Tbi-MAX

okay, so you mean keep the pcvs in the passenger cover (stock pcv pass) and a breather in the driver cover... that would be how my stock setup was... 95.. but i notice on earlier years, its the way you describe.. but ill keep it uniform like stock..

rocko350

correct.

its difficult to track questions and answers in 2 different posts. hopefully i've been consistant with my answers and explanations


just to clerify both pcv in pass side( if desired) and oil fill/breather in driver side.

Tbi-MAX

yea, that will be like my stock setup, pcv on passenger and breather on driver side..

i had to ask, cause you said that from year to year GM was trying stuff, to see what worked best with the low end TQ... the vortec L31 has their pcv valve on the driver side. i am not sure about earlier model TBIs... but i seen quite a few with the oil filler on the passenger side vs my oil filler and breather tube on my drivers side...

but thinking about what you said about the TQ, in 95 the L05 got rated for more TQ by 5ftlbs and went down 5hp .....


well ill set it up like stock and keep it consistent.. i ask, cause i do notice, without a breather on the passenger side, the exhaust smoke was little less.. not sure... even though its not tunned yet, and running rich.

rocko350

my fault i meant that "they" as in fast355 and oldred had tried these things for those reasons. not gm.

Tbi-MAX

its cool... i have the pcvs in the same cover, and breather on my driver cover..

well the truck is at the dyno, babied it 11 miles last night, and i believe it drank 15 gallons or more... i had middle of half and 3/4 tank... when i made it to the dyno, it was 2 clicks above read...

cause of the tune tranny tables, it rarely wanted to shift into 2nd gear.... so most of the trip was 2.5K rpm sometimes 3... hills were hard to go up etc.. but when the map and rpm matched at certain times... it will launch and move out like a bat out of hell... oh yea, the trip average was 20mph!!

the base timing is also set around 6* now.. as well as all the other changes.. i am going up there tonight, to add some more premium to the tank... i think 6-8 gallons might be enough... ?

Tbi-MAX

well this thread needs to update... so here is whats going on... truck is at dyno..

i got the BBC tb working perfectly.. and i got my minimum idle air set correctly... all changes should be found a few posts above...

i got some pictures of how the truck idles... warmed with the new 180*... do note these are without ECU hooked up with timing @ 6*... i did notice with timing hooked up the oil psi is higher, vs ECU timing unpluged.. But i was told my psi levels are still very good and safe. 500 rpm I was at 20 psi i think...

Park Idle


Reverse Idle


500 rpm

500 rpm psi


but yall see my fuel gauge... the 11 mi trip, my fuel went down to 2 clicks over the red without the tune, and i was doing 20-30 mph... BBC tb aint NO joke! but it ran rich.. thats why... cant wait for it to finish tune...

conclusion... the stroker drinks gas in 1st gear! 2.5-3k rpms...

Tbi-MAX

alright guys, i need HELP!

got the truck back, it gave him a hard time... Its a lean spot right around 2kish rpm... he said the 1st tune took 2hrs, and this 1 took about 3 days... Well he also said its the strongest TBI he played with in a long while, and he also had a few tbis tuned last week as well... The exhaust said he felt like it got a extra 50 horses... but he is a bit puzzled with the lean spot.. so i got no dyno untill i bring it back.. the steps he said are: getting it running right 1st, driving it 2nd, and dyno 3rd...

the truck is very drive able, except for the lean spot.. he wants me to put my SBC injectors back in the BBC TB... but i was then told by a close friend the BBC injectors should work just fine (91 454 injectors NEW)

Alvin said since ALL i did was put the BBC stuff on, it has to be the injectors... I then told him i did mess with the PSI, and lowered it estimating it wouldnt need to be turned up that high since the BBC injectors... he wants me to put new plugs too.. Alvin also repined my TPS sensor wire, cause it was backwards.. but the IAC was wired correctly he said.. but the TPS voltage is correct now...

He was surpised my BASE timing was that high the 1st time.. 25*... so we checked my new timing 6*, and it was dead on.. 6* with his gun...

Also on cold start, I have to extended hold the key, and give it some gas on the pedal... it runs and idles perfect once it starts..

