freaky

i just purchased a 454 tbi with 90 lbs injecters . the tps an iac sensors have different plug ins then my 305 tbi . does any one sell a pigtail to connect this tbi to my wire harness ?

RBob

iTrader: (1)

Small round connector for TPS? Ballenger Motorsports has a bunch of pigtails. The P2S Sensor Connector Pigtail is the small round one for TPS and many of the aftermarket pressure transducers.

The small flat four IAC connector is also likely to be a metri-pack.

Note that the injectors at most are 80.5 #/hr.

RBob.

freaky

thanks rbob , the injecter ## is GM5235231*RPD , the info i found said these where 90 lbs injecters . what lbs injecters should i use to calculate the bpc ? also besides changing the bpc is there anything else i'll need to adjust in the ebl flash to get it to run right ?

RBob

iTrader: (1)

They are 80.5 #/hr at 13 psi. Along with the BPC - BPC vs VAC table values, the AE PW (2 tables) and proportional gain (1 table) need to be reduced. Do so by the ratio of the current injector flow over the new injector flow.

RBob.

freaky

thanks rbob for all the help . i'm gonna rebuild this tbi since i got it off ebay used . if i buy the pig tails for the 454 tbi will the wire color be the same so i can just cut one off an splice the new one to it ?

RBob

iTrader: (1)

I doubt it. The Ballenger one uses three black wires.

To figure out the IAC ohm out the pins. There are two coils that are not connected to each other. So two pins will show about 40 ohms, with the other two pins showing about 40 ohms. They are the coils.

The stock wires are usually light green for one coil, and light blue for the other coil. With a black or white stripe on them.

Wire the light green to one coil, and the light blue to the other coil. If the IAC operates in reverse, IOW, the idle keeps going up, then swap the two wires on either one of the coils.

RBob.

RBob

iTrader: (1)

No guarantee that this is correct...

TPS:

A is +5 volts (gray)
B is ground (black)
C is output (blue)

The lettering should be on the TPS, the BMS pigtail has A, B, & C molded in.

IAC:

A is LT BLU/BLK
B is LT BLU/WHT
C is LT GRN/WHT
D is LT GRN/BLK

RBob.

Ronny

iTrader: (1)

Rbob helped me out on this some time ago. I fould another comment by him that may be helpfull.

Another reference: http://www.sonic.net/~mikebr/crower/iac_waveforms1.html

freaky

thanks guys

freaky

ok setting up my tune fore the 454tbi an i want to make sure i understand this .i have #55.0 an i'm putting in 80.5 so do i minus the tables by 31.5% ? or do i just take 80.5 an subtract 55 from that leaving 25.5 .then subtract the values by 25.5 from the tables you listed ? ?
thanks ...

RBob

iTrader: (1)

55 / 80.5 = 0.68, multiply the table values by .68

RBob.

freaky

thanks , i guess my math is rusty .lol

freaky

where do i find proportional gain ?

RBob

iTrader: (1)

These two:

PRP - Gain vs O2 Error
PRP - Gain Muliplier vs Airflow

I usually change the Gain vs O2 table when doing universal changes. Then use the Gain vs Airflow to tweak it in at various loads/RPMs. NOte that the airflow is shown in the analysis screen and dump file.

RBob.

freaky

thanks again , hopefully i'll be running by this evening

freaky

ok got the tbi on changed the tables like suggested .car starts an idles fast dc volts at 17 tps at 0 . the iac isn't hooked up or reset yet i'm waiting on the pigtail to come in on monday .could this be causing the high idle ?

freaky

just hooked up 454 tbi an it wants to idle high . o steps showing on the ebl wud idle at about 1800-2400 rpm 14 % dc volts on the injecter . fuel gauge says 11 psi . if i turn down the injecters will the idle lower ? also the torques screw had been tapered with by po ....

Ronny

iTrader: (1)

I will call it a VAC leak. Be aware the base gasket needs to fit the TB perfectly. I presume you used correct one. I was given wrong one with the adapter plate. So that may then be a vac line cracked or unplugged.

