Man I don't know what it is. It seems like I just cannot get rid of the wiring issue that seems to plague me. Every once in a while while idling it seems like my idle will get rough, my vac gauge will start to bounce a bit, and then I'll shake the wiring to the ECU and everything straightens out. I've soldered all the ground wires together. The only possible problem I could maybe see would be that I took the two wires that came off the ECU, soldered them to a larger gauge wire, then connected that wire to the other 3 ground wires and soldered it all together. I went through and soldered all my connections I made from the Z31 ECU/MAF swap. I soldered the connections that were in the engine bay that run to the MAF. I just can't figure it out. I'm wondering if I could benefit from just buying a new harness?

 

Where would you buy a "new" harness?

Sure your IAC is not fluttering?

 

I see they sell them on ebay. Or through http://oem-surplus.com/ I believe they quoted about $150 for a new harness.

I hope Mhinrichs checks this. I remember he bought a harness on ebay. I was wondering if it was for the ECU, or if it was primarily for the ignition system?

As for my IAC. I have that blocked off, along with the EGR, and VCV. Although I assume it could be possible that not having that causes some sort of slight issue for the ECU, as it's trying to do it's thing, thinking it's going to pulse the AAC and it's not there which might cause an issue. It just seems like when I go to shake the wiring it straightens out, but while sitting and idling, I can keep shaking on the wires and everything I never seem to come across wires that make any difference.

 

Nice.

What kind of voltage are you getting to your ECM? Is it dropping much? What is the resistance to ground? I don't think that the ECM draws a ton of power. If the wires are not getting hot, then I don't think going to a larger gauge is going to help. But, something sounds loose. Are the plug contacs nice and tight, and clean?

 

I'll need to go spray some electrical contact cleaner in there and try that out too. I was looking through my wiring today, and I couldn't tell which, but it seemed like it was down to two different spots. Either pin 24 which controls the O2 sensor or the ground wiring. Although I'm fairly certain the ground wiring is all right as I've no longer had the problems I used to when I had it factory connected, but interestingly enough I found on pin 24 wire black it went into an electrical taped section. I unwrapped it and found that from the factory Nissan had done another one of those crush style connectors just like they did with the ground wiring. The heatshrink tubing or whatever they used really was no longer tight around it. It didn't look corroded, but neither did my old ground wire connector.

Anyway I cut that out, soldered it to the shielded wire, heat shrunk it, then electrical taped it up. We'll see what happens.

 

If you think there is a problem with the o2 sensor wire try disconnecting it at the ECM, and at the o2 sensor to isolate the wire, and then check the wire and see if it has any continuity to ground. There should be none. It could also be an occasional short. Those are the fun ones to find, but if your multimeter beeps, you can clamp it to the pin of the wire, and wiggle the wire in various spots trying to make it beep. In the professional field, we call that a wiggle test. haha

 

you could also do a voltage drop test on it while it live to get a real sense of what is going on. its better than a ohm test, because even if the wire has one strand, it will show cont. but if you do a voltage drop on the same wire, it will show loss of complete power.

 

That is true, if the wire is actually broken. Which is a possibility. Wires get stretched, and break. I was not talking so much about a break in the wire. But resistance is bad when you are talking about the already low amperage output of a o2 sensor. The continuity test will not only tell you if there is a break in the wire, but will also tell you what the actual resistance through the wire is, and will let you know if there is a short anywhere.

It's a matter of preference I guess.

Whatever happens, don't stab the wires insulation to test. I see people do that all the time and it drives me nuts.
Seeing that you are soldering, and heat shrinking, I don't think you would do that.

 

Haha, I used to do that to test the wire. I would stab it, but then it would drive me nuts knowing that there was a tiny hole, then I'd electrical tape it, but then it would drive me nuts seeing that spot electrical taped and it just looked bad so I stopped doing that. I don't know if my multimeter beeps or not. It's a cheapo one I got on sale for $9.99 at the auto parts store. I've heard of that though the one that buzzes or something.

 

I need to go ride around with Nistune hooked up some more. One thing I've noticed is that sometimes when I'm sitting and idling the consult will flash the code real quick for the TPS switch. I'm not sure if that's an indicator of an issue. Really the car seems to have no problems when driving, just my idle every so often gets a little off. It's really not even too bad. Another thing I need to check is my injectors. Make sure they're all spraying properly.

 

If you do an ohm test and see resistance on a line is that a bad thing?

My multimeter doesn't beep and I'm not even sure if the setting I picked fits correctly. I just picked a setting that I had no idea what it was and was experimenting on just pieces of wire. I found a mode that seemed similar to the beeping thing where it would give me a straight reading when it was touching on two points of the same wire and where it would vary if it wasn't touching two points along the same wire.

Anyway I tried this method and setting the meter to Ohms. I tested this on the ground wires. I started at the plug to the first solder joint and found no change when connected and wiggling. Then I tested from the solder point out to the 3 different grounds in the engine bay. I kept it connected at the one solder point that joined the 3 different ground wires and went through one by one in the engine bay and wiggled the wires on both meter settings and the reading never changed as I wiggled away. So I finished this then it began to rain. So when I get a chance I'll just have to start going through and checking various wires. As I mentioned the Nistune Consult flashes the code for the TPS from time to time well idling, so I think that might be my next place to look. Maybe it's a faulty tps or my tps is adjusted improperly.