sniper_dsl

i'm happy that i got to hear my baby come to life after so long, she definately sounded like she had way more power than with the 5.7TB. the exhaust was so sweet... -drools- now if i could only get it to run right...

if any of you remember, i bored the Vortec TBI Intake out to 2" and instaled the 454TB. kept the old injectors and decided not to install the fuel pressure regulator, for it was getting a bit too much fuel before the converson... so i figured more air would equal it out just right. well after playing around with the timing she finally fired up and idled at 400-500rpm very lumpy/chuggy. then it seemed like the computer tried to kick in and suddenly it idled at 1000rpm.. 1200.. 1400... 2000rpm! after fearing it would go higher i cut the engine and tried thinking of causes. vaccume leak? sprayed around some carb cleaner but i couldn't tell as the motor was roaring in my face @2000rpm.

i removed the air cleaner and checked for stuck throttle blades... nope... then with another start i noticed that the injectors were dumping in fuel. is there any way the TPS or IAC on the 454 could have screwed the computer into dumping in fuel? tomorrow i'm gong to attempt to install the pressure regulator and cut down the fuel, but is this not such a good idea to 'combat' the computer? (if it is the computers fault, i have no idea whats going on.. these are merely ideas)

please help guys... i'm stumped and just want my baby back jetting down the streets...

another thing... theres back oil/water substance sprinking out of the exhaust.. heh

Low C1500

Try the IAC reset procedure in the tech article section of this site. If this doesn't work , just reply and we'll try some other stuff.

sniper_dsl

"There is a Torx screw on the side of the throttle body"

its got a dome cap over it... i can't seem to get that lil' ******* out of there for the life of me. can i drill it?

Low C1500

Yeah, drill it out, Its in there pretty good, you 'll have about a 1/4 inch of clearence from the screw, so you shouldn't hit it.

sniper_dsl

yey.. i got it to move!

definately the IAC... did the procedure and it helped.. but the IAC is still letting in TONS of air. so finally i just shoved a peice of cloth so it couldn't let in as much air.. (temorary fix) sure as hell did the job thou. now its still getting too much fuel so i'm installing my pressure regulator to hopefully bing it back to an ideal mix.

sniper_dsl

cut up a peice of gasket and shoved it in there... solved the high-rev problem yet now the service light blinks all the time... heh.

when giving gas it'll stall for a second.. timing off?

installed pressure regulator and hoped the PSI was correct, for the adjusting screw hit the Vac hose between fuel fittings. turbo city says.."may hit vac hose, bend it down for more adjustment room".. riiiiight and risk breaking off another part? i've done screwed things up enough as it is.

did a few test runs and i seemed to have lost more performance than gained... again, could this be due to timing? or is the IAC a nessecary part to leave working? i can adjust the IAC manually with my rigged gasket, i can pull it up/down leaving as much of a gap as i want.

then with my luck after the test runs the cheap pastic radiator nub (where the hose connects onto) was leaking... so i tried to tighten the hose clamps and the damn thing blew off. covering my engine and my upper body in fluid. found a metal pipe that kinda fits, covered it in RTV and wraped cloth around it so it'd fit snugly.. more RTV then pounded the sucker into the radiator. hopefully i'll hold...

Low C1500

You should be getting an error code, check to see what it is. Theres a tech article on how to get error codes.

sniper_dsl

computer didn't tell me anything i already knew...

only got this one error, but i'm thinking there should be more.
"35. Idle speed can not be set to desired RPM"

sprayed the IAC with carb cleaner... re-adjusted the timing, and went through setting the minimum air again. the IAC probably needs replacemnt but GM wants $100. i cannot trust a junk part because i got this TB from a junkard and theres too much risk of picking up another defected IAC... but i don't seem to have any other choice unless an auto store would have it. (which i doubt)

maybe because its made for a 454 is why its letting in so much air... my gasket method enabled me to manually adjust how much it was letting in, but its designed to open upon throttle.. so that defeats what its made to do. yet its the only way to make the vehicle driveable...

i've got the idle just where i like it; surpisingly more smooth than before the conversion. last night i got strange 'new' noises which sounded like a bad lifter... (can anybody explain what a bad lifter sounds like?) upon giving thottle you'd hear like a rappid ticking. i'm thinking it could be a gunked up valve, because i pulled out a cheap rubber PVC grommet and some of the rubber chunked off into my valve cover. with the EGR exhaust tube in the way i can't remove my valve cover... (too much to mess with)

now i'm heading out for a few test runs to see if i've eliminated the throttle stall or if i just made it worse. hopefully that 'noise' is nothing too serious...

