Tbi swap build thread

[skidder111]

Stock harness from an 89 pickup.

[cjracing15]

Well I would re-trace the wires to see what they are doing.

A-10 is a brown wire from the ecm, and B-10 is a org wire with a blk strip on it. let me know what you find, I am just staring my swap as you can see.

[rfmaster]

Originally Posted by cjracing15

Well I would re-trace the wires to see what they are doing.

A-10 is a brown wire from the ecm, and B-10 is a org wire with a blk strip on it. let me know what you find, I am just staring my swap as you can see.

P/N line Orange/black wire is grounded by a P/N switch when in park or neutral position. P/N switch ECM input is used by ECM to compensate idle speed when additional engine loads (AC, PS pressure, etc) are present while in drive and within idle speed range. ECM commands IAC to add additional 50 to 75 RPM over commanded idle speed under such conditions. In your case (manual tranny) leave p/n wire open (i.e always in 'drive')

VSS is extremely important for complete EFI operation. It is unfortunate that many omit VSS during conversion. In your case, having 4 speed manual, it is imperative to have a functioning VSS. Since you have 1227747 ECM you'll need to have 2-pulse square pulse VSS inline unit. These are readily available (JTR, others). VSS provides vehicle speed to ECM which uses this input to accurately set fuel mixture and timing. One common problem with absent VSS and manual tranny is a severe drive train jerking during deceleration. This due to inability of ECM, which uses TPS, MAP and VSS inputs, to enter DE/DFCO mode (Deceleration Enleanment / Deceleration Fuel Cut Off).

When the ECM detects a sudden drop in throttle position and engine load, it reduces the injector pulse width while continuing to monitor engine load and vehicle speed. The purpose of DE is to produce a lean fuel mixture by reducing the amount of fuel gong to the engine. DE mode conditions are determined by ECM on a continuous bases provided that 1) Vehicle speed is above XXMPH (this depends on EPROM calibration value), 2) engine load decrease is below a limit value (this parameter also depends on EPROM calibration value), and 3) Filtered %TPS drop is <1%.

The difference between DE and DFCO parameters is that DFCO parameters are based on fixed values stored in EPROM. The DFCO fuel mode is entered after moderate to heavy acceleration then followed by abruptly releasing the accelerator. Usually ECM will transition into DE prior to entering into DFCO mode as the deceleration continues. Interestingly enough operating conditions may or may not cause ECM to command DE exit by itself. However when ECM enters DFCO mode DE is automatically disabled. Usually DFCO is a 'long' term (self resetting) duration event - coasting down hill in gear for example.

Both DE and DFCO are used for emission control, (keeps CATS from being burned up due to excess fuel during deceleration), but the two will effect drive train and exhaust longevity. There are many other ECM controlled parameters that are derived from VSS input.

//RF

[DirtyLarry]

Rfmaster,

What you said above about VSS sounds right for 1996 and later OBD II sequential multiport EFI systems but I can’t find anything in any of my older GM STG service manuals for TBI years that state the VSS has anything to do with Deceleration Enleanment or Deceleration Fuel Cut Off. It could be one of the functions that takes place behind the scenes that isn’t really called out in the service manual.

From what I understood, the main sensor to control fuel on OBD I such as TBI is the MAP as it constantly monitors engine load and adjusts fuel pulses accordingly. Once you get into OBD II on sequential multiport things get a lot more complicated and more inline with your description above.

The only function I can find for the VSS in TBI years is to provide a pulse signal to the DRAC for the speedometer, RWAL ABS module, and cruise control module. The VSS isn’t even mentioned anywhere in any of the drivability symptom flowcharts or anything other than inop speedometers, cruise, ABS, etc.

For what it is worth, my 8.1L running multiport EFI on a Delphi MEFI-4 controller (similar to a GMPP RamJet engines and GM Marine engines) doesn’t have any VSS inputs either to run, and run well even with a manual trans. The whole MEFI-4 system is an entirely weird deal anyway.

I know you are an engineer and know this stuff a lot better than any of us but are you sure about the VSS function on TBI?

[cjracing15]

I thoght that on OBD II they did not use a vss sensor, but the ecm got it's signal from the abs computer.?

[GlennBrittain]

Many thanks for taking the time to post your info and progress. This will be a great help to myself and I am sure many others when I get to my drive train. Right now I have an 88 GMC for the donor but may look for the last year of TBI.

