Wire harness to sensors

[ironwill11]

Hello,

I am trying to wire my DIY autotune harness to my Chevy 4.3 TBI.

Problem: how to connect the wires to the sensors.
Background info: I have all the connectors for the sensors, I am taking out the old harness for the stock ecm.
I was wondering there was any information on how to connect the wires to the sensors.
For example: I have TBI which has two injectors, but there are 4 wires that are supposed to go to the fuel injectors. How do I connect the 4 wires?
How do I wire up the rest of the sensors.
I am looking for information on how to do this if someone can point me in the right direction. Thank you for your time!

Will

[trakkies]

Generally, keep any joints to a minimum. I also hate two different coloured wires being joined together. Makes it a nightmare doing fault finding if needed years down the line.

You can generally buy new terminals for most connectors - especially the common type used for most injectors. Or even a new connector complete.

Other thing well worth doing is drawing out your actual wiring scheme using the true colours you end up with. Use the MS one as a basis.

It really can't be emphasised enough that a well made wiring loom is essential for reliability.

If there is an EFI version of your engine - or one close - it can make sense to use a used loom from that as the basis and add the MS DB37 to it. Rather than start out with an MS pigtail.

[Matt Cramer]

You would just ignore two of the injector output wires for this. The sensors are shown here, with the colors used on our harness:

[ironwill11]

Thank you for your help!

I have a follow up question though:

As I am cutting out the old harness (painless wiring harness - using the connectors from that harness so I don't have to buy a new set) I got to thinking about the distributor wires.
I have a GM HEI distributor with the 8 pin module (as depicted on the bottom left of the picture on the GM HEI ignition control with megasquirt II) page.
While assembling the MS-II, I completed the circuits for the Hall/optical effect input circuit.
Question 1) I was wondering how this gets wired up from the distributor through the wire harness (In short I don't understand the connection between the two connectors on the control module and the MS-II)?
Question 2) When I bought the megasquirt, I told the people at DIYAutoTune that I didn't need to control timing. Is this something I should reconsider? Any recommendations?
Question 3) If I am not controlling timing with MS-II, do I need to keep the old harness and ECU just to control the timing?
Again, Sorry I am newbie to megasquirt (and tuning in general) and sincerely thank you for your help.

Will

(Background Info - I did a motor swap and put a 4.3 TBI with a TH350 trans into a Suzuki samurai. I am just trying to get it to run right. After sitting for a while I would get a idle hunt. A mechanic that I used to know said he cleared the map sensor and it worked. It sat for a while now the problem is back. The nice folks at DIYAutoTune helped me pick out a megasquirt that would help me with this problem.)

[Matt Cramer]

What documentation are you using on the HEI wiring?

[ironwill11]

Got it figured out, thank you so much.

MS II only does not due sequential right. So I only have two injectors I will disregard two of the injector wires (one on each bank, aka 33 and 35) right?

thank you so much
Will

[trakkies]

Got it figured out, thank you so much.

MS II only does not due sequential right. So I only have two injectors I will disregard two of the injector wires (one on each bank, aka 33 and 35) right?

thank you so much
Will

The reason for the same output being doubled up on two DB37 pins is the output driver can supply more current than one pin can handle.

[Ian]

join the wires in parallel , (32to33 ) and (34to35 ) and then each pair then to your injects , from a poor memory the TBI has LoZ injectors which require higher currents , better with larger return wires to suit

[ironwill11]

Thank you all for your help.

[DonTZ125]

The reason for the same output being doubled up on two DB37 pins is the output driver can supply more current than one pin can handle.

<ObPedantic>The drivers are ground-switching, SINKING the injector current. The power is supplied from the battery via the relays.

Sorry, but I've seen a few people get right confused over this ...

[trakkies]

The reason for the same output being doubled up on two DB37 pins is the output driver can supply more current than one pin can handle.

<ObPedantic>The drivers are ground-switching, SINKING the injector current. The power is supplied from the battery via the relays.

Sorry, but I've seen a few people get right confused over this ...

I'm not confused, Don. I mentioned current. And the injector drivers (and connector pins) have to handle the current that flows to ground through them.