sniper_dsl

computer didn't tell me anything i already knew...

only got this one error, but i'm thinking there should be more.
"35. Idle speed can not be set to desired RPM"

sprayed the IAC with carb cleaner... re-adjusted the timing, and went through setting the minimum air again. the IAC probably needs replacemnt but GM wants $100. i cannot trust a junk part because i got this TB from a junkard and theres too much risk of picking up another defected IAC... but i don't seem to have any other choice unless an auto store would have it. (which i doubt)

maybe because its made for a 454 is why its letting in so much air... my gasket method enabled me to manually adjust how much it was letting in, but its designed to open upon throttle.. so that defeats what its made to do. yet its the only way to make the vehicle driveable...

i've got the idle just where i like it; surpisingly more smooth than before the conversion. last night i got strange 'new' noises which sounded like a bad lifter... (can anybody explain what a bad lifter sounds like?) upon giving thottle you'd hear like a rappid ticking. i'm thinking it could be a gunked up valve, because i pulled out a cheap rubber PVC grommet and some of the rubber chunked off into my valve cover. with the EGR exhaust tube in the way i can't remove my valve cover... (too much to mess with)

now i'm heading out for a few test runs to see if i've eliminated the throttle stall or if i just made it worse. hopefully that 'noise' is nothing too serious...

thank you for your help i couldn't have done this without

Low C1500

Bad lifter sounds like a hollow ticking.

Low C1500

sniper ,

sounds like your still having problems, post on this thread, we should be able to get em fixed.

So your motor ran fine before the 454 tbi swap, right.

Are you running the stock injectors?

Youv'e still got stock intake?

If you can list your problems again, I can help.

In a swap like this, vaccum leaks happen lots. Try tightening dowm the tbi bolts agian.

sniper_dsl

ran fine before swap

stock 55lb injectors, same as before.

intake is a bored GM vortec TBI.

i'll try spraying around carb cleaner again, but i'm almost positive the main 'vaccume leak' was the IAC stuck open...

my IAC is letting in loads of air, and i tried setting the minimum air several times. where would i find a new IAC that doesn't cost $100(dealer)? does the holley fit? (looks like it could)

could that one unit be the root of all my problems, exactly how important is it for the engine to run? i've compensated the idle air screw, and blocked off the IAC with a gasket; just so it could idle under 1000rpm.

upon romping the throttle there will be a dead spot, pop, ping, and once killed the motor. i made it less severe by advanced the timing quite a bit, a good few inches from 0* mark.

is there a corralation with a high fuel pressure, rich running engine, and advanced timing? should i try backing off the pressure and inching up till i find a 'sweet spot'? i've never tweaked with an AFPR before... there has to be a process for tweaking out TBI... what do i adjust and in what order? the more i play around the worse this engine ends up runing.

i've got error codes too.. need some help knowing what i should look for...

32. Fault in barometric pressure sensor circuit OR
Fault in exhaust gas recirculation valve diagnostic switch OR
Fault in electronic vacuum regulator valve

35. Idle speed can not be set to desired RPM
(IAC is bad and stuck open, blocked off with a gasket)

42. Fault at electronic spark timing circuit OR
Fault at direct ignition system OR
Fault at fuel cutoff relay circuit

thanks guys for not letting me give up...

25THRSS

With the timing it sounds like the computer isn't advancing it any. Check and make sure all your wires are plugged into the distributor and your esc wire is connected, etc.

Low C1500

The TPS sensor could be toast, Do you own a multimeter??? Also the IAC on the 454 tbi is the same as most 4 and 6 cyl gm cars from 88 - 94 or so, same with the tps. Most wreckers will sell these cheap if you take them off yourself.

sniper_dsl

i have already replaced the TPS with one from my old 5.7TBI... i didn't notice any change.

yes i've got a voltmeter but haven't tried the test yet... need to get those lil' probes.

i saw the computer advance the timing after i connected the ESD and looked again with the timing light. after that i broke the timing light.. but i assume its still working.

Low C1500

Do you have the injector pod raised up higher, ie: 1/2". I really think you need a new IAC, then disconnect the battery for a litttle bit to reset the computer (just to clear out anythiing that the bad IAC could have caused).

