just bought a used TS ECU from an .org member. it's straight out of a '96 auto maxima - same exact car as mine. when i first plugged the new ECU in yesterday, it drove fantastic with no CEL. i was thrilled. later that day when i started it up again the CEL came on. i took it to nissan to diagnose and it turns out its throwing like 8 codes!! all for completely unrelated stuff! here's the codes its throwing:

1. fuel temp sensor (0180)
2. vc/v bypass/v (1441)
3. absol press sensor (0105)
4. purge cont/v & s/v (0443)
5. vent control valve (0446)
6. purge volume cont/v (1445)
7. map/baro sw sol/v (1105)
8. fpcm (1220)

but here's the thing... i had a weird starting problem with my car where it would die if i didn't give it gas when starting. since i put the new ECU in its totally solved! My IAC valve also made weird clicking noises and didn't function properly but now thats fixed too! the car seems to drive fine too but i'm scared to drive it hard or too much cause i feel like i'm hurting my baby.
so then i tried plugging the old ECU back in to see if anything would change and the same old starting problems and IACV problems happened again. so what am i suppost to do? was my old computer just screwed up and not throwing codes for things that were actually wrong? or is it something with the new computer? is it actually possible that all these things are truly wrong with my car? i'm more inclined to trust the new ECU because it seemed to fix a lot of various weird quirks my car had before. also, since the CEL is on, will that automatically make the car not run as well? like does the ECU hold back the full potential of the car on purpose until it's not throwing any codes? i'm so confused!!! please help!!! i want my car to run right!!!

 

oh yea also, the nissan guy said the codes that the CEL was throwing were "hard codes" which i guess means he couldn't reset them. idk if thats relevant but i wanna give you guys as much info about the situation as possible. thank you so much

 

Just wondering what does the Nissan guy mean "HARD CODE"? Usually the codes stored in ECU could be reset.

I totally agree with your opinions with old and new ECU. The old one could be screwd up long time ago and not respondable.

I would suggest this: Get a (cheap) OBD code scanner and reset the ECU. Or you can use the methods which can be found in sticky "how to" threads. Drive a while and see if codes come back. Try to find if if the codes are false or true.

Good luck!!!

 

it really can't be reset. i tried the manual reset by turning that screw and it didn't work and the guy at nissan said they couldn't be reset cause they were "hard codes." idk what that really means either but he used his little diagnosis computer and normally he said codes could be reset but these wouldn't. anyone wanna shed some light on this? i need help with this deperately

also, the codes that it's throwing are pretty serious codes. don't you think the car would not drive right or die or something if all that stuff was wrong with it?

 

your car can throw codes but it will depend on the code It will depend on what codes your throwing to know what will affect drivability or not. A code for air intake sensor wont affect drivability that much, you throw a code for bank 2 o2 sensor, you’ll fee it.

Its best to get what ever codes fixed, but codes are for something emission related, so your car will still function but maybe not at its peak.

Did the seller have a cali spec 96 and yours is fed spec?

 

You have a 95 fed spec which is nothing like any other 4th gen. Youre going to hve to live with the codes or do some major rewiring. You dont have most of those sensors.

 

omg thats a really good point. it didn't even occur to me that his car could be cali-spec! he shipped it from cali! ****!! assuming that may be the problem, what do i do now? is it gonna screw my car up to drive it with a cali-spec ecu? is it gonna run sluggish? what are the side-effects of that?

i just PM'ed him to ask him, but until then i need my car! i'm afraid to plug the old ecu back in because i think it's bad too!

 

Its going to be hard to get rid of those codes, you dont even have the plugs in your harness to try and fool it. to get rid of it you might have to go back to your 95 ecu. Or while you have that one in your car send your 95 ecu to TS to be "tuned" and when you get it back install back in your car and sell the 96 TS ecu off.

I just realized he's in a 95, and if he is a fed spec, he's genuinely throwing codes.
you can drive throwing those codes, there is nothing wrong with your car. The ecu is just looking for various sensors that Aren’t even suppost to be on your car. You can drive like normal, its performance might be questionable but definitely drivable and no reason to keep it in the driveway and catch the bus.

 

if it's the wrong ecu for fed-spec then why does it start the car better and stop that clicking in the IACV? could it be that my original ECU is bad also?

 

The codes you are throwing are for emission related devices that arent on your harness. The important components for starting your car are still present on your car, and would be regarless of any year fed spec/cali spec.

have you tried cleaning your IACV? they can build up a lot of carbon deposit.

there wasa tsb for the 95/96 ecu, but I've yeat to hear of someone having a bad ecu and having to replace it. Up till the time your removed your ecu it was still working correct? and starting the car?

 

Im pretty sure i have a fed spec '97. The only code I had was the p0136, since i had a 97. So maybe some emissions equipment that came standard on my 97 does not exist on your 95? But that also doesnt make sense, since the person I bought it off had a 96. Unless the emissions equipment that i have also came on some 96's?

 

fed spec 95s had very little emission equipment on the car. in 96 most of the emission equiment was present be it cali spec or fed spec.

some 95s dont have EGR or evap on them, just to name something.

 

95 fed spec has no boost sensor, uses mechanical EVAP, evap and EGR operate off the same solenoid. Apparently it doesnt have a temp sensor in the gas tank either. Cali spec 95 is basically the same as 96-98. In some 97's and all 98's the rear O2 sensor is different from the earlier 4th gens. In a nutshell some very minor things were changed from year to year.
1. fuel temp sensor (0180) <--- self explanitory
2. vc/v bypass/v (1441) <--- Unsure without looking it up
3. absol press sensor (0105) <--- MAP/Boost sensor
4. purge cont/v & s/v (0443) <--- Part of the EVAP
5. vent control valve (0446) <--- Part of the EVAP
6. purge volume cont/v (1445) <---- Part of the EVAP
7. map/baro sw sol/v (1105) <--- MAP/Boost sensor solenoid
8. fpcm (1220) <--- Unsure without looking it up

Most of these things are just for diagnostics and emmissions restrictions. If the car runs good dont worry about it.

 

so i should just ignore all these codes and just drive the car anyway? am i losing ANY power whatsoever? am i doing any sort of damage to anything? i'm very worried about stuff like that and i'm willing to pay the extra money to get the right thing if it will solve any problems. please let me know if there is ANY drawback at all to having the computer throw 8 codes with the wrong ECU. should i just send my stock 95 fed-spec ecu into technosquare to be reprogrammed? they said they would do it for $150. is that the way to go?

 

it was starting the car but very weakly. i had an ongoing electrical problem in my car for several months before i finally found out what it was to fix it. it was causing many electrical problems and shorting various things out which is why i sorta think my ECU went bad or took some serious abuse. the car still runs fine with the original stock ecu, but the starting sucks and the IACV makes weird clicking noises. when i put the new technosquare in, it solved both of those problems perfectly but it's throwing 8 codes. thats why i think my ECU might be bad. i even unplugged the technosquare ecu and plugged the stock one back in and it had the same starting problems and clicking problems

 

Yes if techno will reprogram your 95 ecu for $150 do it. I know your concerned but as we’ve stated, its fine to drive the car, your throwing codes for something your car doesn’t have anyway, so there is nothing to harm. Research the couple that JSutter mention would need further looking into. Keep the 96 TS in your car, send off the the 95. When you get it back switch back to the 95, clean your IACV, and sell off the 96 ecu

 

aright. thank you to eveyone who helped out with this problem. mdeezy you're awesome and and thanks to eveyone else. i dont know what i would do without u guys.