S13 KA24DE stuck in "limp" mode. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

dakotahchore · 09-28-2013, 10:57 PM

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.

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.

cotbu · 09-29-2013, 11:35 AM

1. Open the ecu and look and smell for something burnt or burning.
2. Make sure the diagnostic screw is in the correct position.
3. replace ecu and or check mafs and it's wiring

dakotahchore · 09-29-2013, 02:13 PM

Okay, I just remembered something I did in a moment of stupidity. I'm not positive if this will have anything to do with my problem though. I cut out this plug and the wiring for it thinking it was a consult port (not positive on this). The wiring ran all the way to what I believe is the AICV plug. Anyone know what this is for and if it would force limp mode?
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.

Here's said wires and the dead ends coming from a plug in my harness.

dakotahchore · 09-29-2013, 03:41 PM

So I'm stuck with this: There's a Blue wire with a green stripe and a solid Green wire coming out of that plug. I have a little green plug/relay? with a green wire and a green wire with a blue stripe coming out. I have ECU pins for solid green, green/blue, and blue/green. Any ideas anyone? Grasping at straws here if this has anything to do with my limp home issue in the first place.

09-28-2013, 10:57 PM	#1
dakotahchore Join Date: Mar 2013 Location: san diego Age: 27 Posts: 27 Trader Rating: (0) Feedback Score: 0 reviews	S13 KA24DE stuck in "limp" mode. 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. 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.

09-29-2013, 11:35 AM	#2
cotbu Post Whore! Join Date: Sep 2005 Location: SWFL Age: 47 Posts: 3,318 Trader Rating: (3) Feedback Score: 3 reviews	1. Open the ecu and look and smell for something burnt or burning. 2. Make sure the diagnostic screw is in the correct position. 3. replace ecu and or check mafs and it's wiring __________________ LoverTechnologies "Half Broken Things!"

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09-29-2013, 02:13 PM	#3
dakotahchore Join Date: Mar 2013 Location: san diego Age: 27 Posts: 27 Trader Rating: (0) Feedback Score: 0 reviews	Okay, I just remembered something I did in a moment of stupidity. I'm not positive if this will have anything to do with my problem though. I cut out this plug and the wiring for it thinking it was a consult port (not positive on this). The wiring ran all the way to what I believe is the AICV plug. Anyone know what this is for and if it would force limp mode? 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. Here's said wires and the dead ends coming from a plug in my harness.

09-29-2013, 03:41 PM	#4
dakotahchore Join Date: Mar 2013 Location: san diego Age: 27 Posts: 27 Trader Rating: (0) Feedback Score: 0 reviews	So I'm stuck with this: There's a Blue wire with a green stripe and a solid Green wire coming out of that plug. I have a little green plug/relay? with a green wire and a green wire with a blue stripe coming out. I have ECU pins for solid green, green/blue, and blue/green. Any ideas anyone? Grasping at straws here if this has anything to do with my limp home issue in the first place.