One thing to try now would be : reset the computer, then go for a flog right away. This will have the computer in open loop (until it gets up to temp, and the timers clear, should be about 2- 5min), with default fuel values. If it runs fine, then starts running poor after it go into closed loop, then its something related to the computer, and not a vaccumm leak or something.

sniper_dsl

tomorrow i'm going junk surfing for a new IAC and maybe TPS... shoot.. might as well get the whole TBI if they've got it.

would replacing my injectors with the 85lb do anything?

Low C1500

You need tuning to go with 85lb injectors.

sniper_dsl

after junk surfing all day without any luck... (looks like you can only find a 454 IAC off of a 454, not just any TBI 87'-90's) finally went to GM and paid the $110 for a brand new one.

with the brand new IAC and resetting the min-air i got the exact same problem... 2000rpm idle IAC letting in tons of air still.

now i'm out another $100 because they don't take back parts once you've put them on....

i don't understand, could my wire-splice be cockeyed? its wired as A-B-C-D as one of the old posts stated. two blue two green each other one with a white/black stripe.

this sucks.

sniper_dsl

noticed a few things... upon setting idle air i can have the IAC valve fully extended and unplugged from ECU and it'll idle just fine.

once i got done, and plugged the IAC back in... it'll be fine for a little bit then the idle will shoot back up to 2000rpm. which means it HAS to be the computer opening up the valve.

must this be programmed out? is my wiring backwards?

i tried disconnecting the battery to clear the computer, but the IAC still opened right back up again.

just don't understand it.. why won't that lil bastard do its job? how do i get the computer to understand it shouldn't open that valve?!? maybe its confused about something... what factors go into the degree of 'counts' for the IAC?

RBob

iTrader: (1)

The IAC has to be wired incorrectly. It is the only thing that will cause it to do this.

The 5.0l '8746 IAC wiring is:

COIL A High: Lt Blu/wht Pin A
COIL A Low: Lt Blu/blk Pin B

COIL B High: Lt Grn/wht Pin C
COIL B Low: Lt Grn/blk Pin D

If you can find, or if someone posts the BBC TBI IAC wiring it'll be easy to correct. It may have been posted on this board in the past, I don't know.

HTH's,

RBob.

Low C1500

Could be wiring, but I just color matched too.

With IAC unpluged does the motor run fine, ie: lots of power, no rough spots?

See if your map sensor line is connceted right to the vacumm port at the rear of the TBI, and if possible make sure air blows though with no restriction thought the vac port on the TBI (do when not running).

sniper_dsl

seems to run fine other than the idle. although it isn't making as much power as it should... seems doggy for a 330hp vortec. (fully knowing it ISN'T getting the full 330, probably 270hp?) plus my whole project was to bore 2" for more power, which didn't seem to help much. all it did was create more problems...

i corrected the pop/ping/stall by advancing the timing a lot; its still there, just not as bad.

mine is wired up as one of the older posts dipicted for a 454, but it said something about swaping the blue wires for a 305.

do you just measure the voltage with the connector off and engine running?

i believe the voltage readings are to the right wire...
blue/white A higher voltage..? 13.something?
blue/blk B about .5 at idle
green/white C about .5 at idle
green/black D higher voltage..? 13.something?

if these readings seem goofy just disregard them as poor testing. if anyone has the numbers i should be getting i can fiddle with my meter and see where the lil decimal point should go...

should i try swaping the blue wires? couldn't hurt... remember this truck used to have a 4.3 V6 and this is the same computer/harness, but with custom chip (made before 2" bore coversion), knock, and now a 454TB w/ 55lb inj.

sniper_dsl

wait a second... "HIGH, LOW"

COIL A High: Lt Blu/wht Pin A
COIL A Low: Lt Blu/blk Pin B

COIL B High: Lt Grn/wht Pin C
COIL B Low: Lt Grn/blk Pin D

I COULD SWITCH THE GREEN WIRES?!? cuz i got a LOW then a HIGH on the green wires... this better be it!

yes that might do it... seeing as my readings don't seem to correspond.... i'm gonna try it real quick even though the colors match, but the voltages don't. CROSS YOUR FRIGGIN' FINGERS

RBob

iTrader: (1)

This wiring will probably match:

It is for the Holley TBI, but I believe it uses the same IAC as the BBC TBI. Notice the IAC pin differences.

The IAC is a stepper motor. You can't just read the wire voltages as they will change polarity as the controller moves the mototr.

Here is a thread where someone else had the same problem:

https://www.thirdgen.org/techbb2/sho...IAC+AND+wiring

As for popping with an opening throttle you'll need to add more AE (in the EPROM). This is due to a greater airflow with the same throttle movement opposed to the smaller TBI.

