Swapped ECU and car won't start - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

RanciD · 10-31-2009, 09:48 PM

This is probably something easy to fix but I'm so frustrated with this thing I can't figure it out. Engine is a bone stock KA24DE in a 92 hatch. Everything ran perfectly fine until I swapped out the ECU for one with a daughterboard. The stock ECU is #28, the new one #24, and I put the stock rom from the 28 onto the new one prior to installing it. After I swapped it over the car will not start. Basically all I did was disconnect battery, unplug the old one and plug in the new one then reconnect the battery. It sounds like the fuel pump is priming and what I presume is the starter but the engine does absolutely nothing. I swapped the stock ECU back over and it still won't start. I checked every fuse and relay I could visually check that I could think of. Could I have blown the eccs relay (the green one to the far left I believe) and if so how do I check? Anything else it could be? Is there anything I'm supposed to do aside from just switching the big harness plug over to the new ECU?

Thanks for the help and sorry for the stupid question but searching didn't turn up anything like this.

SidewayZ-s14 · 10-31-2009, 09:54 PM

Are you sure that the #24 even worked?

RanciD · 10-31-2009, 10:01 PM

I was told it worked from the seller and told it was tested when I had the daughterboard installed on it but honestly, no, I'm not. If it didn't work to begin with what could I have blown by trying to start the car with it? The car still won't start now with the original (known working) ECU.

g6civcx · 10-31-2009, 10:06 PM

Oh boy, lots of things could be going on.

If you want to check the ECCS relay, or just about any relay for that matter, pull the relay, apply current and ground to the two small pins, and measure continuity across the big pins.

There is literally thousands of things it could be. Start with the basic. You have starter. Let's assume that's true. Do you have fuel, spark, or compression?

RanciD · 11-01-2009, 01:16 AM

Quote:

Originally Posted by g6civcx

Oh boy, lots of things could be going on.

If you want to check the ECCS relay, or just about any relay for that matter, pull the relay, apply current and ground to the two small pins, and measure continuity across the big pins.

There is literally thousands of things it could be. Start with the basic. You have starter. Let's assume that's true. Do you have fuel, spark, or compression?

Thanks for the relay checking tip, that appears to have been the problem. After a quick replacement the car started up with the stock ecu and feeling daring I plugged the modded one in, this time without disconnecting the battery (at someone else's suggestion) and it started right up with that one too. I'm not exactly sure what caused it but maybe it had something to do with the fact that I disconnected and reconnected the battery the first time.

At any rate thanks for the help!

10-31-2009, 09:48 PM	#1
RanciD Zilvia Junkie Join Date: Apr 2003 Location: Nashville Posts: 375 Trader Rating: (5) Feedback Score: 5 reviews	Swapped ECU and car won't start This is probably something easy to fix but I'm so frustrated with this thing I can't figure it out. Engine is a bone stock KA24DE in a 92 hatch. Everything ran perfectly fine until I swapped out the ECU for one with a daughterboard. The stock ECU is #28, the new one #24, and I put the stock rom from the 28 onto the new one prior to installing it. After I swapped it over the car will not start. Basically all I did was disconnect battery, unplug the old one and plug in the new one then reconnect the battery. It sounds like the fuel pump is priming and what I presume is the starter but the engine does absolutely nothing. I swapped the stock ECU back over and it still won't start. I checked every fuse and relay I could visually check that I could think of. Could I have blown the eccs relay (the green one to the far left I believe) and if so how do I check? Anything else it could be? Is there anything I'm supposed to do aside from just switching the big harness plug over to the new ECU? Thanks for the help and sorry for the stupid question but searching didn't turn up anything like this. __________________ '92 240SX, '07 G35S 6MT, '09 CBR600RR

10-31-2009, 10:01 PM	#3
RanciD Zilvia Junkie Join Date: Apr 2003 Location: Nashville Posts: 375 Trader Rating: (5) Feedback Score: 5 reviews	I was told it worked from the seller and told it was tested when I had the daughterboard installed on it but honestly, no, I'm not. If it didn't work to begin with what could I have blown by trying to start the car with it? The car still won't start now with the original (known working) ECU. __________________ '92 240SX, '07 G35S 6MT, '09 CBR600RR

10-31-2009, 09:54 PM	#2
SidewayZ-s14 BANNED Join Date: Nov 2007 Location: SoCal 714 Posts: 1,061 Trader Rating: (14) Feedback Score: 14 reviews	Are you sure that the #24 even worked?

10-31-2009, 10:06 PM	#4
g6civcx Post Whore! Join Date: Apr 2004 Location: Virginia, USA Posts: 5,764 Trader Rating: (5) Feedback Score: 5 reviews	Oh boy, lots of things could be going on. If you want to check the ECCS relay, or just about any relay for that matter, pull the relay, apply current and ground to the two small pins, and measure continuity across the big pins. There is literally thousands of things it could be. Start with the basic. You have starter. Let's assume that's true. Do you have fuel, spark, or compression?