hi i have an originaly 305, i have just built a 383 .502 .510/ 224 230.@ .050/ lobe sep 110/ 190cc alum. 10.2-1comp. fired it up got the timming set. its running realy rich, i believe this is because of the low vacuum or am i mistaken??? what doesnt make sense is the exhaust is wet coming out the tail pipe??? it dosn't seem to be misfiring, the plugs are all dry, black but dry. It also back fires now and then when your driving it (-50kmh and just short drives half a km or so) i know that my tbi is to small, and the pcm is going to be a problim, but im thinking that i should be able to get it to run good enough to drive for now, or am i mistaken? any help would be great.

 

It's going to run really bad without tuning. When I did my head,intake, and cam swap my car ran like dog crap. After 8 different prom's and switching to a holley tbi it still wasnt great which is when I went to carb. So with you upping the cubes and everything else it's not going to like it. It can be normal to get condensation out of the tailpipes.

 

Get the EBL Flash for tuning, http://www.dynamicefi.com/ burning proms if u ask me is a thing of the past, the EBL has something called VE learn that pretty much takes 50% of the tuning task and does it for you, its gonna be tricky to tune but a 383 TBI is doable , theres others 383 TBIs outthere. And why you are running rich, well that might be cuz the stock tune cant handle all the extra stuff added, but its strange that it runs rich when i should expect it to run lean on a stock tune.

 

Are you in closed loop? May not be since you are not driving sufficiently to heat up NB02sensor. You may need a heated NB02 sensor. Or run WBin place of NB for feedback to ECU. That cam will need to be addressed in tune. Reversion. However it is workable. A WB02 would make it much easier. As would open loop operation with WB as a tuning aid.

 

ok, should i be able to drive it as is, without hurting it? walking to work in this -30oc is getting old lol

 

May pollute the oil...And foul the plugs...

 

ok. so would you you say that i can make it run to its full potential with a tbi setup or am i going to have to go carb?

 

just wondering if im going to spend a bunch of time trying to get it to run properly with the tbi and then having to go carb in the end anyway.

 

Probably so. It wont happen in a weekend of tuning. But then again a carb has pros-cons. Do your reasearch.

 

k ive spent days on the computer trying to find answers to to my problims but found sum saying that there wouldn't be enough vacuum to run a map sensor for a tbi and some saying that it could be done. was looking at that flash ecm but the tuning looks fairly involved for me to do without help and its hard enough to find help and even harder to find help that will come to where the truck is. i don't mind spending time doing the research on the tunning of the ecm if i knew that it would work in the end and not have just spent five hundred bucks and a bunch of my time for nothing, and if i could still drive the thing well i was tunning it. so gues im wondering if there is any one who has a engine close to the same that runs a tbi setup

 

hey how r u i was wondering did u put that lt1 cam in your self im getin a lt1 cam for 25 bucks plus z28 valve springs to the cam only has 80,000 miles on it can i have so imput on how hard it is for a first timer?

 

A WB02 would make it much easier. As would open loop operation with WB as a tuning aid.[/quote]

could you explain this more please.

 

I will say you need an ECU that can handle your needs related to vacuum. Issues will be low VAC at idle and no load conditions. see dynamicefi.com. Send them an email.

Also an option is to use existing ECU and run open loop only with no NB02 feedback. OL should be ans to VAC issue. Then that requires a WB to tune those basic tables. Above ECU allows idle at OL only and then NB use off idle. I run mine in that fashion. Not all ECU's allow that function.

You may not want to bother with the learning process needed. I consider it a hobby and my car is not a daily driver. Carb may be less hassle.

 

see dynamicefi.com. Send them an email. quote]

did this already. it just seems like a complicated system

 

You may not be the guy for EFI tuning, it does take some discipline, not everybody's got it.

 

i wouldn't mind spending the time if i could have it aleast good enough to drive around. The truck is in my grandpa's shop twenty miles away and i have no way to get there unless some one else happens to be going there and then i can't realy do anything anyway i don't have a code reader and no way to change what its doing. and if i got a EBL flash system would i be able to do just a simple tune that would be kinda fast and easy so i could atleast drive it, then atleast i can work on it after work every night rather than a few hours a week

 

Once the EBL is onboard, (as easy as unplugging & plugging back in your ECM if you get one already installed in a c3) set up & tuning is done with a laptop & TunerPro (free). Truth be told more than one of us has run a 20' phone cord to our EBL from a desktop in a pinch.