Then when you decide to put the BBC TBI injectors in the AE will then need to be reduced.

RBob.

sniper_dsl

thank you guys very much, i just got done swaping the green wires and sure enough it worked.

then i looked at robs post and the colors match but voltages don't... i wen't with this:
blu/wht high
blu/blk low
grn/blk high?
grn/wht low?

who cares, it works! i am now happy with TBI once again. last night i raced my friends camaro again and pulled away nicely. maybe the computer just needed time to learn...

next on my list is a reprogramming... but i cannot tell the programmer what he needs to know. i'm going to take it into a performance shop for a diagnostic; this way i can get him the right information to program with. it should help out quite a bit with my running rich@idle problem.

once again i'd like to thank everybody for their advice and not letting me give up over some dumb wires.
:lala: :hail: Rob and LOWC1500
don't you love it when they think your truck is mostly stock?

Low C1500

Thats good to hear, now work on getting it custom tuned, then you can run the big injectors, and get more out of your set up.

lykan

Wondering how this all worked out I was considering going with the 454 tbi and bored out intake. Wondering if you noticed much of an increse in torque and hp

sniper_dsl

if the TBI is starving your motor for air, it can definately benifit from switching to 2" bores.

i got a LOT more noticable horsepower and found even more after pushing the fuel pressure to 18PSI. replaced my fuel pump with the Walbro 255HP this eveing... let me tell you... if your truck/car has severe underbody rust its a real bitch getting those bolts loose. had to saw through a few of them and jimmy rig the tank back up. after about 5 hours of cursing we got it all working happily. tomorrow i'll see if the engine can stand to run a little more pressure untill i can determine its running too rich.

can somebody advise me how the O2 outputs the voltage? is it true that the computer reads the high-low and averages them? In that case my Air/Fuel gage which bounces back and fourth should be read in the middle?

If that is true then i'm running just over lean, which is hard to believe with 18PSI. Anybody else run this high of pressure or more? Injectors can't handle but 25PSI correct?

RBob

iTrader: (1)

The ECM causes the O2 to swing above & below stoich. This is why you see the gauge fluctuate. Yes, in effect the ECM averages the O2 sensor reading.

The stock GM TBI injectors can be run up towards 70 psi. I've run the 350 inj (org/blk) at 30 psi with no problems. I am currently using 454 inj (drkblu/drkred) at a steady 16 psi.

With the design of the TBI having a gasket in the fuel channels I am leery about more then 30 psi for any length of time. GM does run the unit that high. Now, I did run the pressure up (60psi) as a test and the gaskets held. This was only for a short period of time.

RBob.

Low C1500

mine are at 34psi , and its a daily driver.

r90camarors

Glad to hear you got the problem staightened out. Engine and injection swaps can be a pain. As far as the ticking you're hearing goes, it could be the injectors. Those suckers can get noisy-I thought I had a bad lifter for the longest time. Replaced all of them and it still did it. Then I swapped in a fresh 383, and finally figured out it was the injectors.

As far as the fuel pressure goes, I agree with the idea it's ok to run it higher than stock. Mines at 22.5psi and no problems. The only problem I have had is with the regulator diaphram going bad inbetween spring replacements.

kevm14

Does this cause an async idle?

Low C1500

No since it idle at 1000rpm.

snflupigus

glad you got that fixed, i think im going to sit down this week and try to spell this one out better for a FAQ...

Either that or make some of the past post sticky for a while? or link to a list of them on my site.

you can increase the pump shot on the chip a bit to try to compensate for the initial "shock" of air the engine is getting compared to what the computer THINKS its getting. that could compensate, but really. bump in fuel pressure could do the same, then your ecm should tune back the rest of your tables.

its so much fun isnt it?

so did you wire it like my reply on the post below said?

https://www.thirdgen.org/techbb2/sho...hreadid=188744

bright side, you've got a spare iac

sniper_dsl

here is the latest update: FINALLY got my custom chip from www.cfm-tech.com and their 68lb cop car injectors. they were rather steep in price ($250 flow matched injectors, ebay could be way cheaper and $250 for custom chip)

replaced the old chip which was merely guessed on.. WOW its a hell of a difference! supposedly this chip is programmed specifically for the GM crate vortec motor, mods, 68lb inj., and shift points.

i'm FINALLY at the point where i HAVE the powerhouse i wanted from this project. :lala:

next on the list is a ticking rocker arm and general ignition tune-up.

this truck is one runin' SOB.. i'm guessing 13-14 second quarter mile. one of these days i'll get it out to the track so i can post exact times and see how to improve them. i have yet to tweak my fuel pressure (they wanted 13-14 PSI i'm running 15) and properly tune my timing. tune-ups alone should yeild a few more horsies i'm sure...

just wanted to say thanks again for everyones help on this site for i wouldn't have been able to do this myself.

now wheres that lil' honda at? i'm gonna kick its *** and put it in its' place! show him what a truck 3x his weight can do! he can beat me un-tuned, but its not going to happen again!