What I noticed is that the BBC injectors seems to be spraying alot less, thus no black smoke out the exhaust anymore.. but when the truck does LEAN out, you will see some black smoke...


WHAT SHOULD I DO NEXT?

i plan to do, the plugs... but i was told that wouldnt make it have a lean spot... (friend told me)

I want to change the wires, as they are zipped tied together.. and could be jumping..

He also said, that the PSI could be having something to do with it also.. as I did mess with that..

I also want to turn the PSI up or atleast see where it is now, then turn it up with a gauge to about 15 psi... as that could make the injectors spray bad too... and i never measured my fuel PSI!

the leaks on the intake manifold, are fixed... I just got to get a oil pan gasket installed, and NOT over tighten it this time..

but it will be back at the dyno after the 2nd.. so I would like to know what I should do before I take it up there..

when i 1st installed the BBC tb i did notice it didnt want to start.. UNTIL I messed with the injector wires on top of the pod.. they are a little grazed.. so maybe its arcing or grounding to the long stud the holds the element down..

ohh yea MERRY XMAS to all... lol

BMmonteSS

He's just having problems tuning the off idle area. If you swap the SB TB back on it'll clear right up. The BB tb puts a big slug of air into the intake and air speed is too slow to pull the liquid fuel off the intake walls. He's probably seeing the rich slug right past 2000 rpm when this fuel starts seperating from the intake walls and thinks he's got too much pump shot. The trick is to fudge the VE tables to cover up the lean spot and tune the pump shot around the rich spot.

This is one of sthe caveat of a wet flow system, With TBI you can tune around it. With a carb you're stuck with it.

beatercoprice

Does this Alvin guy know this board exists? Sounds like he should be a member here.

Tbi-MAX

so my problems aren't the hardware.. its definitely in my tune.. (software) related... this is what you guys were saying about tuning myself.... so Bmonte exactly what specifically do I need to tell him to try? i understand somewhat what you are saying, work around the problem... good that it is a TBI...

so let me get this right, even with the SBC injectors in the BBC tb, the problem will still occur, cause its getting too much air? I really need to get some help on this guys, cause i want to explain it to him, and not make myself look like a ****... Another thing is that I am going to get this .BIN file asap... so you guys can take a look at it.

If he cant get this, is it something you guys can change in the .BIN file? I really wish I got the Ostrich now, instead of just getting my lift kit.. And im in the process of moving with the wife, so things are a little slow.

Tbi-MAX

I don't think he knows of this board, cause when I told him, it didn't ring a bell... I know he should be a member here, but i really don't think he does that many TBIs moded like mines... but its a world of new TBI tuning tricks and tips over here... I will recommend it for him again..

BMmonteSS

I'm sure fast and the guys will chime in with specifics to your ECM, but it's just a trial and error situation. Just tell him to try to prop up the pump shot in that area but to crutch it with the VE tables. If you try to fix the lean spot completely with pump shot you'll be too rich once you need pump shot above 2000 rpm. It's tough to explain and impossible to tune with out having the vehicle in person. With a wet flow system you are going to have some lean and rich moments when transitioning form idle to WOT. I've never been able to get rid of a momenatry lean spike on my way to WOT from below 2000 rpm, you can't feel it and it last only for a few microseconds so I've just ignored it even though you can see it on the WB.
I'm sure what he's feeling is pretty bad because it took me a while to get it tuned till the point that it didn't lean pop.

Ronny

iTrader: (1)

I have a tiny 350 with 7.4L BBC TBI unit. I would think a 7.4L TBI unit would be better suited to your 383 than my 350. Granted if all one is concerned about is lower RPM use the smaller 350 TBI is the way to go. I understand completely about the shearing of the fuel off the manifold walls as velocity of the intake charge increases. I think of that as an AE event that is over before I see 2000 rpms however. Assuming it is moderate accelleration from stop to start. I believe I can accelerate from stop w/o AE in log if I chose to do so. I am able to datalog successfully that area CL with values that are a bit on rich side in fuel tables. Maybe you need a lot more fuel in those fuel tables around 2000 RPM.