Mind the fact the TBI should be modified for the increased demand of the 383, ideally IMO increased to 46mm w/fuel pressure regulator modified for adjustment. This only because the stock 43mm TB fully modified might be pressed to cover your 383 when she's wound out. You do NOT need a 50mm or larger TB. Your 383 needs less than 600cfm @ 6000rpm.

These guys do a great job http://www.rvmorsemachine.com/

You can mod, tune and run your existing TB with only the very top rpm compromised till everything fits in the budget if that is the case.

 

buget isn't the problim, its just time, and its not realy a problim, just an inconvenience.

i thought that the 305 and 350 had the same size tb, 350 just had bigger injectors nough?

i gues another quistion would be if the the EBL creates fake fuel maps for the engine to run off of does this cut down on the efficiency of the system, thus eliminating the advantage that it would have over a carb? or does this only have affect at idle?

 

The VE tables are not fake maps, it's what your engine needs as far as fuel goes, tuning IS NOT THAT HARD!!!! It just has a little bit of a learning curve. Without the EBL I wouldn't have been able to even start my car after the H/C/I swap. The TBI units are the same between engines but the injectors are different. If I were you I would step up to atleast 61lb injectors and get a good fuel pump to deliver the fuel. A TPI pump will work fine for you.

To help you get a true start on tuning you NEED these.
a good laptop
a good WB O2 sensor. I use the Zeitronix ZT-2 and it works great
And the EBL Flash of course.

Very simple, very easy.

Then once you get these I would try to find a BIN that comes with the EBL to get you started, Rbob will be more than happy to help you find which one since he created the program. After you get a good base line do some VE learns to get the fueling close enough to a passable running engine then manually smooth in the table to get rid of possible surging that might occur when the VE is a little askew. Pay close attention to the WB to monitor where the engine is running rich or lean and modify the VE tables in this respect. That should help you at least get started.

I myself run in OPEN LOOP only. It takes a little of the headache out of tuning. Closed Loop is more for an emission stand point anyway. I don't have my laptop at hand because I could show you what tables to play with.

 

what is the difference between open loop and closed loop?

so a TB like the holley 670 would be to big for this setup?

 

IIRC Open Loop is when the engine is running on what the sensors are telling it whats going on, without NB O2 input, Closed Loop is when the computer is trying to "force" the engine to run at 14.7 afr as much as possible. As far as the 670 I think it might be just right for the 383, alittle to big for a 305-350. It really depends on the operation of the engine. How high do you want it to turn?

 

ok so its the type of ecm, so the ebl flash is an open loop? or am i still not understanding? would there be another type of vehicle that would have an open loop ecm that i could put in my truck so i could drive it till i got a ebl flash? or would just putting in a open loop not make enough difference for me to be able to drive it?

well i would like to turn it as high as it is going to make power, im thinking bout 6000ish

 

No, Open loop is a type of operation, not an ECM. ALL ECM's have both Open loop and Closed loop operation, it just depends when either or if is being used. You can use the EBL for almost any OBD1 GM vehicle if I recall correctly. Just go to www.dynamicefi.com and read up on what all you can do with it. Once you get it just follow the steps provided in both Rbob's site or look up the "tuning with the EBL" thread in the DIY Prom section. Just to give you any idea of what you can do to get started with open loop tuning is once you get all your tuning gear and tunerpro rt in order open a BIN in tunerpro rt and go to the.......


Closed Loop CTS Threshold......

in the "Constants" and set the dial all the way to 151.25 degrees Celsius to turn off closed loop operation.


INJ Constants...

Set all these up high to shut down Async mode.


Open Loop Options

Turn these on by pressing the check button

Open Loop Tables

These are the tables used to "command" the ECM to run in open loop, helps the VE Learns out a touch, I know how to use them but someone else might be better suited at explaining them.

That's it as far as open loop as far as I concerned. There are some other things that are entailed in this but like I said go to Rbob's site and it tells you in further detail

Go to the "Introduction to Tuning, parts 1 and 2" @ dynamicefi.com and read up, it's VERY helpful.

