NA 3900 Build

[zok15]

Rear brace.





Mount trimmed and rear bracket welded. It is very stable. Once I have made actual spacers instead of stacks of washers and weld them to the mount, I will make sure the rear bracket still lines up properly and make adjustments, and then I will give it some gussets. But being 1/4" steel it is already very strong.



Decided notching the crossmember was necessary.





I painted it too.

[Shaun41178(2)]

So I noticed your block only shows "3.9" in the area under the timing cover cast into the block.

I have two different 3900s here, and each block is cast differently. Yours is different from my two, which means there are at least three different castings.

One of mine is an lz9, don't remember what car it came from. Another is an lgd for flex fuel that came from an Impala maybe an 08 or 09.

IMG_20220922_195335595.jpg (3.34 MiB) Viewed 5063 times

[zok15]

Mine is from an 07 Uplander, no flex fuel, and my oil filter area on the block is threaded.

[Shaun41178(2)]

Both my oil filter areas are unthreaded

[zok15]

I decided to start on the wiring today as it is the thing I have been putting off.

A big thank you to Shaun as his wiring video on youtube was very useful.

A note: I want this info to make wiring one of these up to be simple with all the info on one page. I can edit this post if needed.

I first figured out what was going where with the Microsquirt harness. Some useful information:



Have a question on this one though, I intend to use WLED as the IGN3 Output since there is no defined IGN3. Do I need the 1K resistors going to 5VRef?



Here's what it looks like on the Microsquirt side.



First time making a harness so I spent time exploring my old 4 cyl harness. When I bought the car it was a 4 cyl, and I swapped a 2.8 in. I sold the 2.8 with the wiring harness and ECU so it was a good thing I held onto this 4 cyl harness for 12 years. At one point the always hot pins to the ECU became intermittent so I ran a dedicated line. After unwrapping the harness today I found the bad splice that created the condition, 13 years later.



Bunch of unwrapping later...



I traced the tach, ignition, alternator, starter, VSS, fuel pump relay, and oil pressure wires. I also learned that the TBI on the duke was powered by the same pink and black line off the C203 that powers the ECU with key on. That goes to the red wire and the blue wire must have been grounded by the ECU internally when firing the injector. Where it says from C203 is cut off.



This is the wire it is powered from, and the wire I will use to power the Microsquirt. Pin F on C203



Here are the missing J and K pins on my C203 that would be populated on the V6 harness. I will have to add them, and I plan to use them both for my fuel injectors.





Here are the populated pins on the other side of the C203.



Wire and connector coming off power distribution block that would go to ECU, connector lets you reset ECU. Might find a new purpose for this, maybe as a simple antitheft device.



Here's the brown wire coming off the alternator plug that goes to the C500, it is for the battery light on the dash and is needed for the alternator to charge.



The C500 maybe labelled correctly, I need to get a better pic and remake this.



Tach signal wire and ignition power coming from C500. I am assuming the ignition power is with key on and not always hot.



VSS plug and wiring I will be re-using. These go to the C203, will edit to add pic of the wires on C203.



I labelled all these things and then took the bulkhead connector apart with the boiling method from Fieroguru.



All glue removed.



I am pretty much ready to start hacking things up and crimping pins, but I wanted to see if I have any errors before jumping into that.

I was wondering if the 2 wire coolant sensor from the LZ9 is able to run the gauge and feed the Microsquirt? I think I can use an output on the Microsquirt to drive the gauge but not sure if I will have a spare. Worst case I will get a Fiero sensor as a second sensor only for the gauge. Maybe I can use SPAREADC, but it says it is not programmable.



Additionally I plan to use an output on the Microsquirt to control the fan relay, it is something I need to look into more, but I think I can do with ALED.



I also know I need a resistor in the crank sensor wiring somewhere, anyone have the magic value and pin location?

Also are these all correct?

C203 Female Pins:
https://www.mouser.com/ProductDetail/Ap ... vLPw%3D%3D

C500 Male Small
https://www.mouser.com/ProductDetail/Ap ... IpnA%3D%3D

C500 Male Mid
https://www.mouser.com/ProductDetail/Ap ... arzJQOAAFT

C500 Male Large
https://www.mouser.com/ProductDetail/Ap ... uVwg%3D%3D

[zok15]

Additional question, do I still need to trigger the Fuel Pump Relay from the Oil Pressure Sensor? The Microsquirt has a dedicated output to trigger the fuel pump relay, and it turns the pump off if the motor stops running. My thoughts are that I can delete all that crap and run a dedicated relay that has a direct power line from the power distribution to make sure I have good voltage at the pump. I was probably going to add a little fuse block in the car next to the computer to run some additional gauges and things so that will work out well for a fuse location for the fuel pump too.

