crossrush

iTrader: (1)

OK so I bought a Holley hp efi system to run on my 1986 iroc with a modified small block, figuring the plug and play was the way to go. I removed the main wiring harness from the engine bay along with the ECM. Does anyone have a wiring diagram for the harness under the dash that plugged into the main wiring harness. I can't seem to find it anywhere. Any help with this would be appreciated. Thanks.

Orr89RocZ

iTrader: (20)

Austin thirdgen wiring site should have it

crossrush

iTrader: (1)

I looked there. I need the harness pinout more specific. Need to know what these wires are for.

QwkTrip

iTrader: (22)

FYI - It is not plug and play.

The opaque connector is C207. I was never able to find complete documentation for my '89 Firebird either. I ended up backwards engineering it by spending time with a multimeter doing circuit checks. In short, I found most of it is power taps from various fuses, plus a few other things. This is how my car is configured, which will not match your car, but it will give you something to work with so you can do your own circuit checks. Hopefully somebody can post with more relevant info from '86 Camaro but I'm sharing this in the absence of that info.

Pin-----Color----------Purpose

A-------BRN-----------unknown, never did figure it out
B-------PNK/BLK------INJ fuse (10 amp)
C-------BRN/WHT-----Service Engine Soon light bulb in dash (ground side)
D-------BRN-----------FAN fuse
E-------WHT/BLK-----unknown, never did figure it out
F-------PNK/BLK------ENG-IGN fuse (10 amp)
G-------PNK/BLK------GAGES fuse (10 amp)
H-------TAN/BLK------unknown, never did figure it out
J--------ORG----------Datalink connector (the OBD connector)
K-------BRN-----------Vehicle speed sensor (input to the VSS buffer box)
L-------BLU------------VATS (communication between VATS and the ECM)
M-------BLK/WHT-----Ground (must be grounded)
N-------unused
P-------unused
R-------PPL/WHT------CRANK fuse (3 amp)

crossrush

iTrader: (1)

Did you install the same System? Did you use any of the harness to run the holley hp Ecu?

QwkTrip

iTrader: (22)

Yes, I have HP EFI with my LS engine swap.

I chose to install an underhood power center (fuses & relays) for everything engine related. I put a list of links in my build thread that I thought might be of interest/useful to other people. There is a section on electrical. Give it a quick scan and maybe something might catch your eye. If not, that is fine too.

https://www.thirdgen.org/forums/ltx-...ml#post5028823

QwkTrip

iTrader: (22)

Consequently, I made very little use of C207. Most people do, but I did not.

I don't think I ever posted what connections I made at C207. If I remember right, I used one of the fuses to power my Dakota Digital speedometer signal conditioner (SGI-5), used terminal M to ground the SGI-5, and ran the alternator excitation wire through terminal C so that the Service Engine Soon bulb lights up when the alternator isn't working. I think that was all I used.

crossrush

iTrader: (1)

I scanned through the thread on your build and I think I'm in a little over my head. I knew I should have just stuck a carb on the motor and been done with it. I'm not that knowledgeable with relays and wiring. I may have to look for some hired help on this one if I keep the holley system. Thanks for the help.

88Greg

Crossrush, You should be able to get the holley setup running independent of the C207, If you wish to. Which holley harness do you have ? They have a few main harnesses and a few subharnesses. The holley harness has a fuel pump relay that is wired to power everything (injectors etc)

The C207 was how the original injectors got power and the vss signal pass thru to the ECM. Also there's various emission and ALDL conections in there. Since your car probably has a cable speedo you wont have to worry about the VSS stuff. You could re-use the C207 pins that supply injectors power but will have to add your own wiring to the holley harness to do that

crossrush

iTrader: (1)

I have part # 550-601 for the tpi set up. I have a first tpi intake. Like i said before its just a little complicated for someone without a lot of wiring knowledge. Any help is appreciated.

88Greg

When you say removed the main harness did you also take off the C100 connector . Which is part of the main engine harness ?(located behind master cyl ish) ?

crossrush

iTrader: (1)

The harness that comes out on the drivers side is still there.

88Greg

The C100 has 2 seperate harnesses on the front side of firewall. One is the lighting harness, One is the engine harness. If you took your whole engine harness including ECU connectors off without cutting anything, You should have had to unbolt the engine side of C100 too. The engine side of C100 is how all the power gets into the dash/fuse box etc

Ref this excellent thread by Pocket :

https://www.thirdgen.org/forums/ltx-...p-3rd-gen.html

crossrush

iTrader: (1)

That harness is still there. I just removed the passenger side harness and unplugged the computer from under the passenger side dash.

88Greg

What engine did your car have from factory ? Carb or TPI ? Elec fan(s) ?

