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1991 5.7L Bored TBI Upgrade Write-up (warning LOTS of pics!)


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#1 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:37 PM

This write-up is for pretty much all the TBI upgrades you can do. This is done step by step with a ton of pictures so as long as you have basic mechanics skills and a manual at the ready you should be able to do this upgrade. You should also be able to use this write-up as a guide for basic TBI overhauls or fuel injector replacing. I tried to be as thorough as possible. If I missed something please let me know.

Parts:
Bored out Throttle body #62-350b
Rebuilt and matched fuel injectors #62-FI
Injector Pod
Fuel pressure gauge adapter #62-FP
Fuel pressure gauge 62-PG
Adjustable fuel pressure regulator - 62-FR
Injector pod spacer
Powerplate (TBI Spacer) #PP-100
Hypertech Powercharger (Salad Bowl) #4001
Amsoil EA performance dry air filter #EAAR31

Tools:
13mm socket
Standard screwdriver
T-15 Torx
T-20 Torx
T-25 Torx
1/4” allen wrench
Other miscellaneous tools needed as well

NOTE: The Torx bits should be in a screwdriver
setup only. IF NEED BE you can use a ratchet to remove screws but only
use the screwdriver upon reassembly.

Parts to be installed

tbiu-25.jpg


So here we go! We will assume you are starting with the air cleaner off and the battery disconnected. You will need to disconnect these items from the TB in order to remove it from the intake manifold.

Disconnect the two electrical connectors to the Throttle Position Sensor and the Idle Air Controller. NOTE: The clips that hold these on are probably brittle so be careful not to over bend them otherwise they may break like my IAC one did.

tbiu-01.jpg


disconnect the three vacuum lines on the front of the TB

tbiu-02.jpg


Using a 17mm and a 19mm wrench (preferably line wrenches) to remove the main and return fuel lines from the rear of the TB. Remove the single vacuum line as well.

tbiu-03.jpg


Using the flat blade screwdriver pop the two clips off to remove the cruise control and the throttle cables. While hold firm the throttle linkage grab the TV cable connector and pull it forward by hand and it should pop off.

NOTE: DO NOT PRY IT OFF YOU COULD BREAK THE CABLE... BAD!

tbiu-05.jpg


To remove the electrical connectors from the top of the fuel injectors pinch by hand the two points in the middle and carefully wiggle while pulling it up.

tbiu-04.jpg


Using the flat blade screwdriver pop out (working forward) the weather plug that contains the injector wires.


tbiu-06.jpg


Always make sure to cover your intake ports even for just a minute!

tbiu-63.jpg


Use the 13mm socket and remove the 3 bolts on top of the TB. once out you can then remove the TB from the engine.

Use the T-25 Torx on the two screws to remove the TPS sensor from the TB. Use a 32mm socket to remove the IAC from the throttle body.

tbiu-08.jpg


The TPS is under a small amount of sprung wound tension, nothing to worry about. Once both the screws are out it will turn to a natural position like you see in the pic below. REMEMBER: when reinstalling set it back to this position then turn to line screw holes up.

tbiu-09.jpg


Using the same T-20 Torx bit to remove the eight screws that hold the injector pod top.

tbiu-10.jpg


If it doesn't just come loos lightly tap the top housing with a rubber mallet or plastic hammer. Mine just took a small single tap.

tbiu-11.jpg

tbiu-12.jpg


Remove the fuel injectors by using a flat blade screwdriver under the lip in the center of the injector. Use another screwdriver to place on the edge of the housing and use that as a pivot point. the injectors will come out easily just a bit slow.

tbiu-13.jpg


Using a T-25 Torx remove the three screws that hold the injector pod on the main TB housing.

tbiu-14.jpg


Unscrew the fuel line flanges using a 19mm wrench. Hold the TB firmly. When you do remove them make sure the little clear plastic washers came out with them. If you accidentally double stack them they may leak.

tbiu-15.jpg



Continued on next post...


