Re: Tbi swap build thread
 

What about the electronic spark control module. What does it exactly do. If its faulty will it cause no spark. Also if I got the esc off a vehicle with vats is the vats incorporatded into the esc

Re: Tbi swap build thread
 

Lets take a step back... Can you provide a complete listing of your setup?
ECM - service number and broadcast code, distributor type, donor vehicle information, etc.

The ESC module - the black square module

http://www.chevythunder.com/esc_module.jpg

acts as buffer-filter between knock sensor and ECM. Its presence or absence will not affect engine starting.

On the the other hand ECM (Pin B6) presence or absence of VATS signal from the VATS decoder enables or disables the ECM to operate the fuel injectors during cranking. An extensive discussion of how VATS system operates can be found here:
http://www.thirdgen.org/vats_passkey_system

In general if ECM has an EPROM with VATS enabled a VATS system (or VATS emulator) will be required to allow normal starting sequence. Naturally, a custom EPROM can be sourced with VATS function disabled.

//RF

Re: Tbi swap build thread
 

My ecm is the 7477 from a 305, not sure what its out of exactly. I got it off a guy that just had the motor and complete harness sitting on the floor of his garage. My distributor is this one
http://www.jegs.com/i/Proform/778/66...d=#moreDetails

this is my coil
http://www.jegs.com/i/MSD-Ignition/1...d=#moreDetails

I have the painless vss, I also have a 3 wire O2 sensor and I wired to a relay from a digram that was in this tread.

Is there any thing else you need to know. I appreciate the help.

Re: Tbi swap build thread
 

Also egr has been deleted.

Re: Tbi swap build thread
 

The Proform 66938RC and MSD Ignition 8226 should provide spark in TBI system. As a sanity check I would double check the MSD coil winding resistance: Primary should be less than 1 OHm and secondary 5.8 kOhm. It is not unheard of to receive a defective coil! There is a two wire harness running between distributor (ICM) and coil (white and pink wire). Do yourself a favor and make sure that it is in a good shape and circuit continuity is there. A broken wire or intermittent pin connection will render ignition coil or ICM inoperative. Use DVM to check both circuits. Other commonly overlooked problem is to make sure that harness plugs makes contact with module socket pins - paste tiny amount of dielectric compound on each pin of the plug - insert and remove. There should be an indication of a contact between socket contact and plug pin.
//RF

Re: Tbi swap build thread
 

As others have already said thanks what a great thread for the TBI swap! I am still gathering info and in the planning stages for my TBI upgrade. I am at a point right now where I need a little guidance on the Drac issue. What I have and plan to install with the TBI is a 90 corvette 700r4 (will manufacture rear mount for vette tailhousing) with the 4 pulse vss and I also have a 90 suburban speedometer I want to use. I need to know if a DRAC will even work if I am going to use a 7747 ECM or do I need a 90+ TPI ECM? Or any other suggestions?
truck is a 78 SWB BIG10 3.42 rear
350 goodwrench w vortec heads, weind street warrior intake,
Crane cam 100052 (cam specs)
Intake Duration at 050 inch Lift:216
Exhaust Duration at 050 inch Lift:216
Duration at 050 inch Lift:216 int./216 exh.
Advertised Intake Duration:272
Advertised Exhaust Duration:272
Advertised Duration:272 int./272 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.454 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.454 in.
Valve Lift with Factory Rocker Arm Ratio:0.454 int./0.454 exh.
Lobe Separation (degrees):110
1.6 roller tip rockers
2 1/4 true duals with super 44's (plan is for ceramic chevelle headers when I do the upgrade and weld 3 wire 02 right after collector flange)
Has no emission requirements so EGR I am not worried about but will most likely install purge tank from donor. Also do you feel that an alt upgrade would be needed from the stock one considering the extra juice needed?
Right now I am stuck in the planning stages and need to know if the 4 pulse vss is going to work or an idea on what would be the best route with what I have. Thanks

Re: Tbi swap build thread
 

You will need the DRAC to convert AC 4000 ppm signal coming from VSS. The DRAC will provide correct 2000 ppm square wave signal to the 7747 ECM. You do not need 90+TPI ECM. DRAC will also provide 4000 ppm square wave signal to the electronic instrument cluster from 90 burban. Alternative to DRAC is a dakota digital SGI-5 can do the same without DIY alteration of the DRAC to account for tire size, rear end gear ratio and VSS reluctor gear.