Maybe I will use that line with the inline connector originally for resetting the ECU to be able to interrupt power to fuse block powering the pump as an anti-theft feature. Maybe it makes more sense just to add a hidden switch. Maybe it makes the most sense to put a switch inline with the FP wire coming out of the Microsquirt that turns the fuel pump on.

I have made a more complete wiring diagram so I can figure out where I am missing things. Info I am missing is how to wire the oil pressure sensor correctly. It seems like 2 pins are a switch that would go to fuel pump circuit, and the third pin is the pressure output. Does the oil pressure pin just have a resistance value that changes? I am surprised if it does not need a power source.

[ericjon262]

I wouldn't use the wiring in the megasquirt manual for the crank position sensor wiring, it's for an LS, so the V6 pinout may be different, it would be best to check that.

my MS3 pro just used the fuel pump relay trigger, the OPSU is only the sender on my swap.


I'm fairly certain the green/white wire in your C500 picture is for the AC compressor. something to keep in mind, all of the chassis wiring is the same no matter what car you have, or the options your car has, so if your car didn't have AC, or the 2 speed fan factory, the wiring is still there.

[Shaun41178(2)]

Yes you need the pull up resister on the crank wire. I don't know exactly where it's supposed to go off the top of my head. But the instructions are correct. I soldered it in as the instructions stated.

I wish I had gone into detail on the crank wiring, but I forgot to do it, and it seems that one is where people have the most questions. But the instructions provided are correct and will work. If not you have no reference from your crank sensor and it won't run.

For the coolant sensor, if you want it to work the stock gauge, you can use the factory sender, but just find a way to tie it into your coolant system. Put an adapter on the block, or weld in a bung somewhere. I eliminated my stock coolant gauge as I just had an aftermarket I decided to use.

There is no reason to use the oil pressure sensor switch and relay inline with your fuel pump. I eliminated it on mine. I ran a direct wire and relay from the power distribution at the c500 and eliminated all the factory wiring associated with that.

What I did on my setup is I wired in a switch to the 12 volt key on trigger switch to the fuel pump relay. If that switch is off, when turning the key to run, the relay won't get that switched 12 volt power it needs, and the pump won't run. Simple anti theft really.

I used an aftermarket gauge to monitor oil pressure. However I think the Ms can be programmed with an input to use an oil pressure sender of the correct resistance values. I never researched it.

[ericjon262]

if you're feeling especially frisky, you can drive the factory gauges with outputs from a microsquirt, if you have enough IO.

https://youtu.be/cwEE4juNEsk

[The Dark Side of Will]

First time making a harness so I spent time exploring my old 4 cyl harness.

After unwrapping the harness today I found the bad splice that created the condition, 13 years later.

Bunch of unwrapping later...

I've modified old harnesses enough times that I'm building The Mule's harness from scratch with new parts.

This is the wire it is powered from, and the wire I will use to power the Microsquirt. Pin F on C203

In the 2.8 system, ECM power comes from the ECM IGN fuse (C203-F), while injectors are powered from the TBI INJ1 (C203-J) and TBI INJ2 (C203-K) fuses.

I was wondering if the 2 wire coolant sensor from the LZ9 is able to run the gauge and feed the Microsquirt? I think I can use an output on the Microsquirt to drive the gauge but not sure if I will have a spare. Worst case I will get a Fiero sensor as a second sensor only for the gauge. Maybe I can use SPAREADC, but it says it is not programmable.

There is a THREE wire CTS that has the two terminals that work with the ECM and single terminal to housing ground that works with the Fiero gauge.
GM 10096181
pin "A" BLK to ECM
pin "B" YEL to ECM
pin "C" GRN wire to C500 gage connection

C203 Female Pins:
https://www.mouser.com/ProductDetail/Ap ... vLPw%3D%3D

C500 Male Small
https://www.mouser.com/ProductDetail/Ap ... IpnA%3D%3D

C500 Male Mid
https://www.mouser.com/ProductDetail/Ap ... arzJQOAAFT

C500 Male Large
https://www.mouser.com/ProductDetail/Ap ... uVwg%3D%3D

You linked the same part for mid and large.
The 150/280/480/630 numbers are the width of the pin in mm, corresponding to 1/16", 1/8", 3/16" & 1/4"... so you can just measure which size it is.

