TPI harness question

[GreyHoundSteve]

I have an older 350 2 bolt carb motor in my truck now but was wanting to make the leap to fi and like the tpi set up. I havent decided if i am going to replace the entire motor yet (86 + vett) or just buy a tpi set up and put it on my existing motor until i build a better one and then swap the tpi over to it.

My question is about the harnesses. EVERYONE says dont buy an incomplete tpi set up or youll get nickle and dimed to death buying sensors. My question is about AFTERMARKET tpi harnesses, who makes one and does it come complete with sensors for any tpi set up?

The reason i ask is because i will more than likely go with an aftermarket tpi set up after i get my motor built but i would like to install tpi now on my current motor so i was wondering if i should just buy a 86 tpi set up with harness and sensors or if i should go with an aftermarket tpi harness and that way i have more freedom with the set up? My main factors are: do the aftermarket tpi harnesses come with a computer that can be reprogrammed, and do these harnesses come with sensors? Which set up is more easily reconfigured and more affordable in the long run?

[Russell]

Hello Steve

I personally have not seen a company that makes an aftermarket harness that includes sensors. Painless makes an excellent aftermarket harness for the TPI setups, and when you order, you can have them personalize the length of the harness so you have some freedom to mount the ECM wherever you'd like. I have seen some people sell custom made TPI harnesses with sensors attached on Ebay, but like the Painless aftermarket harness, they usually are in the $200 + price range. I personally completely dissassembled my TPI harness, and rewired it removing some emissions wires, fixing broken connectors, and adjusting the harness so it would mount nicely into my truck. So far I have about 30 dollars into the harness for connectors, solder, and shrink wrap for sealing the connections. You'll need wiring harness which can be found at ChevyThunder to figure it all out, but it really isn't all that tough if you have some patience

I'm pretty happy I took my harness down and rebuilt it, it gave me the opportunity to rebuild it as an 86 harness to work with the '165 ECM I bought, and it also taught me gobs about how it all worked together, what systems were directly connected etc.

[tpi72blazer]

Once you decide whether you are going to run either a speed density system, or mass air flow, an aftermarket harness such a painless, Howell, or S&P will GREATLY simplify installation. The harness's have the correct recepticals to plug onto the factory GM ones so there is no confusion or possibility of hooking up wrong wires. The ECM itself only has 4 wires to hookup. The type of system you run - speed density or MAF will dictate which sensors you must run. I have not seen an aftermarker harness that comes with sensors. The MAF harnesses are generally more expensive as they have more sensors than a speed density system. You can expect to pay $300 - $350 for a harness, but it will be setup just for your system, making future engine swaps no problem. Do you already have a TPI unit you are thinking about using?

[GreyHoundSteve]

Thanks for your reply Russell. You said that you had to rewire some of the harness due to emmisions? What exactly did you remove and how difficult was it to rewire? You also said that you modified your harness so that it would except a later model ecm, how did you do that? Would i be better off just buying a harness from an 86 or later tpi motor (what ecm should i look for on a harness?)? As far as the ecm's are concerned, is there one that is able to be reprogramed or do all of them require new chips when the motor is modified? The reason i ask is because i an eager to put tpi on my old motor but i also know that i plan to build a new motor and would like to be able to just drop it in and reprogram the ecm vs having to have to buy a new harness again or having to modify it.

I guess my question is..... would i have to modify anything on a 86+ tpi harness if i were to do a motor swap later? I know the ecm would need a new chip but other than that would everything else still work the same?

Also, if im planning on doing mods that would require the chip to be reprogrammed, would i be better off just going with a speed density tpi set up? On my vette i had MAF but i never modified it past bolt ons, the engine im wanting to build will most likely be a stroker motor or at least something that puts out 400+ horses. I know MAF can be changed to SD but if im having to get chips made anyway is there any other advantages to maf vs sd?