Problems

Crane cam 100052 has duration @0.050 216/216 with LSA of 110. This is a good carburetor camshaft, but it will make MAP sensor very unhappy! I am going to guess your idle vacuum is only 12 to 13 in-Hg at 700 RPM with plenty lopping. Even modified 7747 will have problems at idle. The kicker is 216 duration and tight 110 LSA. If budget permits go for a cam with duration around 210/210 and LSA more than 112 deg. You'll loose a little bit of top end power, but your idle will smooth out.

Close alternatives are Comp Cam 12-365-4
Lift I/E .499/.493
Duration @0.050 216/220
LSA 113 deg

If you heads can not take this much lift Speed Pro CS1013R can be a good candidate
Range 2000-4500 RPM
Duration @.050 214 intake/224 exhaust,
Lift I/E 0.443 /0.465
LSA 112

Disabling EGR is straightforward in EPROM. To get the full power of this engine expect to DIY tune. Please be aware that Vortecs do not require too much timing ~ 32 deg maximum at 3000 RPM vs 36+ for conventional heads. Thirdgen.org has extensive articles that covers this in fine detail.

//RF

Re: Tbi swap build thread
 

Has anybody used the 88-95 headers with this swap? Just wondering because I would rather use headers with the o2 bung already installed vs retrofitting one on the pipe after the collector.

Re: Tbi swap build thread
 

I have a couple questions about my swap. The engine is out of a 88 pickup and going into my 70 Blazer. The air pump was not hooked up and I am going to remove it and use stock 70 manifolds. I tested the EGR valve and it does not operate with vacuum applied. I drove the pickup before pullling the engine and it ran good.

Is the EGR valve necessary, or would I be OK just blocking it off?

Re: Tbi swap build thread
 

My 88 engine has two temperature senders. This one in the intake
http://i737.photobucket.com/albums/x...r/100_3871.jpg

and this one in the head
http://i737.photobucket.com/albums/x...r/100_3872.jpg

Is the one in the intake for the computer and the one in the head for the guage?

It also has this oil sening unit by the oil filter
http://i737.photobucket.com/albums/x...r/100_3873.jpg

Is this for the guage and can I eleminate it for the mechanical guage?

Re: Tbi swap build thread
 

No you do not need egr. If you wish to use your stock intake manifold you can get a block off plate for it or get an aftermarket intake that doesn't use egr. I assume you're using th tbi with ecm so you may have to remove egr from the ecm via a flash, or new prom.
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Re: Tbi swap build thread
 

I belive the prom has been changed, but I know noting about it. If I block off the egr and don't flash the ecm what problems would this cause. I'm thinking a new egr for $50 would probably be easier and no more expensive than sending the prom off somewhere to be flashed. Are there any benifets one way or the other?

Re: Tbi swap build thread
 

Depends on what you're going for, if you're looking to pass emissions then you will need the egr system. But if your going for a cleaner look then you will definitely want to delete egr. You shouldnt see a difference in economy either way just emissions will suffer. Im not exactly sure what will be affected if you do not delete it in the ecm. I dont imagine it would affect anything. Maybe someone else can chime in here.
Posted via Mobile Device

Re: Tbi swap build thread
 

I'm not concerned about emissions. I want reliability and hopefully better than 10 mpg.

Re: Tbi swap build thread
 

You should get better than 10 mpg with TBI unless you have very heavy truck and high gears.

EGR can be blocked off for the non emission application - stock EPROM can not be easily altered (it is an ancient UV erasable 2732A from 70 and 80's). A new EEPROM based on FLASH technology can be sourced with EGR disabled from several outfits or DIY. Interestingly enough functional EGR provides gas mileage improvement, but the difference is very small.

About sensors in your photos

#1 2- wire CTS near thermostat housing - this is one is must have. This provides coolant temperature to ECM.
#2 1- wire sensor screwed into cylinder head (looks like TU-5 or TS-6) - this drives you dash gauge. Can be optional.
#3 oil pressure switch for the oil pressure light - again this can be removed and plugged.

//RF

Re: Tbi swap build thread
 

Thanks, that is what I thought.

Re: Tbi swap build thread
 

rfmaster,

I see a couple pages back you were testing temperature sending units. I need one for the gauges in my 70, but the heads are threaded for a 3/8" sender and the one for my Blazer is 1/2". Do you know of a way to get around this?

