Rebuilding TBI on 454.

i didnt like the afpr. on all my street trucks i run a vafpr more expensive but has a better feel across the board (diagnostically established this by looking at my datalogs)!

id either recomned that or stuff a stainless washer under the stock spring. i wouldnt fuss with adjustable ones honestly.

shave the ridges on the barrels and be done with it really.

if your looking for all around power id go mpfi grab yourself a harness and computer from a 95 and swap to MPFi

dave_erald said:

DerekTheGreat, and soon to be greater, I would definitely do a compression check (including a leak down check), and a fuel pressure check (even though you did just do a fuel pump).

When you do go to order a EGR, it should be fairly simple for them to get you the right one, but I do remember having to dicker with parts guy on getting the correct EGR for GM vehicles before, as some are positive back pressure and some are negative back pressure. I don't what the hell was going on but just remember this being a problem, so if you swap it out and it gets waaaaay worse that might be why.

Here's a good explanation on the different types

http://www.aa1car.com/library/egr.htm

Most TBI engines are notable for plugging the EGR routing in the manifold itself. That's a quick check by grabbing the diaphragm inside the EGR while running and pull up, Does it die?

The shifting gears and rpm hang up crap, do you have a TH400? If so is the vacuum line plumbed correctly and it is not sucking trans fluid through a ****** modulator?


There are probably three or four different threads that could be started from all of this...I need a coffee

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Soon to be greater, lol. Name was sourced from old Diablo game character. Anyway the truck is a stickershift, SM465 trans.

Hmm, I had the GF order parts. Also, it's funny how the truck has tons of bawls when cold. It seems that the moment it goes from open to closed loop it gets stupid and remains stupid until fully hot. Even then it doesn't have much power, not like it did when cold. Firebird has same stupid TBI set-up and it is same hot or cold. If the passages were all plugged up in the manifold wouldn't I get a CEL? Fireturd did that. Also, the little filter inside the air cleaner for the smog pump keeps blowing out of it's seat. The AIR solenoid doesn't respond to the command given to it by that MT2500 scan tool I've got either. Scanner says the thing should go lean when I hit that but it doesn't and nor do I hear a clicking. Wonder if the smog pump is just dumping air into the exhaust all the time. That would cause it to think it was lean, right? But then wouldn't the 02 sensor compensate for that? No clue with this thing. I'd be happy with it's performance if I could get it to run like it does when it's cold. Can't check the fuel pressure because there's no fitting for it. I tried buying one of those adaptor fittings that go between the TB & line but it didn't fit. I just assume it's getting the pressure it needs since when cold it runs flawlessly but as soon as the temp needle gets to ~1/4 it acts stupid up until it's right around 195F. Then it seems to drive OK but low on power.

-What does the coolant sensor read cold and warm?

-The o2 sensor only makes minor tweaks, and if it's a single wire only once it's warmed up and off idle. And yes if the AIR pump was always running then yeah it would fool the o2 sensor into thinking you were lean. I would block the air divert solenoids or the hosing itself and see if that changes anything, and if you're not in Cali, just delete it

-How old is the Catalytic Converter on this thing?

-As for fuel pressure you could always tee it in after the fuel filter if you've had that apart. Just splice in some 3/8 hose and clamps for testing. It's worth the time to make sure you got what you need when hot

-And yes if the EGR was fully plugged you should get a code 32...should

-And I'm trying to remember the steps needed to check the knock sensor and circuits...

-Also, yay for Diablo... and the Hellfire expansion...and Diablo 2... and it's expansion pack... and I'm getting off track

-Temp sensor reads correctly, according to the scanner... PO replaced it.

-Hmm. Have a remanned smog pump coming in, I like to keep things as the factory intended but suppose I could delete that if I could find suitable plugs for the inlets on the manifolds.

-Cat was removed & straight piped by the PO.

-Good idea, are those fittings the same as that aftermarket thing I bought or will I have to fab stuff up? Too lazy to fab stuff up and lack the materials & tools.

-Ok, so far no codes with this thing.

-Not sure how to check any of that stuff either. Swapped in an ecm off a different 454 stick shift truck and it ran but lit the check engine light up dimly, code was for the knock sensor but people said that could either be that the knock sensor is bad or that the ecm is bad. I figured that since with the original ecm I had no codes that the new ecm I bought was bad. yay for junk yards and the gamble you take with electronic bits.

-Haha yep, those were my favorites. Played Diablo III for a while but it didn't grab my attention like DII did, I played that for years. DI is still great too.

88 should have an external esc module on the intake on a 350 not sure about 454s but i dont believe any of the earlier computers internally contained the esc module which typically throws a knock or esc code.

as far as getting into warm up times quicker look into a 3 wire 02 sensor.

dave_erald said:

That's a hard one to sell for me just for the simple fact that you have already priced out something (FI TECH), that for another 300 dollars will outperform that newer TBI. And there is also the factory Vortec system that when converted to use a 0411 Pcm would walk all over that TBI unit.