Is Alvin seeing lean on his WB on the dyno? How can that be if engine is CL? I would think he is seeing 14.7 -15.0 in CL on WB. If engine is going lean during accelleration (with AE) then it is understandable as the larger TBI unit will cause fits for tuning AE. I was successfull in getting my "lean" AE in line by using an RPM specific multiplier to increase AE at that RPM. My "lean" condition was at 2400-2600 rpm however.

BMmonteSS

My findings seem to jive with your's Ronny, only the RPM at which it happens is different.....which of course is completely dependent on the combo.

I also assumed this problem was under acceleration, not steady state.

getsideways

i also have a 50mm tbi on my 350 and tune on it myself. and even being a first time tuner and having issues with ae and prop gains,my truck very close on the tune i think and without issues most of the time. its the fine tuning that takes the longest time. i was driving my truck daily from the day after installing it. he should of got it very close with how long he spent on it. how does it drive? is he saying you shouldnt even drive it with the tune the way it is? i am running 23-24 psi with 65lb injectors right now. also you really need to get a gage to check fuel psi. how is he able to tune without putting the proper injector constant in the bin? that and displacement should have been the first thing he changed.

Tbi-MAX

EXACTLY where it seems to lean at!!! right in that range... so you changed the multiplier? the truck hadnt been on the dyno yet.. cause he was getting the tune close 1st..

Tbi-MAX

yes Alvin said its VERY drivable... but as soon as I take it up the street, it will LEAN pop.. like he said... which is exactly what happened... trust me, it will chirp out of the shop... sometimes it wouldn't act up, then other time, it will act up on light throttle... I only drove it 15miles from the shop, so I will have to test some more... I agree on getting the gauge, I will check those things when I get back in town. I have no idea about the tuning... like he said you get it close as possible, drive it, then dyno tune it, the rest of the way... 3 steps!

Tbi-MAX

BMonte, this is a good explanation... Im going to give him this explanation, as well as trying to change the multiplier.. but basically explain he has to work around the problem...

as best as i can explain it again:

on part throttle, its fine till about 23-2600 rpm, then it leans out (or looses pwr) then the power comes in hard after... during the pause black smoke can be seen out the exhaust (little bit)

ON WOT it will chug sometimes, but its not smoothe, like the previous tune...

again its the ultra hard extended starting, you have to give it gas, and revv it for a while then it idles perfect all day long..

i will do some more test and driving with it... but even with the lean spot, its strong as hell, and chirps, it does 45mph almost instantly... and I havent givien it alot of gas yet, or did a hard WOT yet...

getsideways

if it leans out at 2300-2600 under part throttle (like normal accelleration), that makes it seem like its your ve table thats off more than ae tables. ae is tough, especialy with a big tbi, but it wasnt hard for me to give it enough ae to not have a lean pop. might not be perfect but it doesnt pop.

Tbi-MAX

yea, it does it on part throttle as well... so my VE tables are off a good bit... dang. I guess i can drop it off again, and leave it with him, and explain what you guys are saying... but now i wish i had done the tune myself. but then again, im limited on time, especially these days... it poped like 2 times on the trip home, but on part throttle, you can feel it chug some in those rpm ranges...

RBob

iTrader: (1)

None of this makes sense.

Black smoke (you mentioned this is this series of posts) is not lean, it is rich.

Chugging is also rich.

Rich will cause the engine to lay down but not pop.

Popping is either lean or not enough spark timing.

If how the engine runs keeps changing then it isn't the tune. There is something else wrong: fuel pressure/delivery inconsistent, distributor timing moving around, cam timing moving, injector firings erratic, electrical issue (connector, splice, grounds), wrong spark plugs, etc..

RBob.

Tbi-MAX

ok, i will check those things, thanks for that bit of info. I will drive it some more, and see what exactly is going on when i get back in town. I think the psi is to low, but i need to throw a gauge on it. also some new plug wires, cap, and plugs.. gaped @ .045 platnium delcos. msd 6al 6k pill.

it chugged when i stopped, and then try to punch a lil bit on the way back, for a turn. after I fix the other things, ill see how it runs, and also check the fuel psi. and prob end up turning it up..

BMmonteSS

The problem we're talking about is so much more complicated than a simple fuel pressure change. Plus changing the fuel pressure will throw off all the tuning he's already done. Probably best to just check your basics and take him both the SB TB and the 350 injectors to play with.

He's learning, hopefully it's not on your dime.