Re: Tbi swap build thread
 

If you are referring to a temperature sending unit (single wire) for use with dash gauge the closest equivalent is used by fords F5CF-10884-AA, F5CZ-10884-A.

At first look (TU201) measured:
45C 805 Ohm
98C 100 ohms

I have not had a chance to fully characterize this unit as I have been busy with other projects. It may be close enough to OE AC-Delco G1852 sending unit - after being fully characterized. Equivalent aftermarket replacement units are available from usual parts sources:

Autozone, Duralast / Temperature sending Unit: TU201
Rock Auto still has some from defunct parts maker Kem Parts: TW186

Are you sure that you have 3/8"NPT in your heads? Vortec heads are drilled and tapped for 3/8NPT sensor mounts, while common Gen 1 heads use 1/2NPT (aka dry seal).

//RF

Re: Tbi swap build thread
 

Yes, I'm talking about the one wire sender for the gauge. I picked up a new one yesterday for a 70 which is 1/2", when I went to install it in the head I discovered the head is tapped for 3/8".

Re: Tbi swap build thread
 

Ok Guys.

This thread has been languishing for a while so I've decided to add a bit of swap related information.

It has been mentioned that bolting L31 - vortec heads (casting # 602, 906) nets 40+ HP over stock smogger heads. This swap has been covered extensively by performance magazines and countless gear heads elsewhere. This is a great swap for some one on the tight budget, but it is not without its pitfalls. A stock TBI system uses swirl port heads, but will adapt nicely to Vortec heads.

To use L31 heads on Gen 1 block (assuming 350 CID TBI) will require standard head gasket and vortec specific intake manifold and intake gaskets. If the EGR valve is to be retained exhaust gases will have to be plumbed via custom pipe to EGR inlet port on the manifold. If EGR is to be omitted modification to EPROM will be required. All of the above has been covered before.
The issue is that our trucks use 1/2 NPT sized temperature sending units that screw into driver side head providing resistance vs. temperature signal to the instrument cluster gauge. Original GM sending unit is no longer available (GM 1513321) and the closest equivalent is AC-Delco G1852. Aftermarket produces similar units such as Wells TU5, SMP TS6 among many others. None of these sending units will screw into Vortec heads which are drilled and tapped for 3/8 NPT sensors. It has been suggested that 1/2 NPT sensor units can be turned down on a lathe. However, not everyone has a access to one. Drilling and tapping Vortec Head for a larger sensor (1/2 NPT) can be problematic - sensor boss area is very small and CI can be unforgiving.
This begs a question -are there any 3/8 NPT temperature sending units that will work with square body temperature gauges??? In the past it has been suggested that a Ford F5CF-10884-AA , F5CZ-10884-A, Motorcraft SW5051 can be a possible substitute. Lets take a look if it is even close to what we need.


Test setup - side by side TU5 vs Motorcraft SW5051 mounted into the same AL block.

http://i226.photobucket.com/albums/d...psc8d3891b.jpg

Measurement setup 2x Fluke 70 DVM + Fluke 52 Temp sensor meter (in my kitchen - the old lady gave a permission). Ideally, I would rather do this characterization testing in the environmental chamber which allows for soaking at a specified temperature, but it is not available at this time.

http://i226.photobucket.com/albums/d...psfe87e9a6.jpg

Test result speak for themselves. When engine coolant is below 50C SW5051 has high resistance which result in a lazy gauge (not reading anything), but above 78C the SW5051 has lower resistance and would result in a higher indicated temperature then it really is!

http://i226.photobucket.com/albums/d...psc909123a.png

Zooming into high temperature coolant area.
http://i226.photobucket.com/albums/d...psf74f3188.png

Cross over occurs right around 76 to 80C region.

AC Delco G1852 (found on Internet) data stops at 100C (212F) - I do not have this sensor at this time, but would like to re-run it to see how it behaves between 100 and 135C.

Next step is to validate SW5051 with the actual gauge.

Suggestions???? Questions???

//RF

Re: Tbi swap build thread
 

when u ran new lines did u run steel or were they rubber. just asking because i did a swap and need to move the tank but they are all steel and was wondering if i cut out and replace with rubber

Re: Tbi swap build thread
 

I used a combination of 3/8" (SUM-G2538) aluminum fuel lines and short 3/8" SAE 30R7 fuel line which are rated for under 50 PSI working fuel pressure. There are two reason why you want to use metal lines. One that a metal tubing offers lower flow resistance and second that it last a lot longer then a rubber tubing. SS tubing is nice, but it is a real PITA to work with - very hard to bend and bedding of the ends is next to impossible with conventional tools.