Does IAC function? I would do a visual and see if pindle seated. Shaft leak? If no vac leaks then move the TSS till you see 5-10 steps on IAC.

pound

iTrader: (7)

Did you try messing with the idle adjustment screw? It might be keeping the throttle blades open too far at idle.

freaky

i thought i had cracked the aluminum intake taking it off but i put the old tbi on an it idles fine . if my bpc is wrong because of a bad gauge would it cause this condition ?i heard the iac turning when i did the reset on it .the blades are all the way closed in the throttle body . it is suppose to be 0 steps right ? i'll do the visual to make sure it's working ...

Ronny

iTrader: (1)

What does the FPG read key on engine off when cold motor?

i dont think BPC had that kind of affect on idle RPM. If OL BPC could affect the A/F but CL it will run stoich. RPM is set by IAC steps.

It may be the wiring for 454 TB is different than the smaller TB. It may be operating backwards. I believe key on it will cycle closed then open to whatever .bin is asking for. 2000 rpms is very high. the fact it is a 454TB size I dont believe will cause a high idle. The air coming in is based on engine size and vacuum.

GM places steps around 10-20 at idle. I am 5 at idle per the datalog. sometimes zero. Cold start I am 200 steps.

freaky

ok mine was reading 0 steps on the cold start . i'm getting ready to swap my iac wires around an see whjat happens

ok just got done reversing the two green wires an she idles now . still abit high in park it's 1200-1400 rpm an 850 in drive .now that i have my idle down sum i hear a loud whistle i'm gonna take the tbi back of anb reseal the abapter plate again
my dc% is 6-8 idling in drive an my fp cold key on motor not running is 8 . i got a tpi fuel pump brand new still ready to put in it .i have a quetion ronny , how did you hook up the tvs cable ?

freaky

[quote=pound;5382749]Did you try messing with the idle adjustment screw? It might be keeping the throttle blades open too far at idle.[/quot

yes i did they where closed all the way
closed all the way .

freaky

alright finally got it idling good . in drive it idles about 575 rpm in p it idles 785 ish . i have a whistle coming from the tbi i think i'm gonna take it all back off now an seal it up really good . i think it's leaking around the adapter plate . thanks for everybodys help

RBob

iTrader: (1)

A whistle indicates a base gasket leak. Hopefully the adapter plate covers the whole manifold carb base area.

Can you post a picture of the linkage? Whatever you do, don't drive it with the TV cable disconnected. One of two things will occur, either very low line pressure and the clutches fry, or the line pressure will be at the maximum and it won't shift until high RPM. Then shift with a bang.

Which one depends upon whether the TV safety check ball is still in place or not.

RBob.

freaky

thanks rbob for the info . i figured out where to drill a hole to have the arch in it . i bought a new ball from advance . yes i know better than to drive it with the cable unhooked . lol now i gotta redo the gaskets holding the tbi an seal them up good an take her out for some tuning

cam an turbo next ...

freaky

this is gonna sound dumb i'm sure but how come the cable can't just be set pulled out all the time ?

freaky

ok went out for a quick ride . i'm getting back fire sounds at certain throttle positions . i can get a vid if that will help .

RBob

iTrader: (1)

That would produce high line pressure with high shift points and bang shifts. Same as if the cable was disconnected and the TV safety check ball is still in place.

Video is always helpful. Did you update the BIN with new BPC values for the increased injector flow rate. Backfire sound on intake or exhaust?

RBob.

Ronny

iTrader: (1)

My ext backfire 2 weeks ago was due to a fouled plug.

freaky

View My Video
mines only doing it under certain throttle positions ...

Ronny

iTrader: (1)

Why is timing moving around? Am I seeing that correctly?

I see rpms at 1000 and i assume TPS steady and MAP around 40+.

freaky

i was reving the car . it's a bad vid i know . i can send you a data log to look at if you want . i was data logging that video actually

freaky

i gotta looking at the timing after you said it was jumping around . i unhooked the brown wire an reset the timing to 6 btdc like it was before changing tbi . it reved up just fine . i hooked the wire back up an it started doing this again . wtf . with it unhooked the car runs fine tho . .,..

Ronny

iTrader: (1)

With that wire unhooked it is getting no direction from ECU and sensors. It just runs on initial timing 6 deg or whatever.