Ronny

iTrader: (1)

Alvin is pcmforless.com. They do "mail order" tune as well as dyno. I think 95% of his biz is later model stuff not TBI. He is very popular on corvette forum and has been around quite a while. I believe he can get it right.
Question is Port Fuel injection that much easier to tune vs TBI to allow successful mail order tunes? If it is easier to tune then is MAF then even easier than SD for PFI? Obviously the car will run better on a PFI setup. I just wonder if the learning curve is lessened for a neubie

also not to cause trouble but I think the final tune will be "LOCKED". right?

So no way to use that tune as a base tune to improve down the road. sorry to bring that up but i had to ask.

Tbi-MAX

well so far he has been nothing but helpful... i will measure the fuel psi 1st, before i change anything. I will check the basics like you said, cause I never know until i do. Well he only dimed me the 1st dyno, nothing for this, and he wants to finish it right.. so i bring it back after the new year.

yea, he does alot of later model stuff... he is on trailblazerss.com and stuff.. the SS with the turbo is his... He is good at tbi too, like the impala clubs and stuff. but there is still a good bit of TBIs still come in, but mostly 90% newer vehicles. PFI is much easier to tune; TBI is Much harder, any speed density tune. so are you saying ditch the TBI? and go MPFI?
about the tune being locked, I already talked to him about geting me a copy of the .bin file.

getsideways

i still think you should get a gage and find out your pressure and set it right in the bin before you go any farther with the tune. do you have an adjustable regulater or is the original regulater on it? if its adjustable how do you know if your pressure is 9lbs or 25lbs or anywhere for that matter? on the $0d mask there is an injector flow rate and a cylinder displacement setting. you cant set the flow rate without knowing the fuel pressure. so where would he set this in the tune? when haulna$$ and fast355 where helping me get started a year ago, they had me start with a stock bin and set those 2 items to match my set up and data log from there. it seems smart to do it that way.

Tbi-MAX

you are right, cause i NEED a gauge on it 1st! I just approximated, i dont know, it could be way off.. cause its almost all the way shut on the stock AFPR. lower, than it would be in the BBC tb FPR, that was tach welded. but i use the BBC spring, and everything else in the pod. Ill measure it, then if its 9, ill raise it to 15 psi.. and get it back to him. He prob didnt set the psi in the tune, as he didnt know. I never told him. With the psi, and injector sizes, ill see what it does...

rocko350

take this to calculate injector constant. after download change .doc to .xlsBPW.doc

Tbi-MAX

hey Chris, that xls file still has problems... with the spreadsheet... im using Office 2k7

updates
alright here are the codes i got today, just revving in idle and letting it warm up...

35 - IAC problem or idle error
42 - ignition bypass circuit error
54 - fuel pump circuit low voltage

so you guys know the symptoms already listed above... it does the same.. if you punch it fast, it will chug, then pickup. even are part throttle, it chugs if you dont lightly press the gas into it... sorta hard to explain...

what is the next step?

im changing the plug wires tomorrow, and run them better, so they dont jump spark plugs, new rotor and cap. the plugs i will leave them in, cause they are fairly new, and like i was told, that wont make it lean.. i need to get a fuel PSI gauge on it tmrw too... so i can note where its set at, or if I should turn it up some more....

drove it about 40 miles already, and it feels good and all, cept the lean pops.... actually at idle with the element off, i was revving it, and got it to backfire in the throttle body, on the driver side injector bore....

well thats all i did today, as i was out of town in the NY city since last year when i got the truck back.

BMmonteSS

The lean pop is simply you pump shot needing retuned. It's the biggest problem you get when swaping to the bigger TB. Those big 2" throttle bores just move a lot of air when smack them open. You really have to be easy on the throttle and tune your steady state fuel before you jump in and add a bunch of pump shot.

Tbi-MAX

yea, Bmonte what you say so far, makes the most sense out of everyone. cause that is exactly how it acts... if i give it smooth steady acceleration its good... but if i snap the throttle open at any percentage quick; it will chug and pause some. wot you have to slowly tilt it up until 3k or so, then snap it wot.

so BMonte, the pumpshot tables basically has to be tuned finely at steady acceleration??

i ran new wires better at the bottom sides of the engine, then up from the back; sorta like the old bbc.. the rotor and cap were good. i will pull a spark plug to check too. the truck runs about the same. ill post some pics soon.

