S13 KA24DE stuck in "limp" mode.

Information on the naturally-aspirated KA24E and KA24DE engines.
dakotahchore
Posts: 4
Joined: Mon Sep 30, 2013 12:48 am
Car: 1972 datsun 510 ka24de

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Okay, so I have a Datsun 510 with a KA24DE swapped in. Everything was running well, but then I spun a rod bearing.

Fast forward, I fully rebuilt the motor with new everything. Mechanically, the motor is fine and idles really well regardless. No misfiring or bogging or dying. However, it seems to be stuck in the same mode I once experienced with an unplugged MAF... won't rev past 2500, just bounces off that like it's a rev limiter.

I read the codes, which hadn't been reset since the last motor went out.. Got a knock sensor error. Reset codes manually and after multiple starts and several minutes idling/revving still just getting 55 back when I test it. No error codes.

I have tried unplugging the MAF while running, running without the MAF, etc. Nothing changes. It idles fairly well then can't rev any higher than 2500 regardless if the MAF is plugged in or not. Also, I get a faint scent of fuel like the motor is running pretty rich. There are no changes when I unplug or plug the MAF while the car runs. For some reason, even unplugging or running without the MAF my ECU doesn't get any errors.

There's really only one thing I did in a moment of stupidity. My harness had already had many extra wires hanging off the ECU from the previous owner of said harness which I believe were all for the interior plug, yet it worked wonderfully. I cut and depinned these wires from the ECU plug and followed loose ends to pull any extra wire out of the harness. Not sure how or why I ended up cutting these wires out, but here's a photo of the only connector missing wiring in the whole harness.

Image

There's a Blue wire with a green stripe and a solid Green wire coming out of that plug.

Also, I removed this small green plug and the wiring for it thinking it was a consult port.. Just wasn't thinking at the time.
There's a green wire and a green wire with a blue stripe coming out
Image

I'm not positive if this will have anything to do with my problem though. Here's the thing, I can't recall if the wiring for those missing ends in the harness plug had anything to do with this little green plug; all I can see is they both have a solid green wire in common. Anyone know what this is for and if it would force limp mode, and if it has anything in common with the stray wires off that connector plug?



I checked the ECU thoroughly for damage or blown capacitors etc. Nothing.
It's not in Diag mode.
Buying a multimeter today to check MAF wiring..

Although one thing I'm confused about is my ECU isn't getting any error codes regardless of MAF plugged in or unplugged status.

Not really sure where to go from here. I searched and it doesn't seem anyone else has my issue.. the motor doesnt have any trouble starting or running or revving, it's just completely limited to 2500 regardless of my MAF status.


duece_ka24de
Posts: 2
Joined: Thu Jul 17, 2014 8:10 pm
Car: 91 pure stock ka24de 240sx coupe-red
93 hotcammed ka24de 240sx coupe-white

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try a different maf off a known running ka24de, just to b sure


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