Thinking Northstar Conversion?

[a.k.a]

...ok, I have a question...

I noticed while I was there your suspension components...

Are they matched to an 88 Fiero GT or a V8 conversion?
Secondly...Are the fronts going to remain stock or do you need something stiffer to compensate for the mother of an engine you got back there

[hellfish87gt]

the suspension will no doubt be just the gt stuff, the final weight of the N* is only about 45 lbs heavier, than the 2.8 so you really dont need to upgrade but it is a good idea, to maybe jump to coil overs with a 350 or maybe 375 lb spring.

[GSXRBOBBY]

A friend of mine sent a copy of the site to me, after reading this thread I had to sign on and say GOOD JOB! I am also doing the swap this winter, infact I am going to go get the motor this weekend. Please keep it up, it looks like your helping more than just me!!!!

[a.k.a]

the suspension will no doubt be just the gt stuff, the final weight of the N* is only about 45 lbs heavier, than the 2.8 so you really dont need to upgrade but it is a good idea, to maybe jump to coil overs with a 350 or maybe 375 lb spring.

ahh, ok...but is there some heavier springs as an option? like when you do an s-10 conversion, you have to change the springs/dampers because of the extra weight moving around....

[aaron88]

The big news that a lot of people (mostly wanting rides) have been waiting for.  At 01:45 this morning the motor came to life.  Thanks a million to Don and Sacha, who had the insight to bring champagne for the occasion (too bad you couldn’t have stayed for the pop, pop vroooooom...sweeeeeeeet!!!).

I’m sorry I haven’t had time to update the electrical but I have been more busy than expected.  I will get to it shortly, but here is a summery.  All of the components requiring wiring can be run through the two quick disconnect connectors (the one just inside the fire wall C203 and the one in the battery location aria C500).
rpm gauge works but will have to be recalibrated
Oil pressure gauge works but will have to be recalibrated
Coolant temp sensor will have to be added to the manifold somewhere if I want the gauge to work
ECU software (for Holley 950) would only install on win 95 thru 98 SE + NT

I will get back to proper posting soon.



aka;

I have Koni and springs all the way around and poly for the front end (I kept the rubber in the rear because I want it to be a little softer than the front).  I haven’t put in the front end suspension components only because I haven’t gotten to it yet.

Aaron

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[a.k.a]

thanx aaron!

good to hear man! A north* running with no headers....mmmmm....

when can the rest of us posers see her?  

[hellfish87gt]

so guys like myself running win xp cant do a heck of alot for the programing can we. damn

good to hear it's running, as far as recalibration, i think the tach only needs a v-8 tach filter.  at least for me the oil preasure and temp sensors i want to use the v6 ones, saves calibration, i'll just put a T connection on the oil preasure line, the temp may not work so easy.
again congrats on that,

[BootMachine]

ok can you do me a favour please.....there is this guy on the Ottawa Prelude site who thinks his Honda is a friggn Lamborgini....he was dissing Fieros and saying how his car can kill them hands down.....Can you please take his ass to the track when your new engine is tuned and open his eyes a little!

I'd like him to see that yes ...Honda makes a good car...YES....some of them are fast..and NO..yours is not one of them!

Hes got V-tec too which will make it even better when you V8 past his ass!

mou-ha ha ha h ah

[aaron88]

The wires to follow:

I highly recommend getting the GM books for the Fiero of your model year.  These books have the best diagrams for the wiring.  It’s much easier to trace out your circuits that way.  I also highly recommend finding out what each wire is for before you cut it.

Keep in mind that my car is an 88 GT, fully loaded (no AC), the wiring on your Fiero my vary, especially if you have an 84 model.  I’m using a 98 Northstar (meaning OBD II) and hooking up the “Holley commander 950” as purchased from CHRFab.  This information isn’t the gospel, it’s just to give you an idea of what needs to be done and what doesn’t.