//RF

Re: Tbi swap build thread
 

I have a plug from my doner 88 pickup harness that I'm not sure what to do with. One wire goes to the computer labled Air Pump and the other is labled EGR Relay. Did this plug into the air pump? I dont have it anymore to check and it wasn't being used on the donor vehicle. Can these two wires be eliminated or do they plug in somewhere I'm missing?

http://i737.photobucket.com/albums/x...ps7a59caa7.jpg

Re: Tbi swap build thread
 

You'll have several options, but both require that you have EPROM burned that has EGR function disabled. AIR pump elimination does NOT require EPROM changes.

1) do nothing - just let them flop or tape them to the harness.

2) Remove connector ends and tape-up end of the wires and hide them in the main loom. Simple enough and quick.

//RF

Re: Tbi swap build thread
 

Where did this plug in? Is there a way to utilize the EGR without the air pump?

Re: Tbi swap build thread
 

So let me understand this correctly. You want to remove AIR pump, but you want to keep EGR valve??? Right ?

If this the case the EGR system uses EGR control valve which is mounted on a bracket bolted to intake manifold on the passenger side. ECM is uses PWM control signal to control amount of vacuum that reaches EGR valve. You can simply remove plug used to control AIR pump and individually tape of wire ends

http://i226.photobucket.com/albums/d...Picture025.jpg

On this bracket you'll find MAP, ESC module and EGR control valve. On the photo the EGR control valve is mounted on the backside, upper middle of the bracket (you can see white and pink wires protruding).

//RF

Re: Tbi swap build thread
 

truck starts and runs great , but when going down the road and wanting to step hard on the gas truck bogs way down , but if u ease in to it easy it runs fine, here is my couple of questions, i used a wiring harness from 90 suburban,put it all on after wards i had to add 12 volts to the injectors, and to the fuel pump relay. and tie my fuel pump wire in to the relay .then it started right up.but i do not thing it is right, at end of harness for tbi goes in to the fuse box and right now that is not attached to nothing, not exactly sure on how to wire up that tbi,also i dont have the trouble shooting plug are the check engine light hooked up . does that go to end of harness some wear,can some one give me some info on hooking up this tbi harness,

Re: Tbi swap build thread
 

http://i226.photobucket.com/albums/d...Picture025.jpg

On this bracket you'll find MAP, ESC module and EGR control valve. On the photo the EGR control valve is mounted on the backside, upper middle of the bracket (you can see white and pink wires protruding).

//RF[/QUOTE]

Thanks RF, that picture is what I needed. This is the wire for the EGR control valve. Somehow I missed the empty plug when I was running the wires.

Re: Tbi swap build thread
 

@ Dog

It is tough to diagnose what you have going - can you upload couple of good quality photographs of what you have setup and connected? The part of any swap is to document and capture what you have done as when something goes bad you'll have a way to troubleshoot.

From memory - I have pulled 90, 92 burban engine bay harness before. The plug that bolts into firewall bulk head connector (reference designator C100) under brake booster is used ignition and starter solenoid.

Ckt #3 Pink Ignition coil
ckt #430 pink-blk fuel injection power
ckt #120 tan-white Fuel pump supply
ckt #330 orange Battery B+ (always hot)



//RF

Re: Tbi swap build thread
 

ok this is what iv got going , i have read some what every body is written and iv gotten some info, some other questions are about the alternator 90 suburban has 2 wires that come out the side of alternator have been cut and just laying there, I also have the original harness from the 72 on the truck , thoes wires that go 2 the alternator is a fat red that bolts to back and a plug white and a blue wire that would plug in to the 72 style alternator, what do i do with all these wires, the plug on the alternator that is there now from the suburban i under stan needs a ground and the other goes to a light is that right, and what do i do with the wires to the 72. they look like they go to the stock 72 voltage regulator that is in the pic '' black box''. and do i need to hook up the o2 sensor and the park neutral switch to the computer, was reading , if park neutral is not hooked to computer then the computer doesnt read the vss and then wont adjust for timing .. I sure thank evrey body for there help .