Edited by pma4x4, 24 August 2013 - 12:29 PM.

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#2 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:39 PM

Comparison side by side

tbiu-16.jpg


When you place the order make sure you let them know if you have a long or short cruise control shaft on the throttle linkage. I did not know this so I swapped mine out.

tbiu-17.jpg


The short one was riveted on so I used a Dremel to carefully grind away the backside of the rivet. I also had to cut off the front part of it and grind away on the front side of the rivet
as it was tapered.

tbiu-18.jpg

tbiu-19.jpg

tbiu-20.jpg


WARNING: Regulator under a lot of spring pressure.

Use a T-15 Torx to remove the old fuel pressure regulator from the injector top housing. first loosen half way two of the screws kitty corner of each other. then while holding the regulator cup down firmly remove the two already loosened screws. DO NOT loose the spring.

tbiu-21.jpg


One stripped injector pod upper housing

tbiu-23.jpg


I soaked it LA's Totally Awesome cleaner for about 30 minutes. I brushed it then cleaned it off with carb cleaner.

tbiu-24.jpg

tbiu-26.jpg


Take the two new clear plastic washer from the rebuild kit and install them on the fuel adapters. You are now using the new fuel adapter that has the two extra threaded holes in it. This is for the gauge.

tbiu-27.jpg


When installing the new fuel pressure regulator diaphragm make sure the “tipsy table” piece is facing “up” or into the housing.

tbiu-28.jpg


When seated you should have the smooth side facing you.

tbiu-29.jpg


Install the spring that came out of the original regulator and sit the bowl looking piece (that came with the new adj. regulator) on top of the spring.

tbiu-30.jpg


Install the regulator housing cover in reverse order holding it firmly and hand threading two screws kitty corner of each other, then screw in the other two and then tighten all down.

tbiu-31.jpg


Continued on next post...
       

Edited by pma4x4, 24 August 2013 - 12:30 PM.

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#3 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:41 PM

You can see how much thicker the new spacer is to the old one. The old one maybe of a gasket like material but do not worry if your new spacer is hard plastic. That is all the does is raise
the injector pod.

tbiu-32.jpg

tbiu-33.jpg


I chose to get a new (cleaned and inspected) injector pod for an extra $15 bucks. That way you know its not cracked and the threads are good. besides its nice and shiny!

Using the supplied 5/32 Allen screws assemble the injector pod onto the TB housing with the new spacer in between.

tbiu-34.jpg


Flip the TB upside down and drop the adj. fuel pressure regulator handle through the hole. Hold it in place and turn the TB right side up again.

tbiu-35.jpg


Now take the two new O-rings and install them on the bottom part of the fuel injector as shown.

tbiu-36.jpg


from the rebuild kit take the two new thin metal rings and install them in the upper O-ring channel fo the pod housing

tbiu-37.jpg


Then the O-rings

tbiu-38.jpg


Notice on the Injectors there is a peg. Line that peg up with the notch you see int he picture below

tbiu-39.jpg

tbiu-40.jpg


Slide them in smooth and consistent. Mine kind of had a very defined stop when they seated.

tbiu-41.jpg


Continued on next post...
       

Edited by pma4x4, 24 August 2013 - 12:33 PM.

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#4 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:42 PM

Make sure you install that small two hole gasket

tbiu-42.jpg


Install gasket on top of injector pod

tbiu-43.jpg


This is where it gets a little tricky. when setting the injector pod upper housing with the now assembled pressure regulator on the injector pod you actually have to start threading the regulator knob into the regulator housing about half way before the whole injector pod upper housing will seat. Once this is done install the eight screws using the T-20 Torx. REMEMBER use only a screw driver
style tool with torx bit tips. a Ratchet will produce too much torque and strip the threads right out of the aluminum housing.

Fully assembled on the bench. The fuel gauge adapter comes with two holes, a brass plug and a 90* brass elbow. I used teflon tape on both brass fittings and on the gauge.

tbiu-44.jpg

tbiu-45.jpg

tbiu-46.jpg

tbiu-47.jpg


Continued on next post...
       