Bulldog92

iTrader: (1)

Man, I've got the 454 TBI swap blues myself.... It looks like all of the 454 TBI "gurus" are here, so this looks like a good place to post.

I need some help in making a decision regarding my new 330 HP Vortec 350 crate motor with a 454 TBI in my 1992 Camaro RS (previously L03). I'm embarrassed to admit that I did this swap about 4 months ago, ran into some problems, and never finished it. I've gotta get this thing back on the road ASAP...it's been down WAY too long.

My problem is this: I am using a 454 TBI with the factory 75-80 pph injectors (not sure which rating is correct). I had to install the fuel pressure regulator from my 305 TBI for two reasons...1) I was unable to convert the 454 TBI regulator into an adjustable unit and 2) the spring in the 454 TBI is so stiff that I think it was probably increasing my pressure to the max capability of the wimpy stock fuel pump (about 15 psi?). As you would expect, I am running extremely rich. I've got black **** on my bumper from all the smoke coming out of the exhaust. I can actually drive the car, but it runs pretty rough at low rpm because it is overwhelmed with fuel. It smooths out at higher rpm, which makes sense, but I still wouldn't consider it "smooth".

Of course, I expected to have this problem before I even started the swap. I knew that I would have to make SERIOUS changes to the bin file on my EPROM to get the engine to run well. The only modification I've made to the chip so far is I increased the speed governor to 255mph and disabled EGR. However, since I need to get the car back on the road ASAP, I'm thinking that I have two options:

A) Stick with the 454 TBI, do some data-logging with WinALDL, modify the chip, data-log, modify the chip, data-log...you get the picture

B) Change the IAC connector back to the old style, put the wimpy 305 TBI back on for now (w/45pph injectors), and be careful not to hit any WOT runs due to the risk of running too lean

The reason I'm considering putting the 305 TBI back on (just as a temporary measure) is that I'm scared I'm washing the cylinder walls of my brand new engine. I've probably only run the motor for a total of 1 hour unloaded and 10 minutes of actual drive time, so I hope that I haven't done any damage yet. However, if I go through a long series of iterations trying to get the 454 TBI air/fuel mix optimized, I may do some damage due to washing the cylinders (gas is a bad lubricant) . In the meanwhile, I could spend some time doing some research on fuel curves for the 454 TBI that may reduce my trial/error time.

Any thoughts?

Low C1500

bump the injector constant down to like 100 or so.

sniper_dsl

i think a good start would be replacing those large injectors. the problem with 70lb is that you have to lower your fuel pressure a lot, which sorta doesn't make the computer happy? 55lb are too small.. you have to jack up the fuel pressure... so your solution is to go with 65lb cop car injectors.. those work just right for that motor. I didn't do my chip myself, but i'm thinking you might be able to download a bin and start from there; one that is specifically designed for our vortecs w/ 68lb injectors. if your lazy like me you can just buy the custom Vortec chip from CFM-tech. they've already worked through the common bugs for our crate motor; it smoothed the idle and fixed my rich-running problem, i believe they also allow you 3 tries to get the programming as close as possible. they were really cool to work with... although expensive.

if i was in your situation i'd go the extra mile (or buck) to finish it right the first time.

Bulldog92

iTrader: (1)

I know this isn't the PROM tuning board, but this IS also TBI-related and I really appreciate the help.

LowC1500: Are you referring to the BPW Constant? If so, can you explain to me how this ties in with the injector rating and the fuel pressure? I know that there is some kind of formula for this relationship, but I don't know what it is.

sniper_dsl: Check out the post at https://www.thirdgen.org/techbb2/sho...t=fuel+systems...it says that 1 HP requires 0.5 pph of fuel. In other words, my 330HP engine needs 330/2 = 165 pph of fuel, or two 82.5 pph injectors. Using that logic (assuming it's correct), my 75-80pph injectors are almost ideal. I just think I need some serious tuning...could be wrong, though.

kevm14

First, you should know how fuel pressure affects the effective flow you get from the injectors. Flow goes as the square root of pressure, so if you went from 11psi to 14psi, you'd have increased pressure by a factor of 14/11, which is 27.2%. But flow increases only by the square root of 14/11, which is 12.8%.