Re: Tbi swap build thread
 

so if my vss wires from tranny plugs right in to harness it should be hooked up ,and no need to wire any thing.or ground them,

Re: Tbi swap build thread
 

do you know what wires go to check engine light,and to the aldl plug. by there color.

Re: Tbi swap build thread
 

@BigrobDog

OK - thanks for posting photographs - these help quiet a bit.

In Photo # 1
Your 1990 burban donor came equipped with CS-130 Alternator. This alternator has internal regulator. OE external '72 regulator that you have in Photo #2 will not be used. To adapt CS 130 to the '72 wiring is actually straight forward, but it will require a bit of DIY soldering. Are you up for it????

CS130 alternator is rated for 105AMPS maximum output and will deliver around 30 to 35Amps at idle. Which is plenty.

Look at the back of alternator. There, you should see BAT terminal and big fat red wire should be running between alternator BAT terminal and terminal block that is part of EFI harness - mounted on the passenger side firewall. I thinks there is one, but it is taped-up and not clearly visible. That wire should have been a part of '90 burban harness. From the firewall mounted terminal block there also should be a big red wire running to starter main terminal - its also should be a very thick red wire - 8AWG. Please take a close look and capture a photo of it in case if it is not connected. A fuel pump relay should be in close proximity to that firewall mounted terminal block.

Back to CS-130 alternator. There is a multi pin plug with several wires protruding from it.. Most often it is just a brown 16 AWG wire tied to 'L' terminal. This is a alternator light bulb wire. You can NOT connect this wire directly to the instrument alternator light. This connection can only be made if there is a series 150 to 300 OHM 1Watt resistor ( between alternator plug and instrument cluster alternator light). This is done by disconnecting external regulator plug from OE external regulator module and connecting brown wire from CS-130 'L' circuit with a series resistor to terminal 4 of the OE regulator plug - also brown wire. At least GM was consistent with their wire color schemes over decades! . Schematic below does not show this resistor, but it must be there.

http://63nova.nextmill.net/cs-130/CSAltConversion.jpg

Sometime, there is a larger gauge red wire tied to S terminal - this is a voltage sense line. This wire should be tied to a BAT terminal block on the firewall.

Photo #3
This is a tough one - this portion of the harness was connected to 90 burban main feed through block. The wires protruding maybe useless - anti lock computer, windshield wiper motor, temperature sensor, etc. It is best to remove split loom and peel off electrical tape and determine where these wires went.

VSS - this is a long discussion in itself. Do you have 700R4 from donor or you still have THM-350/400???

P/N switch - some DIY is involved but can be easily implemented. Search this thread for schematic.

//RF

Re: Tbi swap build thread
 

no i have the 700r4 . its all suburban put 72 over the top

Re: Tbi swap build thread
 

I wired my alternator like this diagram. This is the first I've heard of needing a resistor in the 'L' circuit. You mention the instrument alternator light, is the resistor just required with the idiot light panel or is it also needed with the guages?

Re: Tbi swap build thread
 

Oh wow - it is nice to have a power lift -> CAT!

With VSS you have a small problem. The 90 burban uses electronic speedometer, while '72 truck is a classic mechanical unit.

http://i226.photobucket.com/albums/d...ps13061542.jpg

To solve this you'll need to find a mechanical speedometer gear cable unit from an earlier 700R4 and add an inline 2000 ppm VSS unit from JTR.com. For example AC-Delco 25512339. But first you need to figure out which speedometer gears to use before ordering.

http://i226.photobucket.com/albums/d...SSretrofit.jpg

Also complicating conversion is that you have a 4x4 burban and VSS may have been installed in a transfer case (I simply do not know).

//RF

Re: Tbi swap build thread
 

Please see this thread - CS-130 conversion from 10 DN
http://67-72chevytrucks.com/vboard/s...d.php?t=436742

Re: Tbi swap build thread
 

Thanks again RF. I hadn't seen that thread. Glad to know this before firing it up and wondering why it didn't charge properly.

Re: Tbi swap build thread
 

i think it is on the back of the transfer case on the out put of yoke.but i dont think u can add a mechanical cable .

Re: Tbi swap build thread
 

your showing a 4 prong plug i only have 2 prong plug brown / and orange.. so brown to 4 plug and and orange to back of + alternator. is this right , nothing at all will be hook to external 72 regulator.is power wier to dash were the light goes , or is that voltage out put.