Have you pulled plugs lately? Is distributor installed correctly(not to far advanced)? Not sure if timing chain being installed incorrectly would cause backfire. maybe someone knows.

freaky

i set the timing up like it was before the tbi change . i'm gonna start from the base bin . on the timing issue . at least i know it's not the tbi unit . i haven't changed the timing chain yet .

fiveoformula

This thread is helpful so I thought id bring it back from the dead..
I have a L31 350 with a Lunati cam, single plain intake, vortec heads and TBI w/ EBL, my current setup is using the original 305 throttle body, with 65lb caprice injectors and 18psi regulator spring (verified correct with FP gauge). I just received my 454 TBI that I purchased on Ebay and have a couple questions.

Looks like my Big Block TBI has the flat 4 IAC connector but the TPS looks very similar to my small block TBI one. Did some 454TBIs come with the same connector as a small block TBI?

Driveability with my current tune is really pretty good, reason for the switch to the bigger TB & injectors is that my wideband gauge gets a little to lean at WOT (13.5-14.0AFR) after 4k rpm with the VE tables maxed out. So I guess the injectors have reached there limit.

Still a little confused on the formula to reduce my fuel for the new injectors and on what the BPC should be set at. Sorry if its been answered before..

RBob

iTrader: (1)

The BPC table is easy. Just use the SS or the Utility to calculate the values and copy & paste them in. Also note that flow rate of one injector.

Now table the old injector value (76.5 #/hr), and divide it by the new injector flow rate (say 94 #/hr , 80's at 18 psi), that gives: 76.5 / 94 =

0.81

Multiply the three tables listed above by that value.

RBob.

Ronny

iTrader: (1)

My 7.4L TBI (1995) has a square IAC connector. My 1984 vintage is flat.

Cadride

My 7.4 TBI has the flat IAC connector, I think it is off of a 93-94, but I could be wrong. I have an extra adapter (square to flat) from when upgraded my TB. I had to cut the wires to switch a couple around cause they were switched from the manufacture. It was a major pain and took a while to figure it out; all good now. If interested $15 shipped.

fiveoformula

That would make it plug and play then? adapt the factory square plug to the flat plug on the new TB? That sounds like it worth $15 bucks to avoid cutting and splicing... lol

fiveoformula

Thanks for the clarifacation, I did it when I swapped from 305 injectors to 350 injectors but that was probably 3 years ago..

fiveoformula

Well I am finally getting the big block TBI on, its been a couple months and have a few thousand miles on the new engine now so I'm ready to start dialing in WOT.

Having trouble now getting it stay running after I installed the 454 TBI, heres what I did...
Bolted on TBI, used upper pod, 18psi spring, and regulator from old sbc tbi.
Wired IAC I believe correctly. Verified it moves, appears to work.
Calculated new bpc for the 350CI, 80.5 pound injectors and 18psi fuel pressure. (Set bpc to 88)
Multiplyed every cell in the VE tables by .81
tried adding to inj correction offset (not sure I need to do this).
Basically now, the engine will fire up and die almost right away, even giving it some throttle, it doesnt want to stay running. Wideband indicates super lean condion as it struggles to run.
Any thoughts? Feel like im overlooking something.

Fast355

iTrader: (2)

Set the BPC but don't touch the VE tables. Only multiply the AE and DE tables by .81.

Ronny

iTrader: (1)

May want to reduce the proportional gains including multipliers significantly. 50% is where I am at from stock LO3 values. Dropping them 60% may be better.

fiveoformula

I had a feeling this was the problem, thanks.
Ill try adjusting proportional gains too, dont think I ever have before.

fiveoformula

Well I went out and changed my VE tables back, did some of the other things you guys suggested, and it idled once I "played with" the throttle for a bit.
WB pegged out lean still but idled (very high I might add). IAC air leak screaming... Then glanced at the injectors and noticed the drivers side one not doing anything.
Im guessing it is plugged somehow... They are used ebay units...

fiveoformula

Fixed that issue, got car running after reducing the AE tables and proportional gain. Noticed it was pig rich at an idle, And found that while putting in some new re-man injectors I must have smashed one of the lower O-rings, because it was leaking. Hopefully that was the whole running rich problem, Ill fix it tonight and let you guys know. This thread has been a big help, thanks!
And by the way, Car felt wayyy stronger last night and rev'd smoother and faster! Its definitely breathing better!

fiveoformula

Another update, was able to slap a new O ring in on my lunch break and fire it up. Runs great! Now just fine tuning I think is all it needs. Excited to see some 13.XX timeslips over 100mph this summer!