The formula that TunerCat has included with the $42 calibration help file is:
BPW = 1461.5 x (cyl vol / inj flow rate)
where cylinder volume is expressed in liters and injector flow rate is grams/second (1 lb/hr = 0.126 grams/sec).

I got tired of dealing with the formula and made myself an excel spreadsheet to handle repeated BPW calculations. I hope you find it useful.

http://kmoore.phzero.net/my%20pictures/BPW.xls

HTH

Low C1500

Alot of smart peoplesay 1 lb of injector = 2hp, but I went 14.2 in the quater with 55lb injectors (well there 62 lb since gm under rates them) , so by that logic I had 248hp, but I'm sure it had to be producing more than that.

I'd guess that 1lb = 2.5 hp (peak)

Bulldog92

iTrader: (1)

Thanks for the BPW spreadsheet...VERY helpful. I wanted to mention that I observed the same thing as you did in your spreadsheet...my 92 L03 has a BPW constant of 134, which implies larger injectors than 40-45 pph. I ran the calculation for my 80 pph injectors and obtained a BPW of 103, but I'm wondering if these injectors are underrated like the factory ones. They may be (55/45) * 80 = 98 pph, which would mean a BPW of 84. I'm going to burn a new program using 100 (like Low suggested) and see what happens...don't want to run it TOO lean. I'm really curious to see how my BLMs turn out.

Low - man, nobody can argue with a timeslip, can they? Looks like your formula is 1 HP requires 0.4 pph as opposed to 0.5 pph.

kevm14

All you really need to do is set the BPW so your highest VE is 95% or lower. Once your VE is dialed in to match BLMs of 128, everything else will fall into place. AE is specified as a pulse width adder, so that's not affected. You will have to pay attention to things like the IAT BPW scaling, EGR and whatever else your ECM changes the BPW for.

Bulldog92

iTrader: (1)

Sorry for the delay...but guys, I'm about fed up with my little "project" that has resulted in turning my '92 RS with 350 H.O. and 454 TBI into a big red paperweight for 4 months.

I changed the BPW constant from 134 to 100 and noticed absolutely NO difference in how incredibly rich the car runs. I'm still getting massive black fumes from the exhaust and it runs horribly.

I'm going to try to find the time to do some data-logging this weekend, but it's kind of useless when I know that my BLMs are going to be WAY low already (I think low means rich, anyway).

I'm going to adjust my fuel pressure down a little bit, too...but I don't see that fixing my problem. Does anyone have any ideas before I go nuts here? Should I swap out these 80-85pph injectors for 65pph injectors?

Low C1500

What the pn of the top of your new injectors, they could be 90pph, which would mean you need a bpw of like 70, and even lower if pressure is above 11psi.

Also if your rich, it doesn't matter a whole lot if you take some fuel out, if you still rich after taking it out. I mean, maybe thats why the motor still ran crappy after reducing the bpw, I think you still need to loew the bpw.

Bulldog92

iTrader: (1)

The tips of the injectors are orange (see attached pic) and there are two part number sequences on the injector, one on the top and one on the bottom:

Top: 17104288xACR
Bottom: 8303 GM

Does that help identify the pph rating? Is there a listing somewhere on the net that identifies the pph rating for GM injectors by part number instead of just color?

Bulldog92

iTrader: (1)

I just did a search on the 17104288 part number on Google and found this catalog of injectors for all makes of cars:

http://www.tomco-inc.com/Catalog/24f...%20-%20tbi.pdf

My injector shows up on page 3 as being from a 94-95 Chevy truck with a 454, which is correct because I know my TBI came from a '95 Chevy C3500 truck...now I just need to figure out the pph rating.

Brent

iTrader: (1)

That change, along with the EGR and speed limiter, are the only ones you've made to the prom?

THere is no need to switch injectors or TB's.

Get into VE#1 table and cut the values from 400-2000RPM x 20-60KPA by 10%. Tunercat has a nice function that'll let you do this in one stroke. This will lean it out in light load areas.

Get the WINALDL on it and see what things look like. Work on getting idle BLMs right first.

Low C1500

pretty sure they would be 80 pph, pretty close pn to the 80 pph on this page.

http://www.diy-efi.org/gmecm/compone...injectors.html