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Discussion Starter · #1 · (Edited)
Some of you may have been following the saga in another thread.

Recapping, my Z24i has been cutting out around 2500 rpms. It ran fine up to that rpm "limit". I'll spare you the parts I've replaced, time and money I've spent. Turns out the issue was with a buried splice connector in the main harness that feeds power to the 2 injectors. For some unimaginable reason, Nissan engineers spliced the 2 power wires (one for each injector) down to one wire, then about 8 inches later, spliced it back to 2 wires. This second splice was completely corroded and came apart with the slightest tug. I clipped, stripped and crimped them back together and problem solved.

Here's a pic of the bad splice.


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Here's a pic of the other splice (sorry for the fuzziness).

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Discussion Starter · #2 ·
Thanks to all of you who've followed the thread, made suggestions and hung in there. A very special thanks to Nissanpartsdept for providing the "silver bullet" that led to the final solution.
 

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Discussion Starter · #6 · (Edited)
Due to a request for some details, I've decided to add to this a bit.

First, the harness in question comes through the firewall on the passenger side then splits. One split runs down the inner fender then splits again into several branches. The pic below shows the harness with a red line. The 2 red circles indicate the approx location of the splices.


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Next, there's more than one spice at the location on the right. When I fixed it originally, I only looked at the injector splice. A week later I sliced it up again to check the other splices. You can see what they looked like.

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So if you're going in there. Take the time to check them all out!
 

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Discussion Starter · #8 ·
Saudade, I am so glad I was able to shed some light on your problem. I guess sometimes us old farts can remember a few helpful tips lol.
As one old fart to another, I too occasionally have moments of genius that always surprises my teenage sons. :)

Glad to see you posted the pics for the future. Wish I had had some when I was explaining it to you.
I knew right where you were talking about. Hopefully the pics will help others.

Again, many thanks!!
 

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This is exactly what my truck is doing! I just got my truck, and it ran fine for a couple of months. A local mechanic confirmed that fuel is cutting out above a certain rev range. I bet this is going to solve it. Thanks in advance....
 

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2006 Pathfinder LE, 2003 Frontier SVE
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I hate those splice connectors! Best thing you can do is break out the soldering gun and solder all of those splice connectors for a better and more permanant repair!
 

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Discussion Starter · #12 ·
I hate those splice connectors! Best thing you can do is break out the soldering gun and solder all of those splice connectors for a better and more permanant repair!
Yep. I cut and re-spliced all of them with solder and heat shrink tubing.

You can see by the dates, this was over 2 years ago. Truck hasn't skipped a beat since.
 

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Ok, today I had some time to look at if, finally. I can't find any loose wires anywhere, all the plastic connection blocks look fine. Are the splice connectors inside the harness itself? In other words, do I need to slice open all the bundled wires to find them? I also found a few vacuum hoses that are missing in the area behind the throttle body.

To recap, the engine cuts out very suddenly and completely over a certain rev range. All cylinders stop firing as though the ignition was switched off. When the revs drop, the engine resumes. Revving in neutral, it sounds like you're gunning the engine. Under load the truck bucks.

I took it to a shop, and they confirmed I have spark throughout the rev range, and that it's fuel that is being cut off. THey were stumped, and replaced the fuel filter, which did not fix the problem.

When I found this thread, it seems to describe my symptoms exactly. But I'm a bit stuck. I have attached a few pics. Any ideas welcome.

 

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Discussion Starter · #15 · (Edited)
Yes, you have to cut open the bundle. Not sure why I don't see it on yours though. Is yours a D21 "HardBody"?

Someone did hack it up. I'd redo those splices.

Follow the harness out of the TB with the red,green white wires showing and see where it goes.
 

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Discussion Starter · #16 ·
If it cuts off, how did they verify spark across the "entire" rev range? Another cause of the same symptoms is a bad Intake ignition coil. Both intake and exhaust fire until about 2500rpm, then the exh cuts off and only the intake fires. If your int coil is bad, then it shuts off completely until the RPMs drop.

I had this happen too once before. Both coils are the same so you can swap them to see if that's it.
 

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Thanks Saudade, looks like we have the same truck...

Not sure how they verified the spark, not too impressed with the shop overall, won't go back. Here's the update. I sliced open the bundle coming off the throttle body, there were no splices. I found one splice nearer the firewall, but it was intact. I opened the plastic block junction that connects the wires that run to the injectors. I tugged on all the wires going into both sides of the block and they all seemed firm. I noticed there was a lot of engine oil inside the block. Weird, but it's close to a vent hose for the rocker cover on the passenger side, and that hose is cracked. That's the only way I can figure that oil might have gotten inside the connector block (?!?). Anyway, I wiped out as much of it as I could, put it all back together, and guess what? It's running great. I think it's probably a coincidence, and I bet this problem comes up again until I find the real solution. Maybe it was the oil, who knows? Running good now....
 
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