BMmonteSS

No, you need to rough in the VE table using steady throttle, then jump over and tune your pump shot. What happens is that you can tune your pump shot around either a too rich or lean VE table and then ahve to go back and retune once you get the VE where it needs to be. Again this is another one of those iterative tuning processes, as one thing effects another. Just have to bounce back and forth untill it's right.

Tbi-MAX

ok i will tell him this and send him a link to this thread. i got to install a new oil pan gasket, and then im going to take it back up there. after thinking about it some more last night, i really need the truck back working asap. i am going to see if he can get the VE table tuned proper, along with the pumpshot tables.. if not, i am going to re-install the SBC throttle body with the BBC injectors.. that way i dont have the air problems i got now..

he wanted me to put the SBC with the BBC tb, but from what you guys are saying, it will still have the same similar symptoms from the too much air at tilt in...

what do you think Bmonte?

Tbi-MAX

this morning on cold start the truck wouldnt idle for crap! ONLY untill it warmed up.. then it idles at 850 or so... but in open loop it would idle about 500 and it would stall out... i would give it gas but same thing once it idles... only until its warmed up it idles right. so i take it the IAC is not tuned properly either?

man, i dont have the time to keep messing with it, especially with all the things i am doing now. today, i am going to reinstall the SBC stuff, and use the BBC injectors, turn the PSI up as well, and drop it off to him... cause he tuned that stuff excellent. i will try to get the .bin as well, so in the future when i start tuning, i can jump back to the BBC swap..

i will attempt to do all of these today, cause i got to get the truck back working and lifted...

Ronny

iTrader: (1)

Can you visually see the IAC pindle moving with key on? pull the air cleaner and visually verify that it is at its fully retracted position when the engine cranks and starts. On cold cold start your WB should read about 12.0/1 A/F. Once coolant is up to 165F on my WB I see 14.7/1 approx. What is the outside temp this morning?

Tbi-MAX

yea, it would move, it was warm on the cold start, and in afternoon, actually it acts up on any start, just more at first couple of starts..

im putting the SBC pod on the heated riser, and the BBC pod and injectors, and targeting for 16psi... rewiring back to SBC tb sensors.

Tbi-MAX

just wanted to say BMonte was correct all along, about the TOO MUCH air... with the BBC tb... i just switched back to the SBC, mounted on top of the BBC heated riser, and i used the BBC injector pod and injectors, turned the PSI up also.. and the truck has NO more issues!! no lean pops at tip in etc... and it fires immediately right up on start ups now...

so all this makes me know that it had to be all that air flow from the BBC tb.. i am going to take it back up to Alvin and have him tweak the tune now, and get some numbers... i got all my leaks fixed pretty much. just minor stuff to finish tmrw. then ill take it to the dyno to drop it off... it even idles properly now too...



here are the latest pics with the SBC tb mounted, and BBC injectors, etc...








after i get it retuned i will get the .bin, and in the future, ill mess with the BBC swap myself.. when i start messing with the Ostrich.. ill post some nice video too....

Ronny

iTrader: (1)

Quote: about the TOO MUCH air... with the BBC tb... i just switched back to the SBC,

try this:

1. key on-engine off. check your MAP reading in your data log. lets say it is 97 kpa or MAP. that is atmospheric pressure dependent on elevation. 100 MAP may be at sea level.

2. Do a WOT datalog and compare MAP to #1. Lets say it is 90. that tells you you have an intake restriction. Not necessarily the TBI SB unit but could be.

That restriction could also be the air cleaner. That may be my case (14x2.25).

Keep the BB TBI as you may find you need it later !

Tuning with the SB TBI will be easier for now.

BMmonteSS

Like Ronny said if you don't show any restiction at WOT with the SB throttle body there really isn't any reason to use the BB unit. I'm going to venture to say that you will see some KPA drop though. My 300hp 350 showed a slight 3-4 kpa drop t 6k rpm.