"CBL RN 1.00-.80MM2" means that the Cable Range is from 0.8mm^2 to 1.0mm^2. The numbers may sound weird, but it's actually "Metric American Wire Guage". Every mm^2 number corresponds to an AWG size. The same terminal can be made to take multiple wire sizes. Be careful of that when you're selecting terminals.

Here's the table:

Code: Select all

mm2	AWG	Cu Dia
0.22	24	0.0201
0.35	22	0.0254
0.5	20	0.0320
0.8	18	0.0403
1.0	16	0.0508
2.0	14	0.0641
3.0	12	0.0808
5.0	10	0.1019
8.0	8	0.1285
13.0	6	0.1620
19.0	4	0.2043
32.0	2	0.2576

[The Dark Side of Will]

Additional question, do I still need to trigger the Fuel Pump Relay from the Oil Pressure Sensor?

I think when GM originally did that, they added that feature so that a failed relay wouldn't stop the car or prevent it from starting.[/quote]

Does the oil pressure pin just have a resistance value that changes? I am surprised if it does not need a power source.

Yeah, it's 0-90 ohms resistance from that terminal to the sensor housing that grounds through the block.

[The Dark Side of Will]

GM typically uses the ECM to ground the control side of a relay. However, you'll notice that the fuel pump relay is different and the ECM provides +12V to trigger that relay.

If the relay has +12V and the ECM provides ground, then any short to ground on that circuit could unintentionally turn on the fuel pump.

If the ECM provides +12V, then there would have to be a wiring fault that shorted the relay trigger wire to +12V in order to turn the fuel pump on. This is FAR less likely than if the ECM provided ground.

[zok15]

Thanks for all the replies everyone lots of super useful info!

Shaun, for your pin C on your ignition module connector, are you using ALED or WLED for that? If you are, are you using the 1K resistor between it and 5VREF?

Here's all the wire going in the bin



And here is the wiring from the car originally that I will retain. I will probably run all new wires but they are placeholders for now to make things easy, and I may have to splice a few. I have it all labelled, I traced everything to confirm the wiring diagrams online.





Much more manageable now. Gotta start populating the motor with connectors and laying things out.

[Shaun41178(2)]

I don't remember if I used the wled or aled. I believe I used wled because if you look at the wiring schematic is lists wled as ignition 3.



Yes, you have to have the correct resistor for that third ignition input/coil wired in.

[zok15]

Cool thanks!

Alright I spent some time getting this together, I have to take a look and figure out all my needs for wire sizes, but I have bought a selection of 8 colors of18awg, and 6 colors of 12awg, and a small spool of 10awg in red. The Microsquirt harness is all 20awg.

In C500:

Starter solenoid wire is pretty large, I will probably use 10awg.

Ignition feed wire is big but smaller than starter solenoid, I will probably use 12awg. I gotta see what the terminals that came with the 6 pin connector can handle, but since 12awg is overkill I could always trim some of the conductors that are getting crimped. I may order another intermediate size if 12awg is way too large for things but 18awg is too small for some.

In the C203:

Everything seems 18-20awg range. I may run a 12gauge wire through the C203 to the fuel pump harness if that works but I need to look at the car more to see what's actually going on. I am assuming the male 280 series pins that are used in the C500 also work on the connectors that plug into the C203, I don't have a plan to mess with those but I might.

**************************************************************************************************************************************************************************************

But here is a useful list of the options with part numbers and links that bring you to the loose terminals. I had to look at the other reel variations for some of the pins to see what size wire they accepted. They are same part number though so should all be good.