 

make sure you don't have a vacuum leak at the IAC, that will cause a lot of headaches.

 

IAC?

would the fuel pump from a vortec engine work?

 

Idle air control valve. I had a leak at mine and it ran horribly.

 

It would, I believe the ones for the vortec trucks and LT1 cars are one and the same.

Here's the pump that myself and many others are using
ACDelco EP241 TPI fuel pump

 

ok, but the pump on a vortec truck is going to give me higher presure right, because i have one that i can use if it will work.

ok where is the iac?

 

The IAC is located on the TBI unit next to the Throttle position sensor on the passenger side of the throttle body. I believe the vortec pumps flow the same as the tpi units.

 

so it isn't any different then the pump i have now?

well now the truck doesn't even wan't to start, and i havent done anything?
it was running the last time i worked on it, and every thing seems to be pluged in, oh well one step forward two steps back lol

 

Make sure your base timing is set with the est connector disconnected.I would set it to around 6 degs base timing and lock it down.If you get EBL make sure the 6 degs is entered in the intial timing box.You will understand why as you learn more about EBL.Im still tuning my 383 with EBL and enjoying every minute of it.

 

how radical is your engine?
how long did it take you to get it good enough to drive?
the macanic that helped me build the engine says that the stock computer should run the engine good enough for me to drive....?

 

You won't even be able to start it I promise you. There's no way around it,you have to get some tuning software and tune. Your MECHANIC is an idiot.

 

well it does run, just not verry well.

i read some where that an air gap intake shouldn't be used with the tbi, is this so? because thats what i have

 

The Air Gap is no good for TBI, TBI actually "likes" a heated manifold for better fuel atomization.

 

why wouldn't a carb like a hot intake then?

 

ok i was reading a sticky that fast355 had written and it said that the pcm in all 93-95 trucks were one of the better ones to use the only thing was they couldn't be used with forced injection, so would that mean that i wouldn't need to get an ebl flash, or am i misunderstanding?

 

Robert is right on. The mechanics of TBI disallow air gap as fuel falls out of atomization and the wall wetting necessary is problematic.

That PCM is most advanced in GM line for TBI. Search for posts on it to learn more. EBL however is possibly way better especially for a novice. EBL is more than an ECU it is also a tuning system. With automatic leaning and .bin creation off learn. Also supports WB use in logs. And alternative induction(me).

 

My cam is the next step down from yours 218/228 duration.With EBL it wont take you long to get it drivable.Just have to do alot of reading on
it and get the hang of it.You will like what it has to offer.Stock ecm may start it by feathering the throttle but thats it.I wouldn t drive like that though

 

It can work fine...it is what I'm using very successfully on my big block.

No not everyone can tune for it & those who can't tend to make up reasons why not.

 

My experience is that the tbi can suffer throttle plate icing during warmup at freezing temperatures on any unheated manifold.
Once warmed all is well.

 

ok so is it going to cause real problims at -40 weather?

so your saying that is hard to tune in a air gap?

 

I would NOT advise using an Air Gap @ those temps, you are just asking for problems.
For temps that low you will want a heated manifold.

How difficult a task is for any individual is directly related to their education, experience & comprehensive understanding.

 

ok now why does it work on carbs ond not the tbi?

 

Why do you think it works on carbs at low temps? Same issues develop. I will say the air gap is for producing max power at warm environmental temps carb or EFI. there is a point where the incoming air is just too cold. I witnessed that at not so cool temps this past fall with use of N20. Now the mechanics of TBI differs from carb so it may be the carb is a bit better in that regard but still suffers the effects.

 

well every one one was saying that is was no good for (TBI), and i see lots of them on carburated cars and trucks out here.

it wouldn't see -40 more than once or twice a year but-30 would be most days for four months or so.

 

After reading this thread, I think a carb might be a better option for YOU.(I can't belive I said that). It will get you running pretty good, fairly easily. If you think the EBL is complicated, FI may not be for you. Even with the "late" truck TBI, ECM, you still have to buy tuning equipment, and learn to tune. And not to bash here, but I don't think you chose your parts very well for a TBI build. Can it be tuned? Yes, but it would be difficult for a novice.