Does anyone know whats wrong with my spec v? rough idle...power loss

[SDspecV]

Hello Nico club. I need help. I have had my 03 spec v for about a year now and i love the car...when its runnin good. When I baught the car it had a slightly rough idle but it ran great and it didnt seem like a serious problem. Not too long ago i made the mistake of trying to clean my throttle body and ended up having to replace it...tps(tb). It took me a good while to get the problem fixd and durring that time the idle got worse. Now after the fix my idle still sux, sometimes its just a little high and sometimes it trys to stall out but its always rough. I have a huge power loss and the car makes some stupid buzzing/whining noise through first and second gear. O i have also replaced the MAF sensor like 4 or 5 times. two of which they sent me the wrong one. My car has thrown codes like multiple missfire, and intake air temp sensor high output. when i cleard them they didnt come back. now my car shows no codes. I took it to the dealer and they told me to replace the pcv valve and i did but no good. now the rpm's will jump around(between 1000 and 2000) while coasting to a stop wthout taking it outa gear(just pushing in clutch). Also my obdII says fuel system closed loop. My throttle pos is at 1% at idle...and my intake air temp says around 150 degrees...if any of that helps. I heard it could be something with the current my IAT sensor is sending to the TPS. I also heard it could be my cat. I have an aftermarket intake, header and exhaust. I have also noticed that this is a common problem with this car and if there is anyone out there that knows what it is or how I can fix it...without spending a fortune at Nissan...then PLEASE let me know.Thanks

[WorrGame13]

I had a 2001 SE that was doing a very similar thing, it was actually stalling though. It was the IAC valve. I needed a new MAF sensor too but you already replaced that. One of the guys I work with is a Nissan tech and when you change the IAC valve you have to relearn the idle. So you might be able to just relearn it but the dealer might charge you anyways if it doesn't work. I got a new IAC valve for about $150 or so. Hope this helps.

[SDspecV]

I put on a new iac...changed the whole tb. they relearned it after i put it on. The problem had gone away kinda...just a lil rough idle but today i changed my oil and the problem started again. Idle fluxn when i push in the clutch and coast. rougher idle and after idlen for a long time it will start to try and die....got any more ideas?

[ABNRML4U]

When was the last time you changed the plugs? How many miles are on the Nissan? What size engine do you have? The 2.5? Looks like It's something simple to my guess. I will have to ask around for more Info. O.K. Peace Out!

[sikkV]

uh oh..i had an episode of something like that 2 weeks ago... after parking my car..shut down by itself..i need to watch this topic...

[SDspecV]

I just hit 80k miles and i changed the spark plugs like a week after i made that first post...so not long ago. I think it might be the fuel pump. i heard there are a few issues with that on my year...03

[keelay]

Try the crankshaft position sensor. It will cause those problems and are known to go bad.

[davidpark9677]

Sounds like you had same problem with mine. I just posted a thread for 1.8 Nissan Sentra GXE. I've cleaned MAF and IAC valves and TB, and it still does it. I am going for EGR valves, but before I waste my time, does anybody think I might need to replace any parts? BTW it's an automatic.

[SpecDRacing]

Another member posted about the crank sensor. This would have been my first part checked. Its located on the back of the engine (near the cabin), low on the block. Those are prone to leak oil through the sensor and disturb the signal. Also, you already know you do NOT have an IAC valve as this is not necessary on a drive by wire car (the ECM angles the throttle just enough to keep it running). You need to have the codes pulled and post them on here. Your buzzing noise could very well be the timing chains. Not to scare you, but it's possible. Post the codes and I'll help you more.

[SDspecV]

I had a new crank sensor put in about a year ago. when I said iac before i ment to say tps. I dont have any codes shown right now but i have seen the multiple cylender missfire code before...when i clear it with my scanner it just goes away and doesnt come back. this has happnd twice in the past like 6 months. I may have a dirty airfilter...if that would cause any of these problems......also i was told that the iat sensor sends current to the tps and that may be the problem...what do you think about that?

[nametakennow]

I'm not quite sure what you mean by sends current. They certainly don't signal each other in any way. They may run off the same power circuit, but they'd certainly not be in series, so they don't have an effect on each other.