The computer that I received, came with a wiring harness that was well labelled.  There were no routing directions but basically, I started at the crank position sensors (near the oil filter) and worked my way around the motor.  I did have to look up a few acronyms so that I could locate the proper sensor, but it’s basically a no brainer.

The motor I bought didn’t come with the MAT Sensor (manifold air temperature) because the wrecker didn’t think I needed it.  I was able to get one from GM for $20 (UAP / NAPA did not have the part).  The GM dealer called it the “intake air temperature sensor” (IAT Sensor).  I’ll just insert this into the air intake line somewhere, not too close to the motor so that it doesn’t heat up from the outside and give a false reading.

Basically the wires you need to find and follow though are the following;
C 500 (wires that went though the connector at the battery location)
starter
alternator (3 wires)
reverse light switch (2 wires)
water temp (2 wires)
fan switch
tach

C 203 (wires that went though the fire wall connector)
Speed sensor (2 wires)
ECU ignition power
ECU constant power (went to the fuel pump relay first on my 88)
Fuel pump (many wires)
Oil pressure (many wires)

Other wires;
Trunk release


Find the components that you need (options vary), and follow the wires back to the respective connectors to the body wiring harness.  Label these wires once you find them (label clearly and don’t use abbreviations if you are not totally familiar with them).  After you know what all the wires are for (and labelled), cut the connectors free from the Fiero engine wiring harness.  (tip: to save some confusion latter it might help to label the wires on both sides of the place you cut them.  This way if you have to go back and rethink some logic, you will have saved yourself a lot of time)


Edited because of insomnia

[aaron88]

CONNECTOR C500
(wires that went though the connector at the battery location)

starter
alternator (3 wires)
reverse light switch (2 wires)
water temp (2 wires)
fan switch
tach
trunk release

The starter; this is the wire that goes from your ignition to the starter.  I had an auto so this involved ignoring the switching that used to go through the transmission (so that your starter would only engage in park or neutral), just connect the wire at C 500 to the one on the Northtar (not the one that goes to the battery, that one attach to the positive battery terminal).

Trunk release; I also had this tiny little wire that followed the starter wire and was connected to the starter (for auto’s).  This is for your trunk release (so that you can only pop it in park or neutral), I just cut this out.  If you want a formal setup for the trunk release, for manual transmissions you could find the trunk release relay under your steering column and wire it though the switch on your emergency brake (so that you can only pop it when the parking brake is on), but I just bypassed all that crap and hooked it up straight to ground (bypassing the relay altogether).  I feel a need sometimes to pop the trunk when the parking brake isn’t on.  Respectively, if you have an automatic and you are planning to keep the Northstar auto, then it’s probably easiest to just hook these wires up, in the original configuration (small wire to small wire, and large wire to large wire).  However if you are using the Northstar auto this write-up is of little use to you since you will need to re-use the Northstar computer and components.

The alternator; (or generator); the Northstar only uses 3 wires for the generator, one of them just gets attached to the battery (that’s the big red one).  For the other two, find the orientation of the connector on you Fiero generator and match that configuration the Northstar generator (if you are using it), ignore the extra wires on the Fiero generator connector unless you are reusing that generator.

Reverse light switch; this is simple.  Attach the reverse light switch wires to the reverse light switch wires.

Water temp; this is many wires on the Fiero and just two on the Northstar (one of them is just a ground).  The Fiero has many coolant sensors, one for the water temp for the ECU, one for the water temp and idiot light in your gauge cluster, one for the fan switch relay and one for the cold start switch.  Did I miss any?  For my 2.8 the wires I needed to follow were the ones from the sensor nearest to the coil.  This is the one for the Fiero gauges.  Things here are a little tricky.  Because I used the Holley computer, it uses the temperature gauge on the Northstar block (don’t splice into that, you will change the readings).  If I want my Fiero gauges to work right, I have to add the same type sensor as the Fiero one (and get yourself an new one, don’t try to reuse the old one on the Fiero block).  There is a plug (with a pipe thread) in the manifold right near the block heater hose line.  I haven’t done this yet but I’m going to make a new plug with the appropriate pipe thread and drill and tap into it the right size pipe thread for the Fiero coolant sensor.  Then I’m going to wire this up accordingly to the Fiero gauge.  For reference, take a meter to the two wires on the Fiero gauge, one of them will have infinite resistance to the gage casing and the other will have a resistance reading.  The wire with the resistance reading is for the temperature gauge and the other is for the idiot light.  Again if you just match up these wires you’ll be fine.  However the replacement sensor you buy may have two wires that are for use with just the gauge, this is because most new sensors use a ground wire instead of grounding through the block.  If you get one of these sensors (you’ll be able to tell when you check it with a meter), hook up the gauge wire to one side and run the other wire on the sensor to ground.  This will mean that your idiot light will not work.

