I recently bought a 1989 240sx but it has a KA24DE instead of the KA24E. The problem is that the guy I bought it out of told me that its a 95 engine but it still has the original harness and ECU. The engine runs ok as long as I don't press and hold the throttle all the way down for too long, because if I do, the fuel cuts off. I think that maybe I have the original 89 harness. The ECU serial I am running is A11-B13-G58 with the ECU number of "14". I also don't get any RPM or KPH readings (the cluster is JDM). I have another ECU with the following numbers, Serial: A11-B46-G75 and a ECU number of "EP". When I plugged up this ECU I got a RPM reading but the engine struggled to stay on and would shortly die after startup. I want to get a KA24DE harness and ECU but I'm not sure what the problem is. I can't seem to find the Engine Serial number either as it is not present where it should be. Is there any other way to identify my engine? Does it really make a difference? Will a KA24DE harness and ECU (say off of a 93) work regardless of the year it was manufactured? I need help!

 

I had that problem with my 90, which had the KA-E in it. Check your throttle position sensor for the fuel cut problem. Mine would get stuck around 4500rpms and power would just cut there, like a rev limiter. Replace the TPS and that might be your problem with that issue.

 

I don't think it's the TPS because I can redline the engine but I just can't hold the throttle down all the way for too long (well at least it feels as though I am redlining because my tach doesn't work!). It feels as though the car isn't getting enough fuel. If I am careful about how I press the throttle, it picks up fine. I think I'm just going to get a DOHC harness off of ebay along with a DOHC ECU. Maybe that will help my troubles. What do you all think?

 

Question: What makes you think that the harness is responsible for your problems? Sounds more to me like a bad swap by a noob

 

Don't be a *****.

If it seems like it isn't getting fuel, check the obvious things (fuel pump, pressure regular, et cetera) to make sure they're fuctioning properly. I'm assuming your motor is stock, so that should keep things simple for troubleshooting.

 

The fuel pump is brand new, and the pressure is fine. I've gone through the lines and everything is okay. Maybe the guy that sold it to me did do a bad swap but that's not the point. I'm just trying to enjoy my car to it's full potential, granted that I know I must go through these things to learn my car. The car ran like **** before and I've gotten it to run pretty well, it's just that fuel cut-off problem. Maybe she just doesn't like it ruff?? LOL. Anyways, let me ask you guys this question...what is the main difference between a SOHC and a DOHC harness? Are the plugs physically different? Are the wires and plugs so similar that a SOHC harness will support the KA24de? Because of the lack of knowledge on the harnesses, that is why I believe that that's where the problem may lie. The ECU is another thing that I believe is causing this. I may be mistaken, but if a SOHC ECU was used on a KA24de, wouldn't the engine be receiving a differnet fuel and air setting than from a DOHC ECU? Couldn't this cause the problem?