DOHC running off of a SOHC ecu??? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Skullavera · 12-10-2005, 01:51 PM

Hey all, I have a problem that I really don't understand. Before my car was running off of a re-pinned KA24DE harness with a SOHC ECU and mickey mouse wiring for the interior harness as well as the harness that plugs up by the battery.. I had an extra DOHC harness, threw it in, got the plugs for the mickey mouse jobs from the junkyard and soldered them back in. I connected the DOHC ecu and started the car. The engine was barely alive. I went ahead and re-adjusted the distributor because it was really off, I mean taking it out and putting it back in repositioned. Well I got the timing fine but the engine runs like shit. Erratic idle, super rich, and misfiring. I'm sure I wired everything correctly too.

Another problem I'm having is that the Coolant temp sensor on my engines, and most that I've seen, has a red connector and two pins. Well on this harness it has a black connector with three pins, like the connector for the MAF. I tried to wire my two pin connector but I couldn't figure it out. I also looked at the Hayes manual and the wiring diagrams but none mentioned this wiring setup for the coolant temp sensor. Any Ideas???

When I'm running the DOHC ecu, set it on Diagnostic mode, unplug the TPS, it runs well but just doesn't stay idling for more than two seconds. I disconnected the MAF and it runs ok while not on diagnostic mode. This has really stumped me because I can't figure this out. You know what the funny thing is to? I decided to just forget it and leave it for tomorrow. Just before I put everything away I decided to connect the SOHC ecu for the hell of it to see if it worked and it did! WTF??? It worked. All I had to do was set the timing again and reposition the distributor. Why is this happening? Any ideas? Thanks, any help is greatly appreciated. Please note that my car was running fine before I tried to put the DOHC ECU. BTW I have a 95 engine.

dct223 · 12-10-2005, 02:00 PM

what intake manifold are you using??

Skullavera · 12-11-2005, 03:08 AM

The 95 intake manifold. It's all stock. I also have a spare 95 engine in my garage for parts if I need them, but I just don't understand why it would run fine with the SOHC ecu and not the DOHC ecu.

darknightMR2 · 12-11-2005, 10:25 AM

i don't think a sohc ecu is meant to run w/ the dohc. you can use and dohc auto ecu to run a 5sp dohc, but not sohc>dohc. maybe thats your problem.

NismoSilvia270R · 12-11-2005, 10:40 AM

Quote:

Originally Posted by darknightMR2

i don't think a sohc ecu is meant to run w/ the dohc. you can use and dohc auto ecu to run a 5sp dohc, but not sohc>dohc. maybe thats your problem.

I think he said he had it running better with the sohc ecu.

did you swap in the dohc intake piping? idr what the plugs look like, but maybe you got the wrong maf in there.

i only suggest this cause the car sounds pretty frankensteined already

Skullavera · 12-12-2005, 03:10 AM

Everything is stock off of a 95 240sx, the engine and tranny. That's how I got the car. the MAF is from the SOHC. I've thought that this might be the problem but I've asked around and people tell me it should be fine. I'll do that though if it may help the problem. It makes sense to me to swap them but I just went off of other people's advice.

NismoSilvia270R · 12-13-2005, 10:18 PM

no shit. so you were actually running the dual cam on the sohc computer and mafs. wild ass guesses kick ass.

ill keep that in mind when i swap in the dual cam and get my daughterboard ready

12-10-2005, 01:51 PM	#1
Skullavera Zilvia FREAK! Join Date: Sep 2005 Location: City of Angels Posts: 1,327 Trader Rating: (1) Rides Gallery: Skullavera Feedback Score: 1 reviews	DOHC running off of a SOHC ecu??? Hey all, I have a problem that I really don't understand. Before my car was running off of a re-pinned KA24DE harness with a SOHC ECU and mickey mouse wiring for the interior harness as well as the harness that plugs up by the battery.. I had an extra DOHC harness, threw it in, got the plugs for the mickey mouse jobs from the junkyard and soldered them back in. I connected the DOHC ecu and started the car. The engine was barely alive. I went ahead and re-adjusted the distributor because it was really off, I mean taking it out and putting it back in repositioned. Well I got the timing fine but the engine runs like shit. Erratic idle, super rich, and misfiring. I'm sure I wired everything correctly too. Another problem I'm having is that the Coolant temp sensor on my engines, and most that I've seen, has a red connector and two pins. Well on this harness it has a black connector with three pins, like the connector for the MAF. I tried to wire my two pin connector but I couldn't figure it out. I also looked at the Hayes manual and the wiring diagrams but none mentioned this wiring setup for the coolant temp sensor. Any Ideas??? When I'm running the DOHC ecu, set it on Diagnostic mode, unplug the TPS, it runs well but just doesn't stay idling for more than two seconds. I disconnected the MAF and it runs ok while not on diagnostic mode. This has really stumped me because I can't figure this out. You know what the funny thing is to? I decided to just forget it and leave it for tomorrow. Just before I put everything away I decided to connect the SOHC ecu for the hell of it to see if it worked and it did! WTF??? It worked. All I had to do was set the timing again and reposition the distributor. Why is this happening? Any ideas? Thanks, any help is greatly appreciated. Please note that my car was running fine before I tried to put the DOHC ECU. BTW I have a 95 engine.

12-10-2005, 02:00 PM	#2
dct223 Nissanaholic! Join Date: Nov 2003 Location: hella NORCAL! Age: 39 Posts: 1,664 Trader Rating: (4) Feedback Score: 4 reviews	what intake manifold are you using?? __________________ Sfourteen

12-11-2005, 03:08 AM	#3
Skullavera Zilvia FREAK! Join Date: Sep 2005 Location: City of Angels Posts: 1,327 Trader Rating: (1) Rides Gallery: Skullavera Feedback Score: 1 reviews	The 95 intake manifold. It's all stock. I also have a spare 95 engine in my garage for parts if I need them, but I just don't understand why it would run fine with the SOHC ecu and not the DOHC ecu.

12-11-2005, 10:25 AM	#4
darknightMR2 Leaky Injector Join Date: Oct 2005 Location: princeton Posts: 54 Trader Rating: (0) Feedback Score: 0 reviews	i don't think a sohc ecu is meant to run w/ the dohc. you can use and dohc auto ecu to run a 5sp dohc, but not sohc>dohc. maybe thats your problem.

12-12-2005, 03:10 AM	#6
Skullavera Zilvia FREAK! Join Date: Sep 2005 Location: City of Angels Posts: 1,327 Trader Rating: (1) Rides Gallery: Skullavera Feedback Score: 1 reviews	Everything is stock off of a 95 240sx, the engine and tranny. That's how I got the car. the MAF is from the SOHC. I've thought that this might be the problem but I've asked around and people tell me it should be fine. I'll do that though if it may help the problem. It makes sense to me to swap them but I just went off of other people's advice.

12-13-2005, 10:18 PM	#7
NismoSilvia270R Zilvia Junkie Join Date: Jan 2004 Location: Clarksville Age: 39 Posts: 510 Trader Rating: (1) Feedback Score: 1 reviews	no shit. so you were actually running the dual cam on the sohc computer and mafs. wild ass guesses kick ass. ill keep that in mind when i swap in the dual cam and get my daughterboard ready