Texas92

found this might help

WIll36

iTrader: (12)

looking to do a TBI to MAF TPI swap to fix my 88 IROC. Started my own thread https://www.thirdgen.org/forums/tpi/...ml#post4094963 opinions and advice would be greatly appreciated.

dwolfe88

iTrader: (2)

Everyone please cross there fingers and pray for me, I'm going to try this over the weekend. And what happened to steps 4-8?

dwolfe88

iTrader: (2)

Alright I got all of this done (quicker than I thought) and the only thing I have a question about is the last 3 items 1) Correct me if I'm wrong I just cut the grn/wht wire at the fan relay and and run it to GE8 2) I'm not very good at wiring and I don't understand the last 2 items, if someone could treat me like a 2yr old and tell me what to do that would be great
Anesthes you are the man you have saved me and I think alot of people time and money, THANK YOU!!

anesthes

iTrader: (12)

From memory and reading the table, BD6 and BD7 is the grounds the ECM uses to fire the two injectors, so you need to tie them into the body some where. D1 is already grounded, so you could splice it there. (although in theory you could run the risk of running too much amperage for the gauge of wire). Just splice them to a black wire, and screw it into the body/frame under the dash.

Good luck!

-- Joe

dwolfe88

iTrader: (2)

Ohhhh, Ok so I just need to put a pin into BD6 and one into BD7 and ground them somewhere. And if I do nothing to GE8 will it work like it did on my TBI setup, or do I have to run a wire from the relay to GE8 and change something on my PROM, because I don't have the stuff to do PROM work right now. Thanks

anesthes

iTrader: (12)

E8 runs the fan. Just run that to the green wire on the fan relay.. the fan is controlled by the ECM on the '730, not the switch in the cylinder head.

D6, and D7 need to go to a ground or your injectors will not work, and you will get a 'no start' condition.

-- Joe

3rdGenFreak1227

ok....so I hate to sound like complete retard but I have an 87 Z with a 305 tpi thats MAF setup right now....and MAFs are expensive and mine is bad of course, so I was contemplating going to a later model 91 or 92 SD swap, I have a spare 91 tbi car complete with harness and '730 ECM....is the stock harness on the 91 the '746 everyone keeps referring to? Would I just refer to the above instructions and charts? Also my car has a cable type speedo, would I still need to follow the instructions about the VSS buffer box? I realize the major difference is a magnetic pickup coil going through an analog to digital converter as opposed to an optical hall effect that just outputs a digital signal. I'm a student out at wyotech and I've been through EMS so I am familiar with what all the sensors do and how they work, just not familiar with the GM numbers on ECMs and harnesses...sorry if this is a repeat question.

dwolfe88

iTrader: (2)

Ok I think I have it now, I Thank You and my 91 Formula Thank's You.

Ruiner

Awesome post!

The L03 in my '91 RS just blew up a few weeks ago, I've been building a 355 TPI motor to replace it

engine is done, and I just repinned the TBI harness for my NVSRAM'ed '7730 this morning thanks to the information in this thread. The swap went perfect, the only wires I had left over were the crank signal and the 2 extra injector wires

should be pulling the L03 and dropping in the new motor this weekend

Ruiner

Ok, I'm completing my TBI to TPI swap right now

My main question right now, is it looks like my throttle and TV cables are too short

I heard no mention of this in this thread, do they need to be changed or is there a way to make them work?

Throttle cable looks easy to change, TV cable is going to be a PITA

dwolfe88

iTrader: (2)

Yes, They need to be changed, As far as I know you can't make the old TBI ones work. There are 2 different Throttle cables depending on the year your TPI unit came off ( unless your using a aftermarket Throttle Body, they usually come with brackets for both styles ) The TV cable is the same for all years, I believe. I just bought a throttle cable from TPI Parts and it was pretty cheap, and a factory original, They also have the TV cables. Good Luck

anesthes

iTrader: (12)

Sorry. I was more getting into the specifics of the wiring when I first wrote this post years ago. You, along with whatever new induction you get (hsr, tpi, singleplane, etc) you would need the correct throttle cable and TV cable if you have an automatic.

When I did my swap, I used a singleplane manifold which puts the throttle body in the same location as a TBI car, so the stock cable would be fine.

Good to see this thread is still getting hits years later.