[DirtyLarry]

Originally Posted by cjracing15

I thoght that on OBD II they did not use a vss sensor, but the ecm got it's signal from the abs computer.?

VSS is still used today to provide data to the PCM/ECM for engine controls, speedo, cruise, trans shifting scheduling, torque converter lockup, etc but not ABS. These days, there is actually a wheel speed sensor at each wheel to provide input to the ABS module to control 4 wheel ABS system and traction control if equipped. In the TBI days the trucks only had rear wheel ABS which the rear wheel speed input to the ABS module was read from the VSS sensor on the tail shaft of the transmission.

[rfmaster]

My apologies - 7747 does not have DFCO - MPH threshold, which is used in 8746 ECM found in TBI passenger cars. Also, DE is mapped to MAP and RPM threshold in 8746.

Now that I looked back at my notes I know where I got confused - in my conversion I used 16136965 from 1991 B-Body which just happens to be almost pin compatible with 1227747 (there are couple more control outputs and MAT input) which in its stock form uses speed threshold for DFCO. In the end it did not matter to me at all since I have converted to EBL which provides full control over DE and DFCO.

VSS in 7747 is used primarily for TCC control, Knock retard, Highway SA, EGR, & Idle speed compensation.


//RF

[skidder111]

So, rf & Dirty Larry, is there any benefit to installing a VSS in my ride? As mentioned above, it is an 89 setup, so there is no DRAC in this setup. I'm still using the mech speedo and have no cruise. THANKS FOR YOUR HELP!

[DirtyLarry]

Skidder,

I would venture to say you are good to go without VSS on a manual transmission. With an automatic, yes, you would need it for the torque converter lockup. Your earlier post mentioned a concern with going into closed loop. Closed loop is achieved by the engine coolant temperature sensor (ECT) and O2 sensor inputs not vehicle speed.

My 8.1L with a manual trans does not have a VSS at all. Even though the 8.1L is multiport EFI, mine is running an OBD I speed density calibration system through a Marine MEFI-4 engine controller with a protocol that is very similar to the old TBI and TPI systems of the late 80’s and early 90’s. As far as fuel delivery, the main difference is my 8.1L fires 8 injectors under a higher fuel pressure in batches where as TBI is firing 2 at a lower fuel pressure. Firing the 8 individual coil packs on the 8.1L is what is unique about the MEFI-4 controllers as they are very versatile in programming what they can control….but that is a whole nuther story.

This is one of the reasons I have chose to go with aftermarket harnesses opposed to reworking a donor vehicle harness. First, a donor vehicle TBI harnesses are getting old (last TBI truck was built 15 years ago!) and the harnesses tend to be very brittle and stiff, end connector break at the touch, etc. Second, a creditable aftermarket harness vendor such as Howell or Street and Performance, etc has already put a lot of research into knowing how to properly wire these things. Most of those companies have gone to the manufactures and purchased the original engineering layout drawings to create stand alone harnesses without all the unnecessary circuitry. For $325 a nice fresh harness is hard to beat vs. pulling your hair out trying to rework an old harness only to still have a 15+ year old harness when you are done.

[cjracing15]

Larry you have a very good point about the old harness on the fact that it is old and the wires are brittle, (mine has been for the most part very managable though) and me and you talked about me buying a harness from Howell. I am right now off work untill the first of the year and I want to get this swap done before I go back to work. Untill I go back to work I really do not need to spend any more money than I have to. So I had the stock harness and decitted to use it. When I decited to do that I thougt while I was searching the net for info on this swap that the info is out there but you really have to look every where for it. So I decited to start this build thread to maybe help other people out that want to do this swap and use salvage parts in the process to save a buck or two.

I really do appreciate the input that people are putting in this thread ( like you and rf).

Got to go and work on my truck now.

[cjracing15]

Well I did not get to work on it as much as I wanted to to day but did get a little done.

First two is a before and after on one side of the motor. This is where the ESC, TPS, MAP, IAC, EGR , and temp plugs are located. You can also see where the wires enter the cab

The others are the wires that I will have to hook up in the cab. They are

B-10 park/neutral
A-5 SES light
A-8 ALDL
A-9 ALDL

[cjracing15]

Here are some of the wires that I will have to hook up that do not have factory plugs.

The first one turned out fuzzy but it is the 12 V feed wire (I am going to put it to the big post on the starter with a inline fuse).