So, See that group of 3-5 thick red wires and fusible links and ring terminals at the end of that harness ? Those red ones go to the starter batt term and are the main (only ? depending on year) source of power to feed the dash/fuseblock. Theres also a thick purple wire in there that goes to the starter solenoid to start the engine. All those will need to be connected up if you want the car to run right (dash/lights/etc). You can either reconnect them to the starter, or re-route them to a new terminal block you fab up.

I would be wanting to deal with all that before worrying about the C207.

crossrush

iTrader: (1)

Car had a 305 tpi originally with single electric fan. I have dual fans going in. I have the new relays for them. I am just trying to figure out where the best place to tie the holley system in.

88Greg

That holley ECU/Harness is fully standalone. You dont need any of the C207 wires. You just need to hook it up to battery pos/neg, And run 12v switched to the free wire. If you reconnected those thick wires on stock harness to the starter, and also the thick pink that goes to the coil, Technically it should run at that point. If you want to integrate things more, you will need to take apart the existing car harness in the C100 area to get at the wiring.

Where do you plan to mount the ECU ? I dont know if the holley harness is long enough to mount the ECU in the stock underdash location. Generally the harness has to be about 10 feet long to the farthest connector (usually TPS and IAC) to underdash mount. Of course the holley is hardened so can be engine room mounted.

On the Fan relays, you will have to come out from the main harness Inputs/out connector and make connections from there, and setup the ecu in software to run those items. You may have to buy another harness to access those in/outs if it did not come with one :

https://www.holley.com/products/fuel.../parts/558-400

crossrush

iTrader: (1)

Thanks so much for the help. It makes things a little more clear. I called holley tech support and they told me about the harness you mentioned. I am placing an order for the harness along with fuel and oil pressure sensors to use with the efi. Also the harness was long enough to get the ecu to mount close to the factory location.

88Greg

QwkTrp's thread there is very informative. I know it seems huge; but it looks like he has encountered and solved every possible stumbling block in such a swap. His is an LS, but the wiring to the holley is very similar to what yours should be like. It would be good to spend a weekend reading it.

crossrush

iTrader: (1)

I did look at it quickly but yes i do have to go over it and read it completely. I have found a couple threads where guys have installed this but i needed more specific details to my application. Im just trying to understand this more clear before going any further.

QwkTrip

iTrader: (22)

You don't need to pay much attention to how I did power distribution. Just change that to suit your situation.

What you do want to pay attention to is how I did AC and dual fans. It is elegant and I have a lot more control of those things than if you follow Holley's recommendations.

I also figured out how to get a speed signal into the ECM. Holley doesn't know how to do that with our type of speed sensors.

QwkTrip

iTrader: (22)

I'm not going to lie, it was a pain in the ***.

crossrush

iTrader: (1)

Going the ls route must be a lot more complicated I'm guessing?

88Greg

The output from the stock yellow box VSS converter is useable by the holley ecu.

crossrush

iTrader: (1)

What is this used for?

88Greg

TCC clutch control for one thing. Can also use it to make a "flight idle" bump when car is moving. Also could be programmed to replicate the T56 reverse lockout with proper wiring.

crossrush

iTrader: (1)

Yeah. I have some homework to do.

QwkTrip

iTrader: (22)

Let me ask, are you under the impression that with this self-tuning EFI you can just start up the car and go for a drive and it will tune itself?

I was. It doesn't.

I didn't want to have to learn how to tune so I bought what is hailed as one of the most advance self-tuning systems. I consider myself a victim of dishonest advertising. The only thing it does is adjust fuel maps, which is the easiest part of tuning. And it can't even do that worth beans at idle. All the details that really matter, the things that make the car drive well, start well, idle well, detect knock..... it's all up to you man. And there are no diagnostics when something goes wrong. It's just you and a pile of data logs that you have to pour over.

Furthermore, I have found it very difficult to find speed shops that will work with HP EFI. Before you get too far into this, you might want to make sure the reality meets up with the dream. Sometimes a carb is the way to go.

crossrush

iTrader: (1)

I did buy it based on the fact that a Holley rep did tell me just that. I was told it controlled everything. Fuel, timing and even lock up control for the 700r4. I will have stop and re think the build. Too bad I already have sunk all the cash into it already.

QwkTrip

iTrader: (22)

Technically true, it can control those things according to the data & rules that you load by hand.

88Greg

The important thing will be to start with the right base tune. There are several included with the holley software for a variety of combos. You will need to get some basic settings right in the configuration (injector size etc).
The base tune will get your spark map close enough. Certainly waaay better than any mechanical distributor setup.

Theres no reason a shop could not handle the Holley tuning, If they truly understand tuning. As opposed to a shop that just downloads tunes off a repository and charges you $300 to burn it into your stock ecu.
The holley fuel map is very similar to other aftermarket ECU's in its layout.