-- Joe

Ruiner

Yeah I just ordered the cables from tpiparts.net, thanks for the link dwolfe88

Got the new engine started today, sounds good, but needs a lot of tuning. The wiring diagrams were spot on though

Still runs super rough, very rich, won't idle. I have my regulator set at 48psi with 24lb LT1 injectors. I was still trying to set the fuel pressure so I haven't connected the vacuum line to the regulator yet, I'll connect that and see how much it lowers my pressure at idle, I'll lower it more on the regulator if I have to then start tuning the PROM

moorepwr

iTrader: (2)

This is an awesome thread. In fact, I'm planning this swap on my 1988 C1500. I'll let you know how it goes. I have to give you a big for putting this together.

dwolfe88

iTrader: (2)

This is probably the best thread I've ever found on TGO. Thanks Joe for creating this and answering questions about it for the past however many years! And Ruiner, No problem glad I could be of some sort of assistance.

Scout

Maybe I'm going about it backwards, but I have a TPI motor, moved a few pins on the harness and am running a 7747. It's still not on the road yet, but should be in a month or so. I also had to add a MAP.
http://www.youtube.com/watch?v=-fNfa0DvL8I

dippin88

i have questions cuz i did a swap on my 88 camaro it was the 305 TBI and put in the 350 5.7 TPI took everything out of an iroc from ecm, wireharness, fuel pump etc and now cant get it to start?? can any1 help it cranks over but dont start

greatwhite

Anyone have a "re-pin" chart to go from a 7747 Ecm to a 7730?

Or is "back into the wiring diagrams" for me.......

310cid

iTrader: (1)

do u have any pictures of how u wired it im not understanding how to wire those four wires i need to put injectors on tbi any help

anesthes

iTrader: (12)

Injectors are batch fire. So all 8 injectors, just need power and ground.

The power is supplied by the fuse block, you will find two of the wires going to the old TBI injectors have power. The other two wires from the old injectors go to the ECM, which provide a pulsed ground to fire the injectors.


-- Joe

310cid

iTrader: (1)

so hook the injectors to the blue and red and white and green on top of motor and ground the injector wires to the body im kind of slow and i have a ppl/white and a blue wire left over what do i do with those i think the blue one is injector a wire and after plugging in my connectors to the 7730 what wires will i have left i have a green wire and blue and purple/white wires left any hepl with this stuff

anesthes

iTrader: (12)

No.

I don't remember the colors. It's been 7 years.


The ECM provides the pulsed ground - that is what makes the injector fire.

The power is constant, and goes to the fuse block.

If you get a whole v8 injector harness, you'll have 8 injector plugs, a bunch of wires, which are all wired together and somehow end up with 2 or 4 wires. The positives go together, and the negatives go to the negative feeds from the ECM.


-- Joe

310cid

iTrader: (1)

so hook two wires to the fuse block going to injectors then ground the injector ground wire to the ecm

scottysbird

I have a 1988 trans with a 305. When i set the timing at factory specs, The engine hesitates then takes off. When I set the timing at say 8 to 10 degrees BTDC, the engine backfires thru the intake. So basically no matter where I set the timing the engine runs crappy and I get no engine check lite or codes.

anesthes

iTrader: (12)

You have four wires to the old injectors. Two of them should show power with key on. Connect those to the two wires with stripes on them from the donor v8 injector harness. Connect the other two to the ECM.

Now when you look at each injector connector, one side should have power with key on.

Get a test light.

-- Joe

anesthes

iTrader: (12)

Does this have anything to do with you swapping to TPI?

I Suggest you start a new thread.

Your problem is fuel starvation I'd guess, but I'd still like you to start a new thread.

-- Joe

310cid

iTrader: (1)

can i use a 89 prom on the 7730 ecm to run tpi or do i need a 90 prom

anesthes

iTrader: (12)

No, you need the '90-92 prom.

The '89 uses an esc module, the '90 has the circuitry for that on the prom, plus the memory locations for the starting point and all that are different, and the program itself is intended for the pinouts of the '89 harness which differs GREATLY from the '90+.

-- Joe

310cid

iTrader: (1)

do i put c15 and d15 in to d6 and d7 for grounds

310cid

iTrader: (1)

my car just keeps turning over

310cid

iTrader: (1)

thanks

310cid

iTrader: (1)

why does my tpi stumble at idle and barely runs is it my map or cts it has a 305 in it but the fuel injectors are 21lbs could the injectors be the problem and when its running the check engine light stays on i just repinnined my tbi to tpi probs help plz

Contrail

okay, so I have an 82 Vette, CFI, wanting to go to the 92 GTA Speed Density set up, I have two iacs, will that make problems for me? ECM is 1225550. Excellent write up, you may have just saved me a ton of time and money

anesthes

iTrader: (12)

I never intended on someone using the '730 fbody speed density ECM to controll cross fire..

