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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: zieg85 on April 21, 2015, 08:32:33 PM

Title: TBI newbie question
Post by: zieg85 on April 21, 2015, 08:32:33 PM
I am doing a 1987 TBI 5.7L from a C3500 GMC into a 1986 C10.  My question is will the ECM care whether it has a standard transmission (NP833) when the 87 had the TH400?  This is the first TBI I've ever messed with so I know nothing but the basics.
Title: Re: TBI newbie question
Post by: Stewart G Griffin on April 21, 2015, 10:00:06 PM
Not sure if you've heard of them, but might want to check this shop out:
http://howellefi.com/
Title: Re: TBI newbie question
Post by: Stewart G Griffin on April 21, 2015, 10:08:48 PM
P.S.

If it's an 87, then i'm guessing the ECM will not care if it doesn't "see" an automagic trans.   Or if it does, then it won't care that much.

This is only my guess though.
Title: Re: TBI newbie question
Post by: zieg85 on April 21, 2015, 10:26:54 PM
Not sure if you've heard of them, but might want to check this shop out:
http://howellefi.com/

Thanks Stewart, that in-line fuel pump is very interesting.  Sure beats a new tank and in-tank fuel pump.  I bookmarked that page
Title: Re: TBI newbie question
Post by: Irish_Alley on April 22, 2015, 12:54:28 AM
if the original ecm had a speed sensor then i would say it would matter. will it still run, yes but the ecm might think its in park and lean out the fuel mixture for not waisting fuel while idling. the egr stuff is based off the speed sensor meaning it order for the egr to work your speed as to be above a certain number and the tps has to be reading a certain load. cel light will be on and it might stall under certain circumstances might also ping due to running lean. idk for sure, i mainly wanted to subscribe so someone will post and either confirm or bust my theory 
Title: Re: TBI newbie question
Post by: Irish_Alley on April 22, 2015, 01:04:04 AM
http://www.jagsthatrun.com/V8-chapters/V8-tpi-Speed-Sensors.pdf
Title: Re: TBI newbie question
Post by: LTZ C20 on April 22, 2015, 01:49:19 AM
Zieg, I have a complete Howell TBI kit on my 73, it works great with my 89 4L60 because the system is based on a 89-90 5.7L truck. Its a pretty sweet setup, was totally worth it.
Title: Re: TBI newbie question
Post by: Irish_Alley on April 22, 2015, 02:10:46 AM
$1500 for a tbi kit? you could get a whole truck with a tbi for half that then scrap the truck
Title: Re: TBI newbie question
Post by: zieg85 on April 22, 2015, 05:39:25 AM
Thanks guys, when I crawl under the truck I will see if it has the sensor or not and reuse it if need be.  This is a budget build so hopefully everything I need, I already have.  Just need to decide what route to go with the tank/fuel pump since this the donor truck is a bit on the crusty side
Title: Re: TBI newbie question
Post by: Irish_Alley on April 22, 2015, 05:43:45 AM
not 100% on these but froto might be able to help
http://forum.73-87chevytrucks.com/smforum/index.php?topic=30829.0
Title: Re: TBI newbie question
Post by: Stewart G Griffin on April 22, 2015, 06:53:22 AM
Also i think one of the Howell brothers worked at GM and helped develop the original TBI system.   Not 100% sure on this though.
Title: Re: TBI newbie question
Post by: LTZ C20 on April 22, 2015, 10:00:47 AM
I think final on mine was $1600 but I didn't want old parts and accessories. I wanted all brand new parts, accessories, wiring, connectors blah blah blah. So for the price and what I got, along with the customer and technical support, it was worth it to me. I'm happy with it.
Title: Re: TBI newbie question
Post by: LTZ C20 on April 22, 2015, 10:05:03 AM
Stewart, you are correct sorta. The way they (Howell) explained it to me, the founder was an engineer at GM when they developed the TBI system. After which he retired, he expected the new system to carry over to the aftermarket/custom car world, so he founded Howell Engine Developments. The rest is history. So yea, not a brother but the founder himself.
Title: Re: TBI newbie question
Post by: pholliday1 on April 22, 2015, 12:53:37 PM
Computer won't care. Just run it and it will be fine.
Title: Re: TBI newbie question
Post by: bd on April 22, 2015, 03:30:27 PM
The 87 TBI should acquire its VSS signal from the buffer that connects into the back of the speedometer head.  As long as you have a suitable cluster with VSS buffer, Code 24 will not set and the ECM will be able to properly register road speed.  If push comes to shove (and IIRC) there's a software switch accessible to a programmer that will toggle VSS diagnostics OFF.

Code 24 will set if:
  CKT 437 voltage is constant.
  Engine speed between 900 and 4400 rpm.
  Less than 2% throttle opening.
  Low load condition (low air flow).
  Not in park or neutral.
  All conditions must be met for 3 seconds.
These conditions are met during a road load deceleration.
Title: Re: TBI newbie question
Post by: zieg85 on April 22, 2015, 05:43:34 PM
The 87 TBI should acquire its VSS signal from the buffer that connects into the back of the speedometer head.  As long as you have a suitable cluster with VSS buffer, Code 24 will not set and the ECM will be able to properly register road speed.  If push comes to shove (and IIRC) there's a software switch accessible to a programmer that will toggle VSS diagnostics OFF.

Code 24 will set if:
  CKT 437 voltage is constant.
  Engine speed between 900 and 4400 rpm.
  Less than 2% throttle opening.
  Low load condition (low air flow).
  Not in park or neutral.
  All conditions must be met for 3 seconds.
These conditions are met during a road load deceleration.

Perfect, I can switch out the speedo cluster or just add the speedometer head.  The clusters are identical being both are dummy lights and not gauges.  I am sure it will be self explanatory when I start the harvest process.  I parted out a 87 TBI truck a couple of years ago and carefully removed the wiring harness to ecm and engine and when I have the trucks side by side it shouldn't be too difficult.   
Title: Re: TBI newbie question
Post by: frotosride on April 22, 2015, 09:05:02 PM
Since you said budget here's a pic of what you will need from a donor. The sensor in my hand has a single screw that attaches it to the back of the speedometer. The green box is the signal converter. It only needs switched power,ground and the brown wire goes to A10 on ythe ECM smaller blue connector.
Title: Re: TBI newbie question
Post by: zieg85 on April 22, 2015, 09:11:04 PM
Looks like what is used on the newer cruise controls
Title: Re: TBI newbie question
Post by: roundhouse on April 24, 2015, 07:18:24 PM
Wow
$1600 for TBI

Guy near me sells LS motors ready to run with harness and reprogrammed computer for $1100

The frame mounted pump may work or it may not
Worked fine on my 73 bronco to supply 50 psi for the 90 mustang engine

But wouldn't work on our 77 K-10 TBI
We wound up ordering a new 87 tank from rock auto for $80 and buying a new In tank pump at a local auto parts store

We bought the complete TBI system from a running truck for $200



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