C203 FEMALE PINS
Metri-pack 280 Series
12-14awg: 12162597
https://www.mouser.com/ProductDetail/Ap ... txsg%3D%3D
17-20awg: 12077411
https://www.mouser.com/ProductDetail/Ap ... PLbg%3D%3D

C500 MALE PINS
Metri-pack 150 Series
17-20awg: 15344866
https://www.mouser.com/ProductDetail/Ap ... AAOA%3D%3D

Metri-pack 280 Series
10-12awg: 12084586
https://www.mouser.com/ProductDetail/Ap ... hgCg%3D%3D
14-16awg: 12020116
https://www.mouser.com/ProductDetail/Ap ... v5ow%3D%3D
18-20awg: 12034047
https://www.mouser.com/ProductDetail/Ap ... lzpg%3D%3D

Metri-pack 480 Series
12awg: 12065197
https://www.mouser.com/ProductDetail/Ap ... awLA%3D%3D
14-17awg: 12065196
https://www.mouser.com/ProductDetail/Ap ... arzJQOAAFT
18-20awg: 12020119
https://www.mouser.com/ProductDetail/Ap ... FjBA%3D%3D

[zok15]

GM typically uses the ECM to ground the control side of a relay. However, you'll notice that the fuel pump relay is different and the ECM provides +12V to trigger that relay.

If the relay has +12V and the ECM provides ground, then any short to ground on that circuit could unintentionally turn on the fuel pump.

If the ECM provides +12V, then there would have to be a wiring fault that shorted the relay trigger wire to +12V in order to turn the fuel pump on. This is FAR less likely than if the ECM provided ground.

This does sound like a nice feature to have, but the Microsquirt grounds the fuel pump relay. I am not too worried about that though because I am going to locate the relay right next to the MS, there will be an extremely low chance that the short wire will ground out by accident somewhere. I will make sure to protect that wire extra well though just incase.

[zok15]

There is a THREE wire CTS that has the two terminals that work with the ECM and single terminal to housing ground that works with the Fiero gauge.
GM 10096181
pin "A" BLK to ECM
pin "B" YEL to ECM
pin "C" GRN wire to C500 gage connection

Awesome thanks, I will order one of these and the correct connector to plug into it. Summit carries the sensor:
https://www.summitracing.com/parts/ado-213-815

[zok15]

if you're feeling especially frisky, you can drive the factory gauges with outputs from a microsquirt, if you have enough IO.

https://youtu.be/cwEE4juNEsk

I think I will use this for the coolant temp, but other than that I only have one more programable output left, I could use this to drive an oil pressure gauge, but I think the factory sender will make it happen, pretty sure it is the same range as the stock sensor, but the PSI it correlates to may be off. For the purpose of gauge though this is no problem as the min and max will still line up with the extreme marks on the gauge.

I wouldn't use the wiring in the megasquirt manual for the crank position sensor wiring, it's for an LS, so the V6 pinout may be different, it would be best to check that.

my MS3 pro just used the fuel pump relay trigger, the OPSU is only the sender on my swap.

I'm fairly certain the green/white wire in your C500 picture is for the AC compressor. something to keep in mind, all of the chassis wiring is the same no matter what car you have, or the options your car has, so if your car didn't have AC, or the 2 speed fan factory, the wiring is still there.

I am pretty sure the way the CPS is wired is the same.

I actually did not have any AC wiring in my C500 connector, it exists on the body side but not on the engine harness side.

*******************************************************************************************************************************************************************************

Side note I pulled the trigger on some exhaust tubing, I got all mild steel 1.75" 16ga tubing, some 304SS 3 cyl collectors from the UK, and 2 2.5" SS V-bands. My buddy has a ton of 2.5" SS exhaust tubing left over from when I built him an exhaust for his E39 540, I think he will let that go to me really cheap. Planning to run true 2.5" duals both out the driver's side exit. They make a bunch of mufflers that are 2 x 2.5" inlets and 2 x 2.5" outlets that will work perfectly for me. If I did not have such a good deal on the 2.5" tubing I would be running a Y pipe and a 3" exhaust. This twin 2.5" exhaust will be heavier, but the true duals gives another dimension to the sound. Here is my buddy's E39 doing a pull, it has long tube headers and straight pipes:

https://youtu.be/Av2kcMFOouo



For the headers the plan is to get them Jet Hot coated, they quoted me $400 which includes return shipping. Probably close to $90 to ship them to them. They are the ones that recommended going mild steel if getting them coated, so I am.

[Shaun41178(2)]

Mine is from an 07 Uplander, no flex fuel, and my oil filter area on the block is threaded.

I just picked up an 08 outlander 3900 supposedly an lgd(flex fuel) and it doesn't have the threaded block.

So far I am 0-3 in this dept.

[zok15]

I've talked with another LZ9 Fiero owner Christopher Brooks, his engine from an 06 Impala has the threaded portion, and his 08 Uplander motor is not threaded. My 07 Uplander is threaded, he believes that all the 08+ motors are unthreaded.