blackboosted2

I just put in the proper p72 obd1 ecu and my tach doesnt work.

We are unsure why since this is not a common thing to happen with swaps. The engine runs fine, and runs quite well I might add.

We can rewire it, but does anyone have any suggestions? I have looked at wiring around the net after searching, but nothing we can find is related to a tach issue.

The car is a 94 Si hatch, and the engine is an obd2 w/obd1 p72. obd2 engine harness, obd2 distributor . . .

No codes are thrown, I just have no tach!

There is an extra plug that was not used from the obd2 engine harness, it contains 3 wires and is located next to the passenger side harness plugs into the firewall..

I know the middle wire is for the Knock Sensor, and what are the other 2?

blackboosted2

Search hasn't helped, anyone have any ideas for me?

I want to keep the stock cluster

Scott - 93HB Si

Is there a solid blue wire coming outta your distributor (if you have 9 wires coming outta the distrib you'll have it).

This wire is your RPM signal. Trace it back and make sure it's properly connected where the engine harness plugs into the carside harness.

blackboosted2

The blue wire does go into the harness, I dont know what the extra plug is for (held in my hand in the pic) I know the middle wire is the knock sensor, and the other 2 are...?

It is the OBD2 Distributor with the OBD2 Engine Harness, This may be the reason for having no tach, i might ned to add a wire to the ECU for it.

I have a CEL on now, for the Knock Sensor, I will run a wire through to the ECU for it.

blackboosted2

Which pin on the ECU is for the Tach? When you look online, all you see is Abbreviations, and I cant tell which one is for the tach

pgpunkguy

are you talking about an aftermarket tach or the tach in your gauge cluster?

blackboosted2

Stock gauge cluster, everything else in the cluster works fine

B16A1-EF9

Easy....
OBD2 distributors don't have the blue wire on the engine harness side of it. Just add that blue wire, it's there from the car anyway...you don't have to go all the way to the other side of the car, just a short wire from the blue on in your harness over the plug or connect it straigh to the other side of your distributor plug.

Everything will work after you do that.

blackboosted2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B16A1-EF9 &raquo;</TD></TR><TR><TD CLASS="quote">Easy....
OBD2 distributors don't have the blue wire on the engine harness side of it. Just add that blue wire, it's there from the car anyway...you don't have to go all the way to the other side of the car, just a short wire from the blue on in your harness over the plug or connect it straigh to the other side of your distributor plug.

Everything will work after you do that.</TD></TR></TABLE>

That is kind of confusing, sorry

The Distributor does have a blue wire coming out of it, so it needs to meet up with...?

LittleG112

Man, i had the same problem with my GSR swap in my civic ex... I sold my motor soo long ago, im not sure if i remember. I know for sure that you have to buy a piece of electrical wiring and tap it to the "blue" wire from ur distributor and run it to ur RPM gauge. I cut my RPM wire (the wire is also blue.. i think) and mated the two wires and then used electrical tape to tape it up. It worked fine after that.

Scott - 93HB Si

I can't see from you pictures, but the RPM signal wire should be on the bottom of the connector (where there are only 2 wires in the row - one is a thick black/yel), the other connector is the one where the RPM signal should be.

blackboosted2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Scott - 93HB Si &raquo;</TD></TR><TR><TD CLASS="quote">I can't see from you pictures, but the RPM signal wire should be on the bottom of the connector (where there are only 2 wires in the row - one is a thick black/yel), the other connector is the one where the RPM signal should be.</TD></TR></TABLE>

so where does this need to go to? It already goes to the car harness..
It must not be in the right pin

I am afraid to just start moving pins around because I dont want to damage a dist.

H23vtecEG

can anyone do some homework with the helms and tell us where to tap into the shock tower

blackboosted2

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B16A1-EF9 &raquo;</TD></TR><TR><TD CLASS="quote">Easy....
OBD2 distributors don't have the blue wire on the engine harness side of it. Just add that blue wire, it's there from the car anyway...you don't have to go all the way to the other side of the car, just a short wire from the blue on in your harness over the plug or connect it straigh to the other side of your distributor plug.

Everything will work after you do that.</TD></TR></TABLE>

actually, I compared my car to a buddy with a b18c hatch, and noticed I AM missing a wire! It looks like it shall run from the extra wire on the Dist. to the harness. Easy fix, thank you! You were right

JTB

the 3 pin connector you are talking about is purge control solenoid (pcs) i think it is wht/red second o2 sensor obd 2 only ofcourse. and you say you know what the middle one is. look at the top of the intake manifold see the pcs look at the wire colors... is it wht/red?? you have a obd 1 ecu so you dont need pcs or secondary o2.. bottom line it the blue wire coming out of the dizzy or from the far right pin on your igniter ( inside the dizzy) is not going from there to the tach. so make it get thee somehow!