# New member, old truck, likely old problem



## mainer52 (Jun 17, 2011)

Hi - just got a truck from my dad who used it very lightly over the past few years. 1986.5 6cyl. Has been running rough for a while. I made some upgrades to the fuel/TBI set up: new fuel pump, new injectors, new fuel regulator, as well as new exhaust.

Funny thing. I started it back up after reassembly, and it ran rough for about ten mins. Had to stay on the accelerator to keep it running. Reved it up a few times, then it just smoothed right out and ran better than it has in years. Idle was steady, but it wouldn't rev past 2500 or so without cycling back down. I shut it down and went to work.

Got home tonight and back at it. Same thing - ran rough for a while with help. them smoothed out. This time I took it on the road for about 20 mins around the neighborhood. Ran great up to 2500 and no more without the cycling. Returned home, shut it down, and it ran like crap on the restart.

After reading stuff in the forum, it appears that it began to run well in "limp" mode, and the ECU reset after it was shut off. Any ideas about what might be going on? I've read a few posts on MAF issues, which might be a place to start. I also don't know where to look for the ECU to use the diagnostic mode. Any help?

Thanks.
Read more at New member with old truck, old problem - Nissan Forum


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## SPEEDO (Jun 9, 2003)

sounds like it is in "fail safe" ("limp") mode, start with pulling codes... should be a "how to" sticky at the top of the forum, if you not sure how to do it


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## saudade (Apr 10, 2010)

I've had this happen twice with mine. 

First time, it was one of the coils. Both plugs fire until about 2500 rpm, then one (I think the exh) shuts off. Coils are interchangeable and only take a few minutes to swap.

Next time was a broken splice buried in a harness that powers the injectors. You can check for voltage at the injector connectors. Here's the link:

http://www.nissanforums.com/hb-truck/160226-86-5-z24i-engine-cutout-solved.html

The ECU is under the seat, passenger side.


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