The second is C-9 this wire goes to the sm post on the stater.

The Third is the switched 12 volt wire. ( I am going to put it on the smaller wire that pluged into the orginal HEI BAT terminal).

The Foruth is the ground wire for the system.

The Fifth pic is the wire that will power the dist. ( I am going to tie it to the big HEI wire that is on the truck now.

[rfmaster]

Gents

VSS is important as it is not only used for the lock-up torque converter control. The VSS is also used to control the EGR valve, idle speed, and air/fuel ratio. I have to emphasize that the VSS is used to control the idle speed when the vehicle is moving. Without the VSS, engine may have stalling problems under certain conditions, which in itself is dangerous. You can increase minimum idle speed with the adjusting screw and eliminate stalling, but the engine will still not run optimally without a VSS.
Somewhat erroneously many think that running "closed loop" is best for fuel mileage - it is not. In closed loop NBO sensor is being used to monitor the exhaust O2 content and ECM changes commanded AFR. There are ECM's that allow engine to run very lean (15:1 to 17:1) under certain conditions (called "highway lean mode") to improve fuel mileage during - for example steady cruise conditions (no delta TPS, no delta MAP). Without VSS, ECM will not get the correct signals to run the engine for best fuel mileage. So if you are planning to drive long distances and burn less fuel VSS is a must. For my retrofit I used JTR Part #2PRS which is two-pulse per revolution, square wave unit for all TBI installations, 7/8-18 thread, .104" square drive. BTW, I get 17.5 MPG on extended cruises (that's 6500lbs moving at 65 MPH).

//RF

[rfmaster]

Photos from my swap

It all started innocently enough in the fall of 06 - another tune-up and idle quality and cold starts are hideous with old Q-jet. After a bit of reading I came across a TBI 4.3 swap into a Jeep...
http://www.bustedjeep.com/projects/junkyardtbi.asp

After reading and a quick trip to a local pull it your self JY


ECM / Harness /Dizzy (useless) / sensors


It took over 2 hours at JY to carefully pull this tangled mess without breaking anything in the process. The firewall grommet in this B body used epoxy like filler to keep everything together - nasty to remove.


After another 2 hours the harness was hanged like a deer for cleaning.



Removed wires and vacuum lines used by AC control circuits



Final harness, arranged and labeled


Surprisingly enough wires were in excellent shape - no breaks this was a low millage car. I did had to replaced several connectors - broken tabs and shorter overall runs. However in my next conversion I will get new harness - just to save time! Initial harness fitting:

[DirtyLarry]

Originally Posted by phase_one

I know I cant use the towers out of the van can I use the towers off of the inline 6 (250)?

The 6 cylinder engine mount towers in your ’70 C10 will not work. If you plan on using the G-van or any of the newer style exhaust manifolds you will need either 67-72 big block towers or use 73-87 2wd towers like I did on my ’72.

[79blazer]

I did a TBI swap on my Caprice a couple years ago. Donor vehicle was a 88 truck. I was fortunate to have the complete factory service manual, including complete wiring diagram book. I did reorganize wires, so that FI input/output were together, all other wiring separate.

After much research, I found that the ford E2000 Inline fuel pump works good. It is capable of much higher pressures than a stock TBI requires, yet it doesn't flow too much to where a 5/16 return line would cause over pressure. It runs cool, an doesn't draw too much amps. You can use quick connections, or clamp hoses to it. I doubled clamped. I bought two (one for spare) for $30 at a pick-and-pull I think. It was in many Ford vehicles, so it was easy to find. http://www.partsamerica.com/ProductG...rtnumber=E2000 One advantage is you wouldn't have to drop the tank to repair it, should it fail. Buy it used cheap (try to find a newer, cleaner one) or instantly, no shipping necessary.

The sock filter in the tank also acts like a baffle.

Disadvantage to some inline pumps (some times the e2000 too, according to my research) they may be difficult to prime. As in: if you run out of gas, it may be hard to get fuel pressure back. That is because they are better at pumping fuel, than drawing a vacuum.

There's pro's and con's to everything. I am glad I used a old harness, because I learned alot about fuel injection when I did it.

Man reading this thread brings back memories of when I did mine! Mine was a 7747 ECM too. For example a simple brass male/female 90 degree elbow from Homedepot works for the oil pressure sensor.