Fan switch; the fan switch in my case is controlled by the computer, so what I did once I found this wire on the harness, is follow it though until it came close to the location that I mounted the Holley computer, and spliced in a quick disconnect.  This way I can unplug this wire and remove the harness as one, if I need to drop the engine for any reason.  This wire (along with the tach wire) can be seen in the photo showing the Holley computer, if you look closely it’s on the right side of the harness that comes through the fire wall on the passenger side.

Tach; Once this wire was found it was traced back to the wiring harness that comes though the fire wall on the passenger side.  I used a quick disconnect connector so that the wire can be removed with the engine side of the harness.  I’ll explain this a bit better.  The tack wire comes from the Northstar engine and goes into the Holley computer, then out of the computer for your gauge, but is attached to the engine side of the wiring harness.  Therefore if you want to remove (or drop) the engine, the wire can simply be unplugged.  Be sure that the wire from the computer is connected properly with the wire that goes to the tack and not the end that goes to the connector C 500 (in the battery location).  I have a bit of a problem with gauge because it's set up to read the input of 6 cylinders and I want it to read for 8 cylinders.  At this time I’m not fixing this because I’m still trying to decide if I want to do a 4th gen Firebird dash conversion, in which case I would just use the tack there, already calibrated for a V8.  But for now the tach will just read 25% higher than actual, as long as I know this, it isn’t a big concern of mine right now.  The computer has a rev limiter anyway (and the computer knows the actual rpm which I can simply read on a computer screen).

Aaron

Edited for insomnia

[aaron88]

CONNECTOR C203
(wires that went though the fire wall connector)

Speed sensor (2 wires)
ECU ignition power
ECU constant power (went to the fuel pump relay first on my 88)
Fuel pump (many wires)
Oil pressure (many wires)


Speedo; hook up your speed sensor wires to your speedometer wires, simple, but with one catch.  Your speedometer doesn’t go high enough.  Make sure you correct this.  I’m going a different rout and getting an aftermarket pulse sensing speedometer to go with my pulse sensing transmission sensor.

ECU ignition power; I used the wire that was for the Fiero ECU ignition power and used it for the Holley ignition power.  What a concept.

ECU constant power; I used the wire that used to supply constant power to the fuel pump relay and the Fiero ECU and used it for the Holley ECU constant power.  The Holley ECU controls the fuel pump through it’s own relay (already wired into the harness that was prepared by CHRFab).  Also don’t forget to replace the fuel pump fuse with one of a higher rating.  Alternately you could run a wire from the battery to the Holley ECU, since it has it’s own fuse, but I figured that I’d skip the need to run the extra wire.