It's not that the BB unit supplies too much air, it's just that the tune needs to compensate for the air being supplied. You'll find with it tuned properly that the BB unit will feel very "responsive", sometimes in a light car too responsive. It made my car about undrivable in inclimate weather as it was impossible to take off super smooth.....then again I was trying to drive a 300hp rear wheel drive car in snow.

Tbi-MAX

BBC idle underbody (camera too close)


Walkaround video... (pay attention to how my injectors fire)
it looks different than they did before... this is also with the BBC tbi


-----------------------------------
I have not took any video of the SBC tbi.. but it seems to run lots smoother and quieter. (almost as if it was still setup for the SBC config)


Important question about AFPR...

now if the screw is all they way tightened... (compress spring) [is that turning the psi up?]

if the screw is all the way un-tightened (backed out) (counter clockwise) [is that LOWERing the psi? psi down]


cause i think i was confused, and back the screw outwards, thinking i was raising the psi... and i just found out today, i might have in fact lowered the psi..

zap

Put a gauge on it !

Ronny

iTrader: (1)

Compressing the spring raises the FP. You really need a gauge. You may want to consider the slighly stronger spring that top down solutions sells. I believe that will allow you to raise FP higher than your stock spring. If the coils bind I believe bad things happen to the diaphragm.

titchener

The regulator works by having the diaphram push against the spring and move back and forth against the spring pressure to provide constant fuel pressure as the flow demand changes. So if the regulator is adjusted so the spring is at bind or close to bind the regulator won't work properly.

As said above, a stiffer spring is the way to go in this case, that way you can crank it up to the higher pressure while still having some travel left in the spring so it can regulate.

Paul T.

sixty

Tbi-Max,

I've been following your build for the last few months and it has inspired me to follow in your footsteps! Its been a very informative post. I'm planning on swaping to a 454 tbi, but I'm a little confused on the IAC & TPS wiring. Could you post up the specifics of the correct wiring as well as what you did for connectors? Any upclose pics of the TB would be greatly apreciated.

oh yeah, & get a fuel pressure gauge . Great job on the build.

Thanks in advance!

Ronny

iTrader: (1)

I ruptured a diaphragm with a coil bind on stock weak TBI spring and a TPI fuel pump. It sprays copious amounts of gas all over engine.

Tbi-MAX

yea, ive been adjusting the FP wrong all this time, infact when i thought i was raising it, I was lowering it.. yea, this happens when you dont have a FP gauge.. trust me 1 is on order for a fitting next.

ill be playing with it some more tmrw, and raising the psi this time.... this might just explain why Alvin said it was going lean at 1800 so rpm, as i actually lowered the PSI when i installed the BBC tbi..

ill update things tmrw; what ill do is tighten the regulator all the way, then back it off maybe 1/4 turn or so.. so the coil will not bind, and still have little flex to regulate. i also am using the BBC regulator coil spring; yes its stiffer than the SBC spring, and looks thicker.

Tbi-MAX

aiight, so this is what im going to do... rewire and tap/Y both connectors to the stock wiring.. that way both the BBC & SBC harnesses for TPS & IAC will be wired up and soldered up, so if i switch, its always plug and play..

but i plan to put back on the BBC tbi tmrw, and get the fuel psi higher this time... and see if it still leans out... i doubt it will this time.. i was told the starting issues would have to do with the choke in the tune for the BBC..

91chevz71

yah. crank AFR needs to be adjusted. had to lean mine out a bit with the 90's and ++ psi

Tbi-MAX

yea, that has to explain the hard starts, i had to give it gas, just to start with the BBC tb, sorta like a carb.

well seems like im making more changes again.. im gettin rid of the heated riser!! as hot air realy cant be doing me any good at all... ill have to bore out my tbi-to-carb adapter plate some more to clear the BBC blades..

hey Mike i just made plans for the future to run MPFI feed by the 454 BBC tb just for air... no injector pod mounted to it.. (but i think ill have to seal off where the regulator goes on the base) im going to get a manifold bored for the injectors, then im going to do the rails... but this will not be till summer or lil after..

91chevz71

if you follow through with that, you need to post on the contact and pricing and stuff!!!

on the crank thing- mine you take about 2-3 seconds then fire, flare up to 500, drop down to like 0 or 100 (rpm), then rise to the cold idle RPM.
too much fuel was drowning my cranking and fire up