[cjracing15]

Well I have got a few update pics for ya. I have run all my wires, mounted the computer, I have even tested the fuel pump in the tank and ses light to see if it worked. Well as soon as I hooked the battery back up the fuel pump relay clicked on so first test done. Then I put a hose from the tank into a bucket and hooked the fuel pump wire and a ground wire. Then I hooked up the ses wire ( I am going to use the old choke light for the ses light because I will not need a choke light anymore). Well I took a deep breath with my dad watching the the bucket that I had the hose in and turn the key to the on position. To my delight the ses light came on like it was suppose to and dad said that the pump came on for about 3 sec's and shut off.

So my next project is to run the F.I. fuel lines and install the other tank and see what happens.

Here are a few pics that I took for every-one.

1st. pic Is the computer monted under the dash and the wires run to it.
2nd. pic Is the fuel pump relay mounted on the fire wall.
3rd pic is the fuel pump pump plate that I stole off of the suburban. Had to take off one side of the accs brackets to take the pump off.

The last two are of all the wires run on the engine and, I stuck the breather up there just to see how it would look. After I repaint it I think it will look stock, witch is what I am going for.

I am going to start on the fuel lines Monday and I will update with pics later next week.

Stay tune.

[rfmaster]

Nice progress.
FYI - do not forget to use EFI rated fuel hoses clamps when plumbing your system. Even though TBI system is rated for 13 to 15 PSI operating many pumps are capable of delivering 30+ when deadhead.

So, what's on your XMAS wish list??

//RF

[phase_one]

What fuel tanks are yall guys using? I got my engine out of a van and that tank is too large, but the fuel sending unit on it is new a was hoping to use the unit. Just wondering what you guys are doing?

[cjracing15]

Originally Posted by rfmaster

Nice progress.
FYI - do not forget to use EFI rated fuel hoses clamps when plumbing your system. Even though TBI system is rated for 13 to 15 PSI operating many pumps are capable of delivering 30+ when deadhead.

So, what's on your XMAS wish list??

//RF

Thanks, Pick-up EFI hoses today but I am having a hard time finding the clamps for some reason. But the parts store I usually buy my parts from was closed today so I will check with them Friday.(I am sure they will have them) Also picked up a new pump to put in my tank this morning.
Thanks Jamie

[cjracing15]

Originally Posted by phase_one

What fuel tanks are yall guys using? I got my engine out of a van and that tank is too large, but the fuel sending unit on it is new a was hoping to use the unit. Just wondering what you guys are doing?

I am using a used tank off of a 87 truck. you can use a frame mounted pump like some others have done on this thread. I am using the EFI tank because I have it and I want this to be a low buck swap.

[DirtyLarry]

Yep, me too. I am using a 1987 TBI fuel tank as well. The frame mounted pump didn’t work so well on my ’78 but on the ’72 it is working find so far.

Hey, Jamie… I have a few of those EFI hose clamps left over. The cheap Chinese hose claims I found at Autozone and Checker scared me as they were so flimsy so I wound up buy a box full from Napa. I’ll email you a few...

[rfmaster]

Originally Posted by DirtyLarry

I have a few of those EFI hose clamps left over. The cheap Chinese hose claims I found at Autozone and Checker scared me as they were so flimsy so I wound up buy a box full from Napa. I’ll email you a few...

I second this as well - worst yet the garbage Chinese made hose clamps are prone to rust through - I had several fail before. A while back I took the failed clamps to my failure analysis engineer for failure analysis. He told me that they used 'pot' steel and cheap cadmium plating to make it look shiny. Once the set screw striped off surface plating rust started immediately. It's a good thing we found in time during our annual maintenance cycle. End up getting some Ideal clamps - these are wider (5/16") than normal hose clamps and have beveled edges and solid clamping face that does not bite into the rubber hose. Look for them in specialty industrial supply places or online.
http://www.autobarn.net/iddifuincl.html
If you are really serious (or paranoia) - use marine grade 304SS clamps - but these are very expensive for automotive use and will last a long time!

//RF

[cjracing15]

I have had bad luck with the cheap clamps and DO NOT use them any more. I will hold off a few days untill I can get some real ones at the good parts house here in town. ( but thanks for the link for auto barn i will check them out.)
I hardly buy anything anywhere else in town unless it is after hours and I HAVE TO. I hate the cheap crap,.. you waste your time and money with it.

Larry if you can find out a way of E-Mailing those clamps go ahead and send them.

Thanks, Jamie