[GreyHoundSteve]

tpi72, no i have not yet purchased a tpi set up, im still in the planning stages and trying to figure out what i will need to make the swap. As i explained before, i would like to set tpi on my current motor (older 2 bolt 350) but build a NICE motor and later swap the tpi over to it and be able to install the new motor without having to modify the harness. I understand that it will need to be rechipped but would i need to do anything else to the old tpi harness?

[tpi72blazer]

As long as you are running the same system, you won't have to make any other mods besides the chip. If you build a 383 for instance, you may need to run larger injectors. Stock injectors are 22#.

[Russell]

Ok, I think that in your case I would suggest a speed density system. You're gonna need to do some major modifications to the TPI setup later on for it to be able to feed that stroker. One of which would be to get either a high flow MAF sensor (stock is a pretty big bottleneck, and high flow aftermarket MAF sensors are VERY expensive) or to swap to Speed density.

You'll need bigger injectors (Ford 32 #/hr injectors work very well for a hot 383), aftermarket high flow runners, a ported upper plenum, bigger throttle body, and a new high flow TPI intake (basically replace all of the original TPI parts, less electronics). Speed density is a more effecient setup, and will get slightly better economy / produce slightly better power. Now, here is the part that may make you happy:

http://cgi.ebay.com/ebaymotors/ws/eB...931078784&rd=1

This ebay auction comes with everything you need to convert any TPI setup your bought over to your 350, all you'd need would be some 22 #/hr injectors and a VSS (can be bought from Summit for something like 50 bucks, the seller says he'll help with that)

Basically be able to plug it in and go this way, then when it comes time to swap over to your new setup, you'd only need new injectors, new / ported TPI intake parts and the new "hot" chip to get it working with your 383.

Its expensive, but just for the included sensors alone you'd be looking at around 250 bucks.

I've got a brand new never used fuel pump I'd be willing to sell you (150 psi @ 43 gph, stock TPI pump is 50 psi @ 25 gph) for 100 bucks US shipped, I paid something like 200 bucks for it when I bought it, but I decided to go with a stock EFI tank from a TBI Suburban with a TPI pump I bought to replace it, bit quieter than the inline pump I'd sell you.

So yeah, you'd basically only be needing a VSS and injectors, fuel pump, and TPI intake then you'd pretty much be good to go

[GreyHoundSteve]

Whats vss?

I know all about the actual components of the tpi since i had an 86 vette. When it comes time to put the new motor in i will most likely use an aftermarket tpi set up (accel, tpis and edlebrock make some nice ones). I was just wondering if any of those tpi set ups would plug right in to any tpi harness as long as the chip was reprogrammed to meet the specs of that particular motor?

Also, ive heard talk of one ecm's being better than another, which one is best and why? Ive seen people post emc #'s and say "this is the good one" ..... what are they talking about?

p.s. ive been watching that auction on ebay, what a good price for that harness and what else would i need if i bought a "take off" L98 minus the electronics?

[tpi72blazer]

Originally Posted by GreyHoundSteve

Whats vss?

I know all about the actual components of the tpi since i had an 86 vette. When it comes time to put the new motor in i will most likely use an aftermarket tpi set up (accel, tpis and edlebrock make some nice ones). I was just wondering if any of those tpi set ups would plug right in to any tpi harness as long as the chip was reprogrammed to meet the specs of that particular motor?

Also, ive heard talk of one ecm's being better than another, which one is best and why? Ive seen people post emc #'s and say "this is the good one" ..... what are they talking about?

p.s. ive been watching that auction on ebay, what a good price for that harness and what else would i need if i bought a "take off" L98 minus the electronics?

Your 86 Vette had a MAF tuned port system in it. A Vehicle Speed Sensor (VSS) is for speed density systems. They will run without a VSS, but the ECM will not have as much information to go by. Basically you thread it on the end of your speedometer cable, then put your cable back in place - that's all there is to hooking up a VSS.
Typically the 1227727 ECM is the most desirable speed density ECM. It was used in Corvette's and is a heat/weather-proof design which allows you to mount it anywhere - even in your engine compartment as was original in Vette's.

