I have a square, green, two pin connector with about a foot of wire leading back to where the primary injector wiring comes ot of the harness. It looks just like the connector that plugs into the BACV.

I just got my car back together after about three months of sitting while I waited for parts and such. It starts up and runs up through the RPMs fine but it won't idle at all. If I let the RPM's get between 1000-1500 it starts to stutter and anything under 1000 it really struggles. It seems to me like it's running too lean or something. I had this same issue once when I disconnected the air hose to the BACV but I double checked and all the vacuum lines and air hoses look good. There's no problem starting the car back up after it dies so I don't think it's flooding.

I'm thinking it has to be one of three things...

1. The BACV that I got from the Junk Yard is bad.
2. That Green plug is supposed to be plugged in somewhere.
3. My newly cleaned injectors are making the mix leaner than it was before.

Thoughts please, and thank you.

 

Does anyone know what that green connector plugs into?

 

Off hand I don't remember where the green connector goes, but your problem sounds like un-metered air entering the engine. Make sure the AFM connector is attached and look for intake pipe air leaks after the AFM. Unconnected vacuum lines or leaks could also be the problem.

EDIT: What are the colors of the wires attached to the green connector? The BACV connector has one blue/green wire and one black/white wire.

 

yeah, That's why I was thinking maybe the BACV was bad but, I swapped my old one back in (it works it's just ugly) and I still have the same issue. I've tripple checked for unconnected vacuum lines (I replaced a bunch while I had it apart). I also made sure the intake is all connected up properly, the AFM is plugged in, and both the hoses to the air pump and the hose to the metal tube on the back of the TB are there. I'm starting to wonder if I screwed up and plugged the injectors in wrong...

The sleeving that covers the connector's wiring is still good so I don't know what color the wires are but, here is a pic of it's location.

 

Unfortunately, that pic doesn't help me. Peel back the sleeve a bit at the connector to determine the wire colors. Only way I can help.

If the wires are: one black and one green with white stripe the connector is for the water thermo sensor. [As I recall, the connector for that is green.] See the attached image and the green connector partly visible at the far right edge of the image.

 

hmm, that may be what it is. I don't have the electric fan though so, I don't have that sensor. I don't think the wiring for it is even long enough to reach to the front of the engine like that.

What about the vacuum lines running down from the front and back of the TB? Is there any chance that connecting those up out of order could cause an issue? They're all in the correct general area but I may have switched the positions of a couple where they connect to two nipples that are right next to each other.

Just to clarify, I really don't think I connected the injectors up wrong. I checked the wiring in my haines manual to make sure which one was which so, I'm trying to exhaust any other possibilities.

 

I think you are thinking about another sensor. My N/A S5 with conventional fan has the green connector and it attaches at the back of the water pump or front housing (I can't remember and it's too cold to go out and check).

See the attached pics. I struggled with these vacuum line connections after I failed to take note of them when disassembling the manifold. I'm pretty sure this is the correct matchup.


Best to check the wire colors at each injector connector with the wiring diagram. If you need that information look in the shop manual or get back to me and I will provide.

 

Ah, My vacuum lines are different than that... I found a pic posted by another user of an S4 N/A diagram.

https://www.rx7club.com/attachment.p...6&d=1148300104

 

Yeah, the diagram and pic I sent are for an S5. Sorry.

As far as the injector connections go, here's what the shop manual says. Each connector has two wires. One wire on all four connectors is Black with a Yellow stripe.

The color of the other wire for the following specific injectors is listed below:

Front/Primary=Light Green
Front/Secondary=Light Green with White stripe
Rear/Primary=Light Green with Black stripe
Rear/Secondary=Light Green with Red stripe

 

for confirmation that green plug wire is for the electric fan, well actually the plug for the switch/sensor that would be on the filler neck if you would have had an electric fan

 

Yeah, I checked the injector wiring before I plugged them up so, I'm relatively sure that's not the issue. I'm going to check the vacuum lines on my lunch break.

 

I checked my vac lines at lunch and they all check out ok.. I guess I'm going to have to tear it apart agin and recheck the wiring to the injectors.

 

with an S4 the injector harness splits. One side goes to the firewall side injectors, one long wire for secondary, and one short wire is for primary and this is the harness that has the the white connectors that extend past the injector wires The other side has 4 green connectors and the o2 sensor connector. the bac wire wll be longer than the injector wires. There will be three remaining green plugs, two short and one long. The short one with an off center notch will be water thermo and the remaining short one will be primary and you get the rest. You WILL need the water thermo plugged in regardless of fan option. that connector is a spade type on top of filler neck. I know this isnt a perfect response but i was just relaying what i see when i look at the harness. hope it helps. However after writing this i realized that i don' t think wiring is your prob, it sounds like vac leak all the way. use unlit propane torch to seach if you can, vac lines aren't the olny source of a vac leac.

 

If this is correct then I have the injectors connected wrong for sure. I have both of the primaries plugged into the rear half of the harness and the secondaries plugged into the front half. I'll tear it back apart and swap them around as soon as I can and update this thread for reference.

 

the connector for the fan is a ONE pin connector, the green TWO pin connector is for the water thermo sensor, which can cause some cold start / idle problems if not connected.

edit: didn't realize that is was an s4.... you may be correct in that case, I'm still learning s4's

 

I tried moving the injector wiring as described in several threads to:

short front connector --> front primary
long front --> front secondary
short rear --> rear primary
long rear --> rear secondary

Now I have an idle... kinda... a VERY rough idle that sounds like a two stroke. And I have no power at all now, it struggles to run up in the RPM's at WOT and I didn't try to force it.

Any more ideas?

 

No YOU are right I came back to correct myself (hate bad info and usually shut up unless positive) The green 2 pin connector DOES need to be hooked up to the thermo sensor at base of filler neck...the BLACK connector is for electric fan IF you had one, I brain farted because the black single connector is a green w/black stripe wire and the pic in my head made me answer
Hope this clears this part up anyhow...sorry

 

Allright, I double checked the injector wiring today and I had it right the first time so I put it back the way it was. I also plugged up the water thermo sensor but it made no difference. I checked the TPS and that's good too. I made a video of it running and put it on youtube. Every time it starts to die is when I'm trying to slowly remove my foot from the gas pedal.

http://www.youtube.com/watch?v=0tthfg0icWs

I need ideas ppl.

 

Ok... Can anyone tell me what injectors are firing at idle? Is it the primaries only or secondaries only or both? I'm assuming it's primaries only so, if one of my primaries is failing to fire perhaps that could cause this issue?

Also, The car previously had the wrong injectors installed in it. It had 3 low impedence 86-87 injectors and one 88 high impedence in it. Is is possible that the ECU has been damaged by the low impedence injectors? The only reason I wouldn't think that's the case is because the car ran fine before I pulled the other(wrong) injectors...