than 6 attepmts to turn the car on. itll turn on then just shut off. or idle like CRAP then shut off instead of just idling rough like it did before.. hell today it took like over 25 tries. i left it alone for about 15 minutes. on the second try it started righ tup idled perfect like there was nothing wrong. now i dont think the alternator has anything to do with it but it did start happening since then. hell i dont know if the pump not turning off the right way has anything to do with my starting/idling problem either. its just things that are happening around the same time u kno? as far as the other qu3stions they're just random questions i had. any ideas? could the fuel pump relay be bad?

Tru2Chevy · 03-24-2008, 07:55 PM

Can't help you with the 9th injector stuff, but the TPI 305 and 350 computers are often the same, just have a different chip in them to compensate for the differences.

The TB bypass mod shouldn't give you any noticeable difference. All it does is keep the warm antifreeze out of the throttle body, so it should keep intake temps down a very slight amount.

- Justin

V · 03-24-2008, 10:36 PM

there are several model number for tpi ecms, but they are year specific for the most part. 86-88, 89, and 90-92 i believe. first was mass air setup, then mass air with no cold start then finally speed density. Engine size was determined only by the chips plugged into the ecm. in the 90-92 V6 3.1L cars the ecm is the same one as the 90-92 TPIs, just different chips.

as for the fuel issue, yes, i would suggest swapping out the fuel pump relay. its right on the drivers corner under the hood. Perhaps its sticking, and the slamming of the door would help release it. It doesnt hurt to try first.