If you are intending on keeping the two throttle bodies (and two iacs), I'd suggest trying dynamicefi. RRob should be able to help you.

-- Joe

Contrail

No, i don't want to keep both Throttle Bodies, I'd rather go straight TPI, was hoping this was an option to having to get an aftermarket harness, but I guess not. Painless has one for almost 400 bux, but that seems kinda steep. Anyone know of a more affordable alternative? I have the complete set up ready to go, just was hoping to do a pin swap to control it. CFI is nice, but not very well supported, so I want to move away from it to a true TPI system and use my existing harness if possible with the '730 ecu I have.

anesthes

iTrader: (12)

In that case, you should be able to perform the repin, but you're going to want to find a corvette schematic first and figure out the pinouts from there. I imagine there will be a hand full of left over wires.

-- Joe

310cid

iTrader: (1)

hello i have to old tbi ingector wires that have power were do i put the other two should i splice wire to the ecm or splice them to the injector wiresthat are a solid color

anesthes

iTrader: (12)

The negative side of the injectors go to the ECM. The hot side goes to those power wires.

-- Joe

310cid

iTrader: (1)

d7 and d6 get grounded to the body and the injectors negative gose to the ecm where

310cid

iTrader: (1)

hello where do the negative wires on the injectors go on the ecm thats not what im getting

anesthes

iTrader: (12)

C11, and C12.

So you had your old injector plugs right. One side was positive, the other side went to the ECM on I think D14 and D15. You simply move those to C11, and C12 on the new '730 ECM.

Now on the engine side, you just wire all the negatives together to one negative wire to C11, and all the negitives on the other bank to C12. Power comes from the fuse block.

-- Joe

310cid

iTrader: (1)

ok when i wired the negatives to each bank the car keeps turning over i ran wires from fuse block to the injectors and on the old tbi wires two have power and two do not the injector wires for the tpi are green and blue and two have a black stripe which ones go were i need some help

71ChevelleSS

The pink and black striped wires are the hot wires on the tpi harness. On the TBI harness the hots are red and white. green and blue on the tbi injector wires are ground.

Then the green and blue are negative on the tpi side. Greens passenger side and blues driver side. (not that it really matters)


Make sure you get a 90-92 V8 Memcal with the swap or the engine will run very rough with the v6 memcal. However there is a way to turn the v6 memcall into a v8 one by grounding a pin on the chip itself. However I do not reccomend that route unless you are set up to tune the vehicle being that the v6 tune is not sufficient for the 5.7 tpi motor.


Oh and thanks again Joe!!! My swap is running!! Turns out I had a bad maf and I just happened to have everything already to convert to SD. Did it the 749 way cause I plan on a procharger kit at 10 psi. Thanks to you man my 71 chevelle has a new heart!

310cid

iTrader: (1)

thanks for all of ur help my tbi didnt come with a pulsation dampener so i bought one today and put it on now i burning tires like crazy dam thing made car stumble and have flat spots

JP92RS

I have a 92' RS TBI that I put a 350 in place of the 305. Now I'm getting ready to switch to TPI but I bought an ECM for a 1990 TPI Corvette. It's a 727 ecm. Can I use the same chart for this ecm from my 746 instead of a 730 or?

anesthes

iTrader: (12)

Hrmm.. No but if I have time this week I'll make a new chart.

Honestly, I'd keep the memcal and swap the memcal into a '730 ecm, and sell that weatherpack ECM on ebay. It's worth WAY MORE to a corvette owner than it is to use, and because it uses weatherpack connectors it's more trouble than it is worth.

Keep the v8 memcal however!

'730 ecm's were in just about everything so you should have no trouble finding one in the junkyard.

-- Joe

JP92RS

Cool, thank you for the info. I will just keep the memcal and get a 730 ecm. Going to the junkyard today to track down injectors, connectors and an ecm. With a 350 I think I need 24# injectors but not sure. I believe I read that they used 24# inkectors in early 90's 3.8 V6s. I hope I'm right because that's what I'm going to find today. Thanks again Joe,
Jeremy

free48

I have a 1990 tunedport intake and custom wiring harness speed density that i'd like to use on my 1994 GMC sierra, how will this work together and what about the 4l60e trans.

JP92RS

I have a 92' Camaro and my memcal is from a 90' Corvette. AZ TPI said that I have to get the Vette memcal's vats disabled. Is this true? I'm getting ready to do this swap and this is a big speed bump cause they want 150 dollars to disable it for me. I thought because I have a 92 that it would be fine. Am I wrong? Or will I be ok not having it disabled?