Edited by pma4x4, 24 August 2013 - 12:34 PM.

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#5 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:43 PM

Installing back onto engine.

You will get two gaskets with your TB spacer. Mine had two different shaped gaskets I assume your will be the same. One gasket the material goes fully in between the two ports and the
other does not.

Install the gasket that fully separates the two ports on the bottom. then the spacer then the gasket that's one hole as in the pic.

tbiu-48.jpg


Use the 3 new bolts and washers that came with the spacer and tighten down the TB with a 13mm ratchet.

tbiu-49.jpg

tbiu-50.jpg


The fact is the fuel lines need to be routed higher which interferes with the Coil mounting location. I removed the coil all together to deal with the fuel lines.

NOTE: the coil bracket uses two 13mm bolts one shared with the throttle bracket and the other one right in front of the distributor.

tbiu-51.jpg

tbiu-52.jpg


OK, fuel line routed and installed. and by routed i mean tweaked up and bent just a hair. I think had to remove the one side of the bracket that mounts the coil to the intake. Ive seen coils held on by less so I didn't have a problem with it. Take your preferred metal cutting tool and remove the side of the bracket that mounts in front of the distributor.

tbiu-53.jpg

tbiu-54.jpg



There are two bracket spacers that come with this TB spacer. I ended up using them. If you have cruise control you will have to remove the two 10mm bolts that bolt it onto the throttle bracket in back. My cruise is still firmly bolt to the head so I decided to leave it. You may want to do something else. Use the two supplied bolts that go into the intake as well.

I had a hell of a time getting this part done as I have meat hooks for hands and it's just a PITA to get back in that area. I got so frustrated with it I forgot to take pics of the bracket spacers and installation. but they are pretty self explanatory.
 

Continued on next post...
       

Edited by pma4x4, 24 August 2013 - 12:36 PM.

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#6 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:44 PM

Air cleaner housing modification for the Hypertech Powercharger, or as we like to call it... the “Salad Bowl”.
 
WARNING: THIS IS A PERMANENT MOD.
 
This is where you want to cut. about in the middle of this section of housing. Lay the bowl onto the bottom side of your cleaner and see just to verify
before cutting.

tbiu-55.jpg

tbiu-56.jpg


Pre-drilling a hole will make life easier. I then used a jigsaw with a metal blade. It sounds like a cat being ran through a bandsaw but its quick!

tbiu-57.jpg


Double check where you need your port hole to be. instead of keeping a two piece unit I decided to make it one so I used hi temp black RTV and sealed it together. If you do this make sure on the top side you smooth out the RTV that squeezes out. Do this for two reasons. 1) so you dont disrupt the airflow you are so desired to gain and 2) if left unattended a glob of that RTV can makes its way into the engine... nuff said.

tbiu-58.jpg

tbiu-59.jpg


Finishing up

tbiu-60.jpg

tbiu-61.jpg

tbiu-62.jpg





Continued on next Post...
       

Edited by pma4x4, 24 August 2013 - 12:39 PM.

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#7 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:45 PM

Final thoughts



All parts except the salad bowl and air filter were purchased through
Roy Morse over at RVMorsemachine.com. The quality of the machining was
great and the parts were well packaged. Roy Morse has a very
professional out look with his business and is quick with emails. He
also wants to make sure you are getting the right product. I cannot say
enough of how smooth the transaction went with him!



If you do get a bored out TB and a Powerplate (spacer) make sure you
mention you need to have the spacer bored out as well so it matches. I
didn't think about this so I emailed Roy and he told me it was $25 for
the boring i said go ahead so he actually shipped out another spacer and
I shipped the original one back. I highly recommend going with RVMorse
for any TBI upgrades in the future.



Disassembling and reassembling the old and new TB was pretty straight forward. its hard to screw it up. Just take your time.



