1997 240sx (Running Rich)

[ellocodiablo53]

Hello, I am new to this forum. I am on here a lot looking at the guides and tutorials, but I never got around to making an account.

Anyways, I recently bought a 1997 240sx with 13k miles on a rebuilt engine put in by nissan. The guy before me had a turbo setup on the KA, but blew it. (hence the rebuilt engine) When I bought the car, it was running extremely rich. He was running SR20 injectors, which were still on when I bought it. The car also sometimes seems to have a rev limiter on it at 2500 RPM. The car will drive fine, and all of the sudden the MAF voltage drops to 0.03V and won't rev past 2500 RPM. Then the voltage goes back up and it is fine.

I have gone back to stock injectors, I have changed the O2 sensor, I cleaned the MAF sensor, I checked the TPS sensor and it was fine. Also the "MAF circuit" seems to be tripping a code.

Please, if anyone could help me out? I love this car, but I hate to see it like this

[ellocodiablo53]

Anyone? Please?

[ellocodiablo53]

I figured posting on a forum with so much knowledge, someone would be smart enough to figure it out :/

[thoughtless]

aye man, usually if the car is limited around 2500 rpms its a bad MAF, just cleaning it wont fix it. try replacing it.

[obg3506]

I figured posting on a forum with so much knowledge, someone would be smart enough to figure it out :/

Saying things like this is a good way to have 10 times more veiws then replies!

[ellocodiablo53]

Oh, I meant no offense by it, if any was taken. It was more of stoking the forums ego, hoping to provoke a response :P

[ellocodiablo53]

Alright, I'll look into replacing the MAF soon. I'm hoping thats also why its been rich. Thank you. Any other ideas are welcome too.

[Second Shadow]

have gone back to stock injectors, I have changed the O2 sensor, I cleaned the MAF sensor, I checked the TPS sensor and it was fine. Also the "MAF circuit" seems to be tripping a code.

hold the phone man. I was about to agree with bad maf, (which it still might be) but then I noticed this. you can't just swap stock KA and SR injectors back and forth. they have different CC/min, and require the ECU to tuned. otherwise it's going to give the injectors the same pulse width, and with bigger injectors that means more gas, and with smaller injectors less gas.

the 2500RMP thing is still screaming bad maf, but until you know which injectors your car is tuned for it's still not gonna run right. and if it's tuned for SR(370cc/min) and you run KA injectors, you could blow the engine all over again. call the guy, or nissan(whoever knows) back and find out what it's tuned for, then use those injectors.

also, if it was tuned for SR injectors, it's possible he swapped the maf out at the same time(this also requires a new tune, so doing and injector upgrade and maf upgrade at the same time is very common). the most common maf upgrade is to a z32 maf. theres pics of both all over the place though so just google-pic both s14 and z32 maf and see what you've got. a few tuners(jwt for example) also use some other mafs but 90% chance it's s14 or z32.

[comatoseculture]

I agree. Bad MAF and you need knowledge on the ecu tune. You may have fixed the rich mixture by going back to ka injectors IF it's tuned for stock injectors, but still need a new MAF. If it's not the MAF itself it is possible the shielded wire has gotten chewed up/exposed/open. That will cause the intermittent 2500rpm bounce just like a completely faulty MAF.

[ellocodiablo53]

Thanks all, My car runs great now. I replaced the MAF and it runs like a beast. As I said before, he was running a turbo so he used the sr injectors without a tune for more fuel.

[thoughtless]

+1 for thoughtless..
kouki love

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