Fuel pump; First off, you need a higher flow fuel pump, so get one and install that into your fuel tank.  I got the high flow fuel pump from the Fiero Store online, I’ll let you know if it’s going to be big enough.  I used this fuel pump because if it availability and convenience, it’s a straight drop in, even has the right connector on it.  For the wiring, the Fiero fuel pump power goes through a parallel circuit with the ECU.  The power comes from the fuel pump fuse goes to the fuel pump relay (pin 30) and to the constant power for the ECU, the switched power goes from the ECU to the coil for the fuel pump relay.  The power for the fuel pump also comes from the oil pressure switch.  This is supposed to be a protection circuit for the motor.  It looks complicated when you start tracing the wires but it’s quite simple.  The ECU turns on the fuel pump, once the motor is started and running, the ECU cuts the power to the fuel pump relay coil, but because the power for the fuel pump also comes from the oil pressure switch and the motor is running, so there is oil pressure, this switch is closed (that means power runs thought the switch) therefore latching the fuel pump on until the oil pressure drops to zero.  Then the switch opens and therefore cuts the power to the fuel pump.  But if you are using the Holley computer (or the Northstar computer for that matter) you don’t have to worry about this circuit, because the computer will totally control the fuel pump relay.  What I did was find the wire that went from the fuel pump relay to the fuel pump and tapped into that wire (on the engine harness side, at the connector C 203).  That way I didn’t have to rewire the fuel pump at all.  So the power went (and still goes) through C 203 to the fuel pump relay and then back through C 203, down the body harness that goes through the fire wall on the passenger side, through another connector (C 502) then finally to the fuel pump.

Oil pressure sensor; I reported having a problem with the oil pressure calibration, this can be easily fixed by swapping the oil pressure sensor on the Northstar for the one on the Fiero (here as well, I recommend getting a new sensor).  You should have 3 wires (may have 4) coming out of your oil pressure sensor on the Fiero.  One is for your oil pressure gauge (may have 2 wires), and the other two are for the cut off switch for the fuel pump.  Of course this will depend on the options with your Fiero.  Just make sure you trace your wires back and know where they go.  Of course, you won't need the old fuel pump switch wires, so just ignore them for now.  It isn’t possible to use the Northstar Oil pressure sensor for you Fiero gauge because the Northstar uses a switch that opens (breaking the circuit) once 1 to 4.5 psi are obtained, where you Fiero uses a variable resistor that increases in resistance to 90 ohms when full pressure is obtained.

Aaron

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Edited for insomnia.

[aaron88]

The computer location, if you look closely at it you can see the tack and fan switch wires attached to the harness that comes through the fire wall on the pasenger side.

[Slammed Fiero]

Great writeup ont he wiring!! Im nearly at that point in my project. One thing I did do was toss the Fiero AUX gauges in Favour of autometer.. I just figured it would be easier in a lot of cases.

you have taken a lot of the guess work out for me , thanks and keep up the good work!

JM

[aaron88]

Please forgive me, I seem to have made a few errors in the electrical right up.  Instead of having errors in this write-up and then corrected in a latter post, I’m just going to edit the original post.

For some reason I decided to do the write-up in the wee hours of the morning after having only two hours of sleep from the night before.  And because I didn’t have my notes handy I did it all from memory.  Not a good idea.  So now I have my notes in front of me and should be prepared to fix the troubled arias.

If there are any mistakes here and someone is sure of it, or has more information to post on the subject at hand, feel free to do so.  This write-up is intended to help others, and the more information there is here the less guessing someone else may have to do.

Aaron

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[aaron88]

Battery relocation:

I chose to relocate the battery to the front of the car.  As far forward as possible.  The intention here is to fix a little bit of the weight distribution on the car.  The battery would have fit back into it’s original location with only slight modification to the battery tray, but I decided that this wasn’t an optimal solution.

I’m not using the traditional mounting system that most people adopt, with the battery in the spare tire location.  I’m using a method inspired my a local Ottawa Fiero Club member.  I mounted the battery under the right side headlight assembly.

I used isolated battery post terminals in the traditional location, in case the need ever arises to boost the car or charge the battery etc...

A set of cables were run to the front of the car.  For the power cable I used a 1/0 AWG although only a 2 gauge cable was required (I used what I had on hand).  For ground I used two 4 AWG cables.  One followed the power cable and the other was grounded to the body.  The body was then grounded to the engine with two separate 4 AWG cables.  I can’t stress enough the need for proper grounding.  You should ground the transmission to the engine as well, and the body to the ground (Earth).

Aaron

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