Test drive showed massive improvements in low end and passing. I have
the fuel PSI about 13.5lbs. It idles much smoother, starts quicker and
whats odd is the exhaust note is a bit more noticeable. This maybe do to
the fact its inhaling more air now.

I will be driving it for a small trip in a few weekends so MPG testing will be done then.

End result I do not regret spending the money this is a very simple no nonsense upgrade that will offer great benefits!

 

 

Not including the Amsoil air filter or the salad bowl was $540 to my
door from RVMorse. The salad bowl is another $40 and the air filter was
$62

If its one thing I am good at is wasting money!

and I don't regret any dime of it.

 

 

Quicker starts
Crisper throttle (more responsive)
Climbs in RPMs a bit quicker
Better bottom end power
Smoother idle

I also have a new high flow cat and series 70 muffler but those were done before the TBI upgrade.


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#8 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 04:46 PM

I just duplicated our original mpg drive, this time with the TBI upgrades.

Original was 15.01 mpg
After upgrades is 14.58 mpg

Now, before you start saying WTF. keep this in mind. The original mpg drive was done on half tread 32x11.50x15 BFG ATs. The new mpg drive was done with new 33x10.50x15 BFG ATs. This give more diameter to rotate and
a bit more rotational mass. I noticed right off the bat after the tire swap that I lost some power and this was before I did the TBI upgrade.

the difference is .43mpg a total of 17.2 miles less per 40 gallon tank. I think I may gain that back plus some after i move from 3.42s to 4.10s.

 

Keep in mind all the other benefits that was gained from the TBI upgrade. I think if I still had the 32s on It may have seen 16 maybe 16.5 mpg but that's a guesstimate.

Fact is when doing testing make sure you only change ONE variable at a time otherwise you wont know what did what.


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#9 OFFLINE   DonYukon

 
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Posted 16 February 2013 - 05:02 PM

GREAT WRITE UP 

Consider it Pinned , this is really good Lots of Tech data , and pictures to back it up Plus a Review 

 

:goodpost:


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#10 OFFLINE   Scrib

 
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Posted 16 February 2013 - 05:32 PM

Great info, thanks!



#11 OFFLINE   DirtRidinZ71

 
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Posted 16 February 2013 - 08:04 PM

Excellent writeup! I know I experinced smoother idle and better throttle response from when I did a tbi rebuild (minus injectors) and the ultimate tbi mods. I've been planning on doing the salad bowl mod or just removing the choke collar all together.

 

One question I have is with the bored throttle body and spacer you didnt have the intake manifold done to match or was it not needed (taperd bore)?


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#12 OFFLINE   pma4x4

 
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Posted 16 February 2013 - 08:37 PM

Excellent writeup! I know I experinced smoother idle and better throttle response from when I did a tbi rebuild (minus injectors) and the ultimate tbi mods. I've been planning on doing the salad bowl mod or just removing the choke collar all together.

 

One question I have is with the bored throttle body and spacer you didnt have the intake manifold done to match or was it not needed (taperd bore)?

 

The intake is large enough. Just when you order the Spacer you need to make usre ite bored out. When you go to install have all the bolts just before tightened and rotate the butterfly vlaves to make sure they clear the spacer and the gasket. there is enough slop ont he bolt holes that you could catch the edge of the spacer with a valve.


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#13 OFFLINE   Chevrolado

 
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Posted 16 February 2013 - 10:02 PM

Excellent info and writeup with perfect amount of pictures documenting. Awesome. Thank you. :D


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#14 OFFLINE   digdug18

 
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Posted 24 June 2014 - 04:33 PM

Any idea how this would affect emissions testing? I'm guessing that it would be the same, maybe a bit cleaner, but thought I'd ask. Does your suburban go through emissions where your at?



#15 OFFLINE   pma4x4

 
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Posted 24 June 2014 - 04:37 PM

Yes I have emissions in my area. It did in fact show a bit cleaner. With smoother idle came less fouling. Thats due to the psi being bumped up a bit. All connections on the throttle body are still stock. Nothing changes with emission hook ups.
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