Yes the self-learning part is not perfect and universal. The engine has to run and be fully warmed for it to begin working. And there are areas of the map where manual tweaking will be neccesary.

Whats the alternative ? Carb ? really ? What better EFI system is there out there Qwk ?

QwkTrip

iTrader: (22)

I am helping him adjust expectations. I've been where he is and that is why I can pretty much read his mind.

crossrush

iTrader: (1)

Unfortunatly. I already have too much invested in this set up, so i am going to have to stick with it and figure it out. Im just going to leave it for now and going to another part of the car until i can do so more homework on this money pit.

CHRISMAN2000

iTrader: (1)

Sorry to jump on the thread. Just looking for a similar questioned answered.
So I'm going with a holley hp system as well for my 91 tpi. Once the stock ecu is gone will a yellow buffer box wired in line restore the speedi, tach and cruise?

Abubaca

iTrader: (3)

I just wanted to jump in here and offer my two cents. I have the Holley HP EFI running my heads/cammed 383 TPI. I have been nothing but impressed.

Yes there is a learning curve, and I'm no expert, but I think there's a certain amount of experience that's expected before you tackle this. I had never done anything remotely that involved, but I read instructions on the CD, was on the Holley forums for hours reading, and when the time came, it was pretty straightforward and I only had minimal issues. Nothing is TRULY bolt on...nothing is TRULY plug and play. It's hot rodding.

I do agree that the term "self tuning" contains a lot of gray area. As for me, I've read ALL the tuning threads on this site, as well as having a basic understanding of engine theory, and my expectations were to have to go in and tinker. What I did NOT want was a car that I couldn't drive WHILE I learned. My car cranked on the second turn of the key, idled "pretty good", and after about 100 miles, it ran beautifully. Now, I know there's power still in it, and I read a little every day, and tweak on it on most weekends. But I don't feel I'd HAVE to do that. It's just my desire to learn. I enjoy it. To touch on another point, I know 3 shops in the area (Actually purchased from Tick in Mooresville) and they all tune Holley. ...but I actually am proud that thus far it's MY tune, not sourced out. For better or worse it's MY work. (so far better, lol)

I guess my point is that if you're spending that kind of money, it's on each of us to do our research. I KNEW it wasn't a bolt on, that wasn't guaranteed NOT to require any tuning. Again, yes, it says self tuning I know, but my research on various forums quickly showed the reality of these systems. ...and most people feel they "self tune" ....pretty good. Not perfect by any means, and of course your combo will affect how well it does, but I've been impressed.

To bring it full circle for the OP, I used the Harness that came with the kit. Did you not have that? Maybe you said and I missed it. I didn't splice into the car at all. I did remove a lot of wiring though, just for aesthetics. I also have a TKO spinning a cable up to my speedo so no electronics

I'm also running the 3.5 LCD screen on the dash. Shows up to 16 parameters at a time. I'm using it for Oil/water/volts, and I change it up from there based on what I'm tuning. Typically I'm showing timing, fuel pressure, duty cycle etc. etc.. SUPER helpful.

Abubaca

iTrader: (3)

Chrisman2000 - I believe the Holley CAN control those things, however, I'm not familiar with what is involved. Tach is easy, and you should probably have a few options on how to do that. I know there's a certain speed sensor you can get that the Holley can read. Looked into it just to have it on datalogs, but ultimately decided I didn't need it. Actual speedo itself is cable driven, but yeah...I get why you'd need it on yor 91. Cruise....I have no idea.

Check out the forums.
https://forums.holley.com/forumdispl...?13-Holley-EFI

Abubaca

iTrader: (3)

Keep in mind I'm pretty sure the instructions and the software are all free downloads on their site. Even before you buy, download and get familiar with it. I was building the engine so I had a while. Man I looked through the software and the base tune calibrations for months before I actually installed the electronics!!!!!!!!

CHRISMAN2000

iTrader: (1)

Abubaca. Thanks for the response.
Rather then totally tackle the install myself a speed shop two provinces over is going to do my install.
They are Holley tech certified which is nice. My biggest reason for going this route is my engine is brand new and I can have them break it in then tune on the dyno.
Cheers man. Great to be back on the board.

crossrush

iTrader: (1)

Sounds like we both have the same situation. I also have a new engine that needs break in as well. I would like to be able to do the install myself but just don't want to miss anything and cause any damage. I know someone with a shop that knows the holley stuff and will be able to get the tune the car to get the most out of it while it's there. My motor is pretty mild for what he's used to working on.

CHRISMAN2000

iTrader: (1)

The shop owner has the Holley training and came recommended by them. He was able to answer all my questions and knew his way around thirdgens. I was really impressed.
Wish me luck still waiting for them to call to book in. New home during the slow season
Hope your build goes well partner.

