I have a 97 and am planning on upgrading the ecu. I got a 96 and decided to test it out to make sure that my car ran fine with it. The car ran fine, but after 2 days driving around with the 96 plugged in, my CEL came on. I know from reading that this is common, and codes always get thrown when you use a 96 in a 97. But my question is this: the codes that were thrown were the KS code, and the rear O2 sensor code, will this hurt my performance in any way even though the sensors are fine? Does the CEL actually matter, or will I only see poor performance if the codes are for real?

 

these codes are real, they are stored in the ECU. The ECU will default into base timing and will rely on the other two o2 sensors, despite the fact that the sensors are good. The ECU needs to recognise this also (no stored codes) in order for it to run properly.

 

So how did the people with 97s who got an upgraded 96 ecu deal with the codes? Will this hurt my performance to the point where getting the upgrade is a bad idea? Or, is there anyway to trick the ecu into getting rid of these codes itself?

 

i have a 95 auto in a 97 5speed with no code except the

0503 -front oxygen sensor

0504-auto transmission communication line (ecu not receving signal from tcm)

0804-which is another ecu not communicating with the transmission computer code.(doesnt affect the cars performance at all)

 

Clear the codes and see if they come back. Most likely you will get the rear O2 sensor again. The 95/96 use a 3 wire O2 sensor while the 97+ use a 4 wire O2 sensor. Someone on here did a pin out for the ECU and found the difference with a write up and explanation for resolving the rear heated O2. Just found it http://forums.maxima.org/showthread....44#post3390144
as for the KS code, a lot of people claim it to be a "ghost code." Meaning that it pops up with other codes. The truth is, the KS doesn't illuminate the CEL/MIL and is usually only discovered when another sensor has tripped the CEL/MIL. Quote from my FSM "the knock sensor does not have the two trip detection logic, and will not light up the MIL." Malfunction is detected when an excessively low or high voltage from the KS is entered to ECM. Possible causes are the harness or connectors as-well-as the KS itself. Hope this helps some, good luck.

Btw, yes, a bad KS will affect performance and fuel consumption.

 

Thanks, I will work on getting rid of the rear O2 sensor code, and maybe the KS code will go away too. Since the KS is ok as far as the 97 ecu is concerned, atleast I know that the sensor itself is functioning.

 

toss back in the 97 ecu and see if the codes come up, i can understand rear o2 sensor and wouldnt worry about that, but if the knock sensor is dead, replace it. then go ahead and send the ecu off for the upgrade.

 

I have driven with the 97 auto for a day and a half now, no codes have come up and the car feels fine.

 

How about if you are running a 99 ECU, sorry to hi-jack thread but I was just wondering if it is possible to switch with another ECU to remove the speed limiter?? Or could I just revert back to an older ECU to do that also? I don't wanna clip the wire and have a code to clear out all the time.

 

Dman832 have you actually checked for codes or are you saying the CEL/MIL hasn't come on with the 97 ECU. I bet you'll probably still find the KS. I'm really curious about this because I have the exact same issue and after thoroughly checking the KS circuit I've decided to replace the KS. Should get here today and go in ASAFP.

 

you know, I haven't. With the 97, there is no cel, but I didn't check the code. I will do it at lunch, and post the answer after I get back, shouldn't be too long.

 

Well, I checked the codes and here's what I got...I have the KS code, 0304, but also, now, I have an 0201, which is primary ignition signal. I think I know why I get the ignition signal code, and will try to fix it tomorrow...it has to do with the way my rpm switch is hooked up. But, I do still get the ks code, if I can get rid of the 0201, and the ks code is still there, I will have to replace the KS...damn!

 

Yeah, sorry to hear that. My KS just arrived now I've just gotta find some spare time.

 

ha ha, yeah, that is my other problem...no time for anything! I might not be upgrading my ecu now afterall though, atleast not for a while. I might be getting a SC, so if I do, the ecu upgrade can wait.

 

Yeah, that KS code has probably been there for a long time... Had nothing to do with running the 96 ecu in there. The rear O2 code will not harm performance though.

 

Oh and unless your thinking about doing a home brew SC, I suggest you get your @ss in gear. I am #3 on a 3 man list (they are made to order) and stillen said as soon as they get to #5 or 6 the SC will be discontinued.