Probably the best answer I could give you is decide what you are going to do with that 454 mill first, and if any of the future modifications include heads or camshaft swaps then don't even waste any money on the TBI injection, it won't keep up. However, if you are going to leave it stock, or very near stock, and if this guy is going to give you money for your TBI core then I would say yes, giver and do the ebay replacement. That ebay replacement looks like he has everything covered as far as replacing and upgrading is concerned and when priced separately without the new throttle bushings is probably the same if not more.

***A fair warning though, its pretty safe to assume that upping the injector size and doing mods on a throttle boy injected big block is going to make it that much more difficult to pass a smog test in the future, if at all. I imagine there is a balancing point somewhere, though I haven't the foggiest where it would be, but I would be hesitant going BIG on TBI injection and then asking it to pass smog***

The cheapest answer by far is if you find your TBI isn't worn out, and isn't leaking anywhere odd, then I would throw in a new regulator, possibly new injectors (nevermind, a flow matched set for sale on ebay is 211 dollars.... yuck) and drive it.

Based on your smog numbers it's a fair assumption to make that you are already starting with a healthy big block. And that's a good thing.


If you have the time and you know of some people (or others can chime in hear anytime) I would ask some others how there trucks run with bigger Throttle Bodies and bigger injectors, and if any of them have passed smog (I am willing to throw money down that they haven't and can't, and until they show you smog tests proving otherwise I would assume no)

I would save the money and do a Multi Point Fuel injection swap, or step up to a FI TECH or Atomic EFI, but that's because if I had a Big block I would be throwing heads, cam and intake at it...but that's me.

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Ive been going back and fourth with Dctrumpet, the guy on ebay,(SPR performance) and then had about an hour conversation with him on the phone today. This guy knows TBI like the back of his hand. super knowledgeable about the variations differences problems with the whole TBI setup, he runs it on his 3rd gen Firebird still.. and says hes gets about 375hp out of it, on a 355 small block. Ive been telling him where I wanna go with this truck, (nothing crazy) and so we made a deal today and hes gonna send me out a bored out to 54mm unit with flow matched injectors that he actually tests to make sure they really do flow the same. the Injectors are still 80lb injectors so I didnt bump up the injectors they'll just be flow matched Factory original injectors new IAC, New TPS and sets the voltage on the TPS, bushings on the throttle shaft and an new adjustable regulator with new spring and Diaphragm... the guy has no negatives on eBay or on the thirdgen.com forums and hes rebuilt over 1300-1400 TBI's it was hard to pass up in my opinion.

I also Inquired about smog and it wasn't a concern at all to him, hes says California is one of his largest customer base, and if anything the truck will run as clean, if not cleaner, hes never had an issue with it.... talking to the guy really sold me on it, real stand up guy.

I definitely wanted to go the Fitech route (probably gonna do it on my Monte Carlo) it specifically says its not California emissions compliant, which never stops me, because that really just means they haven't paid off the California smog mob. but then I did research on integrating it into the stock computer, and I could see it wasn't gonna be just a few hundred dollars more.

the Truck is a Daily driver, I cant afford any down time so really this is my best route. pricing all the parts that are new and flow matched injectors, adding bushings myself the price is very reasonable as it would cost me nearly the same, if not more to do all the work hes doing myself. Ill have more info on it when I get it hopefully next friday.

you can check out his website

http://www.sprperformance.com/

No hate here. You've done the homework and sounds like you are going to get a good product. And it's good to actually talk to a person who has done real world builds and smog testing on this stuff to say that it is good and will pass, I have my reservations on whether a "hopped" up TBI would pass smog, but having somebody with proof saying otherwise does make me feel better.

And yeah, I had in my mind you were dickering around with this until you were sure you had a good truck to start daily driving with. Sure other mods can be done over the weekend, but not nearly as quick or reliably as a straight up Throttle Body swap.

Glad you found a route to go with. Keep us informed on how this works and what the shape of the old one is when you take it off.

EDIT == I did have a look over his website, and to be perfectly honest I have always preferred the TBI trucks over anything else. So simple and reliable, hmm, that reminds me of one more thing, when was the last time the ignition module in the distributor cap was replaced? And have a good look at the rest of the ignition components in there while you are monkeying around with the throttle body off and the dizzy cap off if you haven't already

Ignition Control module Is brand new along with the Ignition coil, cap and rotor, the Pickup coil on the distributor was replaced (it was thrashed) I have brand new spark plugs and wires as well, It was the first thing I did, you can find it on the first page of my build. I re-timed it to factory settings after all that, It felt a little better, but the idle tends to get choppy, its weird some times its choppy, sometimes I feel like its just idling a tad bit too high, never seems to make up her mind. The TBI makes this really high pitched Whistling sound through one of the machined holes right above the driver side throttle blade... it doesn't look like its ever been touched either, probably has never been rebuilt and I have about 148k miles on her.

modded tbi isnt gonna pass smog without tuning for efficiency. id doubt that just a throttle body with a FP bump helped pass.