LB9GTA

iTrader: (1)

Any update from Crossrush or Chrisman2000?

I also bought a Holley HP and going coil near plug, but staying with the carb, and nitrous

crossrush

iTrader: (1)

Update. Finally got the car all wired up. Had a remote tune done for the break in of the engine. Fired right up and sounded amazing. It's crazy what the hp system is capable of doing. Had to cut things short because of a strange noise while doing the break in. Starter gear was just slightly hitting the flexplate. Have a couple things to address before I continue on with a final tune of the engine.

3rdgenzroc

Just wondering, I also have an 86 Iroc that I am putting an HP efi in. So I took out all of the stock wiring harness from passenger side also (with the ECU), and left the same harness from the C100 on the driver side. I put in a new 383 with the HSR intake. I have the new TPI wiring harness from holley to use with the HP ECU. I have converted my accessories to the serpetine setup from the v-belt, so I realize I will have to extend some of the wiring to the opposite side (from the stock C100 harness). Did you have to use anything (wiring) from the C200 that was under the dash previously hooked up the the stock ECU? and did you have an auto (700R4) that you had to do lock up on. Did you go to a small cap dizzy and have to wire for that? Anything else you had to do (rewire or modify) that I am missing. Thanks for any details!

crossrush

iTrader: (1)

I also removed the passenger side wiring harness. I didnt use any of the old ecu wiring. What are you using for ignition? What distributor are you using? I have a msd ignition and holley dual sync distributor. I also have a complete after market gauge set up. Just had to wire up what the holley hp connections called for.

3rdgenzroc

I have left everything stock (except the dizzy). Since I am using the HSR I had to go to a small cap, so I bought one from Jegs with the recommended coil. Just trying to figure where to mount that (and how to wire everything to it). I left the C100 harness there, it has the AC plugs for the clutch and power? I think it was (have to look again). the temp gauge, the Alt. wire, and I believe just my starter wires. Not sure where the fan power comes from, or the oil pressure gauge wire (in this too?) (have to look). I know i need to wire the tranny for lockup (I read that I need to wire it to the I/O's on ECU and program parameters. I think thats it, unless I'm needing something from the C200. (?) And then I'm just going to put in all new wiring that goes to the batt. and alt charge wire.

crossrush

iTrader: (1)

My car doesn't have a/c. Are you using a dual post battery? I powered my ecu from the side post on my battery, and just used some switched power from under the dash that was no longer being used. I had to run new wires for my gauges. I also used oil and fuel pressure transducers the hp uses. I have them on the 3.5 lcd display. You can use the i/o harness to control your fans if you want to set it up that way. I ran a separate fan switch to run off the thermostat.

3rdgenzroc

"You can use the i/o harness to control your fans if you want to set it up that way."

Yes, I want close to factory control as I can on everything, so i will go that route, but I'm still wondering if I need anything from the c200, not sure what all it was for. Does the fuel pump need it or?? I'm planning on using all my factory gauges. I put in a brand new a/c conversion system made for this car, so the wiring is the same (except for the compressor is on opposite side). I'm thinking with the holley harness, that I will have everything I need to plug in for the ecu side of the harness (sensors, injectors, etc) and was thinking with the exception of what I mentioned previously, that the c100 harness that I left on would have everything I else that I needed to hook up the acc's/starter/etc.

Also, did you mount the ecu under the dash like the factory was? If so, what did you use to "plug up" the entry hole in the kick panel for the harness? I read someone using spray foam (and not working to seal it up), and another using original rubber grommet, but painfully taking it apart from the octopus mess of wires and glue. Neither way sounds good to me, and I definitely don't want to leave it open.

crossrush

iTrader: (1)

Sounds like your wiring will differ from my set up. I mounted the ecu beside the battery and will be installing a new split grommet to run the wires into the car at the kick panel. As far as the fuel pump wiring, just need to run the green wire from the hp harness to the fuel pump wire on the pump. I dont think I used the c100 harness at all.

3rdgenzroc

Yea, after doing some more looking, i realized that I was actually meaning to refer to the c207 that plugs into the original ecu, not the c200. Anyway, you say you didnt use the c100 that is on the drivers side? Did you you wire your starter up different then? I was just going to use it because all my switched power from the ignition is already there, so why not? Also if you have your holley ecu mounted outside of the cabin, why would you have your wiring going thru the kick panel?, unless this is what you did for switched power wiring i guess? Did you find a split grommet anywhere that fits that kick panel hole by the way?

crossrush

iTrader: (1)

I did use the factory starter wires and and other accessories from the c207 harness. I used a split grommet from summit. They sell different size ones. I had to run a couple wires for my gauges in through there along with the usb and wires for the digital lcd screen.