[Russell]

Ok, assuming that the speed density harness isn't missing anything but the VSS (vehicle speed sensor BTW), all you'd need would be the entire intake setup, injectors, fuel system components (fuel lines, fuel filter, fuel pump etc) and a small cap HEI distributer with a remote coil, and the ring gear at the bottom of the distributer shaft swapped to one with a big cap (I probally have one around here somewhere)

In my opinion, the 89 '165 is the best computer for the MAF systems, I'd assume most of the Speed Density computers were fairly equal.

The 89 '165 computer has the most options, and the most recent prom for MAF systems. Cold start injectors were eliminated by then, so the computer just had the injectors put more fuel in when you first start it rather than running with the 9th injector. It also eliminated the ESC module, having the computer control the distributer directly with input from the knock sensor rather than having the ESC module do it.

As far as doing bolt on swaps, 86 corvette ECM with an 85-86 Camaro lower intake, 85-88 runners, 85-88 Corvette fuel rail and a set of 90-92 350 injectors is the best setup. It will bolt to all heads from 55 - 87, and the Corvette fuel rail will have the fuel lines pointed at the correct side of the engine where our fuel lines run up on. The top end will need to be from an 85-88 as well, so it has the cold start provisions. If you go with a speed density system, you can buy a little plate to cover the cold start injector hole, but I'd guess things would be just dandy if you simply left the cold start injector in there. Everything else would be totally compatable with the speed density harness and computer (though you'd end up replacing almost all of the sensors that came new with the harness / speed density computer anyways)

[GreyHoundSteve]

Thanks for the info guys. Looking at that ebay auction it seems like a pretty good deal if all thats needed is a $50 vss sensor. The guy states that he can eliminate the emmisions as well, is this something i would want to have done? What emmision sensors is he refering too and if i had them removed would it be easier or more difficult to use this harness later on with another motor? Also he said that the ecm is 1227730, tpi72 says i should look for a 1227727, whats the difference?

Finally, what do you guys think; should i buy this harness or rob one from a specific year/make tpi car? If i should buy this one then what is a fair price? His buy it now is $350 but i have seen complete tpi set ups with harnesses and sensors sell for around $500 on ebay and so $350 seems high, what do you guys think?

[GreyHoundSteve]

What about this set up guys? Would i be able to bolt it on and go or is this too much for my current motor to handle (is there such a thing)?

http://cgi.ebay.com/ebaymotors/ws/eB...e=STRK:MEWA:IT

[GreyHoundSteve]

Now this is a tpi set up ....... but at that price i would be too poor to ever get a motor built for it.

http://cgi.ebay.com/ebaymotors/ws/eB...e=STRK:MEWA:IT

[GreyHoundSteve]

Alright, sorry for all the questions guys but one last one (today anyway)

What do you guys think about this harness? Better than the one listed above or worse for what im looking to do?

http://cgi.ebay.com/ebaymotors/ws/eB...MakeTrack=true

[red71cheyenne]

Personally, I think I would go with a new harness. I got mine here

I think I paid $295, and it was custom made, with all the parameters I wanted for my engine. He's very helpful and has great customer service.

Good luck, Jeff.

[72 3/4 ton]

I run a stroked sb in my 88 IROC (see my webpage ).
I currently have the stock MAF set up. I'll be changing to a SD set up soon mostly to avoid the the restricting MAF sensor.
I recommend the SD or LT1

[Russell]

The first ebay link you posted with the 92 Corvette setup looks like a very good deal if it has all of the sensors, the second link looks sweet, but yeah, its pretty pricy, lol. Third setup is ONLY the wiring harness, no sensors...

[GreyHoundSteve]

Thanks again for your help guys. Im going to throw in a bid for that corvette set up and cross my fingers.

[Russell]

doh! Another forum member beat you to it, lol