I have a 89 Trans am that had a LB9.

I dropped a 5.7L 2 days ago.. and were currently
in the process of getting it to run.

my main question is can I use the current ECM for this 350,
with the TPI setup off the 5.0? or do I have to re-calibrate it? I thought the Lb9 has the same stroke as a 350.. and
everthing else was similar.

Im using the LB9 heads for this particular motor.

 

The ECM will be just fine, but you'll need to do some calibration reprogramming because fo the change in displacement and compression. A stock 350 chip would probably be close, but the compression change is going to throw the calibration off no matter what you do.

Start reading up on PROM burning if you want to get the most out of it.

 

I'm using a 305 PROM with my 355 (because MAF with manual trans, no PROM burning tools yet to get rid of VATS in the later stuff) and although not ideal, it works.

It is certainly not ideal, but I've put over 1000 miles on it with no issues I didn't expect.

It is far from a 305 of that era (different heads, cam, intake, engine size, etc) but as I say, it still works.

 

Yea .. like you said, its not ideal.

im glad itll run get get me to work and back until I sink a chip in her.

so I just get a remanufactured IROC or T/A 5.7L chip?
eventually we are gunna build this motor to be a performer,
but for now ..

hows your performance?? .. does she still get up and run? why would a 305 ECU screw with a 350s performance??

what are the differences?? are they just fractions off ??


I know im in the wrong forum ..

but how expensive is the PROM equipment just off the top of your head??

less than 1G?? without laptop?

 

If the engine is "stock" then a stock PROM should be fine.

I would think that posting/searching in the classifieds here should net you a PROM for cheap. It's where I'd ask for one.

I'm running a 1987 TPI setup.(essentially)

Yes, it gets up and goes. The only person I feel qualified to judge how it runs based on experience and knowledge of engines in general, (although he'd never run EFI) was impressed at how well it ran, and how it gets up and goes.

305 timing is all wrong for the heads I have, (down to 2* base timing to keep out of detonation) exhaust, and the injector info is going to be wrong since it is driving 350 injectors now.

If things are a fraction off, then fractions count. The problems are quite a few in my opinion, but still livable until I get my PROM tuning stuff. Some of this may not be PROM related, but if it isn't, I'll figure it out.

I don't like the way it acts while I'm idling in gear, or if I'm trying to turn a corner in gear without my foot on the gas.

For what I do, the stall saver (if thats what it is) comes in too early.

Idle RPM's are impossible to bring down to where they should be with a manual trans. 750 or so is as low as it will go, 50RPM below that and the engine dies every time trying to set min. idle.

Letting it idle in gear, eventually the vehicle will start to "buck" like you are running out of gas. Some of that is driveline slack, some of it is how fast/slow the ECM is responding to the load on the engine.

Off the line, there is a big hesitation. If I'm smooth into the pedal, it's not apparent. If I floor it, the vehicle doesn't move for a goodly time.

It's not running a cold start injector, so first start of the day is annoying. (trick for anyone living with this: crank engine for a split second, then crank again, it will fire right up)

Fuel economy is not where it should be. Brand new engine, fuel injection, roller cam, roller rockers, vortec heads, full length headers, and my MPG is about what it was carbed with same size engine, exact same vehicle. I've not had a chance to do a full freeway test, but around town, the numbers haven't changed.

Once in a GREAT while, it won't want to start for whatever reason, except with some serious cranking.

But again, these are all "nitpicky" things. It's never stranded me, and it's fun to drive as is. I could start researching what the problems are, but I know there are some "serious" issues that need addressed in the PROM first, and it makes no sense to me to even bother worrying about the above issues. But they do exist, and driveability is one of the reasons I went TPI in the first place.

Last I checked on PROM stuff, you could get pretty basic stuff (that works fine) for around $150-200, like you said, not including a laptop. Now there seems to be an even more choices in the same price range, the prominator being one of them.

 

You can get an AutoProm from moates.net for $400 with most of the accessories you'll need. It'll basically do everything. TunerPro is a free editing program, and a very good one IMHO. Beyond that, you just need the laptop, and lots of time and patience. Check out the DIY-PROM forum.

As far as the 305-350 differences, the ECM's are interchangable. The differences are in the tuning. Different displacement, different compression, different cam profile....these will significantly affect the characteristics of the engine. It's kinda like putting a stock carb on a built engine...sure it'll run, but it won't make the power it's capable of and it won't drive as smoothly as it could with tuning.

 

Ok ok


I gotta one more lil question w/ the injectors.

those 305 injectors wont be good for this motor?
im strapped on cash at the moment and need it to run.
and injectors are bit pricy.. I can afford em, but I know im
gunna run into bigger problems that are gunna need those funds.

either way .. well make it work properly and emission compliant ... i hope


BTW, thanks for the detail Dyeager.
ill be sure to look out for those problems and adjust em accordingly

and thanks for the moates info.

I know about Craig, but Ive never been at this stage of a build before(this car anyway) to even think about buying anything .. we finished assembling the bottom end, total valvetrain rebuild,extremly clean (like new) LB9 heads .. eventually port them. The plenum, runners, and intake were polished to a mirror finish, inside were all clean of the carbon build-up.. serviced the tranny. and dropped her on in.


so this motor isnt new .. its just pretty dam close

everything fresh .. its the best way to go and I did it all on a $600 budget ..

now its all about tuning it