# Intermittent Poor Running - Fixed



## saudade (Apr 10, 2010)

Been a while since my last visit. Had a recent issue with my son's 86.5 D21 2WD I thought I'd share.

Problem was the engine would intermittently stumble, run rough and even cut out. Initially, it would restart right away, but it got progressively worse over the past few months. Naturally, it never acted up when I had it.

Finally, he limped home with it a week ago Sunday and it seemed to run on only 2 cyls. No power, engine rocking badly, then stalled, couldn't restart. After a bit of checking a few things, it cranked right up and ran smoothly, just like always. A bit of tugging here, and bit of wiggling there, still runs fine. Then suddenly, back to erratic, rocking, shaking. No amount of wiggling and tugging worked. Finally dies and won't restart. It would restart occasionally but still die out right away, even when I let it sit for hours to fully cool.

So begins the hunt. The short version is fuel pressure was fine. Compression fine. My inductive timing light showed regular spark when it did run, and showed erratic or no spark when it acted up. Since it was truly intermittent, didn't seem heat related, I figured I had bad connection somewhere. So I unplugged, cleaned and reconnected every connector I could find in the engine bay. Even replaced the rotor, cap and spark plugs (it needed it). Nothing!!

So now I'm worried. I had a fuel problem with it a few years ago that turned out to be a bad splice joint inside the main harness (you can search for my earlier post). That took months to find with help from this forum but at least it was driveable. I don't have months to trace all of the wiring which would require the truck remain "broken".

I figure , I guess I should check the codes to see if I get any. I didn't when I had the bad splice issue so I'm not hopeful. 

So I flip the bench forward to access the rear bolts. Hmm.. lot's of trash back here so I start pulling out the trash. Reaching under the bench I stick my had into a pile of Goo. Likely the remnants of Latte's, Boba's, Dr Pepper, and who knows what. While reaching around, I find the connectors to the ECU and give them a good shake. On a hunch, I turn the key. Like magic it springs to life. Runs great. Idles for 20 minutes with no stumble, hiccup or other sign of illness. Shut it down, let it cool off, starts right up. Drive around the block, all is well.

So off comes the bench, out comes the ECU, clean the connections, inspect the connectors, vacuum up remaining litter, left some goo behind for my son to clean. Put it all back together and it's been running fine ever since. I don't know if there was really any goo in any of the connectors (didn't see any), but cleaning them out seems to have done the trick.

I've done a lot of work on this over the years (been in the family since new). While, in the end, typically cheap and easy to fix, these electrical problems are the most aggravating.


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## Car guy (Mar 31, 2016)

Nice saudade. Good find. Thanks for sharing with everyone.


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## saudade (Apr 10, 2010)

Well, not so fast!! Apparently, it did it again. Crank but no start, then crank, start, die, then finally started and ran fine the rest of the way home. Gonna take the ECU out and carefully inspect each pin on both sides of the connectors. 

This is maddening.


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## rogoman (Dec 16, 2004)

Check out this posting, it might be your problem also:

FIX: erratic idle, low speed driveability, possibly more - Infamous Nissan - Hardbody / Frontier Forums


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## saudade (Apr 10, 2010)

Thanks for the link but I think I found it. It's still a bad connection at the ECU. However, upon closer inspection and using a brighter light I see one of the terminals is burned. Not sure how I missed it before. Here are pics of both sides.





















Seems like enough of the plastic housing on the harness end melted to prevent pulling the connector out to thoroughly clean it. I ran some fine emory paper on the terminal on the ecu side to shine it up a bit. Globbed in some dialectric grease. It starts and runs fine now. Btw, it was a Black wire with red tracer. There are sure a lot of them on that connector.


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## saudade (Apr 10, 2010)

Well, that pin connections appears to be #109 based on a chart I found from Nissan Nut. The schematics shows it's a ground. There are several of them on that connector. Perhaps if it still acts up I can internally jump one grnd to another. <sigh>


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## Car guy (Mar 31, 2016)

Great find Suad. Great link Rogo.


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## CMax03 (Jan 17, 2009)

I had a bad splice for the water temp sensor in the engine harness...That I fixed and it was doing that samething...The coolant ref was unknown by the ECU so it was hard to start when cold and drinking fuel like crazy...Good find bro!


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