I have a TBI 350 in a 95 S-10. pulls very strong up untill 3000 rpm then it stubles and hesitates but still will rev past 3000, just barely. the truck came with the TBI 4.3, but it has the bastard VCM that isn't programable. i'm looking for a solution without changing to a carb... timing is set at 6* initial 32* total. i'm using a mechanical/vac HEI thats custom wired for the FI to work. the thing i don't know is weather the engines leaning out, or running too rich. i don't have access to a wideband to check either. the injectors fire in proportion to the dist reference signal and when i go WOT it sprays continously like it should. i'm using a stock 4.3 TBI unit with stock injectors. i had 350 injectors in and it was running very rich at idle and still stumbled at WOT. the engine is a stock LO5 350 with a RV cam specs are 401/423 lift and 194/204* duration @.050 with a 104 LSA. i need to find out what computers are programable that will plug right into my stock wiring harness so i don't have to change everything. anyone can help i'd appreciate it thanks

 

What are the numbers on the ECM/PCM? Consider converting to something else? If it has 32/24 pin connectors, EBL will slide in with maybe some repinning of the two connectors. If it has the blue/red 32/32 pin connectors, there are likely def. files for it. Worst case would be that you would just switch to another mask like the $0D or $0E and tune with that.

 

16184738 is the service number on the vcm which is under the hood and has 3 connectors plugged into it.. i know i need a computer from a fullsize with a V8 and it'll run perfect, but i really want to avoid changing all the wiring harness and all that. if i can find a computer that will simply plug in or even if i have to repin the connector thats fine...i asked this guy who does dyno tuning and he said i should either oput a carb on it, or change everything to an older computer. i can get a camaro tbi computer but no plug or wiring harness to splice into. so that won't really help either. i drive this truck everyday so i need it to run better then it does.

 

anyone?

 

Got news, the 1995 S10 4.3 TBI should have an underdash PCM, a variant of the "427". That PCM was used in lots of fullsize vans, trucks, suburbans, etc. Are you sure you are not looking at an ABS control module or something. I will admit though, I don't know every ECM that GM used, its possible they had some weird one year thing going on.

 

thanks for replying. no my truck has a vehicle control module which is under the hood. little black box with 3 plugs. on top of the coolant recovery tank. i think what i need to do is find out if the vcm from a 95 k1500 350 5 speed 4x4 uses the same plugs. problem is finding one to look at it and compare.

 

Ok, never seen one, but it is possible. I know that a fullsize Chevy truck will NOT have a VCM. It will have either a 427 PCM or one of the earlier TBI ecms with a re-mapped code.

 

the first thing i would do is change your fuel filter. this happened to me when i swapped to a 350. took it to the track and as soon as i hit 3000 it went really lean. to the point where it was lean misfiring. changed the fuel filter and the problem went away.

 

The fuel filter is the least of his worries right now. It is only running 46# injectors, where a stock 200 HP TBI 350 uses 61# injectors. The PCM is also not operating correctly, because it falsely believes that it is still running a V6 engine and running a V8 on that makes the VCM recieve TWO additional distributer reference pulses each distributer rotation, and makes it believe that the engine is going in 4/3s speed. The VCM sees it as a V6 that is running at a higher RPM.

 

correct. problem is i hate wiring, and i'd really like to not have to rewire the whole truck, but it looks like i'm going to have to do that anyways...it seems that fullsizes didn't use the underhood computer/vcm till 96 or up vortecs, and that won't do me any good with a tbi engine. hmm to carb, or to change computer and wiring. hmm decisions, decisions